dynamic mic self noise (and my re15)

[Nate Najar]

I don't know enough about microphones, I do know a moving coil microphone is a fairly simple electro mechanical device.....

If I could change one and only one thing about my re15's it's that they seem to be a bit noisy. Not a terrible deal breaker, but those mics are so good otherwise it would be nice to have a specimen that went all the way. Would changing the transformer help? I don't want to use an re20 (except when I want to use an re20)- the response is crispier and that mic is more difficult to place.

And then of course the low output introduces the option for preamp noise to compound the issue. I'm using good preamps (prism orpheus) but if you get up to about 50db of gain they start to add their own noticeable noise. But the mics themselves are a bit white noisy.

What causes that to be the case and is there anything that can be done? It's not like anyone out there is making a comparable product.....

N

[Adrian Tuddenham[_2_]]

Nate Najar > wrote:

> I don't know enough about microphones, I do know a moving coil microphone
> is a fairly simple electro mechanical device.....
>
> If I could change one and only one thing about my re15's it's that they
> seem to be a bit noisy. Not a terrible deal breaker, but those mics are
> so good otherwise it would be nice to have a specimen that went all the
> way. Would changing the transformer help? I don't want to use an re20
> (except when I want to use an re20)- the response is crispier and that mic
> is more difficult to place.
>
> And then of course the low output introduces the option for preamp noise
> to compound the issue. I'm using good preamps (prism orpheus) but if you
> get up to about 50db of gain they start to add their own noticeable noise.
> But the mics themselves are a bit white noisy.
>
> What causes that to be the case and is there anything that can be done?
> It's not like anyone out there is making a comparable product.....
>
> N

There could be several possible causes, what does the noise sound like?


--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

[Dave Plowman (News)]

In article >,
Nate Najar > wrote:
> And then of course the low output introduces the option for preamp noise
> to compound the issue. I'm using good preamps (prism orpheus) but if
> you get up to about 50db of gain they start to add their own noticeable
> noise. But the mics themselves are a bit white noisy.

In the old days we used to have 30/300 ohm input matching transformers on
the amp input for those low impedance STC mics in use then. But that was
with valve pre-amps. When transistors came along they were dispensed with
- the transistor amps said to have a good enough noise performance even
with the 30 ohm mics.

--
*Acupuncture is a jab well done*

Dave Plowman London SW
To e-mail, change noise into sound.

[Mike Rivers[_2_]]

On 1/16/2015 4:13 AM, Nate Najar wrote:

> If I could change one and only one thing about my re15's it's that
> they seem to be a bit noisy. Not a terrible deal breaker, but those
> mics are so good otherwise it would be nice to have a specimen that
> went all the way. Would changing the transformer help? I don't want
> to use an re20 (except when I want to use an re20)- the response is
> crispier and that mic is more difficult to place.

The microphone itself doesn't generate noise since it's totally passive.
The noise is actually from the input stage of the mic preamp as it sees
the mic's source impedance. Now you know one more thing about
microphones. When you need to run the preamp near maximum gain in order
to get a decent record level, the hiss increases. Changing the
transformer would change the mic. You might like it or you might not.

A small step up transformer between the mic and preamp, maybe a 1:2
ratio, would give you 6 dB of noise-free gain. A Jensen JT-16ATB in a
box would be an easy to build project and probably wouldn't change the
sound of the mic or preamp much. You might even like your Prism with a
transformer input with other mics. I wouldn't mess with changing the
transformer in the mic, though. Now that Jensen is owned by Radial,
maybe there's a ready-made Radial "problem solver" box that you could
try. I'll try to remember to look for one or ask at their booth at NAMM.

> I'm using good preamps (prism orpheus)
> but if you get up to about 50db of gain they start to add their own
> noticeable noise. But the mics themselves are a bit white noisy.

I found, when I had a Lyra here for a review, that I could hear (and
hence record) a little hiss with my "M260-DX" ribbon mics, and even with
an SM-57. Preamps like the AEA TRP are designed to alleviate that
problem. A less expensive alternative for you to try is the Cloudlifter.
That's something you can buy, try, and return if it doesn't make the mic
more usable. I had the opportunity to plug the M260-DX into one once and
it definitely gave me significantly more level above the hiss. I didn't
spend any time trying to hear any change in the sound of the mic, but
since Cloud makes it to use with their own ribbon mics which are pretty
good RCA style ribbon mics, he must think it's OK.


--
For a good time, visit http://mikeriversaudio.wordpress.com

[Adrian Tuddenham[_2_]]

Mike Rivers > wrote:

> On 1/16/2015 4:13 AM, Nate Najar wrote:
>
> > If I could change one and only one thing about my re15's it's that
> > they seem to be a bit noisy. Not a terrible deal breaker, but those
> > mics are so good otherwise it would be nice to have a specimen that
> > went all the way. Would changing the transformer help? I don't want
> > to use an re20 (except when I want to use an re20)- the response is
> > crispier and that mic is more difficult to place.
>
> The microphone itself doesn't generate noise since it's totally passive.

Moving-coil microphones do generate noise: the resistance of the coil
generates Johnson noise due to thermal movement of the electrons. There
is also noise from the Brownian movement of the air molecules impacting
on the diaphragm (you may consider that this is not actually generated
by the microphone, but it is an inevitably part of the inherent
microphone noise in normal use).

In a well-designed microphone, the Johnson noise and the Brownian noise
will be of similar magnitude. In a well designed pre-amp, the
electronic noise should be significantly lower than the total inherent
microphone noise.

Igor M and I did some experiments on popular moving coil mics and found
that the inherent noise of most of them was too high to use them for
talking book work, regardless of how good the pre-amp was.

--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

[Mike Rivers[_2_]]

On 1/16/2015 3:47 PM, Adrian Tuddenham wrote:
> Moving-coil microphones do generate noise: the resistance of the coil
> generates Johnson noise due to thermal movement of the electrons. There
> is also noise from the Brownian movement of the air molecules impacting
> on the diaphragm (you may consider that this is not actually generated
> by the microphone, but it is an inevitably part of the inherent
> microphone noise in normal use).
>
> In a well-designed microphone, the Johnson noise and the Brownian noise
> will be of similar magnitude. In a well designed pre-amp, the
> electronic noise should be significantly lower than the total inherent
> microphone noise.

I know about the physics of moving molecules, both air and electrical.
But every time I say that to someone knowledgeable, they always say that
it's the current noise when the input of the input transistor(s) is
connected to the microphone that does most of the damage. There's
between 3 and 6 dB less noise coming out of a preamp with the input
shorted than when it has 150 ohms or so to develop voltage across.

But, for sure, if you really need quiet output with a quiet source at a
reasonable working distance, you need a microphone with higher output
voltage than most dynamics can provide.

--
For a good time, visit http://mikeriversaudio.wordpress.com

[Nate Najar]

On Thursday, January 15, 2015 at 10:13:59 PM UTC-5, Nate Najar wrote:
> I don't know enough about microphones, I do know a moving coil microphone is a fairly simple electro mechanical device.....
>
> If I could change one and only one thing about my re15's it's that they seem to be a bit noisy. Not a terrible deal breaker, but those mics are so good otherwise it would be nice to have a specimen that went all the way. Would changing the transformer help? I don't want to use an re20 (except when I want to use an re20)- the response is crispier and that mic is more difficult to place.
>
> And then of course the low output introduces the option for preamp noise to compound the issue. I'm using good preamps (prism orpheus) but if you get up to about 50db of gain they start to add their own noticeable noise. But the mics themselves are a bit white noisy.
>
> What causes that to be the case and is there anything that can be done? It's not like anyone out there is making a comparable product.....
>
> N

I learned something today. This is helpful, thanks!

[Adrian Tuddenham[_2_]]

Mike Rivers > wrote:

> On 1/16/2015 3:47 PM, Adrian Tuddenham wrote:
> > Moving-coil microphones do generate noise: the resistance of the coil
> > generates Johnson noise due to thermal movement of the electrons. There
> > is also noise from the Brownian movement of the air molecules impacting
> > on the diaphragm (you may consider that this is not actually generated
> > by the microphone, but it is an inevitably part of the inherent
> > microphone noise in normal use).
> >
> > In a well-designed microphone, the Johnson noise and the Brownian noise
> > will be of similar magnitude. In a well designed pre-amp, the
> > electronic noise should be significantly lower than the total inherent
> > microphone noise.
>
> I know about the physics of moving molecules, both air and electrical.
> But every time I say that to someone knowledgeable, they always say that
> it's the current noise when the input of the input transistor(s) is
> connected to the microphone that does most of the damage. There's
> between 3 and 6 dB less noise coming out of a preamp with the input
> shorted than when it has 150 ohms or so to develop voltage across.

It depend entirely on the pre-amp and what it was designed to do. A
pre-amp designed to match 150 ohms should give *more* noise when it is
shorted then it does when terminated with 150 ohms. This is because the
current and voltage noise sources should be optimally balanced at the
correct terminating impedance and any move away from that impedance will
give poorer noise figures (Do not be mis-led by looking only at voltage
and ignoring power, which is the only true measure of noise and signal.)
If this doesn't happen, the pre-amp is not correctly matched.

> But, for sure, if you really need quiet output with a quiet source at a
> reasonable working distance, you need a microphone with higher output
> voltage than most dynamics can provide.

Or a dynamic mic with the same output voltage from a lower source
impedance - again, *power* is the key to everything when you are trying
to keep the noise down.


--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

[Don Pearce[_3_]]

On Fri, 16 Jan 2015 17:17:51 +0000,
(Adrian Tuddenham) wrote:

>Mike Rivers > wrote:
>
>> On 1/16/2015 3:47 PM, Adrian Tuddenham wrote:
>> > Moving-coil microphones do generate noise: the resistance of the coil
>> > generates Johnson noise due to thermal movement of the electrons. There
>> > is also noise from the Brownian movement of the air molecules impacting
>> > on the diaphragm (you may consider that this is not actually generated
>> > by the microphone, but it is an inevitably part of the inherent
>> > microphone noise in normal use).
>> >
>> > In a well-designed microphone, the Johnson noise and the Brownian noise
>> > will be of similar magnitude. In a well designed pre-amp, the
>> > electronic noise should be significantly lower than the total inherent
>> > microphone noise.
>>
>> I know about the physics of moving molecules, both air and electrical.
>> But every time I say that to someone knowledgeable, they always say that
>> it's the current noise when the input of the input transistor(s) is
>> connected to the microphone that does most of the damage. There's
>> between 3 and 6 dB less noise coming out of a preamp with the input
>> shorted than when it has 150 ohms or so to develop voltage across.
>
>It depend entirely on the pre-amp and what it was designed to do. A
>pre-amp designed to match 150 ohms should give *more* noise when it is
>shorted then it does when terminated with 150 ohms. This is because the
>current and voltage noise sources should be optimally balanced at the
>correct terminating impedance and any move away from that impedance will
>give poorer noise figures (Do not be mis-led by looking only at voltage
>and ignoring power, which is the only true measure of noise and signal.)
>If this doesn't happen, the pre-amp is not correctly matched.
>
>> But, for sure, if you really need quiet output with a quiet source at a
>> reasonable working distance, you need a microphone with higher output
>> voltage than most dynamics can provide.
>
>Or a dynamic mic with the same output voltage from a lower source
>impedance - again, *power* is the key to everything when you are trying
>to keep the noise down.

Quite so. I've designed preamps for all sorts of applications. I did
one for a mic with a 30 ohms impedance. I achieved best noise figure
using a high speed op amp with discrete bipolars feeding it - six of
them on each polarity, wired in parallel to make a pair of
super-transistors..

If you want to use just an integrated amp, look at both voltage and
current noise specs. Turn the current noise into voltage noise using
Ohms law and the total loaded input impedance, then sum the two
powers. For any combination of voltage and current noise, there will
be an optimum impedance.

d

[Les Cargill[_4_]]

(Adrian Tuddenham) wrote:
> Mike Rivers > wrote:
>
>> On 1/16/2015 4:13 AM, Nate Najar wrote:
>>
>> > If I could change one and only one thing about my re15's it's that
>> > they seem to be a bit noisy. Not a terrible deal breaker, but those
>> > mics are so good otherwise it would be nice to have a specimen that
>> > went all the way. Would changing the transformer help? I don't want
>> > to use an re20 (except when I want to use an re20)- the response is
>> > crispier and that mic is more difficult to place.
>>
>> The microphone itself doesn't generate noise since it's totally passive.
>
> Moving-coil microphones do generate noise: the resistance of the coil
> generates Johnson noise due to thermal movement of the electrons. There
> is also noise from the Brownian movement of the air molecules impacting
> on the diaphragm (you may consider that this is not actually generated
> by the microphone, but it is an inevitably part of the inherent
> microphone noise in normal use).
>
> In a well-designed microphone, the Johnson noise and the Brownian noise
> will be of similar magnitude. In a well designed pre-amp, the
> electronic noise should be significantly lower than the total inherent
> microphone noise.
>
> Igor M and I did some experiments on popular moving coil mics and found
> that the inherent noise of most of them was too high to use them for
> talking book work, regardless of how good the pre-amp was.
>


What was the relative level of room tone? Were these used only in a
voiceover booth?

I would think room tone would be more than all the other noise added.

--
Les Cargill

[Les Cargill[_4_]]

(Adrian Tuddenham) wrote:
> Mike Rivers > wrote:
>
>> On 1/16/2015 3:47 PM, Adrian Tuddenham wrote:
>>> Moving-coil microphones do generate noise: the resistance of the coil
>>> generates Johnson noise due to thermal movement of the electrons. There
>>> is also noise from the Brownian movement of the air molecules impacting
>>> on the diaphragm (you may consider that this is not actually generated
>>> by the microphone, but it is an inevitably part of the inherent
>>> microphone noise in normal use).
>>>
>>> In a well-designed microphone, the Johnson noise and the Brownian noise
>>> will be of similar magnitude. In a well designed pre-amp, the
>>> electronic noise should be significantly lower than the total inherent
>>> microphone noise.
>>
>> I know about the physics of moving molecules, both air and electrical.
>> But every time I say that to someone knowledgeable, they always say that
>> it's the current noise when the input of the input transistor(s) is
>> connected to the microphone that does most of the damage. There's
>> between 3 and 6 dB less noise coming out of a preamp with the input
>> shorted than when it has 150 ohms or so to develop voltage across.
>
> It depend entirely on the pre-amp and what it was designed to do. A
> pre-amp designed to match 150 ohms should give *more* noise when it is
> shorted then it does when terminated with 150 ohms. This is because the
> current and voltage noise sources should be optimally balanced at the
> correct terminating impedance and any move away from that impedance will
> give poorer noise figures (Do not be mis-led by looking only at voltage
> and ignoring power, which is the only true measure of noise and signal.)
> If this doesn't happen, the pre-amp is not correctly matched.
>
>> But, for sure, if you really need quiet output with a quiet source at a
>> reasonable working distance, you need a microphone with higher output
>> voltage than most dynamics can provide.
>
> Or a dynamic mic with the same output voltage from a lower source
> impedance - again, *power* is the key to everything when you are trying
> to keep the noise down.
>
>

Has anyone tried a Cloudlifter? Does it only solve impedance problems (
(???)_, or does it help with noise as well?

Or is it just another denuded emperor?

--
Les Cargill

[PStamler]

Whether the Johnson noise or the current noise predominates, or the preamp's voltage noise, will depend entirely on the design of the preamp. But the fact is that dynamic mics do generate self-noise via the DC resistances of their coils and/or transformers.

And yes, a Cloudlifter may ease the problem; it has gain as well as selectable loading.

Warning: just patching a transformer into the circuit, say a 1:2, as someone suggested, probably won't give good results. If the preamp has an input impedance of 1500 ohms (typical), a 1:2 transformer will show the mic a load impedance of (1500 ohms/4), or 375 ohms. The mic probably won't like that load, and it'll drop the signal level, which will aggravate the preamp noise problem as you need to dial in more gain. Plus the transformer has DC resistance of its own that adds to the mess.

Go with the Cloudlifter.

Peace,
Paul

[Mike Rivers[_2_]]

On 1/16/2015 7:18 PM, Les Cargill wrote:
> Has anyone tried a Cloudlifter? Does it only solve impedance problems (
> (???)_, or does it help with noise as well?

I used one for an hour and a half with my Stephen Sank modified Beyer
M260. I was able to use less gain on the Mackie mixer's mic preamp for
the same mix level, and got less hiss in the bargain. I'd say that was a
good thing. I didn't attempt to evaluate whether it changed the "sound"
of the mic. The bottom line is that it worked better with the
Cloudlifter than without, and the quiet banjo I was miking sounded fine.

--
For a good time, visit http://mikeriversaudio.wordpress.com

[hank alrich]

Nate Najar > wrote:

> I don't know enough about microphones, I do know a moving coil microphone
> is a fairly simple electro mechanical device.....
>
> If I could change one and only one thing about my re15's it's that they
> seem to be a bit noisy. Not a terrible deal breaker, but those mics are
> so good otherwise it would be nice to have a specimen that went all the
> way. Would changing the transformer help? I don't want to use an re20
> (except when I want to use an re20)- the response is crispier and that mic
> is more difficult to place.
>
> And then of course the low output introduces the option for preamp noise
> to compound the issue. I'm using good preamps (prism orpheus) but if you
> get up to about 50db of gain they start to add their own noticeable noise.
> But the mics themselves are a bit white noisy.
>
> What causes that to be the case and is there anything that can be done?
> It's not like anyone out there is making a comparable product.....
>
> N

How much more gain do you desire between mic and conversion?

So far I have not been impressed that much with the "good" preamps in
most convertors. Most of those I have met, admittedly casually, seem
almost as good as the preamps in a Mackie Onyx 1620i.

I know an original Great River is not going to hiss at me wide open,
unless the mic is hissing at the preamp.

--
shut up and play your guitar * HankAlrich.Com
HankandShaidriMusic.Com
YouTube.Com/WalkinayMusic

[Nate Najar]

Well the reason I'm asking about mic noise and assuming it isn't all preamp noise is that when I plug in a 4038 with the same amount of gain, it isn't as hissy.....

[hank alrich]

Nate Najar > wrote:

> Well the reason I'm asking about mic noise and assuming it isn't all
>preamp noise is that when I plug in a 4038 with the same amount of
>gain, it isn't as hissy.....
>

RE15 roll-off switch set to <Flat>?

A look at specs says they offer the preamp different source impedances,
150 versus 300 ohms, probably different sensitivities and max SPL specs,
too.

http://www.coutant.org/data/re15.pdf

http://www.coleselectroacoustics.com/images/pdfs/4038Spec.pdf

--
shut up and play your guitar * HankAlrich.Com
HankandShaidriMusic.Com
YouTube.Com/WalkinayMusic

[Trevor]

On 18/01/2015 9:39 AM, Nate Najar wrote:
> Well the reason I'm asking about mic noise and assuming it isn't all
preamp noise is that when I plug in a 4038 with the same amount of gain,
it isn't as hissy.....
>

Presumably the mics are different internal impedances then.

Trevor.

[Nate Najar]

On Sunday, January 18, 2015 at 12:49:53 AM UTC-5, Trevor wrote:
> On 18/01/2015 9:39 AM, Nate Najar wrote:
> > Well the reason I'm asking about mic noise and assuming it isn't all
> preamp noise is that when I plug in a 4038 with the same amount of gain,
> it isn't as hissy.....
> >
>
> Presumably the mics are different internal impedances then.
>
> Trevor.

they are. the RE15 is 150ohms and the 4038 is 300ohms. I don't know how that affects the preamp in terms of noise though. That's basically why I'm asking the questions.

Don't get me wrong, it isn't too noisy to not use, not at all, but it's much noisier than most of my mics and I just am trying to educate myself as to why.

[Dave Plowman (News)]

In article >,
Nate Najar > wrote:
> Well the reason I'm asking about mic noise and assuming it isn't all
> preamp noise is that when I plug in a 4038 with the same amount of gain,
> it isn't as hissy.....

Is that a 30 or 300 ohm 4038?

--
*When everything's coming your way, you're in the wrong lane *

Dave Plowman London SW
To e-mail, change noise into sound.

[Scott Dorsey]

>Nate Najar > wrote:
>
>> Well the reason I'm asking about mic noise and assuming it isn't all
>>preamp noise is that when I plug in a 4038 with the same amount of
>>gain, it isn't as hissy.....
>>
>
>RE15 roll-off switch set to <Flat>?
>
>A look at specs says they offer the preamp different source impedances,
>150 versus 300 ohms, probably different sensitivities and max SPL specs,
>too.

It's the source impedance that makes the difference in preamp noise. Notice
with neither microphone plugged in, the noise is probably much higher.

Marshall Leach has a paper on preamp input stage design where he actually
goes through all the math for noise on fet, tube, and transistor input
stages with and without transformers.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Adrian Tuddenham[_2_]]

Nate Najar > wrote:

> Well the reason I'm asking about mic noise and assuming it isn't all
preamp noise is that when I plug in a 4038 with the same amount of gain,
it isn't as hissy.....


If you want to see a pre-amp that was designed specifically to give the
best possible S/N ratio from a 4038, have a look at the AMC/5 in:

<http://www.poppyrecords.co.uk/other/BBCamplifiers.pdf>

The key to its low noise is the combination of voltage and current
feedback, which gets around the problem of noise generated in
input-loading resistors.

A lot of modern pre-amps don't bother with this and think that by
choosing a low-noise input transistor and slapping a loading resistor
across it, everything will be all right. The S/N ratio from this
method is always at least 6dB worse than the best that could have been
achieved by a good feedback design. Your pre-amp might fall into this
category or it might have been designed for lowest noise at an impedance
other than the one you are using it at - and the 4038 is nearer than the
RE15 to that impedance.


--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

[Scott Dorsey]

Les Cargill > wrote:
>
>Has anyone tried a Cloudlifter? Does it only solve impedance problems (
>(???)_, or does it help with noise as well?
>
>Or is it just another denuded emperor?

Because the cloudlifter has a high-Z input stage, it will be noisier than a
perfectly matched preamp.

However, in practice you'll find that it's often much quieter than the preamp
in an inexpensive console, even if it's still a lot noiser than the input to
a John Hardy or Millennia preamp, so it can still be a useful tool for that.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Les Cargill[_4_]]

(Scott Dorsey) wrote:
> Les Cargill > wrote:
>>
>> Has anyone tried a Cloudlifter? Does it only solve impedance problems (
>> (???)_, or does it help with noise as well?
>>
>> Or is it just another denuded emperor?
>
> Because the cloudlifter has a high-Z input stage, it will be noisier than a
> perfectly matched preamp.
>

Then why does it have a big "Z" knob on the top?

> However, in practice you'll find that it's often much quieter than the preamp
> in an inexpensive console, even if it's still a lot noiser than the input to
> a John Hardy or Millennia preamp, so it can still be a useful tool for that.
> --scott
>

--
Les Cargill

[Mike Rivers[_2_]]

On 1/20/2015 8:08 PM, Les Cargill wrote:
>> Because the cloudlifter has a high-Z input stage, it will be noisier
>> than a
>> perfectly matched preamp.

> Then why does it have a big "Z" knob on the top?

They don't publish the input impedance of the standard Cloudlifter, but
as I recall, it's "pretty normal," maybe 1500 or 3,000 Ohms. Roger told
me once, but I forgot. The one with the big Z on it is the
Cloudlifter-Z. This has a pot hanging across a fairly high input
impedance to vary the load on the mic from 150 ohms to 15 k ohms.

--
"Today's production equipment is IT based and cannot be operated without
a passing knowledge of computing, although it seems that it can be
operated without a passing knowledge of audio" - John Watkinson

Drop by http://mikeriversaudio.wordpress.com now and then

[Adrian Tuddenham[_2_]]

Mike Rivers > wrote:

> On 1/20/2015 8:08 PM, Les Cargill wrote:
> >> Because the cloudlifter has a high-Z input stage, it will be noisier
> >> than a
> >> perfectly matched preamp.
>
> > Then why does it have a big "Z" knob on the top?
>
> They don't publish the input impedance of the standard Cloudlifter, but
> as I recall, it's "pretty normal," maybe 1500 or 3,000 Ohms. Roger told
> me once, but I forgot. The one with the big Z on it is the
> Cloudlifter-Z. This has a pot hanging across a fairly high input
> impedance to vary the load on the mic from 150 ohms to 15 k ohms.

So it is at least 6dB noiser than it needs to be. If they had varied a
current-determining component in the feedback loop, the results would be
a lot better.

--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

[Scott Dorsey]

Les Cargill > wrote:
(Scott Dorsey) wrote:
>> Les Cargill > wrote:
>>>
>>> Has anyone tried a Cloudlifter? Does it only solve impedance problems (
>>> (???)_, or does it help with noise as well?
>>>
>>> Or is it just another denuded emperor?
>>
>> Because the cloudlifter has a high-Z input stage, it will be noisier than a
>> perfectly matched preamp.
>
>Then why does it have a big "Z" knob on the top?

That adds a shunt resistor in parallel with the input. So the microphone
sees a lower impedance load, but the noise is not decreased (and is actually
slightly increased).

The only way to get a real adjustable input Z that maintains noise performance
at all settings is to use a multitap transformer. And that has other issues.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

In article >, Mike Rivers > wrote:
>On 1/21/2015 12:05 PM, Scott Dorsey wrote:
>> That adds a shunt resistor in parallel with the input. So the microphone
>> sees a lower impedance load, but the noise is not decreased (and is actually
>> slightly increased).
>>
>> The only way to get a real adjustable input Z that maintains noise performance
>
>I've only found one microphone, a CAD ribbon, that sounded better with a
>low impedance load than it did with a conventional 1.5-2.5k ohm mic
>preamp input. I think it's a gimmick, but if it makes a too-bright mic
>sound less bright, I suppose it's good for those who have that problem
>(or that mic).

The SM-57 sure sounds better with a low-Z load!

>The thing is that overall, adding 20 dB of output level to the preamp
>input when you need it while increasing the preamp noise by only a few
>dB, is better for most everyone. The only reason to fuss with that is if
>you insist on only using the best designs (or nothing).

It sure would be better if more people used better preamps, though.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Mike Rivers[_2_]]

On 1/21/2015 1:56 PM, Scott Dorsey wrote:
> The SM-57 sure sounds better with a low-Z load!

The SM-57 sounds better with the PROPER load (thanks, Paul Stamler). The
only preamp I have with a selectable input impedance is a Mackie 800R,
and they missed the SM-57 sweet spot on that one (probably never knew
about Paul's tests). As I recall, its choices are 300, 500, 1300, and
2400 ohms. My SM-57 sounds dull at 300 ohms, about the same at 500 and
1300 ohms, and like an SM-57 at 2400 ohms.

--
"Today's production equipment is IT based and cannot be operated without
a passing knowledge of computing, although it seems that it can be
operated without a passing knowledge of audio" - John Watkinson

Drop by http://mikeriversaudio.wordpress.com now and then

[jason]

On Wed, 21 Jan 2015 21:10:09 -0500 "Mike Rivers" > wrote
in article >
>
> On 1/21/2015 1:56 PM, Scott Dorsey wrote:
> > The SM-57 sure sounds better with a low-Z load!
>
> The SM-57 sounds better with the PROPER load (thanks, Paul Stamler). The
> only preamp I have with a selectable input impedance is a Mackie 800R,
> and they missed the SM-57 sweet spot on that one (probably never knew
> about Paul's tests). As I recall, its choices are 300, 500, 1300, and
> 2400 ohms. My SM-57 sounds dull at 300 ohms, about the same at 500 and
> 1300 ohms, and like an SM-57 at 2400 ohms.

This may be a silly question - squelch it if so, but what makes "good"
preamps so expensive? I presume all the designers know of the good parts
to use and of good designs (wrong?) but beyond that what accounts for the
price? ..better design? good testing? careful component matching? just
askin'

[PStamler]

On Wednesday, January 21, 2015 at 8:09:39 PM UTC-6, Mike Rivers wrote:
> On 1/21/2015 1:56 PM, Scott Dorsey wrote:
> > The SM-57 sure sounds better with a low-Z load!
>
> The SM-57 sounds better with the PROPER load (thanks, Paul Stamler). The
> only preamp I have with a selectable input impedance is a Mackie 800R,
> and they missed the SM-57 sweet spot on that one (probably never knew
> about Paul's tests). As I recall, its choices are 300, 500, 1300, and
> 2400 ohms. My SM-57 sounds dull at 300 ohms, about the same at 500 and
> 1300 ohms, and like an SM-57 at 2400 ohms.

I think they may have known; my tests were done at 2,000 and 500 ohms (the only two choices on the UA 2-610 preamp I used). Incidentally, I don't know if those settings include the phantom power resistors, but in any case adding those to a 500 ohm load makes it 482 ohms, which I'd call not enough change to shake a stick at. Incidentally, the 699 ohm Gizmo brought the 2,000 ohm load down to about 518 ohms. That was as close to 500 ohms as I could get with the resistors my surplus store had in stock.

As the "Taming of the Shure" article said, I found the 500 ohm setting a great improvement over 2,000 ohms. Dunno if that's the exact "sweet spot" for an SM57, but to my ears it's close.

Incidentally, I've tried changing the loading on other mics, with a null result; on most mics I tried (explicitly including the BETA 57A), changing the load from 2,000 to 500 ohms made little or no difference. One condenser mic (the Shure SM81 sounded worse at 500 than 2,000, but the only other mic I tried that was somewhat improved by a lower impedance load was an AKG D112 -- and it sounded a bit overdamped to me at 500 ohms. Would like to spend some time trying it at various intermediate loads.

Peace,
Paul

[PStamler]

On Wednesday, January 21, 2015 at 9:19:54 PM UTC-6, Jason wrote:

> This may be a silly question - squelch it if so, but what makes "good"
> preamps so expensive? I presume all the designers know of the good parts
> to use and of good designs (wrong?) but beyond that what accounts for the
> price? ..better design? good testing? careful component matching? just
> askin'

Depends on the preamp. The designer of the original Great River preamp once talked about the discrete-component FET-input opamp he used, and noted that it needed a whole lot of parts and careful hand-matching of the input devices to give him the kind of linearity he wanted. Then there were the input transformers at $100 a pop, with little discount for quantity purchases. Good transformers are hard to build, and there's no longer a mass market for them, so they're expensive.

In transformerless preamps, the good ones also often require hand-matching of their input devices. That's labor, which costs money.

What else drives up the prices of preamps? Good parts, including pots and switches that will take a lot of cycles without becoming noisy, and electrolytic capacitors that will last a long time. Those nice thick front panels cost money, and so does drilling holes in them. Robust power supplies, including good filtering to keep out line-borne and diode-generated garbage. If the preamp's transformerless, good filtering of the input signal to keep out RFI. As you mentioned, testing/quality control. And if the preamp has an inboard power supply rather than a wall wart, UL certification.

There are the costs of labor and keeping a factory open. Then of course the manufacturers need to make some profit, or they'll be out of business. There are markups by distributors and dealers. I think pro audio gear still has about an 8-to-1 price:parts cost ratio; a $2,000 preamp probably has about $250 worth of parts in it, wholesale cost.

Peace,
Paul

[PStamler]

On Wednesday, January 21, 2015 at 9:58:58 PM UTC-6, Jeff Henig wrote:

> Paul, I keep reading that ribbon mics like high impedance. Is that in any
> way accurate?

Well, my experience with classic-style ribbons is limited, but it would bear out that idea. I borrowed Bill Schulenburg's RCA ribbon when I was testing out the Benchmark preamp, and it sounded a whale of a lot better than it did through a Grace preamp. The Benchmark's input impedance is about 6.8k; the Grace's is about 1.5k.

So based on that one-time test, I'd go with high impedance loads for old-style ribbons. More modern ribbons seem to be optimized for modern-style preamps, with input Zs of 1.2k-2.4k,And active ribbons have their termination resistors inside, chosen by the designer, and work fine into just about anything. In fact, that's the idea.

Peace,
Paul

[Les Cargill[_4_]]

Jason wrote:
> On Wed, 21 Jan 2015 21:10:09 -0500 "Mike Rivers" > wrote
> in article >
>>
>> On 1/21/2015 1:56 PM, Scott Dorsey wrote:
>>> The SM-57 sure sounds better with a low-Z load!
>>
>> The SM-57 sounds better with the PROPER load (thanks, Paul Stamler). The
>> only preamp I have with a selectable input impedance is a Mackie 800R,
>> and they missed the SM-57 sweet spot on that one (probably never knew
>> about Paul's tests). As I recall, its choices are 300, 500, 1300, and
>> 2400 ohms. My SM-57 sounds dull at 300 ohms, about the same at 500 and
>> 1300 ohms, and like an SM-57 at 2400 ohms.
>
> This may be a silly question - squelch it if so, but what makes "good"
> preamps so expensive? I presume all the designers know of the good parts
> to use and of good designs (wrong?) but beyond that what accounts for the
> price? ..better design? good testing? careful component matching? just
> askin'
>


I'm reasonably sure good preamps are still very much craft goods, where
Mackie mixers have a minimum of human involvement in their
manufacture.

--
Les Cargill

[Les Cargill[_4_]]

(Scott Dorsey) wrote:
> Les Cargill > wrote:
>> (Scott Dorsey) wrote:
>>> Les Cargill > wrote:
>>>>
>>>> Has anyone tried a Cloudlifter? Does it only solve impedance problems (
>>>> (???)_, or does it help with noise as well?
>>>>
>>>> Or is it just another denuded emperor?
>>>
>>> Because the cloudlifter has a high-Z input stage, it will be noisier than a
>>> perfectly matched preamp.
>>
>> Then why does it have a big "Z" knob on the top?
>
> That adds a shunt resistor in parallel with the input. So the microphone
> sees a lower impedance load, but the noise is not decreased (and is actually
> slightly increased).
>

Makes sense.

> The only way to get a real adjustable input Z that maintains noise performance
> at all settings is to use a multitap transformer. And that has other issues.
> --scott
>

--
Les Cargill

[hank alrich]

Mike Rivers > wrote:

> On 1/21/2015 12:05 PM, Scott Dorsey wrote:
> > That adds a shunt resistor in parallel with the input. So the
> > microphone sees a lower impedance load, but the noise is not decreased
> > (and is actually slightly increased).
> >
> > The only way to get a real adjustable input Z that maintains noise
> >performance
> >

>
> I've only found one microphone, a CAD ribbon, that sounded better with a
> low impedance load than it did with a conventional 1.5-2.5k ohm mic
> preamp input. I think it's a gimmick, but if it makes a too-bright mic
> sound less bright, I suppose it's good for those who have that problem
> (or that mic).
>
> The thing is that overall, adding 20 dB of output level to the preamp
> input when you need it while increasing the preamp noise by only a few
> dB, is better for most everyone. The only reason to fuss with that is if
> you insist on only using the best designs (or nothing).

Look at the input impedance of the Gordon preamp. Never heard one that
sounded that good, more there there than I'd ever realized before.

http://gordonaudio.com/specs.htm

--
shut up and play your guitar * HankAlrich.Com
HankandShaidriMusic.Com
YouTube.Com/WalkinayMusic

[Mike Rivers[_2_]]

On 1/21/2015 10:19 PM, Jason wrote:

> This may be a silly question - squelch it if so, but what makes "good"
> preamps so expensive? I presume all the designers know of the good parts
> to use and of good designs (wrong?) but beyond that what accounts for the
> price? ..better design? good testing? careful component matching? j

Mostly it's the last little bit of performance in one or a few different
ways that people who want something different. Part of the reason why we
have so many expensive mic preamps is that 20 years ago there were a lot
of mediocre preamps because that was all they could do for the price
that would allow them to sell a whole lot of them.

Today, you can make a very serviceable preamp for $25 worth of parts.
Putting it in a box with a power supply, connectors, switches, etc. can
add another $100, add in marketing and profit and $200 per channel will
get 95% or more users a good recording, all other things being equal.
The other 5% are willing to pay 5-10 times that for a special color,
another 10 dB of gain without noise, and bragging rights.

If you look inside a Gordon preamp, you'll easily see why it's worth
$2500. If you look inside your heart, you'll wonder if you'd get more
bang for your bucks with something else. Some will, some won't.


--
"Today's production equipment is IT based and cannot be operated without
a passing knowledge of computing, although it seems that it can be
operated without a passing knowledge of audio" - John Watkinson

Drop by http://mikeriversaudio.wordpress.com now and then

[Dave Plowman (News)]

In article >,
PStamler > wrote:
> On Wednesday, January 21, 2015 at 9:58:58 PM UTC-6, Jeff Henig wrote:

> > Paul, I keep reading that ribbon mics like high impedance. Is that in
> > any way accurate?

> Well, my experience with classic-style ribbons is limited, but it would
> bear out that idea. I borrowed Bill Schulenburg's RCA ribbon when I was
> testing out the Benchmark preamp, and it sounded a whale of a lot better
> than it did through a Grace preamp. The Benchmark's input impedance is
> about 6.8k; the Grace's is about 1.5k.

> So based on that one-time test, I'd go with high impedance loads for
> old-style ribbons. More modern ribbons seem to be optimized for
> modern-style preamps, with input Zs of 1.2k-2.4k,And active ribbons have
> their termination resistors inside, chosen by the designer, and work
> fine into just about anything. In fact, that's the idea.

Don't all classic ribbons have a built in transformer? If so you'd expect
that to be designed to work best with the normal input impedance of the
day.

--
*24 hours in a day ... 24 beers in a case ... coincidence? *

Dave Plowman London SW
To e-mail, change noise into sound.

[Scott Dorsey]

Jason > wrote:
>On Wed, 21 Jan 2015 21:10:09 -0500 "Mike Rivers" > wrote
>in article >
>>
>> On 1/21/2015 1:56 PM, Scott Dorsey wrote:
>> > The SM-57 sure sounds better with a low-Z load!
>>
>> The SM-57 sounds better with the PROPER load (thanks, Paul Stamler). The
>> only preamp I have with a selectable input impedance is a Mackie 800R,
>> and they missed the SM-57 sweet spot on that one (probably never knew
>> about Paul's tests). As I recall, its choices are 300, 500, 1300, and
>> 2400 ohms. My SM-57 sounds dull at 300 ohms, about the same at 500 and
>> 1300 ohms, and like an SM-57 at 2400 ohms.
>
>This may be a silly question - squelch it if so, but what makes "good"
>preamps so expensive? I presume all the designers know of the good parts
>to use and of good designs (wrong?) but beyond that what accounts for the
>price? ..better design? good testing? careful component matching? just
>askin'

Some of it is smaller production runs. Costs don't get amortized among as
many units.

In the case of transformer-input preamp, a vast amount of the total cost is
the transformer. The cost of the input transformer on the original Great
River is greater than the total parts cost on those smaller Mackie consoles.

Some of it is fancy metalwork, and these days a shocking amount of it is in
the power supply.

And, surprisingly, getting quiet transistors has become very difficult, since
everything is digital and nobody wants to make transistors for high performance
linear circuits. So we have $10 front end transistor arrays now. (In the
case of the original Great River, Dan put a dozen $2 jfets in parallel for
low noise... but you can't even get those jfets anymore).

The industry is moving far away from low-noise low-frequency stuff, it is
very difficult to find anything at reasonable prices. I keep being visited
by sales reps trying to sell me three-cent transistors, and I tell them I'd
be happy to pay a dollar for a transistor if they could get the 1/f noise
down and they tell me that I only buy thousands of transistors, not millions,
and they make parts for the people who buy millions.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

Jeff Henig > wrote:
>
>Paul, I keep reading that ribbon mics like high impedance. Is that in any
>way accurate?

For the most part, a traditional RCA-style ribbon will have more accurate
high frequency response but more noise going into a high-Z load.

Get Harry Olsen's book "Music, Physics and Engineering." There's a paperback
reprint on Amazon for $5 and it will be the best $5 you ever spent.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

>On Wednesday, January 21, 2015 at 9:19:54 PM UTC-6, Jason wrote:
>
>> This may be a silly question - squelch it if so, but what makes "good"=20
>> preamps so expensive? I presume all the designers know of the good parts=


I think a better way to look at this is to look at what makes cheap preamps
so cheap.

For many years, all of the professional audio gear was built and sold like
the high end boutique gear today. What has changed is the introduction of
cheap mass-produced gear.

Take a look at what has been gone in order to make cheap gear cheap... a lot
of it are things like eliminating IC sockets and internal connectorization
since it's not intended to be maintained. Some of it is replacing expensive
precision power supplies will wall warts. Some of it is in the control design
and in the controls used; buttons are much cheaper than pots and dual pots
that need to track are way more expensive than single pots.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

hank alrich > wrote:
>Mike Rivers > wrote:
>
>> On 1/21/2015 12:05 PM, Scott Dorsey wrote:
>> > That adds a shunt resistor in parallel with the input. So the
>> > microphone sees a lower impedance load, but the noise is not decreased
>> > (and is actually slightly increased).
>> >
>> > The only way to get a real adjustable input Z that maintains noise
>> >performance
>> >
>
>>
>> I've only found one microphone, a CAD ribbon, that sounded better with a
>> low impedance load than it did with a conventional 1.5-2.5k ohm mic
>> preamp input. I think it's a gimmick, but if it makes a too-bright mic
>> sound less bright, I suppose it's good for those who have that problem
>> (or that mic).
>>
>> The thing is that overall, adding 20 dB of output level to the preamp
>> input when you need it while increasing the preamp noise by only a few
>> dB, is better for most everyone. The only reason to fuss with that is if
>> you insist on only using the best designs (or nothing).
>
>Look at the input impedance of the Gordon preamp. Never heard one that
>sounded that good, more there there than I'd ever realized before.
>
>http://gordonaudio.com/specs.htm

The specs don't tell you the full story, though. The input impedance of the
Gordon is pretty resistive and does not change at all with level. I don't
think that's a big secret to the transparent sound but it's certainly a
contributor.

That said, if you're using Schoeps mikes or something else with a super low
effective output impedance, it doesn't matter much at all. The low output
impedance of the mike means variations in input impedance on the preamp are
less of an issue.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Mike Rivers[_2_]]

On 1/22/2015 9:54 AM, Dave Plowman (News) wrote:
> Don't all classic ribbons have a built in transformer? If so you'd expect
> that to be designed to work best with the normal input impedance of the
> day.

"Impedance Of The day" sometimes was directly into the grid of a tube.

--
"Today's production equipment is IT based and cannot be operated without
a passing knowledge of computing, although it seems that it can be
operated without a passing knowledge of audio" - John Watkinson

Drop by http://mikeriversaudio.wordpress.com now and then

[Dave Plowman (News)]

In article >,
Mike Rivers > wrote:
> On 1/22/2015 9:54 AM, Dave Plowman (News) wrote:
> > Don't all classic ribbons have a built in transformer? If so you'd
> > expect that to be designed to work best with the normal input
> > impedance of the day.

> "Impedance Of The day" sometimes was directly into the grid of a tube.

Never seen that with a low impedance mic. I'm surprised you could get
enough gain.

--
*Forget about World Peace...Visualize using your turn signal.

Dave Plowman London SW
To e-mail, change noise into sound.

[Scott Dorsey]

In article >, Mike Rivers > wrote:
>On 1/22/2015 9:54 AM, Dave Plowman (News) wrote:
>> Don't all classic ribbons have a built in transformer? If so you'd expect
>> that to be designed to work best with the normal input impedance of the
>> day.
>
>"Impedance Of The day" sometimes was directly into the grid of a tube.

Well, through a step-up transformer... but not a very high ratio transformer
because making high ratio transformers with any high end at all is hard.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Les Cargill[_4_]]

Mike Rivers wrote:
> On 1/21/2015 10:19 PM, Jason wrote:
>
>> This may be a silly question - squelch it if so, but what makes "good"
>> preamps so expensive? I presume all the designers know of the good parts
>> to use and of good designs (wrong?) but beyond that what accounts for the
>> price? ..better design? good testing? careful component matching? j
>
> Mostly it's the last little bit of performance in one or a few different
> ways that people who want something different. Part of the reason why we
> have so many expensive mic preamps is that 20 years ago there were a lot
> of mediocre preamps because that was all they could do for the price
> that would allow them to sell a whole lot of them.
>


If you wanted good preamps, you bought a whole console. There've
probably always been bespoke preamps but it really picked up
in the '90s, when people started being unhappy with DAW preamps.

> Today, you can make a very serviceable preamp for $25 worth of parts.
> Putting it in a box with a power supply, connectors, switches, etc. can
> add another $100, add in marketing and profit and $200 per channel will
> get 95% or more users a good recording, all other things being equal.
> The other 5% are willing to pay 5-10 times that for a special color,
> another 10 dB of gain without noise, and bragging rights.
>
> If you look inside a Gordon preamp, you'll easily see why it's worth
> $2500. If you look inside your heart, you'll wonder if you'd get more
> bang for your bucks with something else. Some will, some won't.
>
>

I've done mixes from studios with good preamps, and I've done mixes
using my own modest prosumer preamps ( say, Symmetrix quality ) and
in neither case was it clear the preamps were the bottleneck.

But I'm not exactly recording finely crafted acoustic instruments
with expensive mics.

--
Les Cargill

[Scott Dorsey]

Dave Plowman (News) > wrote:
> Mike Rivers > wrote:
>> On 1/22/2015 9:54 AM, Dave Plowman (News) wrote:
>> > Don't all classic ribbons have a built in transformer? If so you'd
>> > expect that to be designed to work best with the normal input
>> > impedance of the day.
>
>> "Impedance Of The day" sometimes was directly into the grid of a tube.
>
>Never seen that with a low impedance mic. I'm surprised you could get
>enough gain.

Although a step-up transformer was pretty much always used, it was seldom
more than 1:10 and often just a 1:5. You could get 1:20 transformers for
communications applications where trading bandwidth for noise was worthwhile.

As far as I know, the only commercial preamp using a tube front end without
a step-up transformer is one made by Fred Forssell. It uses a long-tailed
pair in a trick circuit and sounds amazingly clean. Noise floor with a low-Z
condenser mike is higher than a Millennium but way better than a Mackie.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Dave Plowman (News)]

In article >,
Scott Dorsey > wrote:
> >Never seen that with a low impedance mic. I'm surprised you could get
> >enough gain.

> Although a step-up transformer was pretty much always used, it was
> seldom more than 1:10 and often just a 1:5. You could get 1:20
> transformers for communications applications where trading bandwidth for
> noise was worthwhile.

I've seen two lower ratio transformers daisy chained.

--
*Cover me. I'm changing lanes.

Dave Plowman London SW
To e-mail, change noise into sound.

[Scott Dorsey]

Dave Plowman (News) > wrote:
>In article >,
> Scott Dorsey > wrote:
>> >Never seen that with a low impedance mic. I'm surprised you could get
>> >enough gain.
>
>> Although a step-up transformer was pretty much always used, it was
>> seldom more than 1:10 and often just a 1:5. You could get 1:20
>> transformers for communications applications where trading bandwidth for
>> noise was worthwhile.
>
>I've seen two lower ratio transformers daisy chained.

I have too. Normally, this is not a win. It is a big, big lose.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[[email protected]]

Be mindful when talking about transformer turns ratios
A transformer with TURNS ratio of 10:1
Will have voltage ratio of also 10:1
And a current ratio of 1:10
Which results in an impedance ratio of 100:1

Mark

[PStamler]

And back in the old days, when ribbon mics were most common in studios, there were indeed transformers with step-up ratioa > 1:10 -- sometimes 1:20 or 1:30. They showed up in some RCA mic preamps and consoles -- sometimes driving pentode tubes as amplifiers (yeah, really). One RCA circuit used a 1620 pentode, which I believe is really a power tube, for an input tube with a high-ration transformer.

Mind you, I make no claims that these high-ratio transformers actually measured flat or sounded good. I don't know, not having heard them, but I suspect they didn't.

Peace,
Paul

[Dave Plowman (News)]

In article >,
Scott Dorsey > wrote:
> Dave Plowman (News) > wrote:
> >In article >,
> > Scott Dorsey > wrote:
> >> >Never seen that with a low impedance mic. I'm surprised you could get
> >> >enough gain.
> >
> >> Although a step-up transformer was pretty much always used, it was
> >> seldom more than 1:10 and often just a 1:5. You could get 1:20
> >> transformers for communications applications where trading bandwidth
> >> for noise was worthwhile.
> >
> >I've seen two lower ratio transformers daisy chained.

> I have too. Normally, this is not a win. It is a big, big lose.
> --scott

True - but in the days when it was common, it may have been the best
compromise.

--
*Work is for people who don't know how to fish.

Dave Plowman London SW
To e-mail, change noise into sound.

[Scott Dorsey]

PStamler > wrote:
>And back in the old days, when ribbon mics were most common in studios, the=
>re were indeed transformers with step-up ratioa > 1:10 -- sometimes 1:20 or=
> 1:30. They showed up in some RCA mic preamps and consoles -- sometimes dri=
>ving pentode tubes as amplifiers (yeah, really). One RCA circuit used a 162=
>0 pentode, which I believe is really a power tube, for an input tube with a=
> high-ration transformer.
>
>Mind you, I make no claims that these high-ratio transformers actually meas=
>ured flat or sounded good. I don't know, not having heard them, but I suspe=
>ct they didn't.

Want to try some if I can find where I put them? I have some 600-80k RCAs
here out of some broadcast gear. (There are here because I put Jensens in.)
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[PStamler]

On Friday, January 23, 2015 at 7:46:00 AM UTC-6, Scott Dorsey wrote:

> Want to try some if I can find where I put them? I have some 600-80k RCAs
> here out of some broadcast gear. (There are here because I put Jensens in.)


Thanks, I'll pass. Those transformers are only 1:11.5 or so, which isn't much greater than 1:10. Unless they have the option of a 50 ohm primary, which makes them 1:40. Now that would be fun. Not good audio, probably, but fun.

Peace,
Paul

[Peter Larsen[_3_]]

"PStamler" > skrev i en meddelelse
...

> On Friday, January 23, 2015 at 7:46:00 AM UTC-6, Scott Dorsey wrote:

>> Want to try some if I can find where I put them? I have some 600-80k
>> RCAs
>> here out of some broadcast gear. (There are here because I put Jensens
>> in.)

> Thanks, I'll pass. Those transformers are only 1:11.5 or so, which
> isn't much greater than 1:10. Unless they have the option of a
> 50 ohm primary, which makes them 1:40. Now that would be fun.
> Not good audio, probably, but fun.

I have one or perhaps two Sennheiser TM514x cable transformers that I
soldered a jack and a male switchcraft on for use as step down and balancing
around 1977. I don't want to rush things, but some day I hope to get to test
them with guitar and a bass, I expect them to mellow things a wee bit and it
may be an advantage. I think it was the tape recording utensils shop in
Elmegade in Copenhagen, I found them in.

> Peace,
> Paul

Kind regards

Peter Larsen