[Tobiah[_4_]]

I have an amp on order. Here is what the rear looks like:

http://tinyurl.com/6m4cv7e

I am not familiar with the speaker outputs near the
top. Apparently they are called Speakon's. I figured that
I'd use them because they look cool, but thought I'd ask about
them to see whether they are recommended. My speakers have two
posts in the back that look they are meant to receive banana plugs
(Energy C7's). I saw this cable:

http://tinyurl.com/7lspxsj

I've never owned banana plugs either. Am I to assume that there
is a standard for the distance between them and that this cable
will fit the spacing of the posts on my speaker?

I'll be using a Mackie mixer for input to the amp. Any reason
I should use the XLR outs since the amp has XLR ins?

Thanks!

Tobiah

[Tobiah[_4_]]

I just realized that my old amp has two sets of speaker
outs, while this one has only one. I use the second
pair to drive a set of outdoor speakers. I guess I'll
have to use another amp for those. It seems to me that I could
hook up the new amp using the Mackie XLR outs, and use the
1/4" outs to feed the outdoor speaker amp. The outdoor amp
would be off most of the time.

Any problems there?

Thanks,

Tobiah

[John Williamson]

Tobiah wrote:
I have an amp on order. Here is what the rear looks like:

http://tinyurl.com/6m4cv7e

I am not familiar with the speaker outputs near the
top. Apparently they are called Speakon's. I figured that
I'd use them because they look cool, but thought I'd ask about
them to see whether they are recommended. My speakers have two
posts in the back that look they are meant to receive banana plugs
(Energy C7's). I saw this cable:

http://tinyurl.com/7lspxsj

I've never owned banana plugs either. Am I to assume that there
is a standard for the distance between them and that this cable
will fit the spacing of the posts on my speaker?

Speakons are good for when you move stuff round a lot. You pay for the
convenience.

The binding posts/ sockets on your speakers will probably accept either
standard banana plugs or bare wire ends by loosening the plastic socket
surround by hand, and clamping the wire. There is a sort of customary
distance between banana plugs in this application, but I'd not guarantee
anything.

I'll be using a Mackie mixer for input to the amp. Any reason
I should use the XLR outs since the amp has XLR ins?

If you've got XLR outputs on your mixer, then use them. They are, in
theory, a match for the XLR inputs on the amp. Either way, you'll get
slightly better performance by using a balanced connection from mixer to
amp.
--
Tciao for Now!

John.

[John Williamson]

Tobiah wrote:
I just realized that my old amp has two sets of speaker
outs, while this one has only one. I use the second
pair to drive a set of outdoor speakers. I guess I'll
have to use another amp for those. It seems to me that I could
hook up the new amp using the Mackie XLR outs, and use the
1/4" outs to feed the outdoor speaker amp. The outdoor amp
would be off most of the time.

Any problems there?

Nope.

--
Tciao for Now!

John.

[PStamler]

There is one issue with using the Mackie to drive two separate
amplifiers, one of which is sometimes turned off.

Are the 1/4" jacks in the Mackie TRS-balanced jacks, in parallel with
the XLRs? If so, then you *may* have a problem running the XLRs into
one amp while running the 1/4" jacks into another. If one of the amps
is turned off, you may be hanging an unbiased transistor junction on
that output, which is a pretty nonlinear load, and cause some
distortion in the Mackie's output circuit, which you'd hear through
the amp that's turned on.

Or none of the above. Try it and see; hook up both amps, then see if
the sound of the indoor speakers changes when the outdoor amp is
turned off. It's quite possible that there will be no problems, in
which case you can grin. But there is a small possibility for trouble
(not destructive trouble, just some distorted signal), and you should
at least be prepared.

Peace,
Paul

[Ron Capik[_3_]]

On 11/14/2011 1:08 PM, PStamler wrote:
There is one issue with using the Mackie to drive two separate
amplifiers, one of which is sometimes turned off.

Are the 1/4" jacks in the Mackie TRS-balanced jacks, in parallel with
the XLRs? If so, then you *may* have a problem running the XLRs into
one amp while running the 1/4" jacks into another. If one of the amps
is turned off, you may be hanging an unbiased transistor junction on
that output, which is a pretty nonlinear load, and cause some
distortion in the Mackie's output circuit, which you'd hear through
the amp that's turned on.

Or none of the above. Try it and see; hook up both amps, then see if
the sound of the indoor speakers changes when the outdoor amp is
turned off. It's quite possible that there will be no problems, in
which case you can grin. But there is a small possibility for trouble
(not destructive trouble, just some distorted signal), and you should
at least be prepared.

Peace,
Paul

The 1402 vlz provides a lot of options. One could use
the aux outs, 3/4 out, or control room out for the 2nd amp.
The OP should check the block diagram for routing options
and work out one that works for him.

Later...
Ron Capik
--

[Tobiah[_4_]]

The 1402 vlz provides a lot of options. One could use
the aux outs, 3/4 out, or control room out for the 2nd amp.
The OP should check the block diagram for routing options
and work out one that works for him.

When I use the outdoor speakers, I generally want the indoor
speakers on at the same time.

I was thinking about using the main and control room outs,
but It would be difficult to get the signal to show up on
both. Now, your idea of using the Aux outs is a good one.
I could use the send knobs as my outdoor volume. Thanks
for the idea.

Tobiah

[Tobiah]

One more thing - the amp has Speakon and banana plug
terminals. What would happen if I connected the Speakon
outputs to my inside speakers, and my outdoor speakers
to the others? I assume I'd be dividing or adding ohms.
The amp says it will take 4-16 ohm speakers. It says
it will do 500W/channel into 4, and 250W/channel into 8.
I'm guessing my Energy speakers are 8 ohm. I'm not sure
about my wall mount Infinity outdoor speakers.

Thanks,

Tobiah

[PStamler]

On Nov 14, 7:14*pm, Tobiah wrote:
One more thing - the amp has Speakon and banana plug
terminals. *What would happen if I connected the Speakon
outputs to my inside speakers, and my outdoor speakers
to the others? *I assume I'd be dividing or adding ohms.
The amp says it will take 4-16 ohm speakers. *It says
it will do 500W/channel into 4, and 250W/channel into 8.
I'm guessing my Energy speakers are 8 ohm. *I'm not sure
about my wall mount Infinity outdoor speakers.

You need to find out. If they're 8 ohms you won't blow up the
amplifier by connecting up both. *However* you won't have independent
control of the inside and outside speakers' volumes, nor on-off
controls for the speakers other than unplugging the ones you want to
turn off.

Oh, and this amp may be powerful enough to blow up most consumer
speakers if there's any kind of a problem, such as an input cable
coming half-out.

Peace,
Paul

[Mike Rivers]

On 11/14/2011 1:00 PM, John Williamson wrote:

If you've got XLR outputs on your mixer, then use them. They
are, in theory, a match for the XLR inputs on the amp.

That's good advice only if you know what's coming out the
output and what's supposed to go into the input.

All too often I've seen people wanting to connect things
like a mic preamp with line level output on XLR to a mic
input on a mixer simply because they have the same type of
connector. Then they wonder why they have to turn the gain
all the way down and ask "is this normal?"

In the case of Mackie mixers, XLR outputs are line level
(though some have a switch to attenuate the signal to mic
level). Generally for a power amplifier that has XLR inputs,
those are line level inputs. I'm pretty sure that's the case
with this one, but a "DJ Amplifier" might have a mic input.
You can't tell the players without a program.


--
"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

http://mikeriversaudio.wordpress.com - useful and
interesting audio stuff

[Mike Rivers]

On 11/14/2011 1:55 PM, Tobiah wrote:

When I use the outdoor speakers, I generally want the indoor
speakers on at the same time.

I was thinking about using the main and control room outs,
but It would be difficult to get the signal to show up on
both.

OK, WHICH Mackie mixer are you using? They're not all the
same, you know. However, in general, it's just a matter of
pressing the right button to get the main mix to the control
room outputs (simultaneously). RTFM ferchrssake!


--
"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

http://mikeriversaudio.wordpress.com - useful and
interesting audio stuff

[Ron Capik[_3_]]

On 11/15/2011 7:16 AM, Mike Rivers wrote:
On 11/14/2011 1:55 PM, Tobiah wrote:

When I use the outdoor speakers, I generally want the indoor
speakers on at the same time.

I was thinking about using the main and control room outs,
but It would be difficult to get the signal to show up on
both.

OK, WHICH Mackie mixer are you using? They're not all the same, you
know. However, in general, it's just a matter of pressing the right
button to get the main mix to the control room outputs (simultaneously).
RTFM ferchrssake!


He posted in a previous thread that it's a 1402 vlz pro.
Yes, it would have helped if he posted that information
in this thread.


Later...
Ron Capik
--

[Arny Krueger[_4_]]

"Tobiah" wrote in message
news
I have an amp on order. Here is what the rear looks like:

http://tinyurl.com/6m4cv7e


Hmm "Pyle Pro"? Pyle are best known for their low end car audio products.

I am not familiar with the speaker outputs near the
top. Apparently they are called Speakon's. I figured that
I'd use them because they look cool, but thought I'd ask about
them to see whether they are recommended.

Speakons are about a lot more than just good looks. They have many
advantages over the alternatives, being bare wires, 1/4" jacks, and dual
bananna jacks. They can't be hooked up wrong, they can't short out when
unplugged, and they don't short out if hot-plugged. They are ultra-reliable
because of their excellent built-in strain relief on the cable.

My speakers have two
posts in the back that look they are meant to receive banana plugs
(Energy C7's). I saw this cable:

http://tinyurl.com/7lspxsj

This is the usual kind of cable that one uses to interface home audio and
some pro speakers with the world of Speakons. I use Speakons in my home
audio system as they are nice and flush against the wall.

I've been known to modify consumer speakers so that they have Speakons, as
well.

I've never owned banana plugs either. Am I to assume that there
is a standard for the distance between them and that this cable
will fit the spacing of the posts on my speaker?

The U.S. standard is 3/4" spacing.

Yes, except in the case of some European speakers that avoid having 3/4"
spacing to avoid confusion with local power cords with similar pins and
spacing.

I'll be using a Mackie mixer for input to the amp. Any reason
I should use the XLR outs since the amp has XLR ins?

That's what I do. It lets me use standard mic cables to hook the mixer to
the power amp. One less different kind of cable needed for setup.

[Tobiah]

OK, WHICH Mackie mixer are you using? They're not all the same, you
know. However, in general, it's just a matter of pressing the right
button to get the main mix to the control room outputs (simultaneously).
RTFM ferchrssake!

1402-VLZ PRO

I've poured over that manual and the block diagram many times. I know
that I can get both Main Out and Control Room to appear at the Control
Room out. I was talking about having one input blade's input appearing
in both places. I think it would take a patch or a Y. The Aux out
thing seems more reasonable.

[Ron Capik[_3_]]

On 11/15/2011 8:29 PM, Tobiah wrote:
OK, WHICH Mackie mixer are you using? They're not all the same, you
know. However, in general, it's just a matter of pressing the right
button to get the main mix to the control room outputs (simultaneously).
RTFM ferchrssake!

1402-VLZ PRO

I've poured over that manual and the block diagram many times. I know
that I can get both Main Out and Control Room to appear at the Control
Room out. I was talking about having one input blade's input appearing
in both places. I think it would take a patch or a Y. The Aux out
thing seems more reasonable.


A patch or Y is not necessarily a bad thing. Feel free
to think outside the box. As I said before, you have a
lot of options. A lot depends on your end goal.

Note: the more you tell us up front the better we may
be able to help you.


Later...
Ron Capik
--

[John Williamson]

Tobiah wrote:
OK, WHICH Mackie mixer are you using? They're not all the same, you
know. However, in general, it's just a matter of pressing the right
button to get the main mix to the control room outputs (simultaneously).
RTFM ferchrssake!

1402-VLZ PRO

I've poured over that manual and the block diagram many times. I know
that I can get both Main Out and Control Room to appear at the Control
Room out. I was talking about having one input blade's input appearing
in both places. I think it would take a patch or a Y. The Aux out
thing seems more reasonable.


I assumed you would be using the outputs on the main amp to feed the
signal to the "outdoor" amp.

There are, as others have said, many ways to get the result you require.

--
Tciao for Now!

John.

[Mike Rivers]

On 11/15/2011 8:29 PM, Tobiah wrote:

1402-VLZ PRO

I've poured over that manual and the block diagram many
times. I know
that I can get both Main Out and Control Room to appear at
the Control
Room out. I was talking about having one input blade's input
appearing
in both places.

What's an "input blade's input"? Can you give a really
detailed example of what you're trying to do? Like connect a
CD player to a pair of inputs and have it come out the Main
and Control Room outputs? If that's what you're after, this
is exactly what the control room outputs are for. You can
hear exactly the same things from both sets of outputs, and
you have independent volume control of both. Well, almost -
If you change the volume in the Main outputs, you'll hear
that change at the Control Room outputs. If you want totally
independent outputs, that's what the pre-fader auxiliary
sends are for.

--
"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

http://mikeriversaudio.wordpress.com - useful and
interesting audio stuff

[Tobiah[_4_]]

What I don't understand is Tobia's assertion that he can't
understand the block diagram for signal routing in the
Mackie mixer manual, those things are usually done with the
neophyte in mind.

I didn't make myself clear. What I meant to say, was that
I've been over the block diagram many times, and I feel that
I have a very thorough understanding of all aspects of the mixer's
capabilities. I was trying to defend myself against the RTFM
when the answer given did not accomplish what I was talking about
doing.

[Tobiah[_4_]]

On 11/16/2011 04:32 AM, Mike Rivers wrote:
On 11/15/2011 8:29 PM, Tobiah wrote:

1402-VLZ PRO

I've poured over that manual and the block diagram many
times. I know
that I can get both Main Out and Control Room to appear at
the Control
Room out. I was talking about having one input blade's input
appearing
in both places.

What's an "input blade's input"?

I've made the mistake of using that 'term' here before. It's
obviously erroneous. Somewhere I got the idea that it referred
to one column of controls on the mixer. It's my alternative to 'channel'
in the case of the 1402, because it can refer to one fader, whether
that be a stereo channel or not. Maybe such a word exists?

Can you give a really detailed example
of what you're trying to do? Like connect a CD player to a pair of
inputs and have it come out the Main and Control Room outputs? If that's
what you're after, this is exactly what the control room outputs are
for. You can hear exactly the same things from both sets of outputs, and
you have independent volume control of both. Well, almost - If you
change the volume in the Main outputs, you'll hear that change at the
Control Room outputs. If you want totally independent outputs, that's
what the pre-fader auxiliary sends are for.


I was thinking AUX out also, as I mentioned in a previous post.
Now that I think better of it, I can't get two channels out that
way pre-fader. I think I might just scrap this amp anyway, and get
something more suited to the home studio. I read the manual *after*
ordering, and found that the THD spec is .1%. I think this thing
is meant to power a PA system at large volume. That's why it's
got the Speakon connecters. I think I'll look for a less portable
amp with better specks that has two speaker outs.

Thanks,

Tobiah

[Scott Dorsey]

Tobiah wrote:

I've made the mistake of using that 'term' here before. It's
obviously erroneous. Somewhere I got the idea that it referred
to one column of controls on the mixer. It's my alternative to 'channel'
in the case of the 1402, because it can refer to one fader, whether
that be a stereo channel or not. Maybe such a word exists?

"Channel strip."

Can you give a really detailed example
of what you're trying to do? Like connect a CD player to a pair of
inputs and have it come out the Main and Control Room outputs? If that's
what you're after, this is exactly what the control room outputs are
for. You can hear exactly the same things from both sets of outputs, and
you have independent volume control of both. Well, almost - If you
change the volume in the Main outputs, you'll hear that change at the
Control Room outputs. If you want totally independent outputs, that's
what the pre-fader auxiliary sends are for.

I was thinking AUX out also, as I mentioned in a previous post.
Now that I think better of it, I can't get two channels out that
way pre-fader. I think I might just scrap this amp anyway, and get
something more suited to the home studio. I read the manual *after*
ordering, and found that the THD spec is .1%. I think this thing
is meant to power a PA system at large volume. That's why it's
got the Speakon connecters. I think I'll look for a less portable
amp with better specks that has two speaker outs.

The THD specs at full power are meaningless, really, since you don't use the
amp under those conditions. Listen to how it sounds. If it sounds good,
keep it, if it sounds bad, get rid of it.

There's nothing wrong with just using a Y-cable to drive both amps from one
pair of outputs.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Don Pearce[_3_]]

On 16 Nov 2011 12:35:32 -0500, (Scott Dorsey) wrote:

There's nothing wrong with just using a Y-cable to drive both amps from one
pair of outputs.

Provided the grounds are taken care of to make sure the result doesn't
hum.

d

[Tobiah[_4_]]

The THD specs at full power are meaningless, really, since you don't use the
amp under those conditions. Listen to how it sounds. If it sounds good,
keep it, if it sounds bad, get rid of it.

It's true, that that spec was at rated power, which I will never
approach. So maybe they could have posted a better distortion spec
at the cost of what they think is the more important value, being max
output power. I was worried because I checked some Yamaha amps that
quoted .003% or less.

As far as how it sounds, I guess I don't trust my ears there. I could
run some music through it and it might sound ok, but most of what I
do is sound synthesis with csound. I don't even know what a sound is
supposed to sound like until I hear it generated. It's a little like
buying say, a scale. I could put some clay on it so that it reads a
pound, then heft the clay, and say, "Yeah, that's about a pound". But
really I'm going to want to look at the tolerance specs.

Same with the amp. I've gone to a great deal of effort to get the
weak links out of my signal chain. I just want to know that I'm getting
the closest thing to truth out of the amp.

Is it possible to measure the thing myself at home? I suppose there
must be software for that.

Thanks,

Tobiah



There's nothing wrong with just using a Y-cable to drive both amps from one
pair of outputs.
--scott

[PStamler]

An amp with a THD spec of 0.1% can sound great Or it can sound
horrible. The fact is that the single number doesn't tell you anything
about how the amp is going to perform playing music into a
loudspeaker.

The one place where your deductions are right is that this is almost
certainly intended as a high-powered PA amp. The SpeakOn connectors
tell you that. And if you make one little tiny mistake, you can blow
your speakers in a few milliseconds.

Go find an Adcom or Parasound amplifier, 100W max, maybe 40W for real,
and be happy. Find another one -- or a used receiver in working
condition -- for the outdoor speakers.

Peace,
Paul

[Scott Dorsey]

Tobiah wrote:
The THD specs at full power are meaningless, really, since you don't use the
amp under those conditions. Listen to how it sounds. If it sounds good,
keep it, if it sounds bad, get rid of it.

It's true, that that spec was at rated power, which I will never
approach. So maybe they could have posted a better distortion spec
at the cost of what they think is the more important value, being max
output power. I was worried because I checked some Yamaha amps that
quoted .003% or less.

That's a meaningless number too. Part of the problem is that various different
harmonics have different degrees of audibility, so THD is only useful when
comparing amplifiers with the same distortion spectrum. That made it very
useful back in 1945 when all amplifiers had similar topology and most of the
distortion came from the transformer, but today it is a totally, totally
useless value.

As far as how it sounds, I guess I don't trust my ears there. I could
run some music through it and it might sound ok, but most of what I
do is sound synthesis with csound. I don't even know what a sound is
supposed to sound like until I hear it generated. It's a little like
buying say, a scale. I could put some clay on it so that it reads a
pound, then heft the clay, and say, "Yeah, that's about a pound". But
really I'm going to want to look at the tolerance specs.

If you can't trust your ears, you're in the wrong business. Because really,
when it comes to evaluating equipment, that's all you _can_ trust.

I mean, if you want you can run a distortion spectrum on it with an FFT
analyzer... but you sure can't expect the manufacturer to do that for you
and put it on the datasheet.

Same with the amp. I've gone to a great deal of effort to get the
weak links out of my signal chain. I just want to know that I'm getting
the closest thing to truth out of the amp.

Then you should have taken the advice I gave when you were looking at buying
the amp in the first place.
--scott

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

[Tobiah[_4_]]

If you can't trust your ears, you're in the wrong business. Because really,
when it comes to evaluating equipment, that's all you _can_ trust.

Good thing I'm a programmer. I'm a musician hobbiest, but after
learning how to record on a four-track cassette machine, I have
a passion for low noise and distortion.


Then you should have taken the advice I gave when you were looking at buying
the amp in the first place.

*slap* Ouch. That may be so. I was seduced by the price, which
is not normally like me.

[Don Pearce[_3_]]

On Wed, 16 Nov 2011 10:42:43 -0800, Tobiah
wrote:

Good thing I'm a programmer. I'm a musician hobbiest, but after
learning how to record on a four-track cassette machine, I have
a passion for low noise and distortion.

Hobbiest. Is that the most ardent hobbyist possible?

d

[Tobiah[_4_]]

On 11/16/2011 10:55 AM, Don Pearce wrote:
On Wed, 16 Nov 2011 10:42:43 -0800,
wrote:

Good thing I'm a programmer. I'm a musician hobbiest, but after
learning how to record on a four-track cassette machine, I have
a passion for low noise and distortion.

Hobbiest. Is that the most ardent hobbyist possible?

d

Yeah, I'm an athiest too.

[Richard Webb[_3_]]

On Wed 2011-Nov-16 07:32, Mike Rivers writes:
What's an "input blade's input"? Can you give a really
detailed example of what you're trying to do? Like connect a CD
player to a pair of inputs and have it come out the Main and
Control Room outputs? If that's what you're after, this is exactly
what the control room outputs are for. You can
hear exactly the same things from both sets of outputs, and you
have independent volume control of both. Well, almost - If you
change the volume in the Main outputs, you'll hear
that change at the Control Room outputs.
I'm with MIke here, it sounds like you want to maybe run the inside amp and speakers from yoru control room out, and the
outdoor set from main outs.

What I don't understand is Tobia's assertion that he can't
understand the block diagram for signal routing in the
Mackie mixer manual, those things are usually done with the
neophyte in mind.
If you can't understand signaled routing as described by
Mackie in their mixer manuals then I don't know what to tell you. This isn't rocket science.

AGain the Mackie mixers do a good signal flow 101 for the
newbie. Take a real good look at it.


Regards,
Richard
--
| Remove .my.foot for email
| via Waldo's Place USA Fidonet-Internet Gateway Site
| Standard disclaimer: The views of this user are strictly his own.

[William Sommerwerck]

Same with the amp. I've gone to a great deal of effort to get the
weak links out of my signal chain. I just want to know that I'm
getting the closest thing to truth out of the amp.

I don't know if there is any completely neutral power amp. There might be,
but if there is, I don't know what it is.

I've owned amplifiers designed by Dan D'Agostino and John Curl, two of the
all-time greats. They sound completely different. In my system, I prefer the
Curls (but I wish they had more of the liquidity and transparency of the
D'Agostinos).

The closest you can come to determine whether the amp is neutral is to stick
a resistive load on the output, and pad the input so the amp has unity gain
(to within 0.1dB or better). You can then run a bypass test through the
line-level input to see if it's audible. This isn't a completely valid test,
as the amp won't be driving a reactive load, but it's a start.

[Les Cargill[_4_]]

Don Pearce wrote:
On Wed, 16 Nov 2011 10:42:43 -0800,
wrote:

Good thing I'm a programmer. I'm a musician hobbiest, but after
learning how to record on a four-track cassette machine, I have
a passion for low noise and distortion.

Hobbiest. Is that the most ardent hobbyist possible?

d


It's a Sears catalog thing - Hobby, Hobbier and Hobbiest.

--
Les Cargill

[Don Pearce[_3_]]

On Wed, 16 Nov 2011 17:24:39 -0600, Les Cargill
wrote:

Don Pearce wrote:
On Wed, 16 Nov 2011 10:42:43 -0800,
wrote:

Good thing I'm a programmer. I'm a musician hobbiest, but after
learning how to record on a four-track cassette machine, I have
a passion for low noise and distortion.

Hobbiest. Is that the most ardent hobbyist possible?

d


It's a Sears catalog thing - Hobby, Hobbier and Hobbiest.

Not just Sears, I'm afraid.

http://micro-surface.com/index.php?m...products_id=76

d

[Peter Irwin]

William Sommerwerck wrote:

The closest you can come to determine whether the amp is neutral is to stick
a resistive load on the output, and pad the input so the amp has unity gain
(to within 0.1dB or better). You can then run a bypass test through the
line-level input to see if it's audible. This isn't a completely valid test,
as the amp won't be driving a reactive load, but it's a start.

Peter Walker of Quad did a demonstration many years ago in which
he hooked up fifty Quad 303 amplifiers in series this way. The result
had audible hiss, but did not sound distorted or coloured.

(I seem to remember reading, but can not now find the source,
that fifteen Quad II valve amplifiers hooked up this way did have
distortion audible on programme material.)

Peter.
--

[Mike Rivers]

On 11/16/2011 12:04 PM, Tobiah wrote:

What's an "input blade's input"?

I've made the mistake of using that 'term' here before. It's
obviously erroneous. Somewhere I got the idea that it referred
to one column of controls on the mixer. It's my alternative
to 'channel'

Well, if you're going to make up your own language, it's no
wonder nobody can understand what you're asking about. It's
usually called the "channel strip." But not all channel
strips have the same controls so it's important to know
which mixer. Also, in the case with the Mackie 1402, not all
the channel strips are the same (I trust you noticed that)
so it's also important to know which channel or channels
you're talking about.

in the case of the 1402, because it can refer to one fader,
whether
that be a stereo channel or not.

That's because channels 1-6 are mono and channels 7-14 are
stereo.

And you STILL haven't explained what you're trying to do in
sufficient detail that anyone can help you further.

--
"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

http://mikeriversaudio.wordpress.com - useful and
interesting audio stuff

[William Sommerwerck]

"Peter Irwin" wrote in message
...
William Sommerwerck wrote:

The closest you can come to determine whether the amp is neutral is to
stick
a resistive load on the output, and pad the input so the amp has unity
gain
(to within 0.1dB or better). You can then run a bypass test through the
line-level input to see if it's audible. This isn't a completely valid
test,
as the amp won't be driving a reactive load, but it's a start.

Peter Walker of Quad did a demonstration many years ago in which
he hooked up fifty Quad 303 amplifiers in series this way. The result
had audible hiss, but did not sound distorted or coloured.

This is unlikely, because no amplifier has infinite bandwidth. At the very
least, there would have been a noticeable loss in bass extension and
(especially) a severe rounding-off of high frequencies.

Also, the IM would pile up to a point where you'd expect it to be audible.

[Peter Irwin]

William Sommerwerck wrote:
"Peter Irwin" wrote in message
...

Peter Walker of Quad did a demonstration many years ago in which
he hooked up fifty Quad 303 amplifiers in series this way. The result
had audible hiss, but did not sound distorted or coloured.

This is unlikely, because no amplifier has infinite bandwidth. At the very
least, there would have been a noticeable loss in bass extension and
(especially) a severe rounding-off of high frequencies.

It doesn't need to have infinite bandwidth, it only needs to be
very very flat within the audio band when driving a resistor.
(The 303 is not all that perfectly flat when driving a
speaker load). At any rate Peter Walker actually did the
demonstration.

Also, the IM would pile up to a point where you'd expect it to be audible.

Distortion products when playing music were a good 90dB down for a
single amplifier in a nulling test. Distortion should voltage add,
so one would expect IM products to be 56dB down - that's about 0.15%,
not a whole lot. Since the amplifier inverts, the even order products
should cancel to some extent, so distortion might be a little lower
than that.

Peter.
--

[Arny Krueger[_4_]]

"Peter Irwin" wrote in message
...
William Sommerwerck wrote:

The closest you can come to determine whether the amp is neutral is to
stick
a resistive load on the output, and pad the input so the amp has unity
gain
(to within 0.1dB or better). You can then run a bypass test through the
line-level input to see if it's audible. This isn't a completely valid
test,
as the amp won't be driving a reactive load, but it's a start.

Peter Walker of Quad did a demonstration many years ago in which
he hooked up fifty Quad 303 amplifiers in series this way. The result
had audible hiss, but did not sound distorted or coloured.

(I seem to remember reading, but can not now find the source,
that fifteen Quad II valve amplifiers hooked up this way did have
distortion audible on programme material.)


Probably not bad recollections.

There are a number of reasons why a demo like the 50 Quad 303s would have
the results you mention. The first of which is the fact that the demo was
not a well-run ABX test with close, carefully chosen comparisons. Let me
choose the program material and any number of potentially audible sins will
not be heard. I know of audio gear that can come out clean over 20 passes,
but the same equipment would have audible effects over 50 passes.

Secondly, the audible noise probably masked a certain number of audible
flaws.

Thirdly, there are some non-obvious things about how distortion adds up
across multiple passes like this. For example, even-order nonlinear
distortion cancels when the number of passes is even, and is never gets to
be more than what you would have in one pass through the component.

[William Sommerwerck]

"Peter Irwin" wrote in message
...
William Sommerwerck wrote:
"Peter Irwin" wrote in message
...

Peter Walker of Quad did a demonstration many years ago in which
he hooked up fifty Quad 303 amplifiers in series this way. The result
had audible hiss, but did not sound distorted or coloured.

This is unlikely, because no amplifier has infinite bandwidth. At the
very
least, there would have been a noticeable loss in bass extension and
(especially) a severe rounding-off of high frequencies.

It doesn't need to have infinite bandwidth, it only needs to be
very very flat within the audio band when driving a resistor.
(The 303 is not all that perfectly flat when driving a
speaker load). At any rate Peter Walker actually did the
demonstration.

You need to look at the math of it. A low-pass filter has /some/ effect
octaves below its nominal corner frequency. Stick enough in series, and you
get a measurable and audible effect.

I remember hearing a ReVox test with five tape recorders in series. Under
the admittedly bad listening conditions of a hi-fi show, there was no
obvious loss in quality -- but no one would consider a ReVox a "perfect"
recorder.


Also, the IM would pile up to a point where you'd expect it to be
audible.

Distortion products when playing music were a good 90dB down for a
single amplifier in a nulling test.

What is your basis for this claim? QUAD never claimed such a deep null,
though a former Crown exec told me they'd gotten levels cose to -90dB with
the PL-1 and other amps of that era.


Distortion should voltage add,
so one would expect IM products to be 56dB down - that's about 0.15%,
not a whole lot. Since the amplifier inverts, the even order products
should cancel to some extent, so distortion might be a little lower
than that.

Again, I don't think that's true. The effect is probably multiplicative, so
you have IM on top of IM. Nor am I certain that the amplifier's non-linear
transfer characteristic can be modeled in such a simple way.

[Scott Dorsey]

In article , Peter Irwin wrote:
William Sommerwerck wrote:

The closest you can come to determine whether the amp is neutral is to stick
a resistive load on the output, and pad the input so the amp has unity gain
(to within 0.1dB or better). You can then run a bypass test through the
line-level input to see if it's audible. This isn't a completely valid test,
as the amp won't be driving a reactive load, but it's a start.

Peter Walker of Quad did a demonstration many years ago in which
he hooked up fifty Quad 303 amplifiers in series this way. The result
had audible hiss, but did not sound distorted or coloured.

That's impressive and says a lot about the Quad 303.

Bob Pease used to do a demonstration with a high gain monolithic op-amp
stage. He would show the 1 KHz square wave response and it looked pretty
good. Then he'd pull out a board with ten op-amps on it and attenuators
between them... and the response looked pretty good... then he'd pull out
a board with a hundred op-amps on it... and the response didn't look so
good. Then he went behind a partition and carried out a huge board with
a thousand op-amps on it... and the square wave was hardly square at all
on the output.

(I seem to remember reading, but can not now find the source,
that fifteen Quad II valve amplifiers hooked up this way did have
distortion audible on programme material.)

I bet it depends on the operating levels, but I could see that being the
case, especially on material with a lot of low-end content.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

William Sommerwerck wrote:

Peter Walker of Quad did a demonstration many years ago in which
he hooked up fifty Quad 303 amplifiers in series this way. The result
had audible hiss, but did not sound distorted or coloured.

This is unlikely, because no amplifier has infinite bandwidth. At the very
least, there would have been a noticeable loss in bass extension and
(especially) a severe rounding-off of high frequencies.

There's no infinite bandwidth source, but the 303 is remarkably flat across
the passband. Although mind you, if you're 1dB down at 20 KHz, after fifty
trips through, you're pretty far down there.

Also, the IM would pile up to a point where you'd expect it to be audible.

Yes, that's usually the most dramatic part.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Peter Irwin]

William Sommerwerck wrote:
"Peter Irwin" wrote in message

Distortion products when playing music were a good 90dB down for a
single amplifier in a nulling test.

What is your basis for this claim? QUAD never claimed such a deep null,
though a former Crown exec told me they'd gotten levels cose to -90dB with
the PL-1 and other amps of that era.

My memory is not necessarily correct. I seem to remember some such
claim in the March 1972 issue of Audio in an article on null testing
amplifiers, but I do not have access to that issue at the moment. It
should be at least the right order of magnitude for a high quality
transistor amplifier of that era.


Again, I don't think that's true. The effect is probably multiplicative, so
you have IM on top of IM. Nor am I certain that the amplifier's non-linear
transfer characteristic can be modeled in such a simple way.

I'm certainly not an expert at this. I was thinking that the random noise
should power-add so you get 17dB more noise, but the odd order distortion
will add in phase so you get 34dB more distortion. You seem to be right
that this fails to take distortion of the distortion products into
account, but surely this won't amount to very much extra at such
low levels of distortion.

Peter.
--