Low Noise Sound card [Archive]

Ian Bell[_2_]

March 8th 10, 08:02 PM

Dirk Bruere at NeoPax wrote:
> On 08/03/2010 08:59, Ian Bell wrote:
>> Dirk Bruere at NeoPax wrote:
>>> On 07/03/2010 23:05, geoff wrote:
>>>> Dirk Bruere at NeoPax wrote:
>>>> ?
>>>>>
>>>>> The o/p of a low noise card (Auzentech), fed through a crap DSP (95dB
>>>>> s/n) into a 105dB amp. So most of the noise is coming from the DSP.
>>>>>
>>>>> I am getting rid of the DSP by using VST functions in the PC. Since I
>>>>> am using 64 bit processing I doubt it will add any significant noise.
>>>>> Which leaves the soundcard.
>>>>
>>>> You have the amp sitting there with the volume cranked up full all
>>>> the time
>>>> ?
>>>
>>> Embedded in the speaker.
>>> Volume is controlled from the PC soundcard.
>>>
>>>> I think you may be inventing not-existing problems, or attributing
>>>> another
>>>> problem to a soundcard spec that is only semi-relevant.
>>>>
>>>> Or the active speaker (or old soundcard) is unduly noisy,
>>>> over-optimistically specced, or faulty (ie not 105dB).
>>>
>>> When the amp alone is connected the noise is negligible.
>>> The DSP does make a very significant difference.
>>>
>>
>>
>> Then it is likely you have your level matching wrong. The solution may
>> be little more than a simple pad at the input to the amp.
>
> I'm pretty sure its correct.
> We have a 105dB amp being fed by 2 DSPs, each with a 95dB s/n
> That alone reduces the s/n ratio overall by 12dB
>
> My first task is to eliminate the DSP elements by replacing them with
> PCs running VST in 64 bit mode. I can't get rid of the amp, and so the
> weakest link then becomes the soundcard driving the amp.
>

You are assuming you want digital full scale to produce the full 800
watts with the listener pressing his ear to the cone. The threshold of
pain is 140dB SPL so 105dB below that is 35dB SPL - it is virtually
certain that the ambient noise in the room exceeds that level so you do
not need 105 dB of dynamic range or s/n.

Cheers

Ian

Mr.T

March 9th 10, 06:47 AM

"Dirk Bruere at NeoPax" > wrote in message
...
> >> I am getting rid of the DSP by using VST functions in the PC. Since I
> >> am using 64 bit processing I doubt it will add any significant noise.
> >> Which leaves the soundcard.
> >
> > You have the amp sitting there with the volume cranked up full all the
time
> > ?
>
>
> Volume is controlled from the PC soundcard.

So there is your problem!
Using the soundcard digital attenuator to reduce volume to an 800W power amp
is just asking for trouble.
Crank the soundcard to maximum output and turn down the power amp volume
controls if any, or use a separate input attenuator.

MrT.

Dirk Bruere at NeoPax

March 9th 10, 07:11 PM

On 08/03/2010 20:02, Ian Bell wrote:
> Dirk Bruere at NeoPax wrote:
>> On 08/03/2010 08:59, Ian Bell wrote:
>>> Dirk Bruere at NeoPax wrote:
>>>> On 07/03/2010 23:05, geoff wrote:
>>>>> Dirk Bruere at NeoPax wrote:
>>>>> ?
>>>>>>
>>>>>> The o/p of a low noise card (Auzentech), fed through a crap DSP (95dB
>>>>>> s/n) into a 105dB amp. So most of the noise is coming from the DSP.
>>>>>>
>>>>>> I am getting rid of the DSP by using VST functions in the PC. Since I
>>>>>> am using 64 bit processing I doubt it will add any significant noise.
>>>>>> Which leaves the soundcard.
>>>>>
>>>>> You have the amp sitting there with the volume cranked up full all
>>>>> the time
>>>>> ?
>>>>
>>>> Embedded in the speaker.
>>>> Volume is controlled from the PC soundcard.
>>>>
>>>>> I think you may be inventing not-existing problems, or attributing
>>>>> another
>>>>> problem to a soundcard spec that is only semi-relevant.
>>>>>
>>>>> Or the active speaker (or old soundcard) is unduly noisy,
>>>>> over-optimistically specced, or faulty (ie not 105dB).
>>>>
>>>> When the amp alone is connected the noise is negligible.
>>>> The DSP does make a very significant difference.
>>>>
>>>
>>>
>>> Then it is likely you have your level matching wrong. The solution may
>>> be little more than a simple pad at the input to the amp.
>>
>> I'm pretty sure its correct.
>> We have a 105dB amp being fed by 2 DSPs, each with a 95dB s/n
>> That alone reduces the s/n ratio overall by 12dB
>>
>> My first task is to eliminate the DSP elements by replacing them with
>> PCs running VST in 64 bit mode. I can't get rid of the amp, and so the
>> weakest link then becomes the soundcard driving the amp.
>>
>
> You are assuming you want digital full scale to produce the full 800
> watts with the listener pressing his ear to the cone. The threshold of
> pain is 140dB SPL so 105dB below that is 35dB SPL - it is virtually
> certain that the ambient noise in the room exceeds that level so you do
> not need 105 dB of dynamic range or s/n.

I do if its a demo room at a dealers.

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK
http://www.theconsensus.org/ - A UK political party
http://www.blogtalkradio.com/onetribe - Occult Talk Show

Dirk Bruere at NeoPax

March 9th 10, 07:14 PM

On 09/03/2010 06:47, Mr.T wrote:
> "Dirk Bruere at > wrote in message
> ...
>>>> I am getting rid of the DSP by using VST functions in the PC. Since I
>>>> am using 64 bit processing I doubt it will add any significant noise.
>>>> Which leaves the soundcard.
>>>
>>> You have the amp sitting there with the volume cranked up full all the
> time
>>> ?
>>
>>
>> Volume is controlled from the PC soundcard.
>
> So there is your problem!
> Using the soundcard digital attenuator to reduce volume to an 800W power amp
> is just asking for trouble.
> Crank the soundcard to maximum output and turn down the power amp volume
> controls if any, or use a separate input attenuator.

And ask the customer to go round each speaker and twiddle knob?
Or build a comms network to link each speaker.
Or remove the amps from the speakers and just have them in a huge pile
with hefty power cables everywhere.
Those would seem to be the alternatives, and we have ruled them out on
commercial grounds.

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK
http://www.theconsensus.org/ - A UK political party
http://www.blogtalkradio.com/onetribe - Occult Talk Show

Ian Bell[_2_]

March 9th 10, 11:25 PM

Dirk Bruere at NeoPax wrote:
> On 08/03/2010 20:02, Ian Bell wrote:
>> Dirk Bruere at NeoPax wrote:
>>> On 08/03/2010 08:59, Ian Bell wrote:
>>>> Dirk Bruere at NeoPax wrote:
>>>>> On 07/03/2010 23:05, geoff wrote:
>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>> ?
>>>>>>>
>>>>>>> The o/p of a low noise card (Auzentech), fed through a crap DSP
>>>>>>> (95dB
>>>>>>> s/n) into a 105dB amp. So most of the noise is coming from the DSP.
>>>>>>>
>>>>>>> I am getting rid of the DSP by using VST functions in the PC.
>>>>>>> Since I
>>>>>>> am using 64 bit processing I doubt it will add any significant
>>>>>>> noise.
>>>>>>> Which leaves the soundcard.
>>>>>>
>>>>>> You have the amp sitting there with the volume cranked up full all
>>>>>> the time
>>>>>> ?
>>>>>
>>>>> Embedded in the speaker.
>>>>> Volume is controlled from the PC soundcard.
>>>>>
>>>>>> I think you may be inventing not-existing problems, or attributing
>>>>>> another
>>>>>> problem to a soundcard spec that is only semi-relevant.
>>>>>>
>>>>>> Or the active speaker (or old soundcard) is unduly noisy,
>>>>>> over-optimistically specced, or faulty (ie not 105dB).
>>>>>
>>>>> When the amp alone is connected the noise is negligible.
>>>>> The DSP does make a very significant difference.
>>>>>
>>>>
>>>>
>>>> Then it is likely you have your level matching wrong. The solution may
>>>> be little more than a simple pad at the input to the amp.
>>>
>>> I'm pretty sure its correct.
>>> We have a 105dB amp being fed by 2 DSPs, each with a 95dB s/n
>>> That alone reduces the s/n ratio overall by 12dB
>>>
>>> My first task is to eliminate the DSP elements by replacing them with
>>> PCs running VST in 64 bit mode. I can't get rid of the amp, and so the
>>> weakest link then becomes the soundcard driving the amp.
>>>
>>
>> You are assuming you want digital full scale to produce the full 800
>> watts with the listener pressing his ear to the cone. The threshold of
>> pain is 140dB SPL so 105dB below that is 35dB SPL - it is virtually
>> certain that the ambient noise in the room exceeds that level so you do
>> not need 105 dB of dynamic range or s/n.
>
> I do if its a demo room at a dealers.
>

If it is a demo room at a dealers you should NOT be using a PC sound card.

Cheers

Ian

Dirk Bruere at NeoPax

March 9th 10, 11:59 PM

On 09/03/2010 23:25, Ian Bell wrote:
> Dirk Bruere at NeoPax wrote:
>> On 08/03/2010 20:02, Ian Bell wrote:
>>> Dirk Bruere at NeoPax wrote:
>>>> On 08/03/2010 08:59, Ian Bell wrote:
>>>>> Dirk Bruere at NeoPax wrote:
>>>>>> On 07/03/2010 23:05, geoff wrote:
>>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>> ?
>>>>>>>>
>>>>>>>> The o/p of a low noise card (Auzentech), fed through a crap DSP
>>>>>>>> (95dB
>>>>>>>> s/n) into a 105dB amp. So most of the noise is coming from the DSP.
>>>>>>>>
>>>>>>>> I am getting rid of the DSP by using VST functions in the PC.
>>>>>>>> Since I
>>>>>>>> am using 64 bit processing I doubt it will add any significant
>>>>>>>> noise.
>>>>>>>> Which leaves the soundcard.
>>>>>>>
>>>>>>> You have the amp sitting there with the volume cranked up full all
>>>>>>> the time
>>>>>>> ?
>>>>>>
>>>>>> Embedded in the speaker.
>>>>>> Volume is controlled from the PC soundcard.
>>>>>>
>>>>>>> I think you may be inventing not-existing problems, or attributing
>>>>>>> another
>>>>>>> problem to a soundcard spec that is only semi-relevant.
>>>>>>>
>>>>>>> Or the active speaker (or old soundcard) is unduly noisy,
>>>>>>> over-optimistically specced, or faulty (ie not 105dB).
>>>>>>
>>>>>> When the amp alone is connected the noise is negligible.
>>>>>> The DSP does make a very significant difference.
>>>>>>
>>>>>
>>>>>
>>>>> Then it is likely you have your level matching wrong. The solution may
>>>>> be little more than a simple pad at the input to the amp.
>>>>
>>>> I'm pretty sure its correct.
>>>> We have a 105dB amp being fed by 2 DSPs, each with a 95dB s/n
>>>> That alone reduces the s/n ratio overall by 12dB
>>>>
>>>> My first task is to eliminate the DSP elements by replacing them with
>>>> PCs running VST in 64 bit mode. I can't get rid of the amp, and so the
>>>> weakest link then becomes the soundcard driving the amp.
>>>>
>>>
>>> You are assuming you want digital full scale to produce the full 800
>>> watts with the listener pressing his ear to the cone. The threshold of
>>> pain is 140dB SPL so 105dB below that is 35dB SPL - it is virtually
>>> certain that the ambient noise in the room exceeds that level so you do
>>> not need 105 dB of dynamic range or s/n.
>>
>> I do if its a demo room at a dealers.
>>
>
>
> If it is a demo room at a dealers you should NOT be using a PC sound card.

So how do you suggest I get the "sound" out of a computer based AV
system? Most high end soundcards do better than 116dB s/n, with some
exceeding 120dB
http://www.elite*******s.com/index.php?option=com_content&task=view&id=689&Itemid=27&limitstart=4

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK
http://www.theconsensus.org/ - A UK political party
http://www.blogtalkradio.com/onetribe - Occult Talk Show

Geoff

March 10th 10, 01:40 AM

Dirk Bruere at NeoPax wrote:
>
> So how do you suggest I get the "sound" out of a computer based AV
> system? Most high end soundcards do better than 116dB s/n, with some
> exceeding 120dB

There will be no significant difference with a sound card that does 95dB
s/n.

I mean the average CD player cannot be hooked up to these speakers without
making undue noise ?

geoff

Dirk Bruere at NeoPax

March 10th 10, 03:11 AM

On 10/03/2010 01:40, geoff wrote:
> Dirk Bruere at NeoPax wrote:
>>
>> So how do you suggest I get the "sound" out of a computer based AV
>> system? Most high end soundcards do better than 116dB s/n, with some
>> exceeding 120dB
>
>
> There will be no significant difference with a sound card that does 95dB
> s/n.
>
> I mean the average CD player cannot be hooked up to these speakers without
> making undue noise ?

The source is a PC playing BluRay, as a best case.

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK
http://www.theconsensus.org/ - A UK political party
http://www.blogtalkradio.com/onetribe - Occult Talk Show

Mr.T

March 10th 10, 05:00 AM

"Dirk Bruere at NeoPax" > wrote in message
...
> >> Volume is controlled from the PC soundcard.
> >
> > So there is your problem!
> > Using the soundcard digital attenuator to reduce volume to an 800W power
amp
> > is just asking for trouble.
> > Crank the soundcard to maximum output and turn down the power amp volume
> > controls if any, or use a separate input attenuator.
>
> And ask the customer to go round each speaker and twiddle knob?
> Or build a comms network to link each speaker.
> Or remove the amps from the speakers and just have them in a huge pile
> with hefty power cables everywhere.
> Those would seem to be the alternatives, and we have ruled them out on
> commercial grounds.

So use a proper attenuator between soundcard output and amplifier input. I
fail to see how that is any more difficult than using the soundcard digital
attenuator which WILL reduce your S/N ratio at it's output, whilst an analog
attenuator will reduce both signal and noise keeping the S/N ratio the same.

But probably the best option is to hire someone that actually knows what
they are doing to set it up for you.

MrT.

Ian Bell[_2_]

March 10th 10, 09:46 AM

Dirk Bruere at NeoPax wrote:
> On 09/03/2010 23:25, Ian Bell wrote:
>> Dirk Bruere at NeoPax wrote:
>>> On 08/03/2010 20:02, Ian Bell wrote:
>>>> Dirk Bruere at NeoPax wrote:
>>>>> On 08/03/2010 08:59, Ian Bell wrote:
>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>> On 07/03/2010 23:05, geoff wrote:
>>>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>>> ?
>>>>>>>>>
>>>>>>>>> The o/p of a low noise card (Auzentech), fed through a crap DSP
>>>>>>>>> (95dB
>>>>>>>>> s/n) into a 105dB amp. So most of the noise is coming from the
>>>>>>>>> DSP.
>>>>>>>>>
>>>>>>>>> I am getting rid of the DSP by using VST functions in the PC.
>>>>>>>>> Since I
>>>>>>>>> am using 64 bit processing I doubt it will add any significant
>>>>>>>>> noise.
>>>>>>>>> Which leaves the soundcard.
>>>>>>>>
>>>>>>>> You have the amp sitting there with the volume cranked up full all
>>>>>>>> the time
>>>>>>>> ?
>>>>>>>
>>>>>>> Embedded in the speaker.
>>>>>>> Volume is controlled from the PC soundcard.
>>>>>>>
>>>>>>>> I think you may be inventing not-existing problems, or attributing
>>>>>>>> another
>>>>>>>> problem to a soundcard spec that is only semi-relevant.
>>>>>>>>
>>>>>>>> Or the active speaker (or old soundcard) is unduly noisy,
>>>>>>>> over-optimistically specced, or faulty (ie not 105dB).
>>>>>>>
>>>>>>> When the amp alone is connected the noise is negligible.
>>>>>>> The DSP does make a very significant difference.
>>>>>>>
>>>>>>
>>>>>>
>>>>>> Then it is likely you have your level matching wrong. The solution
>>>>>> may
>>>>>> be little more than a simple pad at the input to the amp.
>>>>>
>>>>> I'm pretty sure its correct.
>>>>> We have a 105dB amp being fed by 2 DSPs, each with a 95dB s/n
>>>>> That alone reduces the s/n ratio overall by 12dB
>>>>>
>>>>> My first task is to eliminate the DSP elements by replacing them with
>>>>> PCs running VST in 64 bit mode. I can't get rid of the amp, and so the
>>>>> weakest link then becomes the soundcard driving the amp.
>>>>>
>>>>
>>>> You are assuming you want digital full scale to produce the full 800
>>>> watts with the listener pressing his ear to the cone. The threshold of
>>>> pain is 140dB SPL so 105dB below that is 35dB SPL - it is virtually
>>>> certain that the ambient noise in the room exceeds that level so you do
>>>> not need 105 dB of dynamic range or s/n.
>>>
>>> I do if its a demo room at a dealers.
>>>
>>
>>
>> If it is a demo room at a dealers you should NOT be using a PC sound
>> card.
>
> So how do you suggest I get the "sound" out of a computer based AV
> system? Most high end soundcards do better than 116dB s/n, with some
> exceeding 120dB
> http://www.elite*******s.com/index.php?option=com_content&task=view&id=689&Itemid=27&limitstart=4
>
>

Come out digitally and use a quality external DtoA.

Cheers

Ian

Dirk Bruere at NeoPax

March 10th 10, 12:17 PM

On 10/03/2010 09:46, Ian Bell wrote:
> Dirk Bruere at NeoPax wrote:
>> On 09/03/2010 23:25, Ian Bell wrote:
>>> Dirk Bruere at NeoPax wrote:
>>>> On 08/03/2010 20:02, Ian Bell wrote:
>>>>> Dirk Bruere at NeoPax wrote:
>>>>>> On 08/03/2010 08:59, Ian Bell wrote:
>>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>>> On 07/03/2010 23:05, geoff wrote:
>>>>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>>>> ?
>>>>>>>>>>
>>>>>>>>>> The o/p of a low noise card (Auzentech), fed through a crap DSP
>>>>>>>>>> (95dB
>>>>>>>>>> s/n) into a 105dB amp. So most of the noise is coming from the
>>>>>>>>>> DSP.
>>>>>>>>>>
>>>>>>>>>> I am getting rid of the DSP by using VST functions in the PC.
>>>>>>>>>> Since I
>>>>>>>>>> am using 64 bit processing I doubt it will add any significant
>>>>>>>>>> noise.
>>>>>>>>>> Which leaves the soundcard.
>>>>>>>>>
>>>>>>>>> You have the amp sitting there with the volume cranked up full all
>>>>>>>>> the time
>>>>>>>>> ?
>>>>>>>>
>>>>>>>> Embedded in the speaker.
>>>>>>>> Volume is controlled from the PC soundcard.
>>>>>>>>
>>>>>>>>> I think you may be inventing not-existing problems, or attributing
>>>>>>>>> another
>>>>>>>>> problem to a soundcard spec that is only semi-relevant.
>>>>>>>>>
>>>>>>>>> Or the active speaker (or old soundcard) is unduly noisy,
>>>>>>>>> over-optimistically specced, or faulty (ie not 105dB).
>>>>>>>>
>>>>>>>> When the amp alone is connected the noise is negligible.
>>>>>>>> The DSP does make a very significant difference.
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Then it is likely you have your level matching wrong. The
>>>>>>> solution may
>>>>>>> be little more than a simple pad at the input to the amp.
>>>>>>
>>>>>> I'm pretty sure its correct.
>>>>>> We have a 105dB amp being fed by 2 DSPs, each with a 95dB s/n
>>>>>> That alone reduces the s/n ratio overall by 12dB
>>>>>>
>>>>>> My first task is to eliminate the DSP elements by replacing them with
>>>>>> PCs running VST in 64 bit mode. I can't get rid of the amp, and so
>>>>>> the
>>>>>> weakest link then becomes the soundcard driving the amp.
>>>>>>
>>>>>
>>>>> You are assuming you want digital full scale to produce the full 800
>>>>> watts with the listener pressing his ear to the cone. The threshold of
>>>>> pain is 140dB SPL so 105dB below that is 35dB SPL - it is virtually
>>>>> certain that the ambient noise in the room exceeds that level so
>>>>> you do
>>>>> not need 105 dB of dynamic range or s/n.
>>>>
>>>> I do if its a demo room at a dealers.
>>>>
>>>
>>>
>>> If it is a demo room at a dealers you should NOT be using a PC sound
>>> card.
>>
>> So how do you suggest I get the "sound" out of a computer based AV
>> system? Most high end soundcards do better than 116dB s/n, with some
>> exceeding 120dB
>> http://www.elite*******s.com/index.php?option=com_content&task=view&id=689&Itemid=27&limitstart=4
>>
>>
>
> Come out digitally and use a quality external DtoA.

Any suggestions as to one that will match an Auzentech card at around
the same price?

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK
http://www.blogtalkradio.com/onetribe - Occult Talk Show

Mr.T

March 10th 10, 12:17 PM

"Ian Bell" > wrote in message
...
> > So how do you suggest I get the "sound" out of a computer based AV
> > system? Most high end soundcards do better than 116dB s/n, with some
> > exceeding 120dB
> >
http://www.elite*******s.com/index.php?option=com_content&task=view&id=689&I
temid=27&limitstart=4
> >
> >
>
> Come out digitally and use a quality external DtoA.

You know of one that exceeds 120dB then?

MrT.

Arny Krueger

March 10th 10, 12:27 PM

"Mr.T" <MrT@home> wrote in message
u...
>
> "Dirk Bruere at NeoPax" > wrote in message
> ...
>> >> Volume is controlled from the PC soundcard.
>
>> > So there is your problem!
>> > Using the soundcard digital attenuator to reduce volume to an 800W
>> > power amp
>> > is just asking for trouble.
>> > Crank the soundcard to maximum output and turn down the power amp
>> > volume
>> > controls if any, or use a separate input attenuator.

>> And ask the customer to go round each speaker and twiddle knob?
>> Or build a comms network to link each speaker.
>> Or remove the amps from the speakers and just have them in a huge pile
>> with hefty power cables everywhere.
>> Those would seem to be the alternatives, and we have ruled them out on
>> commercial grounds.

> So use a proper attenuator between soundcard output and amplifier input.

It would have to attenuate between 6 and 8 channels, if I understand this
application correctly. Got an off-the-shelf part in mind?

> I fail to see how that is any more difficult than using the soundcard
> digital
> attenuator which WILL reduce your S/N ratio at it's output, whilst an
> analog
> attenuator will reduce both signal and noise keeping the S/N ratio the
> same.

Not necessarily.

Both the sound card and the amplifier are properly modeled as a fixed noise
source and a variable signal. Therefore, as you turn the signal down, the
SNR of both the sound card and the amplifier will get worse because there is
less signal but the same amount of noise.

Ian Bell[_2_]

March 10th 10, 02:08 PM

Dirk Bruere at NeoPax wrote:
> On 10/03/2010 09:46, Ian Bell wrote:
>> Dirk Bruere at NeoPax wrote:
>>> On 09/03/2010 23:25, Ian Bell wrote:
>>>> Dirk Bruere at NeoPax wrote:
>>>>> On 08/03/2010 20:02, Ian Bell wrote:
>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>> On 08/03/2010 08:59, Ian Bell wrote:
>>>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>>>> On 07/03/2010 23:05, geoff wrote:
>>>>>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>>>>> ?
>>>>>>>>>>>
>>>>>>>>>>> The o/p of a low noise card (Auzentech), fed through a crap DSP
>>>>>>>>>>> (95dB
>>>>>>>>>>> s/n) into a 105dB amp. So most of the noise is coming from the
>>>>>>>>>>> DSP.
>>>>>>>>>>>
>>>>>>>>>>> I am getting rid of the DSP by using VST functions in the PC.
>>>>>>>>>>> Since I
>>>>>>>>>>> am using 64 bit processing I doubt it will add any significant
>>>>>>>>>>> noise.
>>>>>>>>>>> Which leaves the soundcard.
>>>>>>>>>>
>>>>>>>>>> You have the amp sitting there with the volume cranked up full
>>>>>>>>>> all
>>>>>>>>>> the time
>>>>>>>>>> ?
>>>>>>>>>
>>>>>>>>> Embedded in the speaker.
>>>>>>>>> Volume is controlled from the PC soundcard.
>>>>>>>>>
>>>>>>>>>> I think you may be inventing not-existing problems, or
>>>>>>>>>> attributing
>>>>>>>>>> another
>>>>>>>>>> problem to a soundcard spec that is only semi-relevant.
>>>>>>>>>>
>>>>>>>>>> Or the active speaker (or old soundcard) is unduly noisy,
>>>>>>>>>> over-optimistically specced, or faulty (ie not 105dB).
>>>>>>>>>
>>>>>>>>> When the amp alone is connected the noise is negligible.
>>>>>>>>> The DSP does make a very significant difference.
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Then it is likely you have your level matching wrong. The
>>>>>>>> solution may
>>>>>>>> be little more than a simple pad at the input to the amp.
>>>>>>>
>>>>>>> I'm pretty sure its correct.
>>>>>>> We have a 105dB amp being fed by 2 DSPs, each with a 95dB s/n
>>>>>>> That alone reduces the s/n ratio overall by 12dB
>>>>>>>
>>>>>>> My first task is to eliminate the DSP elements by replacing them
>>>>>>> with
>>>>>>> PCs running VST in 64 bit mode. I can't get rid of the amp, and so
>>>>>>> the
>>>>>>> weakest link then becomes the soundcard driving the amp.
>>>>>>>
>>>>>>
>>>>>> You are assuming you want digital full scale to produce the full 800
>>>>>> watts with the listener pressing his ear to the cone. The
>>>>>> threshold of
>>>>>> pain is 140dB SPL so 105dB below that is 35dB SPL - it is virtually
>>>>>> certain that the ambient noise in the room exceeds that level so
>>>>>> you do
>>>>>> not need 105 dB of dynamic range or s/n.
>>>>>
>>>>> I do if its a demo room at a dealers.
>>>>>
>>>>
>>>>
>>>> If it is a demo room at a dealers you should NOT be using a PC sound
>>>> card.
>>>
>>> So how do you suggest I get the "sound" out of a computer based AV
>>> system? Most high end soundcards do better than 116dB s/n, with some
>>> exceeding 120dB
>>> http://www.elite*******s.com/index.php?option=com_content&task=view&id=689&Itemid=27&limitstart=4

>>>
>>>
>>>
>>
>> Come out digitally and use a quality external DtoA.
>
> Any suggestions as to one that will match an Auzentech card at around
> the same price?
>

Not off hand. Google is your friend.

Cheers

ian

Ian Bell[_2_]

March 10th 10, 02:09 PM

Mr.T wrote:
> "Ian Bell" > wrote in message
> ...
>>> So how do you suggest I get the "sound" out of a computer based AV
>>> system? Most high end soundcards do better than 116dB s/n, with some
>>> exceeding 120dB
>>>
> http://www.elite*******s.com/index.php?option=com_content&task=view&id=689&I
> temid=27&limitstart=4
>>>
>> Come out digitally and use a quality external DtoA.
>
> You know of one that exceeds 120dB then?
>
> MrT.
>
>

If you REALLY can achieve 120dB INSIDE a PC then you can certainly
achieve it outside.

Cheers

Ian

Arny Krueger

March 10th 10, 02:40 PM

"Ian Bell" > wrote in message
...

> Mr.T wrote:
>> "Ian Bell" > wrote in message
>> ...
>>>> So how do you suggest I get the "sound" out of a computer based AV
>>>> system? Most high end soundcards do better than 116dB s/n, with some
>>>> exceeding 120dB
>>>>
>> http://www.elite*******s.com/index.php?option=com_content&task=view&id=689&I
>> temid=27&limitstart=4
>>>>
>>> Come out digitally and use a quality external DtoA.
>>
>> You know of one that exceeds 120dB then?
>>
>> MrT.

> If you REALLY can achieve 120dB INSIDE a PC then you can certainly achieve
> it outside.

Ian, for a guy who is so bright with tubes, you surely have missed the boat
with PCs and ICs.

The limit to dynamic range in audio interfaces is generally the IC chips.
Where the chips are sited matters, but *all* converter chips by definition
are sited intimately with logic and clock signals, just like the ones in a
PC. Maybe you need to look at some converter data sheets, if you didn't know
that converter chips have clock and logic lines running right up to them and
going inside where they are even closer to the precious analog signals.

The business of siting converter chips and still obtaining good dynamic
range is called "Mixed-signal design". Is it a coincidence that Mixed-signal
design generally post dates tubes? You should at least show the art of
mixed-signal design a little respect, even if you don't want to understand
it.

Bottom line Ian, yourself no favors by ranting and raving against situations
that are known by many of us to be solved problems. OTOH, what should we
expect from someone who doesn't get "sand state"? ;-)

Arny Krueger

March 10th 10, 04:51 PM

"Mr.T" <MrT@home> wrote in message
...
>
> "Ian Bell" > wrote in message
> ...
>> > So how do you suggest I get the "sound" out of a computer based AV
>> > system? Most high end soundcards do better than 116dB s/n, with some
>> > exceeding 120dB
>> >
> http://www.elite*******s.com/index.php?option=com_content&task=view&id=689&I
> temid=27&limitstart=4

Look like pretty much flawed tests.

Dirk Bruere at NeoPax

March 10th 10, 06:32 PM

On 10/03/2010 14:08, Ian Bell wrote:
> Dirk Bruere at NeoPax wrote:
>> On 10/03/2010 09:46, Ian Bell wrote:
>>> Dirk Bruere at NeoPax wrote:
>>>> On 09/03/2010 23:25, Ian Bell wrote:
>>>>> Dirk Bruere at NeoPax wrote:
>>>>>> On 08/03/2010 20:02, Ian Bell wrote:
>>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>>> On 08/03/2010 08:59, Ian Bell wrote:
>>>>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>>>>> On 07/03/2010 23:05, geoff wrote:
>>>>>>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>>>>>> ?
>>>>>>>>>>>>
>>>>>>>>>>>> The o/p of a low noise card (Auzentech), fed through a crap DSP
>>>>>>>>>>>> (95dB
>>>>>>>>>>>> s/n) into a 105dB amp. So most of the noise is coming from the
>>>>>>>>>>>> DSP.
>>>>>>>>>>>>
>>>>>>>>>>>> I am getting rid of the DSP by using VST functions in the PC.
>>>>>>>>>>>> Since I
>>>>>>>>>>>> am using 64 bit processing I doubt it will add any significant
>>>>>>>>>>>> noise.
>>>>>>>>>>>> Which leaves the soundcard.
>>>>>>>>>>>
>>>>>>>>>>> You have the amp sitting there with the volume cranked up
>>>>>>>>>>> full all
>>>>>>>>>>> the time
>>>>>>>>>>> ?
>>>>>>>>>>
>>>>>>>>>> Embedded in the speaker.
>>>>>>>>>> Volume is controlled from the PC soundcard.
>>>>>>>>>>
>>>>>>>>>>> I think you may be inventing not-existing problems, or
>>>>>>>>>>> attributing
>>>>>>>>>>> another
>>>>>>>>>>> problem to a soundcard spec that is only semi-relevant.
>>>>>>>>>>>
>>>>>>>>>>> Or the active speaker (or old soundcard) is unduly noisy,
>>>>>>>>>>> over-optimistically specced, or faulty (ie not 105dB).
>>>>>>>>>>
>>>>>>>>>> When the amp alone is connected the noise is negligible.
>>>>>>>>>> The DSP does make a very significant difference.
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Then it is likely you have your level matching wrong. The
>>>>>>>>> solution may
>>>>>>>>> be little more than a simple pad at the input to the amp.
>>>>>>>>
>>>>>>>> I'm pretty sure its correct.
>>>>>>>> We have a 105dB amp being fed by 2 DSPs, each with a 95dB s/n
>>>>>>>> That alone reduces the s/n ratio overall by 12dB
>>>>>>>>
>>>>>>>> My first task is to eliminate the DSP elements by replacing them
>>>>>>>> with
>>>>>>>> PCs running VST in 64 bit mode. I can't get rid of the amp, and so
>>>>>>>> the
>>>>>>>> weakest link then becomes the soundcard driving the amp.
>>>>>>>>
>>>>>>>
>>>>>>> You are assuming you want digital full scale to produce the full 800
>>>>>>> watts with the listener pressing his ear to the cone. The
>>>>>>> threshold of
>>>>>>> pain is 140dB SPL so 105dB below that is 35dB SPL - it is virtually
>>>>>>> certain that the ambient noise in the room exceeds that level so
>>>>>>> you do
>>>>>>> not need 105 dB of dynamic range or s/n.
>>>>>>
>>>>>> I do if its a demo room at a dealers.
>>>>>>
>>>>>
>>>>>
>>>>> If it is a demo room at a dealers you should NOT be using a PC sound
>>>>> card.
>>>>
>>>> So how do you suggest I get the "sound" out of a computer based AV
>>>> system? Most high end soundcards do better than 116dB s/n, with some
>>>> exceeding 120dB
>>>> http://www.elite*******s.com/index.php?option=com_content&task=view&id=689&Itemid=27&limitstart=4
>
>
>>>>
>>>>
>>>>
>>>
>>> Come out digitally and use a quality external DtoA.
>>
>> Any suggestions as to one that will match an Auzentech card at around
>> the same price?
>>
>
>
> Not off hand. Google is your friend.

Well, some "good" ones are to be had at around $600 it seems.
In which case, a dedicated PC and sound card will certainly be cheaper
and may well match it in quality.

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK
http://www.blogtalkradio.com/onetribe - Occult Talk Show

Ian Bell[_2_]

March 10th 10, 09:44 PM

Arny Krueger wrote:
> "Ian Bell" > wrote in message
> ...
>
>> Mr.T wrote:
>>> "Ian Bell" > wrote in message
>>> ...
>>>>> So how do you suggest I get the "sound" out of a computer based AV
>>>>> system? Most high end soundcards do better than 116dB s/n, with some
>>>>> exceeding 120dB
>>>>>
>>> http://www.elite*******s.com/index.php?option=com_content&task=view&id=689&I
>>> temid=27&limitstart=4
>>>> Come out digitally and use a quality external DtoA.
>>> You know of one that exceeds 120dB then?
>>>
>>> MrT.
>
>> If you REALLY can achieve 120dB INSIDE a PC then you can certainly achieve
>> it outside.
>
> Ian, for a guy who is so bright with tubes, you surely have missed the boat
> with PCs and ICs.
>

Really? I made my living designing microprocessor based hardware.

> The limit to dynamic range in audio interfaces is generally the IC chips.

The limit is, indeed that.

> Where the chips are sited matters, but *all* converter chips by definition
> are sited intimately with logic and clock signals, just like the ones in a
> PC. Maybe you need to look at some converter data sheets, if you didn't know
> that converter chips have clock and logic lines running right up to them and
> going inside where they are even closer to the precious analog signals.
>

You make too many assumption about my supposed lack of knowledge.

> The business of siting converter chips and still obtaining good dynamic
> range is called "Mixed-signal design". Is it a coincidence that Mixed-signal
> design generally post dates tubes? You should at least show the art of
> mixed-signal design a little respect, even if you don't want to understand
> it.

The point of my remark was exactly that. The relatively uncontrolled
environment of one particular sound card made by one manufacturer,
plugged into in a PCB made by another manufacturer, encased in a box by
another and powered from a PSU by yet another, is not a recommended
method of mixed signal design. That's why it is not easy to get the best
audio performance from a PC.

OTOH, siting only the essential components for the job of AtoD
conversion in their own separate box with their own designed for audio
PSU IS a reasonable approach to mixed signal design.

>
> Bottom line Ian, yourself no favors by ranting and raving against situations
> that are known by many of us to be solved problems. OTOH, what should we
> expect from someone who doesn't get "sand state"? ;-)
>

I neither rant nor rave; I merely point out the obvious.

Cheers

Ian

Ian Bell[_2_]

March 10th 10, 09:46 PM

Dirk Bruere at NeoPax wrote:
> On 10/03/2010 14:08, Ian Bell wrote:
>> Dirk Bruere at NeoPax wrote:
>>> On 10/03/2010 09:46, Ian Bell wrote:
>>>> Dirk Bruere at NeoPax wrote:
>>>>> On 09/03/2010 23:25, Ian Bell wrote:
>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>> On 08/03/2010 20:02, Ian Bell wrote:
>>>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>>>> On 08/03/2010 08:59, Ian Bell wrote:
>>>>>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>>>>>> On 07/03/2010 23:05, geoff wrote:
>>>>>>>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>>>>>>> ?
>>>>>>>>>>>>>
>>>>>>>>>>>>> The o/p of a low noise card (Auzentech), fed through a crap
>>>>>>>>>>>>> DSP
>>>>>>>>>>>>> (95dB
>>>>>>>>>>>>> s/n) into a 105dB amp. So most of the noise is coming from the
>>>>>>>>>>>>> DSP.
>>>>>>>>>>>>>
>>>>>>>>>>>>> I am getting rid of the DSP by using VST functions in the PC.
>>>>>>>>>>>>> Since I
>>>>>>>>>>>>> am using 64 bit processing I doubt it will add any significant
>>>>>>>>>>>>> noise.
>>>>>>>>>>>>> Which leaves the soundcard.
>>>>>>>>>>>>
>>>>>>>>>>>> You have the amp sitting there with the volume cranked up
>>>>>>>>>>>> full all
>>>>>>>>>>>> the time
>>>>>>>>>>>> ?
>>>>>>>>>>>
>>>>>>>>>>> Embedded in the speaker.
>>>>>>>>>>> Volume is controlled from the PC soundcard.
>>>>>>>>>>>
>>>>>>>>>>>> I think you may be inventing not-existing problems, or
>>>>>>>>>>>> attributing
>>>>>>>>>>>> another
>>>>>>>>>>>> problem to a soundcard spec that is only semi-relevant.
>>>>>>>>>>>>
>>>>>>>>>>>> Or the active speaker (or old soundcard) is unduly noisy,
>>>>>>>>>>>> over-optimistically specced, or faulty (ie not 105dB).
>>>>>>>>>>>
>>>>>>>>>>> When the amp alone is connected the noise is negligible.
>>>>>>>>>>> The DSP does make a very significant difference.
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Then it is likely you have your level matching wrong. The
>>>>>>>>>> solution may
>>>>>>>>>> be little more than a simple pad at the input to the amp.
>>>>>>>>>
>>>>>>>>> I'm pretty sure its correct.
>>>>>>>>> We have a 105dB amp being fed by 2 DSPs, each with a 95dB s/n
>>>>>>>>> That alone reduces the s/n ratio overall by 12dB
>>>>>>>>>
>>>>>>>>> My first task is to eliminate the DSP elements by replacing them
>>>>>>>>> with
>>>>>>>>> PCs running VST in 64 bit mode. I can't get rid of the amp, and so
>>>>>>>>> the
>>>>>>>>> weakest link then becomes the soundcard driving the amp.
>>>>>>>>>
>>>>>>>>
>>>>>>>> You are assuming you want digital full scale to produce the full
>>>>>>>> 800
>>>>>>>> watts with the listener pressing his ear to the cone. The
>>>>>>>> threshold of
>>>>>>>> pain is 140dB SPL so 105dB below that is 35dB SPL - it is virtually
>>>>>>>> certain that the ambient noise in the room exceeds that level so
>>>>>>>> you do
>>>>>>>> not need 105 dB of dynamic range or s/n.
>>>>>>>
>>>>>>> I do if its a demo room at a dealers.
>>>>>>>
>>>>>>
>>>>>>
>>>>>> If it is a demo room at a dealers you should NOT be using a PC sound
>>>>>> card.
>>>>>
>>>>> So how do you suggest I get the "sound" out of a computer based AV
>>>>> system? Most high end soundcards do better than 116dB s/n, with some
>>>>> exceeding 120dB
>>>>> http://www.elite*******s.com/index.php?option=com_content&task=view&id=689&Itemid=27&limitstart=4
>>>>>
>>
>>
>>>>>
>>>>>
>>>>>
>>>>
>>>> Come out digitally and use a quality external DtoA.
>>>
>>> Any suggestions as to one that will match an Auzentech card at around
>>> the same price?
>>>
>>
>>
>> Not off hand. Google is your friend.
>
> Well, some "good" ones are to be had at around $600 it seems.
> In which case, a dedicated PC and sound card will certainly be cheaper
> and may well match it in quality.
>

Obviously the choice is yours.

Cheers

Ian

Dirk Bruere at NeoPax

March 10th 10, 09:49 PM

On 10/03/2010 21:44, Ian Bell wrote:
> Arny Krueger wrote:
>> "Ian Bell" > wrote in message
>> ...
>>
>>> Mr.T wrote:
>>>> "Ian Bell" > wrote in message
>>>> ...
>>>>>> So how do you suggest I get the "sound" out of a computer based AV
>>>>>> system? Most high end soundcards do better than 116dB s/n, with some
>>>>>> exceeding 120dB
>>>>>>
>>>> http://www.elite*******s.com/index.php?option=com_content&task=view&id=689&I
>>>>
>>>> temid=27&limitstart=4
>>>>> Come out digitally and use a quality external DtoA.
>>>> You know of one that exceeds 120dB then?
>>>>
>>>> MrT.
>>
>>> If you REALLY can achieve 120dB INSIDE a PC then you can certainly
>>> achieve it outside.
>>
>> Ian, for a guy who is so bright with tubes, you surely have missed the
>> boat with PCs and ICs.
>>
>
> Really? I made my living designing microprocessor based hardware.
>
>> The limit to dynamic range in audio interfaces is generally the IC chips.
>
> The limit is, indeed that.
>
>> Where the chips are sited matters, but *all* converter chips by
>> definition are sited intimately with logic and clock signals, just
>> like the ones in a PC. Maybe you need to look at some converter data
>> sheets, if you didn't know that converter chips have clock and logic
>> lines running right up to them and going inside where they are even
>> closer to the precious analog signals.
>>
>
> You make too many assumption about my supposed lack of knowledge.
>
>> The business of siting converter chips and still obtaining good
>> dynamic range is called "Mixed-signal design". Is it a coincidence
>> that Mixed-signal design generally post dates tubes? You should at
>> least show the art of mixed-signal design a little respect, even if
>> you don't want to understand it.
>
> The point of my remark was exactly that. The relatively uncontrolled
> environment of one particular sound card made by one manufacturer,
> plugged into in a PCB made by another manufacturer, encased in a box by
> another and powered from a PSU by yet another, is not a recommended
> method of mixed signal design. That's why it is not easy to get the best
> audio performance from a PC.
>
> OTOH, siting only the essential components for the job of AtoD
> conversion in their own separate box with their own designed for audio
> PSU IS a reasonable approach to mixed signal design.

True, but these days its well into the area of diminishing returns.
I've listened to various audio sources through dedicated DSP boards
costing $5000 going into speakers costing twice as much, and I can't say
that the $5000 DSP is any better than an Auzentech, unless it's in a
totally crap mobo.

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK
http://www.blogtalkradio.com/onetribe - Occult Talk Show

Ian Bell[_2_]

March 10th 10, 11:32 PM

Dirk Bruere at NeoPax wrote:
> On 10/03/2010 21:44, Ian Bell wrote:
>> Arny Krueger wrote:
>>> "Ian Bell" > wrote in message
>>> ...
>>>
>>>> Mr.T wrote:
>>>>> "Ian Bell" > wrote in message
>>>>> ...
>>>>>>> So how do you suggest I get the "sound" out of a computer based AV
>>>>>>> system? Most high end soundcards do better than 116dB s/n, with some
>>>>>>> exceeding 120dB
>>>>>>>
>>>>> http://www.elite*******s.com/index.php?option=com_content&task=view&id=689&I
>>>>>
>>>>>
>>>>> temid=27&limitstart=4
>>>>>> Come out digitally and use a quality external DtoA.
>>>>> You know of one that exceeds 120dB then?
>>>>>
>>>>> MrT.
>>>
>>>> If you REALLY can achieve 120dB INSIDE a PC then you can certainly
>>>> achieve it outside.
>>>
>>> Ian, for a guy who is so bright with tubes, you surely have missed the
>>> boat with PCs and ICs.
>>>
>>
>> Really? I made my living designing microprocessor based hardware.
>>
>>> The limit to dynamic range in audio interfaces is generally the IC
>>> chips.
>>
>> The limit is, indeed that.
>>
>>> Where the chips are sited matters, but *all* converter chips by
>>> definition are sited intimately with logic and clock signals, just
>>> like the ones in a PC. Maybe you need to look at some converter data
>>> sheets, if you didn't know that converter chips have clock and logic
>>> lines running right up to them and going inside where they are even
>>> closer to the precious analog signals.
>>>
>>
>> You make too many assumption about my supposed lack of knowledge.
>>
>>> The business of siting converter chips and still obtaining good
>>> dynamic range is called "Mixed-signal design". Is it a coincidence
>>> that Mixed-signal design generally post dates tubes? You should at
>>> least show the art of mixed-signal design a little respect, even if
>>> you don't want to understand it.
>>
>> The point of my remark was exactly that. The relatively uncontrolled
>> environment of one particular sound card made by one manufacturer,
>> plugged into in a PCB made by another manufacturer, encased in a box by
>> another and powered from a PSU by yet another, is not a recommended
>> method of mixed signal design. That's why it is not easy to get the best
>> audio performance from a PC.
>>
>> OTOH, siting only the essential components for the job of AtoD
>> conversion in their own separate box with their own designed for audio
>> PSU IS a reasonable approach to mixed signal design.
>
> True, but these days its well into the area of diminishing returns.
> I've listened to various audio sources through dedicated DSP boards
> costing $5000 going into speakers costing twice as much, and I can't say
> that the $5000 DSP is any better than an Auzentech, unless it's in a
> totally crap mobo.
>

You may well be right, but change the hard drive, or install a new
graphics card or even upgrade the software and things often change for
the worse in terms of sound quality. The only way to be certain it
remains the highest quality is to do it outside the PC.

Cheers

Ian

Dirk Bruere at NeoPax

March 11th 10, 12:02 AM

On 10/03/2010 23:32, Ian Bell wrote:
> Dirk Bruere at NeoPax wrote:
>> On 10/03/2010 21:44, Ian Bell wrote:
>>> Arny Krueger wrote:
>>>> "Ian Bell" > wrote in message
>>>> ...
>>>>
>>>>> Mr.T wrote:
>>>>>> "Ian Bell" > wrote in message
>>>>>> ...
>>>>>>>> So how do you suggest I get the "sound" out of a computer based AV
>>>>>>>> system? Most high end soundcards do better than 116dB s/n, with
>>>>>>>> some
>>>>>>>> exceeding 120dB
>>>>>>>>
>>>>>> http://www.elite*******s.com/index.php?option=com_content&task=view&id=689&I
>>>>>>
>>>>>>
>>>>>> temid=27&limitstart=4
>>>>>>> Come out digitally and use a quality external DtoA.
>>>>>> You know of one that exceeds 120dB then?
>>>>>>
>>>>>> MrT.
>>>>
>>>>> If you REALLY can achieve 120dB INSIDE a PC then you can certainly
>>>>> achieve it outside.
>>>>
>>>> Ian, for a guy who is so bright with tubes, you surely have missed the
>>>> boat with PCs and ICs.
>>>>
>>>
>>> Really? I made my living designing microprocessor based hardware.
>>>
>>>> The limit to dynamic range in audio interfaces is generally the IC
>>>> chips.
>>>
>>> The limit is, indeed that.
>>>
>>>> Where the chips are sited matters, but *all* converter chips by
>>>> definition are sited intimately with logic and clock signals, just
>>>> like the ones in a PC. Maybe you need to look at some converter data
>>>> sheets, if you didn't know that converter chips have clock and logic
>>>> lines running right up to them and going inside where they are even
>>>> closer to the precious analog signals.
>>>>
>>>
>>> You make too many assumption about my supposed lack of knowledge.
>>>
>>>> The business of siting converter chips and still obtaining good
>>>> dynamic range is called "Mixed-signal design". Is it a coincidence
>>>> that Mixed-signal design generally post dates tubes? You should at
>>>> least show the art of mixed-signal design a little respect, even if
>>>> you don't want to understand it.
>>>
>>> The point of my remark was exactly that. The relatively uncontrolled
>>> environment of one particular sound card made by one manufacturer,
>>> plugged into in a PCB made by another manufacturer, encased in a box by
>>> another and powered from a PSU by yet another, is not a recommended
>>> method of mixed signal design. That's why it is not easy to get the best
>>> audio performance from a PC.
>>>
>>> OTOH, siting only the essential components for the job of AtoD
>>> conversion in their own separate box with their own designed for audio
>>> PSU IS a reasonable approach to mixed signal design.
>>
>> True, but these days its well into the area of diminishing returns.
>> I've listened to various audio sources through dedicated DSP boards
>> costing $5000 going into speakers costing twice as much, and I can't
>> say that the $5000 DSP is any better than an Auzentech, unless it's in
>> a totally crap mobo.
>>
>
>
> You may well be right, but change the hard drive, or install a new
> graphics card or even upgrade the software and things often change for
> the worse in terms of sound quality. The only way to be certain it
> remains the highest quality is to do it outside the PC.

Or have a dedicated PC set up and then left alone with updates etc
turned off.

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK
http://www.blogtalkradio.com/onetribe - Occult Talk Show

Dirk Bruere at NeoPax

March 11th 10, 12:02 AM

On 10/03/2010 21:46, Ian Bell wrote:
> Dirk Bruere at NeoPax wrote:
>> On 10/03/2010 14:08, Ian Bell wrote:
>>> Dirk Bruere at NeoPax wrote:
>>>> On 10/03/2010 09:46, Ian Bell wrote:
>>>>> Dirk Bruere at NeoPax wrote:
>>>>>> On 09/03/2010 23:25, Ian Bell wrote:
>>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>>> On 08/03/2010 20:02, Ian Bell wrote:
>>>>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>>>>> On 08/03/2010 08:59, Ian Bell wrote:
>>>>>>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>>>>>>> On 07/03/2010 23:05, geoff wrote:
>>>>>>>>>>>>> Dirk Bruere at NeoPax wrote:
>>>>>>>>>>>>> ?
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> The o/p of a low noise card (Auzentech), fed through a
>>>>>>>>>>>>>> crap DSP
>>>>>>>>>>>>>> (95dB
>>>>>>>>>>>>>> s/n) into a 105dB amp. So most of the noise is coming from
>>>>>>>>>>>>>> the
>>>>>>>>>>>>>> DSP.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> I am getting rid of the DSP by using VST functions in the PC.
>>>>>>>>>>>>>> Since I
>>>>>>>>>>>>>> am using 64 bit processing I doubt it will add any
>>>>>>>>>>>>>> significant
>>>>>>>>>>>>>> noise.
>>>>>>>>>>>>>> Which leaves the soundcard.
>>>>>>>>>>>>>
>>>>>>>>>>>>> You have the amp sitting there with the volume cranked up
>>>>>>>>>>>>> full all
>>>>>>>>>>>>> the time
>>>>>>>>>>>>> ?
>>>>>>>>>>>>
>>>>>>>>>>>> Embedded in the speaker.
>>>>>>>>>>>> Volume is controlled from the PC soundcard.
>>>>>>>>>>>>
>>>>>>>>>>>>> I think you may be inventing not-existing problems, or
>>>>>>>>>>>>> attributing
>>>>>>>>>>>>> another
>>>>>>>>>>>>> problem to a soundcard spec that is only semi-relevant.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Or the active speaker (or old soundcard) is unduly noisy,
>>>>>>>>>>>>> over-optimistically specced, or faulty (ie not 105dB).
>>>>>>>>>>>>
>>>>>>>>>>>> When the amp alone is connected the noise is negligible.
>>>>>>>>>>>> The DSP does make a very significant difference.
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Then it is likely you have your level matching wrong. The
>>>>>>>>>>> solution may
>>>>>>>>>>> be little more than a simple pad at the input to the amp.
>>>>>>>>>>
>>>>>>>>>> I'm pretty sure its correct.
>>>>>>>>>> We have a 105dB amp being fed by 2 DSPs, each with a 95dB s/n
>>>>>>>>>> That alone reduces the s/n ratio overall by 12dB
>>>>>>>>>>
>>>>>>>>>> My first task is to eliminate the DSP elements by replacing them
>>>>>>>>>> with
>>>>>>>>>> PCs running VST in 64 bit mode. I can't get rid of the amp,
>>>>>>>>>> and so
>>>>>>>>>> the
>>>>>>>>>> weakest link then becomes the soundcard driving the amp.
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> You are assuming you want digital full scale to produce the
>>>>>>>>> full 800
>>>>>>>>> watts with the listener pressing his ear to the cone. The
>>>>>>>>> threshold of
>>>>>>>>> pain is 140dB SPL so 105dB below that is 35dB SPL - it is
>>>>>>>>> virtually
>>>>>>>>> certain that the ambient noise in the room exceeds that level so
>>>>>>>>> you do
>>>>>>>>> not need 105 dB of dynamic range or s/n.
>>>>>>>>
>>>>>>>> I do if its a demo room at a dealers.
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> If it is a demo room at a dealers you should NOT be using a PC sound
>>>>>>> card.
>>>>>>
>>>>>> So how do you suggest I get the "sound" out of a computer based AV
>>>>>> system? Most high end soundcards do better than 116dB s/n, with some
>>>>>> exceeding 120dB
>>>>>> http://www.elite*******s.com/index.php?option=com_content&task=view&id=689&Itemid=27&limitstart=4
>>>>>>
>>>
>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>> Come out digitally and use a quality external DtoA.
>>>>
>>>> Any suggestions as to one that will match an Auzentech card at around
>>>> the same price?
>>>>
>>>
>>>
>>> Not off hand. Google is your friend.
>>
>> Well, some "good" ones are to be had at around $600 it seems.
>> In which case, a dedicated PC and sound card will certainly be cheaper
>> and may well match it in quality.
>>
>
>
> Obviously the choice is yours.

Well, I'll be doing the expt next week with a dedicated mobo, soundcard
and booted from flash

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK
http://www.blogtalkradio.com/onetribe - Occult Talk Show

Arny Krueger

March 11th 10, 12:03 AM

"Ian Bell" > wrote in message
...

> The point of my remark was exactly that. The relatively uncontrolled
> environment of one particular sound card made by one manufacturer, plugged
> into in a PCB made by another manufacturer, encased in a box by another
> and powered from a PSU by yet another, is not a recommended method of
> mixed signal design.

Recommended by who?

Yup, you!

> That's why it is not easy to get the best audio performance from a PC.

Never had it fail after testing nearly 100 audio interfaces in various
randomly-selected PCs for my www.pcavtech.com web site.

> OTOH, siting only the essential components for the job of AtoD conversion
> in their own separate box with their own designed for audio PSU IS a
> reasonable approach to mixed signal design.

Am I reading this in some twinkie audiophile forum?

Feels that way. Iain, you left out the *necessary* housing of the whole
enchelada in a cavity milled in a solid billet of titanium or some such.

>> Bottom line Ian, yourself no favors by ranting and raving against
>> situations that are known by many of us to be solved problems. OTOH, what
>> should we expect from someone who doesn't get "sand state"? ;-)

> I neither rant nor rave; I merely point out the obvious.

In this case you're making it clear that you are drinking audiophile
kool-aid, Ian.

Mr.T

March 11th 10, 06:40 AM

"Ian Bell" > wrote in message
...
> If you REALLY can achieve 120dB INSIDE a PC then you can certainly
> achieve it outside.

Sure, you can do it EITHER way, that's the point.

MrT.

Mr.T

March 11th 10, 06:54 AM

"Arny Krueger" > wrote in message
...
> > I fail to see how that is any more difficult than using the soundcard
> > digital
> > attenuator which WILL reduce your S/N ratio at it's output, whilst an
> > analog
> > attenuator will reduce both signal and noise keeping the S/N ratio the
> > same.
>
> Not necessarily.
>
> Both the sound card and the amplifier are properly modeled as a fixed
noise
> source and a variable signal. Therefore, as you turn the signal down, the
> SNR of both the sound card and the amplifier will get worse because there
is
> less signal but the same amount of noise.

Do tell how a passive analog attenuator will reduce the signal but leave the
noise untouched?
Of course you can't *improve* on the amplifiers s/n, but a digital
attenuator does have a fixed noise floor greater than a passive analog one,
which is only governed by it's thermal noise floor.

MrT.

Ian Bell[_2_]

March 11th 10, 10:07 AM

Dirk Bruere at NeoPax wrote:
> On 10/03/2010 23:32, Ian Bell wrote:
>> Dirk Bruere at NeoPax wrote:
>>> On 10/03/2010 21:44, Ian Bell wrote:
>>>> Arny Krueger wrote:
>>>>> "Ian Bell" > wrote in message
>>>>> ...
>>>>>
>>>>>> Mr.T wrote:
>>>>>>> "Ian Bell" > wrote in message
>>>>>>> ...
>>>>>>>>> So how do you suggest I get the "sound" out of a computer based AV
>>>>>>>>> system? Most high end soundcards do better than 116dB s/n, with
>>>>>>>>> some
>>>>>>>>> exceeding 120dB
>>>>>>>>>
>>>>>>> http://www.elite*******s.com/index.php?option=com_content&task=view&id=689&I
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> temid=27&limitstart=4
>>>>>>>> Come out digitally and use a quality external DtoA.
>>>>>>> You know of one that exceeds 120dB then?
>>>>>>>
>>>>>>> MrT.
>>>>>
>>>>>> If you REALLY can achieve 120dB INSIDE a PC then you can certainly
>>>>>> achieve it outside.
>>>>>
>>>>> Ian, for a guy who is so bright with tubes, you surely have missed the
>>>>> boat with PCs and ICs.
>>>>>
>>>>
>>>> Really? I made my living designing microprocessor based hardware.
>>>>
>>>>> The limit to dynamic range in audio interfaces is generally the IC
>>>>> chips.
>>>>
>>>> The limit is, indeed that.
>>>>
>>>>> Where the chips are sited matters, but *all* converter chips by
>>>>> definition are sited intimately with logic and clock signals, just
>>>>> like the ones in a PC. Maybe you need to look at some converter data
>>>>> sheets, if you didn't know that converter chips have clock and logic
>>>>> lines running right up to them and going inside where they are even
>>>>> closer to the precious analog signals.
>>>>>
>>>>
>>>> You make too many assumption about my supposed lack of knowledge.
>>>>
>>>>> The business of siting converter chips and still obtaining good
>>>>> dynamic range is called "Mixed-signal design". Is it a coincidence
>>>>> that Mixed-signal design generally post dates tubes? You should at
>>>>> least show the art of mixed-signal design a little respect, even if
>>>>> you don't want to understand it.
>>>>
>>>> The point of my remark was exactly that. The relatively uncontrolled
>>>> environment of one particular sound card made by one manufacturer,
>>>> plugged into in a PCB made by another manufacturer, encased in a box by
>>>> another and powered from a PSU by yet another, is not a recommended
>>>> method of mixed signal design. That's why it is not easy to get the
>>>> best
>>>> audio performance from a PC.
>>>>
>>>> OTOH, siting only the essential components for the job of AtoD
>>>> conversion in their own separate box with their own designed for audio
>>>> PSU IS a reasonable approach to mixed signal design.
>>>
>>> True, but these days its well into the area of diminishing returns.
>>> I've listened to various audio sources through dedicated DSP boards
>>> costing $5000 going into speakers costing twice as much, and I can't
>>> say that the $5000 DSP is any better than an Auzentech, unless it's in
>>> a totally crap mobo.
>>>
>>
>>
>> You may well be right, but change the hard drive, or install a new
>> graphics card or even upgrade the software and things often change for
>> the worse in terms of sound quality. The only way to be certain it
>> remains the highest quality is to do it outside the PC.
>
> Or have a dedicated PC set up and then left alone with updates etc
> turned off.
>

That would probably work too.

Cheers

ian

Ian Bell[_2_]

March 11th 10, 10:09 AM

Arny Krueger wrote:
> "Ian Bell" > wrote in message
> ...
>
>> The point of my remark was exactly that. The relatively uncontrolled
>> environment of one particular sound card made by one manufacturer, plugged
>> into in a PCB made by another manufacturer, encased in a box by another
>> and powered from a PSU by yet another, is not a recommended method of
>> mixed signal design.
>
> Recommended by who?
>
> Yup, you!
>
>> That's why it is not easy to get the best audio performance from a PC.
>
> Never had it fail after testing nearly 100 audio interfaces in various
> randomly-selected PCs for my www.pcavtech.com web site.
>
>> OTOH, siting only the essential components for the job of AtoD conversion
>> in their own separate box with their own designed for audio PSU IS a
>> reasonable approach to mixed signal design.
>
> Am I reading this in some twinkie audiophile forum?
>
> Feels that way. Iain, you left out the *necessary* housing of the whole
> enchelada in a cavity milled in a solid billet of titanium or some such.
>
>>> Bottom line Ian, yourself no favors by ranting and raving against
>>> situations that are known by many of us to be solved problems. OTOH, what
>>> should we expect from someone who doesn't get "sand state"? ;-)
>
>> I neither rant nor rave; I merely point out the obvious.
>
> In this case you're making it clear that you are drinking audiophile
> kool-aid, Ian.
>
>

YAWN

Arny Krueger

March 11th 10, 12:10 PM

"Mr.T" <MrT@home> wrote in message
...

> "Ian Bell" > wrote in message
> ...

>> If you REALLY can achieve 120dB INSIDE a PC then you can certainly
>> achieve it outside.

> Sure, you can do it EITHER way, that's the point.

All through the magic of mixed-signal design.

Arny Krueger

March 11th 10, 03:23 PM

"Mr.T" <MrT@home> wrote in message

> "Arny Krueger" > wrote in message
> ...

>>> I fail to see how that is any more difficult than using
>>> the soundcard digital
>>> attenuator which WILL reduce your S/N ratio at it's
>>> output, whilst an analog
>>> attenuator will reduce both signal and noise keeping
>>> the S/N ratio the same.

>> Not necessarily.

>> Both the sound card and the amplifier are properly
>> modeled as a fixed noise source and a variable signal.
>> Therefore, as you turn the signal down, the SNR of both
>> the sound card and the amplifier will get worse because
>> there is less signal but the same amount of noise.

> Do tell how a passive analog attenuator will reduce the
> signal but leave the noise untouched?

Quite easily if the most significant noise source is downstream of the
attenuator, which is often the case.

This is one of my favorite "audiophile myths". The audiophile has a power
amplifier with 80 dB SNR, attached to a CD player (93 dB SNR @ FS) with a
digital attenuator. He's beside himself with anxiety over the issue we are
discussing. He *solves* his alleged problem by introducing a passive
attenuator. In fact, the best case is that he did not further muck things
up.

> Of course you can't *improve* on the amplifiers s/n, but
> a digital attenuator does have a fixed noise floor
> greater than a passive analog one, which is only governed
> by it's thermal noise floor.

Yes, but the amplifier's noise floor is often the weakest link, particularly
if the amp is tubed. Many integrated amps often have actual input
sensitivities on the order of 200 mV, so their SNR in Db isn't all that
great, either. My rule of thumb for a good SS power amp is around 100 dB,
which is about the same as a good CD player.

Mr.T

March 13th 10, 06:08 AM

"Arny Krueger" > wrote in message
...
> >> Both the sound card and the amplifier are properly
> >> modeled as a fixed noise source and a variable signal.
> >> Therefore, as you turn the signal down, the SNR of both
> >> the sound card and the amplifier will get worse because
> >> there is less signal but the same amount of noise.
>
> > Do tell how a passive analog attenuator will reduce the
> > signal but leave the noise untouched?
>
> Quite easily if the most significant noise source is downstream of the
> attenuator, which is often the case.

Arny I'm really surprised I have to spell it out for you, a passive analog
attenuator reduces both signal AND noise at *it's output* (amplifier input)
The OP *wasn't* complaining about his amplifiers noise!
IF that was his problem, asking for a low noise sound card is even more
stupid!

> This is one of my favorite "audiophile myths". The audiophile has a
power
> amplifier with 80 dB SNR, attached to a CD player (93 dB SNR @ FS) with a
> digital attenuator. He's beside himself with anxiety over the issue we are
> discussing. He *solves* his alleged problem by introducing a passive
> attenuator. In fact, the best case is that he did not further muck things
> up.

****, it's a pretty woeful amplifier that only gets 80dB S/N these days!
Hardly "audiophile" quality!!!!

> > Of course you can't *improve* on the amplifiers s/n, but
> > a digital attenuator does have a fixed noise floor
> > greater than a passive analog one, which is only governed
> > by it's thermal noise floor.
>
> Yes, but the amplifier's noise floor is often the weakest link,
particularly
> if the amp is tubed.

For a tube amp perhaps, but power amps with over 100dB S/N are easily
obtained these days.

>My rule of thumb for a good SS power amp is around 100 dB,
> which is about the same as a good CD player.

Exactly! (well actually no CD player can really do 100dB wide band since
it's above the theoretical maximum for 16bits, but let's ignore the slight
difference)
However it can easily be degraded by running the amp gain flat out and using
the soundcard digital attenuator as the OP said he was doing!

MrT.

Arny Krueger

March 13th 10, 02:54 PM

"Mr.T" <MrT@home> wrote in message

> "Arny Krueger" > wrote in message
> ...
>>>> Both the sound card and the amplifier are properly
>>>> modeled as a fixed noise source and a variable signal.
>>>> Therefore, as you turn the signal down, the SNR of both
>>>> the sound card and the amplifier will get worse because
>>>> there is less signal but the same amount of noise.
>>
>>> Do tell how a passive analog attenuator will reduce the
>>> signal but leave the noise untouched?
>>
>> Quite easily if the most significant noise source is
>> downstream of the attenuator, which is often the case.
>
>
> Arny I'm really surprised I have to spell it out for you,
> a passive analog attenuator reduces both signal AND noise
> at *it's output* (amplifier input)

Of course, but read what I wrote: it does nothing to reduce the noise at the
output of the amplifier which is often the weakest link.

> The OP *wasn't*
> complaining about his amplifiers noise!

In this case he had an amplifier with atypically low noise.

> IF that was his problem, asking for a low noise sound
> card is even more stupid!

The problem of coming up with an audio interface with dynamic range and SNR
> 108 dB was solved long ago.

>> This is one of my favorite "audiophile myths". The
>> audiophile has a power amplifier with 80 dB SNR,
>> attached to a CD player (93 dB SNR @ FS) with a digital
>> attenuator. He's beside himself with anxiety over the
>> issue we are discussing. He *solves* his alleged
>> problem by introducing a passive attenuator. In fact,
>> the best case is that he did not further muck things up.

> ****, it's a pretty woeful amplifier that only gets 80dB
> S/N these days! Hardly "audiophile" quality!!!!

Look at the spec sheets for some modern integrated amps.

I'm here to tell you that many power amps that spec > 100 dB are a little
optimistic.

>>> Of course you can't *improve* on the amplifiers s/n, but
>>> a digital attenuator does have a fixed noise floor
>>> greater than a passive analog one, which is only
>>> governed by it's thermal noise floor.
>>
>> Yes, but the amplifier's noise floor is often the
>> weakest link, particularly if the amp is tubed.

> For a tube amp perhaps, but power amps with over 100dB
> S/N are easily obtained these days.

They can be obtained, but 100 dB is not a low mark, especially if you test
them on the bench.

Also consider that most CD players are attached to integrated amps, not
power amps.

> Exactly! (well actually no CD player can really do 100dB
> wide band since it's above the theoretical maximum for
> 16bits, but let's ignore the slight difference)
> However it can easily be degraded by running the amp gain
> flat out and using the soundcard digital attenuator as
> the OP said he was doing!

Like I said, the OPs specific problem is in my views resolved days ago.

Mr.T

March 15th 10, 02:31 AM

"Arny Krueger" > wrote in message
...
> > Arny I'm really surprised I have to spell it out for you,
> > a passive analog attenuator reduces both signal AND noise
> > at *it's output* (amplifier input)
>
> Of course, but read what I wrote: it does nothing to reduce the noise at
the
> output of the amplifier which is often the weakest link.

Read what I wrote, I never said it did. But the OP thinks his amplifier is
not the problem.

> > The OP *wasn't*
> > complaining about his amplifiers noise!
>
> In this case he had an amplifier with atypically low noise.

So why bring up something irelevant to the actual discussion then?

> > IF that was his problem, asking for a low noise sound
> > card is even more stupid!
>
>
> The problem of coming up with an audio interface with dynamic range and
SNR
> > 108 dB was solved long ago.

Never in dispute.

> > ****, it's a pretty woeful amplifier that only gets 80dB
> > S/N these days! Hardly "audiophile" quality!!!!
>
> Look at the spec sheets for some modern integrated amps.

Yep, "audiophile" grade pretty much around 100dB these days.
Your definition of "audiophile" grade may differ of course.

> I'm here to tell you that many power amps that spec > 100 dB are a little
> optimistic.

Sure, and many that aren't, and I've measured quite a few.

> > For a tube amp perhaps, but power amps with over 100dB
> > S/N are easily obtained these days.
>
> They can be obtained, but 100 dB is not a low mark, especially if you test
> them on the bench.
>
> Also consider that most CD players are attached to integrated amps, not
> power amps.

Irrelevant to the current discussion. You are free to make a completely
separate point of course, but don't drag me into it.

> Like I said, the OPs specific problem is in my views resolved days ago.

Years ago in fact, but he doesn't seem to realise it.

MrT.

Ian Bell[_2_]

March 15th 10, 10:03 AM

Mr.T wrote:
> "Arny Krueger" > wrote in message
> ...
>>> Arny I'm really surprised I have to spell it out for you,
>>> a passive analog attenuator reduces both signal AND noise
>>> at *it's output* (amplifier input)
>> Of course, but read what I wrote: it does nothing to reduce the noise at
> the
>> output of the amplifier which is often the weakest link.
>
> Read what I wrote, I never said it did. But the OP thinks his amplifier is
> not the problem.
>
>
>>> The OP *wasn't*
>>> complaining about his amplifiers noise!
>> In this case he had an amplifier with atypically low noise.
>
> So why bring up something irelevant to the actual discussion then?
>
>
>>> IF that was his problem, asking for a low noise sound
>>> card is even more stupid!
>>
>> The problem of coming up with an audio interface with dynamic range and
> SNR
>> > 108 dB was solved long ago.
>
> Never in dispute.
>
>
>>> ****, it's a pretty woeful amplifier that only gets 80dB
>>> S/N these days! Hardly "audiophile" quality!!!!
>> Look at the spec sheets for some modern integrated amps.
>
> Yep, "audiophile" grade pretty much around 100dB these days.
> Your definition of "audiophile" grade may differ of course.
>
>
>> I'm here to tell you that many power amps that spec > 100 dB are a little
>> optimistic.
>
> Sure, and many that aren't, and I've measured quite a few.
>
>
>>> For a tube amp perhaps, but power amps with over 100dB
>>> S/N are easily obtained these days.
>> They can be obtained, but 100 dB is not a low mark, especially if you test
>> them on the bench.
>>
>> Also consider that most CD players are attached to integrated amps, not
>> power amps.
>
> Irrelevant to the current discussion. You are free to make a completely
> separate point of course, but don't drag me into it.
>
>
>> Like I said, the OPs specific problem is in my views resolved days ago.
>
> Years ago in fact, but he doesn't seem to realise it.
>
> MrT.
>
>

And both of you please stop using s/n when you mean dynamic range - they
are not the same thing not to mention simply quoting a totally
unqualified dB figure is quite meaningless.

Cheers

ian

Arny Krueger

March 15th 10, 12:15 PM

"Ian Bell" > wrote in message

> And both of you please stop using s/n when you mean
> dynamic range - they are not the same thing not to
> mention simply quoting a totally unqualified dB figure is
> quite meaningless.

If you could read and remember what other people write for more than a few
seconds Ian, you would see that I used both terms non-interchangably.

And of course totally unqualified dB figures is meaningless, but its one of
those things that happen all the time on online forums that you kinda sorta
have to step over to get to the meat of the problem. You know, like the
self-important luddite ijiots who think that good audio can't come out of a
PC chassis.

Ian Bell[_2_]

March 15th 10, 06:28 PM

Arny Krueger wrote:
> "Ian Bell" > wrote in message
>
>
>> And both of you please stop using s/n when you mean
>> dynamic range - they are not the same thing not to
>> mention simply quoting a totally unqualified dB figure is
>> quite meaningless.
>
> If you could read and remember what other people write for more than a few
> seconds Ian, you would see that I used both terms non-interchangably.
>
> And of course totally unqualified dB figures is meaningless, but its one of
> those things that happen all the time on online forums that you kinda sorta
> have to step over to get to the meat of the problem. You know, like the
> self-important luddite ijiots who think that good audio can't come out of a
> PC chassis.
>
>

LOL

Dirk Bruere at NeoPax

March 15th 10, 07:11 PM

On 15/03/2010 10:03, Ian Bell wrote:
> Mr.T wrote:
>> "Arny Krueger" > wrote in message
>> ...
>>>> Arny I'm really surprised I have to spell it out for you,
>>>> a passive analog attenuator reduces both signal AND noise
>>>> at *it's output* (amplifier input)
>>> Of course, but read what I wrote: it does nothing to reduce the noise at
>> the
>>> output of the amplifier which is often the weakest link.
>>
>> Read what I wrote, I never said it did. But the OP thinks his
>> amplifier is
>> not the problem.
>>
>>
>>>> The OP *wasn't*
>>>> complaining about his amplifiers noise!
>>> In this case he had an amplifier with atypically low noise.
>>
>> So why bring up something irelevant to the actual discussion then?
>>
>>
>>>> IF that was his problem, asking for a low noise sound
>>>> card is even more stupid!
>>>
>>> The problem of coming up with an audio interface with dynamic range and
>> SNR
>>> > 108 dB was solved long ago.
>>
>> Never in dispute.
>>
>>
>>>> ****, it's a pretty woeful amplifier that only gets 80dB
>>>> S/N these days! Hardly "audiophile" quality!!!!
>>> Look at the spec sheets for some modern integrated amps.
>>
>> Yep, "audiophile" grade pretty much around 100dB these days.
>> Your definition of "audiophile" grade may differ of course.
>>
>>
>>> I'm here to tell you that many power amps that spec > 100 dB are a
>>> little
>>> optimistic.
>>
>> Sure, and many that aren't, and I've measured quite a few.
>>
>>
>>>> For a tube amp perhaps, but power amps with over 100dB
>>>> S/N are easily obtained these days.
>>> They can be obtained, but 100 dB is not a low mark, especially if you
>>> test
>>> them on the bench.
>>>
>>> Also consider that most CD players are attached to integrated amps, not
>>> power amps.
>>
>> Irrelevant to the current discussion. You are free to make a completely
>> separate point of course, but don't drag me into it.
>>
>>
>>> Like I said, the OPs specific problem is in my views resolved days ago.
>>
>> Years ago in fact, but he doesn't seem to realise it.
>>
>> MrT.
>>
>>
>
>
> And both of you please stop using s/n when you mean dynamic range - they
> are not the same thing not to mention simply quoting a totally
> unqualified dB figure is quite meaningless.

s/n as in max voltage output with an input of 0dB to the voltage output
with no input signal.

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK
http://www.blogtalkradio.com/onetribe - Occult Talk Show

Arny Krueger

March 15th 10, 08:56 PM

"Dirk Bruere at NeoPax" > wrote in
message
> On 15/03/2010 10:03, Ian Bell wrote:
>> Mr.T wrote:
>>> "Arny Krueger" > wrote in message
>>> ...
>>>>> Arny I'm really surprised I have to spell it out for
>>>>> you, a passive analog attenuator reduces both signal
>>>>> AND noise at *it's output* (amplifier input)
>>>> Of course, but read what I wrote: it does nothing to
>>>> reduce the noise at the output of the amplifier which
>>>> is often the weakest link.
>>>
>>> Read what I wrote, I never said it did. But the OP
>>> thinks his amplifier is
>>> not the problem.
>>>
>>>
>>>>> The OP *wasn't*
>>>>> complaining about his amplifiers noise!
>>>> In this case he had an amplifier with atypically low
>>>> noise.
>>>
>>> So why bring up something irelevant to the actual
>>> discussion then?
>>>>> IF that was his problem, asking for a low noise sound
>>>>> card is even more stupid!
>>>>
>>>> The problem of coming up with an audio interface with
>>>> dynamic range and
>>> SNR
>>>>> 108 dB was solved long ago.
>>>
>>> Never in dispute.
>>>
>>>
>>>>> ****, it's a pretty woeful amplifier that only gets
>>>>> 80dB S/N these days! Hardly "audiophile" quality!!!!
>>>> Look at the spec sheets for some modern integrated
>>>> amps.
>>>
>>> Yep, "audiophile" grade pretty much around 100dB these
>>> days. Your definition of "audiophile" grade may differ of
>>> course.
>>>> I'm here to tell you that many power amps that spec >
>>>> 100 dB are a little
>>>> optimistic.
>>>
>>> Sure, and many that aren't, and I've measured quite a
>>> few.
>>>>> For a tube amp perhaps, but power amps with over 100dB
>>>>> S/N are easily obtained these days.
>>>> They can be obtained, but 100 dB is not a low mark,
>>>> especially if you test
>>>> them on the bench.
>>>>
>>>> Also consider that most CD players are attached to
>>>> integrated amps, not power amps.
>>>
>>> Irrelevant to the current discussion. You are free to
>>> make a completely separate point of course, but don't
>>> drag me into it.
>>>> Like I said, the OPs specific problem is in my views
>>>> resolved days ago.
>>>
>>> Years ago in fact, but he doesn't seem to realise it.
>>>
>>> MrT.
>>>
>>>
>>
>>
>> And both of you please stop using s/n when you mean
>> dynamic range - they are not the same thing not to
>> mention simply quoting a totally unqualified dB figure
>> is quite meaningless.
>
> s/n as in max voltage output with an input of 0dB to the
> voltage output with no input signal.

So far, so good. No noise measurement is complete without a statement of the
measurement bandwidth.

Dynamic range measurements are performed with a test signal present, as it
also includes spurious responses. A typical measurement would be made using
a -60 dB 1 KHz sine wave.

Ian Bell[_2_]

March 15th 10, 10:17 PM

Dirk Bruere at NeoPax wrote:
> On 15/03/2010 10:03, Ian Bell wrote:
>> Mr.T wrote:
>>> "Arny Krueger" > wrote in message
>>> ...
>>>>> Arny I'm really surprised I have to spell it out for you,
>>>>> a passive analog attenuator reduces both signal AND noise
>>>>> at *it's output* (amplifier input)
>>>> Of course, but read what I wrote: it does nothing to reduce the
>>>> noise at
>>> the
>>>> output of the amplifier which is often the weakest link.
>>>
>>> Read what I wrote, I never said it did. But the OP thinks his
>>> amplifier is
>>> not the problem.
>>>
>>>
>>>>> The OP *wasn't*
>>>>> complaining about his amplifiers noise!
>>>> In this case he had an amplifier with atypically low noise.
>>>
>>> So why bring up something irelevant to the actual discussion then?
>>>
>>>
>>>>> IF that was his problem, asking for a low noise sound
>>>>> card is even more stupid!
>>>>
>>>> The problem of coming up with an audio interface with dynamic range and
>>> SNR
>>>> > 108 dB was solved long ago.
>>>
>>> Never in dispute.
>>>
>>>
>>>>> ****, it's a pretty woeful amplifier that only gets 80dB
>>>>> S/N these days! Hardly "audiophile" quality!!!!
>>>> Look at the spec sheets for some modern integrated amps.
>>>
>>> Yep, "audiophile" grade pretty much around 100dB these days.
>>> Your definition of "audiophile" grade may differ of course.
>>>
>>>
>>>> I'm here to tell you that many power amps that spec > 100 dB are a
>>>> little
>>>> optimistic.
>>>
>>> Sure, and many that aren't, and I've measured quite a few.
>>>
>>>
>>>>> For a tube amp perhaps, but power amps with over 100dB
>>>>> S/N are easily obtained these days.
>>>> They can be obtained, but 100 dB is not a low mark, especially if you
>>>> test
>>>> them on the bench.
>>>>
>>>> Also consider that most CD players are attached to integrated amps, not
>>>> power amps.
>>>
>>> Irrelevant to the current discussion. You are free to make a completely
>>> separate point of course, but don't drag me into it.
>>>
>>>
>>>> Like I said, the OPs specific problem is in my views resolved days ago.
>>>
>>> Years ago in fact, but he doesn't seem to realise it.
>>>
>>> MrT.
>>>
>>>
>>
>>
>> And both of you please stop using s/n when you mean dynamic range - they
>> are not the same thing not to mention simply quoting a totally
>> unqualified dB figure is quite meaningless.
>
> s/n as in max voltage output with an input of 0dB to the voltage output
> with no input signal.
>

LOL, that's is awful.

0dB has no meaning.
Input termination in both cases is unspecified
Output termination is unspecified.
No bandwidth is specified.
No weighting or not is specified.
No mention of whether the measurements are rms, peak, quasi-peak
etc

Variations in the way the above are specified can make a large
difference to the 'measured' value and I bet you can guess which set the
marketing department will want to choose.

Cheers

ian

Cheers

Ian

Mr.T

March 16th 10, 12:41 AM

"Ian Bell" > wrote in message
...
> And both of you please stop using s/n when you mean dynamic range - they
> are not the same thing

Who said they were?

>not to mention simply quoting a totally
> unqualified dB figure is quite meaningless.

Neither should be "unqualified", but ANY figure that isn't qualified is
meaningless of course.

MrT.

Dirk Bruere at NeoPax

March 16th 10, 09:49 AM

On 15/03/2010 22:17, Ian Bell wrote:
> Dirk Bruere at NeoPax wrote:
>> On 15/03/2010 10:03, Ian Bell wrote:
>>> Mr.T wrote:
>>>> "Arny Krueger" > wrote in message
>>>> ...
>>>>>> Arny I'm really surprised I have to spell it out for you,
>>>>>> a passive analog attenuator reduces both signal AND noise
>>>>>> at *it's output* (amplifier input)
>>>>> Of course, but read what I wrote: it does nothing to reduce the
>>>>> noise at
>>>> the
>>>>> output of the amplifier which is often the weakest link.
>>>>
>>>> Read what I wrote, I never said it did. But the OP thinks his
>>>> amplifier is
>>>> not the problem.
>>>>
>>>>
>>>>>> The OP *wasn't*
>>>>>> complaining about his amplifiers noise!
>>>>> In this case he had an amplifier with atypically low noise.
>>>>
>>>> So why bring up something irelevant to the actual discussion then?
>>>>
>>>>
>>>>>> IF that was his problem, asking for a low noise sound
>>>>>> card is even more stupid!
>>>>>
>>>>> The problem of coming up with an audio interface with dynamic range
>>>>> and
>>>> SNR
>>>>> > 108 dB was solved long ago.
>>>>
>>>> Never in dispute.
>>>>
>>>>
>>>>>> ****, it's a pretty woeful amplifier that only gets 80dB
>>>>>> S/N these days! Hardly "audiophile" quality!!!!
>>>>> Look at the spec sheets for some modern integrated amps.
>>>>
>>>> Yep, "audiophile" grade pretty much around 100dB these days.
>>>> Your definition of "audiophile" grade may differ of course.
>>>>
>>>>
>>>>> I'm here to tell you that many power amps that spec > 100 dB are a
>>>>> little
>>>>> optimistic.
>>>>
>>>> Sure, and many that aren't, and I've measured quite a few.
>>>>
>>>>
>>>>>> For a tube amp perhaps, but power amps with over 100dB
>>>>>> S/N are easily obtained these days.
>>>>> They can be obtained, but 100 dB is not a low mark, especially if you
>>>>> test
>>>>> them on the bench.
>>>>>
>>>>> Also consider that most CD players are attached to integrated amps,
>>>>> not
>>>>> power amps.
>>>>
>>>> Irrelevant to the current discussion. You are free to make a completely
>>>> separate point of course, but don't drag me into it.
>>>>
>>>>
>>>>> Like I said, the OPs specific problem is in my views resolved days
>>>>> ago.
>>>>
>>>> Years ago in fact, but he doesn't seem to realise it.
>>>>
>>>> MrT.
>>>>
>>>>
>>>
>>>
>>> And both of you please stop using s/n when you mean dynamic range - they
>>> are not the same thing not to mention simply quoting a totally
>>> unqualified dB figure is quite meaningless.
>>
>> s/n as in max voltage output with an input of 0dB to the voltage
>> output with no input signal.
>>
>
>
> LOL, that's is awful.
>
> 0dB has no meaning.

http://jtauber.com/decibels/
"There are actually two reference voltages in use. 1V and 0.775V. When
using the former as the reference, we write 'dBV' and when using the
latter we use 'dBu'. "

Either would do.

> Input termination in both cases is unspecified

As per manufacturers guidelines

> Output termination is unspecified.

As per manufacturers guidelines

> No bandwidth is specified.

We are talking "audio" so perhaps we can suggest it just might be
somewhere between 20Hz and 20,000Hz?

> No weighting or not is specified.

True.

> No mention of whether the measurements are rms, peak, quasi-peak
> etc

Well, maximum Music Power obviously! [not]

> Variations in the way the above are specified can make a large
> difference to the 'measured' value and I bet you can guess which set the
> marketing department will want to choose.

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK
http://www.blogtalkradio.com/onetribe - Occult Talk Show

Arny Krueger

March 16th 10, 11:12 AM

"Ian Bell" > wrote in message

> 0dB has no meaning.

Actually, it does. In the digital domain 0 dB is commonly equated with FS.
While the units are arbitrary and may be confusing to people who still think
100% analog, it is both meaningful and commonly used.

> Input termination in both cases is unspecified.

If the input is a mic input, then the usual standard of 300 ohms applies.

If the input is a line level input, then the source impedance is usually
such that system performance is not affected that much by probable
variations.

> Output termination is unspecified.

The noise performance of line level outputs is minimally affected by
probable and reasonable variations in load impedance.

> No bandwidth is specified.

Relevant and already mentioned

> No weighting or not is specified.

Relevant and already mentioned

> No mention of whether the measurements are rms, peak, quasi-peak

Both SNR and DR are ratios of two measurements. It is most important that
both measurements be done under the same circumstances.

> Variations in the way the above are specified can make a
> large difference to the 'measured' value

Some yes, some no.

> and I bet you
> can guess which set the marketing department will want to choose.

One other benefit of the solid state/digital revolution is that SNR and DR
performance is often so good (> 100 dB) that most variations in how they are
mentioned don't matter that much.

Ian Bell[_2_]

March 17th 10, 12:36 AM

Dirk Bruere at NeoPax wrote:
> On 15/03/2010 22:17, Ian Bell wrote:
>> Dirk Bruere at NeoPax wrote:
>>> On 15/03/2010 10:03, Ian Bell wrote:
>>>> Mr.T wrote:
>>>>> "Arny Krueger" > wrote in message
>>>>> ...
>>>>>>> Arny I'm really surprised I have to spell it out for you,
>>>>>>> a passive analog attenuator reduces both signal AND noise
>>>>>>> at *it's output* (amplifier input)
>>>>>> Of course, but read what I wrote: it does nothing to reduce the
>>>>>> noise at
>>>>> the
>>>>>> output of the amplifier which is often the weakest link.
>>>>>
>>>>> Read what I wrote, I never said it did. But the OP thinks his
>>>>> amplifier is
>>>>> not the problem.
>>>>>
>>>>>
>>>>>>> The OP *wasn't*
>>>>>>> complaining about his amplifiers noise!
>>>>>> In this case he had an amplifier with atypically low noise.
>>>>>
>>>>> So why bring up something irelevant to the actual discussion then?
>>>>>
>>>>>
>>>>>>> IF that was his problem, asking for a low noise sound
>>>>>>> card is even more stupid!
>>>>>>
>>>>>> The problem of coming up with an audio interface with dynamic range
>>>>>> and
>>>>> SNR
>>>>>> > 108 dB was solved long ago.
>>>>>
>>>>> Never in dispute.
>>>>>
>>>>>
>>>>>>> ****, it's a pretty woeful amplifier that only gets 80dB
>>>>>>> S/N these days! Hardly "audiophile" quality!!!!
>>>>>> Look at the spec sheets for some modern integrated amps.
>>>>>
>>>>> Yep, "audiophile" grade pretty much around 100dB these days.
>>>>> Your definition of "audiophile" grade may differ of course.
>>>>>
>>>>>
>>>>>> I'm here to tell you that many power amps that spec > 100 dB are a
>>>>>> little
>>>>>> optimistic.
>>>>>
>>>>> Sure, and many that aren't, and I've measured quite a few.
>>>>>
>>>>>
>>>>>>> For a tube amp perhaps, but power amps with over 100dB
>>>>>>> S/N are easily obtained these days.
>>>>>> They can be obtained, but 100 dB is not a low mark, especially if you
>>>>>> test
>>>>>> them on the bench.
>>>>>>
>>>>>> Also consider that most CD players are attached to integrated amps,
>>>>>> not
>>>>>> power amps.
>>>>>
>>>>> Irrelevant to the current discussion. You are free to make a
>>>>> completely
>>>>> separate point of course, but don't drag me into it.
>>>>>
>>>>>
>>>>>> Like I said, the OPs specific problem is in my views resolved days
>>>>>> ago.
>>>>>
>>>>> Years ago in fact, but he doesn't seem to realise it.
>>>>>
>>>>> MrT.
>>>>>
>>>>>
>>>>
>>>>
>>>> And both of you please stop using s/n when you mean dynamic range -
>>>> they
>>>> are not the same thing not to mention simply quoting a totally
>>>> unqualified dB figure is quite meaningless.
>>>
>>> s/n as in max voltage output with an input of 0dB to the voltage
>>> output with no input signal.
>>>
>>
>>
>> LOL, that's is awful.
>>
>> 0dB has no meaning.
>
> http://jtauber.com/decibels/
> "There are actually two reference voltages in use. 1V and 0.775V. When
> using the former as the reference, we write 'dBV' and when using the
> latter we use 'dBu'. "
>
> Either would do.

Indeed, and most professional equipment operates at +4dBu and some at
+8dBu and then again a lot of commercial power amps have an input
sensitivity of 2V for full output.

Any of these would do, the point is we are not told which.

>
>> Input termination in both cases is unspecified
>
> As per manufacturers guidelines
>

I very much doubt the manufacturer says how the input is terminated when
he measures the amp output noise but I very strongly suspect he short
circuits it to give him the lowest noise figure. Of course you will not
achieve this figure when connected to a real source.

>> Output termination is unspecified.
>
> As per manufacturers guidelines
>

Which are what?

>> No bandwidth is specified.
>
> We are talking "audio" so perhaps we can suggest it just might be
> somewhere between 20Hz and 20,000Hz?
>

Yes, but when measuring noise it is very important. Often a 15KHz
bandwidth with well defined slopes is used because it gives a total
equivalent noise bandwidth of 20KHz which is not the same as a flat
response from 20Hz to 20KHz but is does give a better figure.

>> No weighting or not is specified.
>
> True.
>
>> No mention of whether the measurements are rms, peak, quasi-peak
>> etc
>
> Well, maximum Music Power obviously! [not]
>

LOL

Cheers

Ian
>> Variations in the way the above are specified can make a large
>> difference to the 'measured' value and I bet you can guess which set the
>> marketing department will want to choose.
>
>

Ian Bell[_2_]

March 17th 10, 12:45 AM

Arny Krueger wrote:
> "Ian Bell" > wrote in message
>
>
>> 0dB has no meaning.
>
> Actually, it does. In the digital domain 0 dB is commonly equated with FS.

No, that is 0dBFS.

> While the units are arbitrary and may be confusing to people who still think
> 100% analog, it is both meaningful and commonly used.
>

No it is not.

>> Input termination in both cases is unspecified.
>
> If the input is a mic input, then the usual standard of 300 ohms applies.
>

It is a power amp, it does not have a mic input. 300 ohms is NOT the
'usual standard for a mic input'

> If the input is a line level input, then the source impedance is usually
> such that system performance is not affected that much by probable
> variations.
>

You miss the point. How is the input terminated when noise is measured -
obviously it is not left open circuit is it?

>> Output termination is unspecified.
>
> The noise performance of line level outputs is minimally affected by
> probable and reasonable variations in load impedance.
>
>> No bandwidth is specified.
>
> Relevant and already mentioned
>
>> No weighting or not is specified.
>
> Relevant and already mentioned
>
>> No mention of whether the measurements are rms, peak, quasi-peak
>
> Both SNR and DR are ratios of two measurements. It is most important that
> both measurements be done under the same circumstances.
>

In fact they generally are not since a signal and noise have quite
different characteristics. The signal will be measured rms. The noise
can be measured in several ways each giving a different figure.

>> Variations in the way the above are specified can make a
>> large difference to the 'measured' value
>
> Some yes, some no.
>
>> and I bet you
>> can guess which set the marketing department will want to choose.
>
> One other benefit of the solid state/digital revolution is that SNR and DR
> performance is often so good (> 100 dB) that most variations in how they are
> mentioned don't matter that much.
>
Rubbish. Once again, SNR and DR are different animals. Achieving a 100dB
DR is not hard but unless you run your amp close to clipping all the
time you will not achieve that as a SNR.

The marketing guys are as active as ever in trying to make their product
appear superior to its competitors and will choose the measurement
methods that best do that.

Cheers

ian

Arny Krueger

March 17th 10, 12:05 PM

"Ian Bell" > wrote in message

> Indeed, and most professional equipment operates at +4dBu
> and some at +8dBu and then again a lot of commercial
> power amps have an input sensitivity of 2V for full
> output.

What you've missed is that there is only a few dB between all of these
numbers. The difference between an objectionally noisy system and an
aceeptable system is generally far more than just a few dB, no matter how
you measure things.

> Any of these would do, the point is we are not told which.

It's a hair-splitting, misleading point.

> I very much doubt the manufacturer says how the input is
> terminated when he measures the amp output noise but I
> very strongly suspect he short circuits it to give him
> the lowest noise figure. Of course you will not achieve
> this figure when connected to a real source.

Again, there are only a few dB difference in the noise floor of line-level
products with reasonable variations in source impedance or load.

>>> Output termination is unspecified.
>>
>> As per manufacturers guidelines
>>
>
> Which are what?
>
>>> No bandwidth is specified.
>>
>> We are talking "audio" so perhaps we can suggest it just
>> might be somewhere between 20Hz and 20,000Hz?

> Yes, but when measuring noise it is very important. Often
> a 15KHz bandwidth with well defined slopes is used
> because it gives a total equivalent noise bandwidth of
> 20KHz which is not the same as a flat response from 20Hz
> to 20KHz but is does give a better figure.

Again, there are only a few dB difference in the noise floor of line-level
products with reasonable variations in measurement bandwidth.

Many of these issues are bigger issues for legacy vacuum tube equipment,
where the noise levels were generally closer to the edge of perception.

Ian Bell[_2_]

March 17th 10, 12:13 PM

Arny Krueger wrote:
> "Ian Bell" > wrote in message
>
>
>> Indeed, and most professional equipment operates at +4dBu
>> and some at +8dBu and then again a lot of commercial
>> power amps have an input sensitivity of 2V for full
>> output.
>
> What you've missed is that there is only a few dB between all of these
> numbers. The difference between an objectionally noisy system and an
> aceeptable system is generally far more than just a few dB, no matter how
> you measure things.
>
>> Any of these would do, the point is we are not told which.
>
> It's a hair-splitting, misleading point.
>
>> I very much doubt the manufacturer says how the input is
>> terminated when he measures the amp output noise but I
>> very strongly suspect he short circuits it to give him
>> the lowest noise figure. Of course you will not achieve
>> this figure when connected to a real source.
>
> Again, there are only a few dB difference in the noise floor of line-level
> products with reasonable variations in source impedance or load.
>
>>>> Output termination is unspecified.
>>> As per manufacturers guidelines
>>>
>> Which are what?
>>
>>>> No bandwidth is specified.
>>> We are talking "audio" so perhaps we can suggest it just
>>> might be somewhere between 20Hz and 20,000Hz?
>
>> Yes, but when measuring noise it is very important. Often
>> a 15KHz bandwidth with well defined slopes is used
>> because it gives a total equivalent noise bandwidth of
>> 20KHz which is not the same as a flat response from 20Hz
>> to 20KHz but is does give a better figure.
>
> Again, there are only a few dB difference in the noise floor of line-level
> products with reasonable variations in measurement bandwidth.
>
> Many of these issues are bigger issues for legacy vacuum tube equipment,
> where the noise levels were generally closer to the edge of perception.
>
>

And you add up these several instances of 'a few dBs' as the marketing
guys will certainly do, plus the judicious choice of weighting for the
noise and your 100dB DR spec suddenly becomes in reality in the 80 to
90dB region.

The point is, using several unqualified specs of differing pieces of
connected equipment made by differing manufacturers is not going to tell
the whole story by a long way.

Cheers

ian

Arny Krueger

March 17th 10, 12:14 PM

"Ian Bell" > wrote in message

> Arny Krueger wrote:
>> "Ian Bell" > wrote in message
>>
>>
>>> 0dB has no meaning.
>>
>> Actually, it does. In the digital domain 0 dB is
>> commonly equated with FS.

> No, that is 0dBFS.

Yes, so your use of the word "no" must be some kind of terrible mistake on
your part.

>> While the units are arbitrary and may be confusing to
>> people who still think 100% analog, it is both
>> meaningful and commonly used.

> No it is not.

Assertion without support, which should be immediately dismissed.

>>> Input termination in both cases is unspecified.
>>
>> If the input is a mic input, then the usual standard of
>> 300 ohms applies.

> It is a power amp, it does not have a mic input. 300 ohms
> is NOT the 'usual standard for a mic input'

Good modern power amps are common, and do not have that much variation in
their noise performance with normal variations in source impedance.

>> If the input is a line level input, then the source
>> impedance is usually such that system performance is not
>> affected that much by probable variations.

> You miss the point. How is the input terminated when
> noise is measured - obviously it is not left open circuit
> is it?

I guess you've never measured the actual noise coming out of a good modern
power amp with the normal range of source impedances. They often don't vary
all that much. Remember, this is not legacy vacuum tube equipment which was
generally far noisier.

>>> Output termination is unspecified.
>>
>> The noise performance of line level outputs is minimally
>> affected by probable and reasonable variations in load
>> impedance.

>>> No bandwidth is specified.
>>
>> Relevant and already mentioned
>>
>>> No weighting or not is specified.
>>
>> Relevant and already mentioned
>>
>>> No mention of whether the measurements are rms, peak,
>>> quasi-peak
>>
>> Both SNR and DR are ratios of two measurements. It is
>> most important that both measurements be done under the
>> same circumstances.

> In fact they generally are not since a signal and noise
> have quite different characteristics. The signal will be
> measured rms. The noise can be measured in several ways
> each giving a different figure.

While people could be stupid and compare a noise level measured in
peak-to-peak volts to a signal measured in average volts, I know of no
actual cases where this happens, except perhaps in your mind, Ian. There
could be equipment noise that has a high crest factor, but nature does not
usually go down that path. What is then left is a few dB of ambiguity, and
most good modern equipment (which is common) is not so noisy that a few dB
is a deal breaker in actual use.

> >> Variations in the way the above are specified can make a
>>> large difference to the 'measured' value

>> Some yes, some no.

>>> and I bet you
>>> can guess which set the marketing department will want
>>> to choose.
>>
>> One other benefit of the solid state/digital revolution
>> is that SNR and DR performance is often so good (> 100
>> dB) that most variations in how they are mentioned don't
>> matter that much.

> Rubbish.

Dismissive, unsupported claim, again itself worthy only of dismissal.

> Once again, SNR and DR are different animals.

A truism - therefore something that actually sheds no signficiant light. Why
do you obsess over these things, Ian?

> Achieving a 100dB DR is not hard but unless you run your
> amp close to clipping all the time you will not achieve
> that as a SNR.

Another truism.

> The marketing guys are as active as ever in trying to
> make their product appear superior to its competitors and
> will choose the measurement methods that best do that.

The myth is that some equipment is head-and-shoulders better than its
competition. Everybody pretty much feeds from the same trough.

Ian Bell[_2_]

March 17th 10, 10:28 PM

Arny Krueger wrote:
> "Ian Bell" > wrote in message
>
>> Arny Krueger wrote:
>>> "Ian Bell" > wrote in message
>>>
>>>
>>>> 0dB has no meaning.
>>> Actually, it does. In the digital domain 0 dB is
>>> commonly equated with FS.
>
>> No, that is 0dBFS.
>
> Yes, so your use of the word "no" must be some kind of terrible mistake on
> your part.
>

No, 0dBFS refers to full scale signal in a digital system. It is common,
especially in live recording to set '0dB' to -15dBFS so as to ensure
sufficient headroom. In other words, 0dB can be anything you like and
therefore on its own without context is meaningless.

>>> While the units are arbitrary and may be confusing to
>>> people who still think 100% analog, it is both
>>> meaningful and commonly used.
>
>> No it is not.
>
> Assertion without support, which should be immediately dismissed.
>

OK, then we will dismiss your original unsupported assertion that 'it is
both meaningful and commonly used'.

>>>> Input termination in both cases is unspecified.
>>> If the input is a mic input, then the usual standard of
>>> 300 ohms applies.
>
>> It is a power amp, it does not have a mic input. 300 ohms
>> is NOT the 'usual standard for a mic input'
>
> Good modern power amps are common, and do not have that much variation in
> their noise performance with normal variations in source impedance.
>
>>> If the input is a line level input, then the source
>>> impedance is usually such that system performance is not
>>> affected that much by probable variations.
>
>> You miss the point. How is the input terminated when
>> noise is measured - obviously it is not left open circuit
>> is it?
>
> I guess you've never measured the actual noise coming out of a good modern
> power amp with the normal range of source impedances. They often don't vary
> all that much. Remember, this is not legacy vacuum tube equipment which was
> generally far noisier.
>

A 'good modern one' should not vary much. We have no idea if the OPs's
device falls into this category. However, if the noise is being
minimised then a point will be reached when the source impedance is
relevant because if the amp was extremely noise free that would be the
ONLY source of noise.

OTOH, it will not vary much with source impedance if the amp is very
noisy to start with, like an old tube amp. SO precisdely the coinverse
of what you state is in fact true.

>>>> Output termination is unspecified.
>>> The noise performance of line level outputs is minimally
>>> affected by probable and reasonable variations in load
>>> impedance.
>
>>>> No bandwidth is specified.
>>> Relevant and already mentioned
>>>
>>>> No weighting or not is specified.
>>> Relevant and already mentioned
>>>
>>>> No mention of whether the measurements are rms, peak,
>>>> quasi-peak
>>> Both SNR and DR are ratios of two measurements. It is
>>> most important that both measurements be done under the
>>> same circumstances.
>
>> In fact they generally are not since a signal and noise
>> have quite different characteristics. The signal will be
>> measured rms. The noise can be measured in several ways
>> each giving a different figure.
>
> While people could be stupid and compare a noise level measured in
> peak-to-peak volts to a signal measured in average volts, I know of no
> actual cases where this happens, except perhaps in your mind, Ian.

No, but as I keep saying, manufacturers will show their product in the
best light and judicious use of weighting and bandwidths will alter the
'measured' value considerably. 'A' weighting, which is pretty commonly
used by manufacturers will often improve and amplifiers noise spec. by 10dB.

There
> could be equipment noise that has a high crest factor, but nature does not
> usually go down that path. What is then left is a few dB of ambiguity, and
> most good modern equipment (which is common) is not so noisy that a few dB
> is a deal breaker in actual use.
>

It is more than 'a few dB'

>> >> Variations in the way the above are specified can make a
>>>> large difference to the 'measured' value
>
>>> Some yes, some no.
>
>>>> and I bet you
>>>> can guess which set the marketing department will want
>>>> to choose.
>>> One other benefit of the solid state/digital revolution
>>> is that SNR and DR performance is often so good (> 100
>>> dB) that most variations in how they are mentioned don't
>>> matter that much.
>
>> Rubbish.
>
> Dismissive, unsupported claim, again itself worthy only of dismissal.
>

As I have said before DR and SNR are not the same and they have little
relation to the actual level of noise heard in the speaker. The OP's amp
for instance has an output power of 800W. Suppose this is into a load of
4 ohms then this requires over 56V rms output signal. The DR is 100dB so
the noise at the output is 100dB below 56V rms which which works out at
a mere -65dBu.

The original all tube Leak Point One in 1949 had a measured output noise
and hum of -80dB below 10W into 15 ohms which works out at just over 12V
rms. So its output noise is 80dB below 12V rms which works out to be a
mere -58dBu.

So in 60 years of development there's been only 7dB (oh sorry I should
have said 'just a few dB') of improvement due to the digital revolution.

>> Once again, SNR and DR are different animals.
>
> A truism - therefore something that actually sheds no significant light. Why
> do you obsess over these things, Ian?
>
>> Achieving a 100dB DR is not hard but unless you run your
>> amp close to clipping all the time you will not achieve
>> that as a SNR.
>
> Another truism.
>

Excellent, so then you must agree that SNR is always less than DR.

So to get back to the OP's original problem, having a DR of 100dB is
irrelevant. What matters is what his SNR is. The fact he can hear hiss
from an 800W amp with his ear right next to it further demonstrates this
because that is not where listeners will be when the spekaer pumps outn
800W.

>> The marketing guys are as active as ever in trying to
>> make their product appear superior to its competitors and
>> will choose the measurement methods that best do that.
>
> The myth is that some equipment is head-and-shoulders better than its
> competition. Everybody pretty much feeds from the same trough.
>
>

In reality, marketing departments will aim to make crappy equipment
appear much better than it is using specmanship which is what they have
always done.

Cheers

ian

Mr.T

March 18th 10, 06:43 AM

"Ian Bell" > wrote in message
...
> No, 0dBFS refers to full scale signal in a digital system. It is common,
> especially in live recording to set '0dB' to -15dBFS so as to ensure
> sufficient headroom. In other words, 0dB can be anything you like and
> therefore on its own without context is meaningless.

You are welcome to state your context that would make a 24bit "live
recording" on a 110-120dB souncard at -15dBFS peak level have more noise
than the ambient noise? :-)

And you know what I do in the studio, (and even live if I have a spare
channel) simply record two channels at different peak levels and select from
the one that gives me the highest level with no clipping, for each song!!
It's easy to make sure you do NOT waste that 15dB headroom with minimal
effort, by simply inserting a 20dB pad in one channel and running the other
"hot". In any case if I ever attain a *true* 100dB DNR recording I consider
myself very happy. (assuming no other problems of course :-)

But then we get people like Neil Young who considers a 16-44 CD as not good
enough for the release of an old 2 track 1/2" live analog reording that is
so far below ultimate CD quality as to make him a complete ******! I bet he
is the only one who considers 24-192 actually necessary in this case. I'd
really love to see a recent hearing test of his! :-)
(still love his old music though)

> No, but as I keep saying, manufacturers will show their product in the
> best light and judicious use of weighting and bandwidths will alter the
> 'measured' value considerably. 'A' weighting, which is pretty commonly
> used by manufacturers will often improve and amplifiers noise spec. by
10dB.

Sure, and a manufacturer who doesn't specify it as dBA, should be scorned
and avoided. Reputable manufacturers however provide both weighted and
unweighted figures.

> As I have said before DR and SNR are not the same and they have little
> relation to the actual level of noise heard in the speaker. The OP's amp
> for instance has an output power of 800W. Suppose this is into a load of
> 4 ohms then this requires over 56V rms output signal. The DR is 100dB so
> the noise at the output is 100dB below 56V rms which which works out at
> a mere -65dBu.
>
> The original all tube Leak Point One in 1949 had a measured output noise
> and hum of -80dB below 10W into 15 ohms which works out at just over 12V
> rms. So its output noise is 80dB below 12V rms which works out to be a
> mere -58dBu.
>
> So in 60 years of development there's been only 7dB (oh sorry I should
> have said 'just a few dB') of improvement due to the digital revolution.

Ah, but IF you turn down the gain on the 800W power amp so that it's output
power matches the Leak for the same input voltage, you may find it's DNR now
exceeds the Leak by a MUCH bigger margin! The choice is often in the hands
of the user, higher power, lower noise, or somewhere in between. Some are
too dumb to comprehend that higher power outputs require more gain of
course.

> Excellent, so then you must agree that SNR is always less than DR.

Nope, you must specify all your test conditions. Obviously there will be at
least one set of conditions where they *must* be equal for a start.
And if you measure DNR with an applied signal (as is usually the case for
soundcards) SNR may be *greater* than DNR, given any distortion products.
(and no headroom above 0dBFS like there was in the days of analog recorders,
that will actually add to the DNR)

> So to get back to the OP's original problem, having a DR of 100dB is
> irrelevant. What matters is what his SNR is. The fact he can hear hiss
> from an 800W amp with his ear right next to it further demonstrates this
> because that is not where listeners will be when the spekaer pumps outn
> 800W.

Exactly.

> In reality, marketing departments will aim to make crappy equipment
> appear much better than it is using specmanship which is what they have
> always done.

So true, but then the use of the term "Audiophile grade" was used frequently
in this thread. Your definition of "audiophile grade" may differ from mine
if it includes crappy equipment from disreputable manufacturers! :-)

MrT.

Arny Krueger

March 18th 10, 12:10 PM

"Ian Bell" > wrote in message

> Arny Krueger wrote:
>> "Ian Bell" > wrote in message
>>
>>> Arny Krueger wrote:
>>>> "Ian Bell" > wrote in message
>>>>
>>>>
>>>>> 0dB has no meaning.
>>>> Actually, it does. In the digital domain 0 dB is
>>>> commonly equated with FS.
>>
>>> No, that is 0dBFS.
>>
>> Yes, so your use of the word "no" must be some kind of
>> terrible mistake on your part.
>>
>
> No, 0dBFS refers to full scale signal in a digital
> system.

Of course!

> It is common, especially in live recording to set
> '0dB' to -15dBFS so as to ensure sufficient headroom. In other words, 0dB
> can be anything you like and therefore
> on its own without context is meaningless.

Ian, you seem to be fascinated with telling people that they are wrong, and
then explaining it by reciting either the exact same facts they did, or
paraphrasing them.

>>>> While the units are arbitrary and may be confusing to
>>>> people who still think 100% analog, it is both
>>>> meaningful and commonly used.

>>> No it is not.

>> Assertion without support, which should be immediately
>> dismissed.

> OK, then we will dismiss your original unsupported
> assertion that 'it is both meaningful and commonly used'.

Tit for tat?

>>>>> Input termination in both cases is unspecified.
>>>> If the input is a mic input, then the usual standard of
>>>> 300 ohms applies.
>>
>>> It is a power amp, it does not have a mic input. 300
>>> ohms is NOT the 'usual standard for a mic input'
>>
>> Good modern power amps are common, and do not have that
>> much variation in their noise performance with normal
>> variations in source impedance.

<no response from Ian>

>>>> If the input is a line level input, then the source
>>>> impedance is usually such that system performance is
>>>> not affected that much by probable variations.
>>
>>> You miss the point. How is the input terminated when
>>> noise is measured - obviously it is not left open
>>> circuit is it?

>> I guess you've never measured the actual noise coming
>> out of a good modern power amp with the normal range of
>> source impedances. They often don't vary all that much.
>> Remember, this is not legacy vacuum tube equipment which
>> was generally far noisier.

> A 'good modern one' should not vary much. We have no idea
> if the OPs's device falls into this category. However, if
> the noise is being minimised then a point will be reached when the source
> impedance is relevant because if the amp was extremely
> noise free that would be the ONLY source of noise.

Baseless speculation.

> OTOH, it will not vary much with source impedance if the
> amp is very noisy to start with, like an old tube amp. SO precisdely
> the coinverse of what you state is in fact true.

I thank you for substantiating a point I make below.

>>>>> Output termination is unspecified.
>>>> The noise performance of line level outputs is
>>>> minimally affected by probable and reasonable
>>>> variations in load impedance.
>>
>>>>> No bandwidth is specified.
>>>> Relevant and already mentioned
>>>>
>>>>> No weighting or not is specified.
>>>> Relevant and already mentioned
>>>>
>>>>> No mention of whether the measurements are rms, peak,
>>>>> quasi-peak
>>>> Both SNR and DR are ratios of two measurements. It is
>>>> most important that both measurements be done under the
>>>> same circumstances.
>>
>>> In fact they generally are not since a signal and noise
>>> have quite different characteristics. The signal will be
>>> measured rms. The noise can be measured in several ways
>>> each giving a different figure.
>>
>> While people could be stupid and compare a noise level
>> measured in peak-to-peak volts to a signal measured in
>> average volts, I know of no actual cases where this
>> happens, except perhaps in your mind, Ian.

> No, but as I keep saying, manufacturers will show their
> product in the best light and judicious use of weighting and bandwidths
> will alter the 'measured' value considerably. 'A'
> weighting, which is pretty commonly used by manufacturers will often
> improve and amplifiers
> noise spec. by 10dB.

Believe it or not, "A" weighting has a reasonble justification. It weights
the noise in accordance with the response of the human ear at the levels
that noise from a reasonably clean piece of equipment is likely to be heard.
It properly focuses on noise at frequencies where the ear is more sensitive,
and tends to give less weight to noise at frequencies where the ear is less
sensitive.

>> There
>> could be equipment noise that has a high crest factor,
>> but nature does not usually go down that path. What is
>> then left is a few dB of ambiguity, and most good modern
>> equipment (which is common) is not so noisy that a few
>> dB is a deal breaker in actual use.

> It is more than 'a few dB'

Baseless assertion.

>>> >> Variations in the way the above are specified canmake a
>>>>> large difference to the 'measured' value
>>
>>>> Some yes, some no.
>
>>>>> and I bet you
>>>>> can guess which set the marketing department will want
>>>>> to choose.

>>>> One other benefit of the solid state/digital revolution
>>>> is that SNR and DR performance is often so good (> 100
>>>> dB) that most variations in how they are mentioned
>>>> don't matter that much.

>>> Rubbish.
>>
>> Dismissive, unsupported claim, again itself worthy only
>> of dismissal.

> As I have said before DR and SNR are not the same and
> they have little relation to the actual level of noise
> heard in the speaker.

Ian, I've shown many ways that just your say so is not relevant or binding.
Come up with some authority other than yourself, or watch your whole
discussion flush down the toilet.

>The OP's amp for instance has an
> output power of 800W. Suppose this is into a load of 4
> ohms then this requires over 56V rms output signal. The
> DR is 100dB so the noise at the output is 100dB below 56V
> rms which which works out at a mere -65dBu.

The good news is that nobody in their right minds hooks 800 watt power amps
up to lines where 0 dBu is the reference level. IOW Ian, your example is
irrelevant to good, reasonable practice.

> The original all tube Leak Point One in 1949 had a
> measured output noise and hum of -80dB below 10W into 15
> ohms which works out at just over 12V rms. So its output
> noise is 80dB below 12V rms which works out to be a mere -58dBu.

And the point of equating 10 watt amps to 800 watt amps is?????????????

> So in 60 years of development there's been only 7dB (oh
> sorry I should have said 'just a few dB') of improvement due to the
> digital revolution.

?????????????????????

A claim that comes about due to the incredible folly of equating a 800 wpc
amp to a 10 wpc amp.

>>> Once again, SNR and DR are different animals.
>>
>> A truism - therefore something that actually sheds no
>> significant light. Why do you obsess over these things,
>> Ian?

<no answer>

>>> Achieving a 100dB DR is not hard but unless you run your
>>> amp close to clipping all the time you will not achieve
>>> that as a SNR.
>>
>> Another truism.

> Excellent, so then you must agree that SNR is always less
> than DR.

It can go either way. The most common current standard for measuring DR
involves the presence of a test signal and the inclusion of nonlinear
distortion. Depending on the piece of equipment, either SNR or DR can be the
larger number.

> So to get back to the OP's original problem, having a DR
> of 100dB is irrelevant. What matters is what his SNR is.

> The fact he can hear hiss from an 800W amp with his ear right next to it
> further
> demonstrates this because that is not where listeners
> will be when the spekaer pumps outn 800W.

The sentence itself is a non-sequitor, but if your point is that judging
amps by putting your ear right next to the speaker is questionable, then I
have to agree with that in general. OTOH, if there is some real world
connection between this test and actual use in the real world, then we have
to give the OP a pass.

>>> The marketing guys are as active as ever in trying to
>>> make their product appear superior to its competitors
>>> and will choose the measurement methods that best do
>>> that.

>> The myth is that some equipment is head-and-shoulders
>> better than its competition. Everybody pretty much feeds
>> from the same trough.

> In reality, marketing departments will aim to make crappy
> equipment appear much better than it is using specmanship which is
> what they have always done.

That's just it, the general quality of audio gear has improved signficantly
since the days of the Leak Point One.

Ian Bell[_2_]

March 18th 10, 12:21 PM

Arny Krueger wrote:
> "Ian Bell" > wrote in message
>
>> Arny Krueger wrote:
>>> "Ian Bell" > wrote in message
>>>
>>>> Arny Krueger wrote:
>>>>> "Ian Bell" > wrote in message
>>>>>
>>>>>
>>>>>> 0dB has no meaning.
>>>>> Actually, it does. In the digital domain 0 dB is
>>>>> commonly equated with FS.
>>>> No, that is 0dBFS.
>>> Yes, so your use of the word "no" must be some kind of
>>> terrible mistake on your part.
>>>
>> No, 0dBFS refers to full scale signal in a digital
>> system.
>
> Of course!
>
>> It is common, especially in live recording to set
>> '0dB' to -15dBFS so as to ensure sufficient headroom. In other words, 0dB
>> can be anything you like and therefore
>> on its own without context is meaningless.
>
> Ian, you seem to be fascinated with telling people that they are wrong, and
> then explaining it by reciting either the exact same facts they did, or
> paraphrasing them.
>
>>>>> While the units are arbitrary and may be confusing to
>>>>> people who still think 100% analog, it is both
>>>>> meaningful and commonly used.
>
>>>> No it is not.
>
>>> Assertion without support, which should be immediately
>>> dismissed.
>
>> OK, then we will dismiss your original unsupported
>> assertion that 'it is both meaningful and commonly used'.
>
> Tit for tat?
>
>>>>>> Input termination in both cases is unspecified.
>>>>> If the input is a mic input, then the usual standard of
>>>>> 300 ohms applies.
>>>> It is a power amp, it does not have a mic input. 300
>>>> ohms is NOT the 'usual standard for a mic input'
>>> Good modern power amps are common, and do not have that
>>> much variation in their noise performance with normal
>>> variations in source impedance.
>
> <no response from Ian>
>
>>>>> If the input is a line level input, then the source
>>>>> impedance is usually such that system performance is
>>>>> not affected that much by probable variations.
>>>> You miss the point. How is the input terminated when
>>>> noise is measured - obviously it is not left open
>>>> circuit is it?
>
>>> I guess you've never measured the actual noise coming
>>> out of a good modern power amp with the normal range of
>>> source impedances. They often don't vary all that much.
>>> Remember, this is not legacy vacuum tube equipment which
>>> was generally far noisier.
>
>> A 'good modern one' should not vary much. We have no idea
>> if the OPs's device falls into this category. However, if
>> the noise is being minimised then a point will be reached when the source
>> impedance is relevant because if the amp was extremely
>> noise free that would be the ONLY source of noise.
>
> Baseless speculation.
>
>> OTOH, it will not vary much with source impedance if the
>> amp is very noisy to start with, like an old tube amp. SO precisdely
>> the coinverse of what you state is in fact true.
>
> I thank you for substantiating a point I make below.
>
>>>>>> Output termination is unspecified.
>>>>> The noise performance of line level outputs is
>>>>> minimally affected by probable and reasonable
>>>>> variations in load impedance.
>>>>>> No bandwidth is specified.
>>>>> Relevant and already mentioned
>>>>>
>>>>>> No weighting or not is specified.
>>>>> Relevant and already mentioned
>>>>>
>>>>>> No mention of whether the measurements are rms, peak,
>>>>>> quasi-peak
>>>>> Both SNR and DR are ratios of two measurements. It is
>>>>> most important that both measurements be done under the
>>>>> same circumstances.
>>>> In fact they generally are not since a signal and noise
>>>> have quite different characteristics. The signal will be
>>>> measured rms. The noise can be measured in several ways
>>>> each giving a different figure.
>>> While people could be stupid and compare a noise level
>>> measured in peak-to-peak volts to a signal measured in
>>> average volts, I know of no actual cases where this
>>> happens, except perhaps in your mind, Ian.
>
>> No, but as I keep saying, manufacturers will show their
>> product in the best light and judicious use of weighting and bandwidths
>> will alter the 'measured' value considerably. 'A'
>> weighting, which is pretty commonly used by manufacturers will often
>> improve and amplifiers
>> noise spec. by 10dB.
>
> Believe it or not, "A" weighting has a reasonble justification. It weights
> the noise in accordance with the response of the human ear at the levels
> that noise from a reasonably clean piece of equipment is likely to be heard.
> It properly focuses on noise at frequencies where the ear is more sensitive,
> and tends to give less weight to noise at frequencies where the ear is less
> sensitive.
>
>>> There
>>> could be equipment noise that has a high crest factor,
>>> but nature does not usually go down that path. What is
>>> then left is a few dB of ambiguity, and most good modern
>>> equipment (which is common) is not so noisy that a few
>>> dB is a deal breaker in actual use.
>
>> It is more than 'a few dB'
>
> Baseless assertion.
>
>
>>>> >> Variations in the way the above are specified canmake a
>>>>>> large difference to the 'measured' value
>>>>> Some yes, some no.
>>>>>> and I bet you
>>>>>> can guess which set the marketing department will want
>>>>>> to choose.
>
>>>>> One other benefit of the solid state/digital revolution
>>>>> is that SNR and DR performance is often so good (> 100
>>>>> dB) that most variations in how they are mentioned
>>>>> don't matter that much.
>
>>>> Rubbish.
>>> Dismissive, unsupported claim, again itself worthy only
>>> of dismissal.
>
>> As I have said before DR and SNR are not the same and
>> they have little relation to the actual level of noise
>> heard in the speaker.
>
> Ian, I've shown many ways that just your say so is not relevant or binding.
> Come up with some authority other than yourself, or watch your whole
> discussion flush down the toilet.
>
>> The OP's amp for instance has an
>> output power of 800W. Suppose this is into a load of 4
>> ohms then this requires over 56V rms output signal. The
>> DR is 100dB so the noise at the output is 100dB below 56V
>> rms which which works out at a mere -65dBu.
>
>
> The good news is that nobody in their right minds hooks 800 watt power amps
> up to lines where 0 dBu is the reference level. IOW Ian, your example is
> irrelevant to good, reasonable practice.
>
>> The original all tube Leak Point One in 1949 had a
>> measured output noise and hum of -80dB below 10W into 15
>> ohms which works out at just over 12V rms. So its output
>> noise is 80dB below 12V rms which works out to be a mere -58dBu.
>
> And the point of equating 10 watt amps to 800 watt amps is?????????????
>
>> So in 60 years of development there's been only 7dB (oh
>> sorry I should have said 'just a few dB') of improvement due to the
>> digital revolution.
>
> ?????????????????????
>
> A claim that comes about due to the incredible folly of equating a 800 wpc
> amp to a 10 wpc amp.
>
>>>> Once again, SNR and DR are different animals.
>>> A truism - therefore something that actually sheds no
>>> significant light. Why do you obsess over these things,
>>> Ian?
>
> <no answer>
>
>>>> Achieving a 100dB DR is not hard but unless you run your
>>>> amp close to clipping all the time you will not achieve
>>>> that as a SNR.
>>> Another truism.
>
>> Excellent, so then you must agree that SNR is always less
>> than DR.
>
> It can go either way. The most common current standard for measuring DR
> involves the presence of a test signal and the inclusion of nonlinear
> distortion. Depending on the piece of equipment, either SNR or DR can be the
> larger number.
>
>> So to get back to the OP's original problem, having a DR
>> of 100dB is irrelevant. What matters is what his SNR is.
>
>> The fact he can hear hiss from an 800W amp with his ear right next to it
>> further
>> demonstrates this because that is not where listeners
>> will be when the spekaer pumps outn 800W.
>
> The sentence itself is a non-sequitor, but if your point is that judging
> amps by putting your ear right next to the speaker is questionable, then I
> have to agree with that in general. OTOH, if there is some real world
> connection between this test and actual use in the real world, then we have
> to give the OP a pass.
>
>>>> The marketing guys are as active as ever in trying to
>>>> make their product appear superior to its competitors
>>>> and will choose the measurement methods that best do
>>>> that.
>
>>> The myth is that some equipment is head-and-shoulders
>>> better than its competition. Everybody pretty much feeds
>>> from the same trough.
>
>> In reality, marketing departments will aim to make crappy
>> equipment appear much better than it is using specmanship which is
>> what they have always done.
>
> That's just it, the general quality of audio gear has improved signficantly
> since the days of the Leak Point One.
>
>

Arny, you seem more interested in argument than technical discussion so
I am going to waste no more time on you.

Cheers

Ian