[[email protected]]

In theory the music is not (or barely) changed if we keep all the
knobs at the "U" position. In theory if we keep the trim or fader at
neutral ("U") position for the mixer, we should get only minimum
distortions even with a basic mixer like Mackie 1202.

For testing, we can use a high quality mic (say Neumann 89) and preamp
(say Millannia HV-3) and feed the output into the basic mixer (say
Mackie 1202), then adjust the setting on the preamp so that we can
simply use 'U' for trim and faders on the mixer. The result should be
similar to that of using a top-notch mixer.

Any use of the trim or fader on the basic mixer would kill the music
as many Mackie 1202 users have claimed in the past. I used this
technique to produce decent music, but I have not compared the result
with a top-notch mixer.

Is there any reason that we still have distortions by keeping all the
knobs on the mixer at 'U' position?

[Mike Rivers]

On Mar 3, 8:18 pm, wrote:

Is there any reason that we still have distortions by keeping all the
knobs on the mixer at 'U' position?

Sure. Because you can feed too much level to the channel and cause
clipping right at the front end. And if you have all the channels
operating close to their maximum level, this will overload the mix bus
and cause clipping there. You can't do these things without
understanding what's going on and expect success all the time.

Besides, mixers don't make great music, musicians do.

[Scott Dorsey]

wrote:

Is there any reason that we still have distortions by keeping all the
knobs on the mixer at 'U' position?

Yes. Electronics add coloration. Life is like that. If you spend more
money, you can get better sounding coloration, and sometimes less coloration.
But everything has coloration. Only live acoustic music is accurate.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[[email protected]]

On Mar 3, 5:29 pm, Mike Rivers wrote:
On Mar 3, 8:18 pm, wrote:

Is there any reason that we still have distortions by keeping all the
knobs on the mixer at 'U' position?

Sure. Because you can feed too much level to the channel and cause
clipping right at the front end. And if you have all the channels
operating close to their maximum level, this will overload the mix bus
and cause clipping there. You can't do these things without
understanding what's going on and expect success all the time.

Besides, mixers don't make great music, musicians do.

The premise is using the fader on the preamp (one for each channel) to
control the level of the sound of individual channel. So overloading
the mix bus on the mixer is not a concern under this premise.

I'm thinking about a minimum form of mixer with all the preamp,
effects, EQs, and faders off board. If we remove all the knobs on the
mixer, where does the distortion come from?

I'm just curious whether in theory a bare bone mixer like this can
preserve the music that talented musicians can make. All the
distortions created by the faders of the cheap mixers throughout the
years can be avoided this way.

[[email protected]]

On Mar 3, 5:33 pm, (Scott Dorsey) wrote:
wrote:

Is there any reason that we still have distortions by keeping all the
knobs on the mixer at 'U' position?

Yes. Electronics add coloration. Life is like that. If you spend more
money, you can get better sounding coloration, and sometimes less coloration.
But everything has coloration. Only live acoustic music is accurate.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

I am more thinking about the option of less colorization, which many
musicians have spent billions of dollars trying to get ( but failed).
There should be options for them too.

[Laurence Payne]

On Mon, 3 Mar 2008 17:44:26 -0800 (PST), wrote:

The premise is using the fader on the preamp (one for each channel) to
control the level of the sound of individual channel. So overloading
the mix bus on the mixer is not a concern under this premise.

I'm thinking about a minimum form of mixer with all the preamp,
effects, EQs, and faders off board. If we remove all the knobs on the
mixer, where does the distortion come from?

I'm just curious whether in theory a bare bone mixer like this can
preserve the music that talented musicians can make. All the
distortions created by the faders of the cheap mixers throughout the
years can be avoided this way.

If you pass a signal through ANY circuit distortion will occur.
Keeping the circuitry minimal makes it easier to reduce this
distortion, but by no means guarantees it :-)

Distortion caused by the microphone, loudspeaker and the rooms you
record and listen in will be enormously more significant than that
caused by any modern preamp/mixer (at least, by those which strive for
transparency - not all do.) There are probably much more productive
directions to aim your perfectionist zeal.

[RD Jones]

On Mar 3, 5:29 pm, Mike Rivers wrote:

Sure. Because you can feed too much level to the channel and cause
clipping right at the front end. And if you have all the channels
operating close to their maximum level, this will overload the mix bus
and cause clipping there. You can't do these things without
understanding what's going on and expect success all the time.

Besides, mixers don't make great music, musicians do.

On Mar 3, 8:44 pm, wrote:
The premise is using the fader on the preamp (one for each channel) to
control the level of the sound of individual channel. So overloading
the mix bus on the mixer is not a concern under this premise.

I'm thinking about a minimum form of mixer with all the preamp,
effects, EQs, and faders off board. If we remove all the knobs on the
mixer, where does the distortion come from?

I'm just curious whether in theory a bare bone mixer like this can
preserve the music that *talented musicians can make. All the
distortions created by the faders of the cheap mixers throughout the
years can be avoided this way.

If the purpose is recording then don't use a mixer at all.
Just plug straight into the recorder's input jack, and control
the level as you describe with the preamp.

If the purpose is live sound reinforcement, then all bets are off
since distortions and colorations of varying room acoustics,
loud monitors, poor mic technique, highly efficient but non-linear
reproduction speakers, etc, will swamp any gains in linearity
by using a minimal signal path.

Faders themselves are passive devices not prone to adding
color or distortion except in the case of poor design.

In trying to optimize a signal path by moving all processes
"off-board" you risk the added problems of many more places
where gain staging can be done improperly as compared to a
single well designed channel strip.

And by the way, if you remove all the preamps, EQs, faders,
and effects you're not left with much of a mixer.

In my observations, distortion and coloration comes from
places where gain is the highest and large impedance
differences must be matched.


rd

[[email protected]]

On Mar 3, 6:16 pm, Laurence Payne NOSPAMlpayne1ATdsl.pipex.com
wrote:
On Mon, 3 Mar 2008 17:44:26 -0800 (PST), wrote:
The premise is using the fader on the preamp (one for each channel) to
control the level of the sound of individual channel. So overloading
the mix bus on the mixer is not a concern under this premise.

I'm thinking about a minimum form of mixer with all the preamp,
effects, EQs, and faders off board. If we remove all the knobs on the
mixer, where does the distortion come from?

I'm just curious whether in theory a bare bone mixer like this can
preserve the music that talented musicians can make. All the
distortions created by the faders of the cheap mixers throughout the
years can be avoided this way.

If you pass a signal through ANY circuit distortion will occur.
Keeping the circuitry minimal makes it easier to reduce this
distortion, but by no means guarantees it :-)

Distortion caused by the microphone, loudspeaker and the rooms you
record and listen in will be enormously more significant than that
caused by any modern preamp/mixer (at least, by those which strive for
transparency - not all do.) There are probably much more productive
directions to aim your perfectionist zeal.

This discussion is focused on the transparency of a mixer based on a
given set of music source. Assume we have a transparent source of
music come in from a decent mic and preamp (as I stated), the question
is whether keeping the knobs at 'U' on the mixer or not will affect
the music dramatically.

I was surprised when I found out recently that the same music went
through the mixer without knobs at the 'U' position sounded much more
distorted than I that it was at 'U'. This would not have happened if
the fader indeed contributed little distortion.

[[email protected]]

On Mar 3, 6:20 pm, RD Jones wrote:
On Mar 3, 5:29 pm, Mike Rivers wrote:

Sure. Because you can feed too much level to the channel and cause
clipping right at the front end. And if you have all the channels
operating close to their maximum level, this will overload the mix bus
and cause clipping there. You can't do these things without
understanding what's going on and expect success all the time.

Besides, mixers don't make great music, musicians do.

On Mar 3, 8:44 pm, wrote:

The premise is using the fader on the preamp (one for each channel) to
control the level of the sound of individual channel. So overloading
the mix bus on the mixer is not a concern under this premise.

I'm thinking about a minimum form of mixer with all the preamp,
effects, EQs, and faders off board. If we remove all the knobs on the
mixer, where does the distortion come from?

I'm just curious whether in theory a bare bone mixer like this can
preserve the music that talented musicians can make. All the
distortions created by the faders of the cheap mixers throughout the
years can be avoided this way.

If the purpose is recording then don't use a mixer at all.
Just plug straight into the recorder's input jack, and control
the level as you describe with the preamp.

If the purpose is live sound reinforcement, then all bets are off
since distortions and colorations of varying room acoustics,
loud monitors, poor mic technique, highly efficient but non-linear
reproduction speakers, etc, will swamp any gains in linearity
by using a minimal signal path.

Faders themselves are passive devices not prone to adding
color or distortion except in the case of poor design.

In trying to optimize a signal path by moving all processes
"off-board" you risk the added problems of many more places
where gain staging can be done improperly as compared to a
single well designed channel strip.

And by the way, if you remove all the preamps, EQs, faders,
and effects you're not left with much of a mixer.

In my observations, distortion and coloration comes from
places where gain is the highest and large impedance
differences must be matched.

rd

Yes I sometimes record the music to the recorder directly and bypass
the additional processing of the mixer. Thanks for the reminder.

You made some very good points regarding the overall framework of the
mixer. I do understand the complexity to build a well coordinated
mixer. Though off-board effect and processing are common place and
what I stated was not any different. My main curiosity is whether the
distortion introduced by the fader can be avoided.

It is very true that "distortion and coloration comes from
places where gain is the highest and large impedance differences must
be matched." Though I recently found out that the fader on the mixer
may contribute to more distortion than we might have expected.

So either we need to buy a high-end mixer or skip the mixer to
preserve the transparency of the music source. Though as I stated,
keeping the knobs at 'U' just might be one option if we only have a
basic mixer at hand.

[Chris Hornbeck]

On Mon, 3 Mar 2008 18:32:41 -0800 (PST), wrote:


This discussion is focused on the transparency of a mixer based on a
given set of music source. Assume we have a transparent source of
music come in from a decent mic and preamp (as I stated), the question
is whether keeping the knobs at 'U' on the mixer or not will affect
the music dramatically.

I was surprised when I found out recently that the same music went
through the mixer without knobs at the 'U' position sounded much more
distorted than I that it was at 'U'. This would not have happened if
the fader indeed contributed little distortion.

Your conclusion that the distortion was *caused* by the faders
is incorrect. The topic that you want to research is called
"gain-staging" and will be useful to you in lots of other ways,
too.

All good fortune,

Chris Hornbeck
"It's 90% boilerplate, 1% real work, 9% WTF?"
-Les Cargill

[geezer[_2_]]

Keeping the knobs at 'U' will NOT affect the music dramatically.
Having bad musicians will.

But no-one here can talk you out of what you think you heard. I wonder
if you'd hear the same distortion in a blind test. I'm thinking
probably not...

A fader that is properly designed, even if relatively inexpensive,
coupled with proper gainstage management, should be the least of your
worries. Spend more time on putting the right mic in the right place,
and creating an environment that facilitates great performances by the
musicians.

Without that, you're just spending a lot of thought and energy
polishing turds.

-glenn

On Mar 3, 9:32*pm, wrote:

This discussion is focused on the transparency of a mixer based on a
given set of music source. Assume we have a transparent source of
music come in from a decent mic and preamp (as I stated), the question
is whether keeping the knobs at 'U' on the mixer or not will *affect
the music dramatically.

I was surprised when I found out recently that the same music went
through the mixer without knobs at the 'U' position sounded much more
distorted than I that it was at 'U'. This would not have happened if
the fader indeed contributed little distortion.- Hide quoted text -

- Show quoted text -

[[email protected]]

On Mar 3, 6:48 pm, Chris Hornbeck
wrote:
On Mon, 3 Mar 2008 18:32:41 -0800 (PST), wrote:
This discussion is focused on the transparency of a mixer based on a
given set of music source. Assume we have a transparent source of
music come in from a decent mic and preamp (as I stated), the question
is whether keeping the knobs at 'U' on the mixer or not will affect
the music dramatically.

I was surprised when I found out recently that the same music went
through the mixer without knobs at the 'U' position sounded much more
distorted than I that it was at 'U'. This would not have happened if
the fader indeed contributed little distortion.

Your conclusion that the distortion was *caused* by the faders
is incorrect. The topic that you want to research is called
"gain-staging" and will be useful to you in lots of other ways,
too.

All good fortune,

Chris Hornbeck
"It's 90% boilerplate, 1% real work, 9% WTF?"
-Les Cargill

Yes I committed a common mistake of "gain-staging" that is not
mentioned anywhere in the manual of the mixer nor in common
discussion. Basically I set the trim at +4 db at the input from the
mic preamp and later lower the fader at -3db when I adjust the overall
music. By doing this, I introduced the distortion of 'gain-staging'.

By providing users with a trim (to boost) and a fader (to cut), a
mixer basically inviting users to produce the 'gain-staging'
distortion.

So may be during the whole recording process (mic-preamp-mixerin-
mixdown-mixerout) we should only boost the volume and not cut to avoid
this kind of distortion?

[[email protected]]

On Mar 3, 6:55 pm, geezer wrote:
Keeping the knobs at 'U' will NOT affect the music dramatically.
Having bad musicians will.

But no-one here can talk you out of what you think you heard. I wonder
if you'd hear the same distortion in a blind test. I'm thinking
probably not...

A fader that is properly designed, even if relatively inexpensive,
coupled with proper gainstage management, should be the least of your
worries. Spend more time on putting the right mic in the right place,
and creating an environment that facilitates great performances by the
musicians.

Without that, you're just spending a lot of thought and energy
polishing turds.

-glenn

On Mar 3, 9:32 pm, wrote:



This discussion is focused on the transparency of a mixer based on a
given set of music source. Assume we have a transparent source of
music come in from a decent mic and preamp (as I stated), the question
is whether keeping the knobs at 'U' on the mixer or not will affect
the music dramatically.

I was surprised when I found out recently that the same music went
through the mixer without knobs at the 'U' position sounded much more
distorted than I that it was at 'U'. This would not have happened if
the fader indeed contributed little distortion.- Hide quoted text -

- Show quoted text -

Just learned something called 'gain-staging." See another message.

[Chris Hornbeck]

On Mon, 3 Mar 2008 19:01:31 -0800 (PST), wrote:

Yes I committed a common mistake of "gain-staging" that is not
mentioned anywhere in the manual of the mixer nor in common
discussion. Basically I set the trim at +4 db at the input from the
mic preamp and later lower the fader at -3db when I adjust the overall
music. By doing this, I introduced the distortion of 'gain-staging'.

The "+4 db" sounds suspiciously like a separate error of
technical understanding. You probably really want an appropriate
book on the technical issues of mixing. If you're really lucky
Mike Rivers will see this thread and recommend the correct Mackie
manual, (and he probably even wrote it).

Or some other book-quality source. You seem genuinely
interested, so will need something of book quality.


By providing users with a trim (to boost) and a fader (to cut), a
mixer basically inviting users to produce the 'gain-staging'
distortion.

So may be during the whole recording process (mic-preamp-mixerin-
mixdown-mixerout) we should only boost the volume and not cut to avoid
this kind of distortion?

Primitive mixers *can* be made with a single gain adjustment
for each channel. Sometimes that's the perfect, appropriate
thing. General-purpose mixers are done differently for good
reasons, and those reasons may be interesting to you. Again,
you'll want a good book.

All good fortune,

Chris Hornbeck
"It's 90% boilerplate, 1% real work, 9% WTF?"
-Les Cargill

[RD Jones]

On Mar 3, 6:20 pm, RD Jones wrote:
Faders themselves are passive devices not prone to adding
color or distortion except in the case of poor design.

In trying to optimize a signal path by moving all processes
"off-board" you risk the added problems of many more places
where gain staging can be done improperly as compared to a
single well designed channel strip.

And by the way, if you remove all the preamps, EQs, faders,
and effects you're not left with much of a mixer.

In my observations, distortion and coloration comes from
places where gain is the highest and large impedance
differences must be matched.

On Mar 3, 9:47 pm, wrote:
Yes I sometimes record the music to the recorder directly and bypass
the additional processing of the mixer. Thanks for the reminder.

You made some very good points regarding the overall framework of the
mixer. I do understand the complexity to build a well coordinated
mixer. Though off-board effect and processing are common place and
what I stated was not any different. My main curiosity is whether the
distortion introduced by the fader can be avoided.

It is very true that "distortion and coloration comes from
places where gain is the highest and large impedance differences must
be matched." Though I recently found out that the fader on the mixer
may contribute to more distortion than we might have expected.

So either we need to buy a high-end mixer or skip the mixer to
preserve the transparency of the music source. Though as I stated,
keeping the knobs at 'U' just might be one option if we only have a
basic mixer at hand.

The "U" indicator is nothing Magic or special.
It's just the same as a 0dB gain point and it occurs on both
the trim knob and fader. It's there to assist in setting your
gain staging, quite literally how much gain per stage you
add (or subtract in the case of a fader).

If you are getting audible distortion you have a problem.
Something is being overdriven or overloaded.

So if you have unity gain on the trim and unity at the fader
you are not adding any gain in the strip and no attenuation
at the (post fader) ouput. At this point you could take the
channel strip out of the path and you should be left with
exactly the same signal you put in. A line input from an
external preamp should be capable of exceeding small
amounts of distortion well below the threshold of being
audible. A small amount of gain or attenuation should have
very little effect and a properly designed strip should not
add or subtract anything from the sound.

Remember, a fader is passive, hung on the output of the
channel to control the output level. If there's distortion it's
happening in the active circuits ahead of the fader.

rd

[Paul Stamler]

wrote in message
...
You made some very good points regarding the overall framework of the
mixer. I do understand the complexity to build a well coordinated
mixer. Though off-board effect and processing are common place and
what I stated was not any different. My main curiosity is whether the
distortion introduced by the fader can be avoided.

It is very true that "distortion and coloration comes from
places where gain is the highest and large impedance differences must
be matched." Though I recently found out that the fader on the mixer
may contribute to more distortion than we might have expected.

The only time faders contribute distortion is when they're defective. (Which
I have seen, but not often.) In electronic equipment, distortion only comes
from two places: amplifying circuits and bad contacts, and the overwhelming
percentage of the time it's amplifying circuits. All active circuits produce
some distortion, even if it's sometimes so low it's hard to measure. The
point of gain staging is to keep the levels in the amplifying circuits
sufficiently low that the distortion doesn't become audible, without
seriously compromising noise levels. Some mixers are better at that than
others; some Mackies, in particular, have highish distortion levels in the
bus, summing and output amplifiers, so one needs to run those at
lower-than-usual levels to avoid the distortion.

So either we need to buy a high-end mixer or skip the mixer to
preserve the transparency of the music source. Though as I stated,
keeping the knobs at 'U' just might be one option if we only have a
basic mixer at hand.

What you need to do, instead of flogging this particular dead horse, is two
things. First, take a look at the r.a.p. FAQ, with particular attention to
"gain staging". Second, get a copy of the Yamaha Sound Reinforcement
Handbook and read it from cover to cover. Even if your focus is recording ra
ther than sound reinforcement, this book provides a good overview of what
goes on inside a mixer.

Peace,
Paul

[Chris Hornbeck]

On Tue, 04 Mar 2008 03:44:27 GMT, "Paul Stamler"
wrote:

What you need to do, instead of flogging this particular dead horse, is two
things. First, take a look at the r.a.p. FAQ, with particular attention to
"gain staging". Second, get a copy of the Yamaha Sound Reinforcement
Handbook and read it from cover to cover. Even if your focus is recording ra
ther than sound reinforcement, this book provides a good overview of what
goes on inside a mixer.

And those of a deeply technical bent might also want to
read Paul's AA mixer construction article that ran late
1995 and early 1996. Still the gold standard.

Much thanks, as always,

Chris Hornbeck
"It's 90% boilerplate, 1% real work, 9% WTF?"
-Les Cargill

[[email protected]]

On Mar 3, 7:38 pm, RD Jones wrote:
On Mar 3, 6:20 pm, RD Jones wrote:
Faders themselves are passive devices not prone to adding
color or distortion except in the case of poor design.

In trying to optimize a signal path by moving all processes
"off-board" you risk the added problems of many more places
where gain staging can be done improperly as compared to a
single well designed channel strip.

And by the way, if you remove all the preamps, EQs, faders,
and effects you're not left with much of a mixer.

In my observations, distortion and coloration comes from
places where gain is the highest and large impedance
differences must be matched.

On Mar 3, 9:47 pm, wrote:



Yes I sometimes record the music to the recorder directly and bypass
the additional processing of the mixer. Thanks for the reminder.

You made some very good points regarding the overall framework of the
mixer. I do understand the complexity to build a well coordinated
mixer. Though off-board effect and processing are common place and
what I stated was not any different. My main curiosity is whether the
distortion introduced by the fader can be avoided.

It is very true that "distortion and coloration comes from
places where gain is the highest and large impedance differences must
be matched." Though I recently found out that the fader on the mixer
may contribute to more distortion than we might have expected.

So either we need to buy a high-end mixer or skip the mixer to
preserve the transparency of the music source. Though as I stated,
keeping the knobs at 'U' just might be one option if we only have a
basic mixer at hand.

The "U" indicator is nothing Magic or special.
It's just the same as a 0dB gain point and it occurs on both
the trim knob and fader. It's there to assist in setting your
gain staging, quite literally how much gain per stage you
add (or subtract in the case of a fader).

If you are getting audible distortion you have a problem.
Something is being overdriven or overloaded.

So if you have unity gain on the trim and unity at the fader
you are not adding any gain in the strip and no attenuation
at the (post fader) ouput. At this point you could take the
channel strip out of the path and you should be left with
exactly the same signal you put in. A line input from an
external preamp should be capable of exceeding small
amounts of distortion well below the threshold of being
audible. A small amount of gain or attenuation should have
very little effect and a properly designed strip should not
add or subtract anything from the sound.

Remember, a fader is passive, hung on the output of the
channel to control the output level. If there's distortion it's
happening in the active circuits ahead of the fader.

rd

I am a bit confused. I think the "U" indicator is special because
once we dial to the right, we boost the signal and depend on whether
we are dealing with $500 or $10,000 equipment, there are a bit larger
or small distortion in this process.

If magnifying the electronic signal does not introduce distortion, why
buy preamp or amp costing thousands of dollars to reduce the
distortion?

[[email protected]]

On Mar 3, 7:44 pm, "Paul Stamler" wrote:
wrote in message

...

You made some very good points regarding the overall framework of the
mixer. I do understand the complexity to build a well coordinated
mixer. Though off-board effect and processing are common place and
what I stated was not any different. My main curiosity is whether the
distortion introduced by the fader can be avoided.

It is very true that "distortion and coloration comes from
places where gain is the highest and large impedance differences must
be matched." Though I recently found out that the fader on the mixer
may contribute to more distortion than we might have expected.

The only time faders contribute distortion is when they're defective. (Which
I have seen, but not often.) In electronic equipment, distortion only comes
from two places: amplifying circuits and bad contacts, and the overwhelming
percentage of the time it's amplifying circuits. All active circuits produce
some distortion, even if it's sometimes so low it's hard to measure. The
point of gain staging is to keep the levels in the amplifying circuits
sufficiently low that the distortion doesn't become audible, without
seriously compromising noise levels. Some mixers are better at that than
others; some Mackies, in particular, have highish distortion levels in the
bus, summing and output amplifiers, so one needs to run those at
lower-than-usual levels to avoid the distortion.

So either we need to buy a high-end mixer or skip the mixer to
preserve the transparency of the music source. Though as I stated,
keeping the knobs at 'U' just might be one option if we only have a
basic mixer at hand.

What you need to do, instead of flogging this particular dead horse, is two
things. First, take a look at the r.a.p. FAQ, with particular attention to
"gain staging". Second, get a copy of the Yamaha Sound Reinforcement
Handbook and read it from cover to cover. Even if your focus is recording ra
ther than sound reinforcement, this book provides a good overview of what
goes on inside a mixer.

Peace,
Paul
use


Actually the situation is quite simple. Once we switch to off-board
preamp rather than the built-in preamp of a mixer, we must remember to
dial the input trim all the way back to 'U'. Otherwise we will still
be activating the preamp on the mixer and lose some transparency of
the music.

I do agree that if we use the fader to cut (instead of boost) the
music level, there should be very small distortion.

[[email protected]]

On Mar 3, 7:32 pm, Chris Hornbeck
wrote:
On Mon, 3 Mar 2008 19:01:31 -0800 (PST), wrote:
Yes I committed a common mistake of "gain-staging" that is not
mentioned anywhere in the manual of the mixer nor in common
discussion. Basically I set the trim at +4 db at the input from the
mic preamp and later lower the fader at -3db when I adjust the overall
music. By doing this, I introduced the distortion of 'gain-staging'.

The "+4 db" sounds suspiciously like a separate error of
technical understanding. You probably really want an appropriate
book on the technical issues of mixing. If you're really lucky
Mike Rivers will see this thread and recommend the correct Mackie
manual, (and he probably even wrote it).

Or some other book-quality source. You seem genuinely
interested, so will need something of book quality.

By providing users with a trim (to boost) and a fader (to cut), a
mixer basically inviting users to produce the 'gain-staging'
distortion.

So may be during the whole recording process (mic-preamp-mixerin-
mixdown-mixerout) we should only boost the volume and not cut to avoid
this kind of distortion?

Primitive mixers *can* be made with a single gain adjustment
for each channel. Sometimes that's the perfect, appropriate
thing. General-purpose mixers are done differently for good
reasons, and those reasons may be interesting to you. Again,
you'll want a good book.

All good fortune,

Chris Hornbeck
"It's 90% boilerplate, 1% real work, 9% WTF?"
-Les Cargill

Come to think of it, the rule of thumb should be to use the fader as
booster only if it is on the highest grade preamp/amp in the chain --
normally that means the off-board preamp. Once we get the signal in
the mixer, we probably should use the fader strictly as a passive
device (by dialing to the left) and avoid dialing to the right since
that will cause a lesser amp to increase the signal.

[RD Jones]

On Mar 3, 7:38 pm, RD Jones wrote:

The "U" indicator is nothing Magic or special.
It's just the same as a 0dB gain point and it occurs on both
the trim knob and fader. It's there to assist in setting your
gain staging, quite literally how much gain per stage you
add (or subtract in the case of a fader).

If you are getting audible distortion you have a problem.
Something is being overdriven or overloaded.

So if you have unity gain on the trim and unity at the fader
you are not adding any gain in the strip and no attenuation
at the (post fader) ouput. At this point you could take the
channel strip out of the path and you should be left with
exactly the same signal you put in. A line input from an
external preamp should be capable of exceeding small
amounts of distortion well below the threshold of being
audible. A small amount of gain or attenuation should have
very little effect and a properly designed strip should not
add or subtract anything from the sound.

Remember, a fader is passive, hung on the output of the
channel to control the output level. If there's distortion it's
happening in the active circuits ahead of the fader.

On Mar 3, 10:52 pm, wrote:

I am a *bit confused. I think the "U" indicator is special because
once we dial to the right, we boost the signal and depend on whether
we are dealing with $500 or $10,000 equipment, there are a bit larger
or small distortion in this process.

The channel can be just as easily overdriven with the trim set at
-10dB by simply supplying a 10dB hotter signal. Likewise, a 10dB
lower signal would distort at a gain of +10dB.

But you shouldn't have any audible distortion to begin with.
I think your "+4" is a lot hotter than you realize.

The console channel doesn't have any built-in distortion control
like a fuzzbox or guitar amp. If you hear distortion, you have a
problem.

If magnifying the electronic signal does not introduce distortion, why
buy preamp or amp costing thousands of dollars to reduce the
distortion?

You cannot "reduce distortion".
Once it's there, it's there.

The reason many preamps are so expensive is to achieve lower
noise and less response variation. They are also built better and are
more reliable. Transformers are also costly, but can add a bit of
coloration.

Another word for gain staging is "gain structure"


rd

[Chris Hornbeck]

On Mon, 3 Mar 2008 20:09:03 -0800 (PST), wrote:

Come to think of it, the rule of thumb should be to use the fader as
booster only if it is on the highest grade preamp/amp in the chain --
normally that means the off-board preamp. Once we get the signal in
the mixer, we probably should use the fader strictly as a passive
device (by dialing to the left) and avoid dialing to the right since
that will cause a lesser amp to increase the signal.

Again, you really want to read up about gain-staging. IIRC,
the r.a.p FAQ is a pretty good starting point.

All good fortune,

Chris Hornbeck
"It's 90% boilerplate, 1% real work, 9% WTF?"
-Les Cargill

[[email protected]]

On Mar 3, 8:21 pm, Chris Hornbeck
wrote:
On Mon, 3 Mar 2008 20:09:03 -0800 (PST), wrote:
Come to think of it, the rule of thumb should be to use the fader as
booster only if it is on the highest grade preamp/amp in the chain --
normally that means the off-board preamp. Once we get the signal in
the mixer, we probably should use the fader strictly as a passive
device (by dialing to the left) and avoid dialing to the right since
that will cause a lesser amp to increase the signal.

Again, you really want to read up about gain-staging. IIRC,
the r.a.p FAQ is a pretty good starting point.

All good fortune,

Chris Hornbeck
"It's 90% boilerplate, 1% real work, 9% WTF?"
-Les Cargill

Will do. Thanks!

[jakdedert]

Scott Dorsey wrote:
wrote:
Is there any reason that we still have distortions by keeping all the
knobs on the mixer at 'U' position?

Yes. Electronics add coloration. Life is like that. If you spend more
money, you can get better sounding coloration, and sometimes less coloration.
But everything has coloration. Only live acoustic music is accurate.

In a good room....

jak
--scott

[Eeyore]

wrote:

In theory the music is not (or barely) changed if we keep all the
knobs at the "U" position. In theory if we keep the trim or fader at
neutral ("U") position for the mixer, we should get only minimum
distortions even with a basic mixer like Mackie 1202.

NO !

The FADER should be indeed operated around the 'U' mark generally speaking
but the input trim needs to be adjusted to suit the signal source.

Depending on the sensitivity of the microphone in use and the distance of
the performer from it and how loud their voice or instruemnt is, the
output from ther mic will vary HUGELY ! That's why you need a trim with a
50dB (or more) range, to get the right 'working level' going through the
channel.

A 'loud' signal might clip the mic preamp set at 'U' whereas a quiet
signal would suffer poor signal to noise figures if dealt with this way.

This is FUNDAMENTAL stuff.

Graham

[Eeyore]

wrote:

All the distortions created by the faders of the cheap mixers throughout
the
years can be avoided this way.

With today's technology, even the cheapest mixers ( e.g. Behringer - not
total junk ) barely add any distortion now. Look elsewhere.

Graham

[Eeyore]

Laurence Payne wrote:

If you pass a signal through ANY circuit distortion will occur.

National's latest op-amps have THD figures of -130dB.

Your statement is false. Such circuitry will not add distortion in any
meaningful way.

Graham

[Eeyore]

Laurence Payne wrote:

Keeping the circuitry minimal makes it easier to reduce this
distortion, but by no means guarantees it :-)

Often the best kit has rather more circuitry than others !

Honestly, today's tecnology makes your suggestion baseless.

Graham

[Eeyore]

wrote:

Yes I committed a common mistake of "gain-staging" that is not
mentioned anywhere in the manual of the mixer nor in common
discussion. Basically I set the trim at +4 db at the input from the
mic preamp and later lower the fader at -3db when I adjust the overall
music. By doing this, I introduced the distortion of 'gain-staging'.

By providing users with a trim (to boost) and a fader (to cut), a
mixer basically inviting users to produce the 'gain-staging'
distortion.

You're talking complete nonsense. You need to learn how to 'drive' a mixer
competently instead of using it amateurishly.

There's plently of guidance on the Mackie site.

Graham

[Eeyore]

wrote:

I am a bit confused.

VERY confused.


I think the "U" indicator is special because
once we dial to the right, we boost the signal and depend on whether
we are dealing with $500 or $10,000 equipment, there are a bit larger
or small distortion in this process.

Surprisingly little difference in fact. Indeed many use exactly the same
active components. With more expensive kit you're paying a lot extra for
extra features and facilities, more durable (longer lived) parts and the
added cost of manufacturing in smaller numbers (higher R&D overhead too).


If magnifying the electronic signal does not introduce distortion, why
buy preamp or amp costing thousands of dollars to reduce the
distortion?

NO competently designed modern audio electronics will introduce distortion
that's genuinely audibly offensive unless *abused* or misused.

Graham

[Eeyore]

Paul Stamler wrote:

some Mackies, in particular, have highish distortion levels in the
bus, summing and output amplifiers, so one needs to run those at
lower-than-usual levels to avoid the distortion.

They simply have inadequate headroom on the mix bus in a misguided attempt to
keep the bus noise down.

Graham

[Chevdo]

In article ,
says...



Laurence Payne wrote:

If you pass a signal through ANY circuit distortion will occur.

National's latest op-amps have THD figures of -130dB.

THD isn't rated in dB, it's rated as a percentage across a particular frequency
band.


Your statement is false. Such circuitry will not add distortion in any
meaningful way.


THD is a specific type of distortion, and certainly not all types of distortion
are THD. He was referring to distortion in the general sense of the term, in
other words, the signal not being perfectly reproduced and any difference from
the signal on one side of the circuit to the other referred to as distortion.
Not total harmonic distortion, just distortion.

[Chevdo]

In article ,
says...

wrote in message
...
You made some very good points regarding the overall framework of the
mixer. I do understand the complexity to build a well coordinated
mixer. Though off-board effect and processing are common place and
what I stated was not any different. My main curiosity is whether the
distortion introduced by the fader can be avoided.

It is very true that "distortion and coloration comes from
places where gain is the highest and large impedance differences must
be matched." Though I recently found out that the fader on the mixer
may contribute to more distortion than we might have expected.

The only time faders contribute distortion is when they're defective. (Which
I have seen, but not often.) In electronic equipment, distortion only comes
from two places: amplifying circuits and bad contacts, and the overwhelming
percentage of the time it's amplifying circuits. All active circuits produce
some distortion, even if it's sometimes so low it's hard to measure. The
point of gain staging is to keep the levels in the amplifying circuits
sufficiently low that the distortion doesn't become audible, without
seriously compromising noise levels. Some mixers are better at that than
others; some Mackies, in particular, have highish distortion levels in the
bus, summing and output amplifiers, so one needs to run those at
lower-than-usual levels to avoid the distortion.


This is the best reply in the thread, by far. I peg it at 85% on the
Chevdo Usenet Quality Meter, compared to an average of 20% for the rest of the
posts to this thread. And speaking of distortion, upon popping in today for
the first time in a year or so, I've observed that the distortion of
signal-to-noise on rec.audio.pro is as dismal a spec as always..

[Chevdo]

In article ,
says...



Paul Stamler wrote:

some Mackies, in particular, have highish distortion levels in the
bus, summing and output amplifiers, so one needs to run those at
lower-than-usual levels to avoid the distortion.

They simply have inadequate headroom on the mix bus in a misguided attempt to
keep the bus noise down.


The inadequate headroom is what brings the bus noise into the picture, and the
inadequate headroom is a byproduct of an underpowered preamp. All of these
pro-sumer mixer preamps are under-powered as a cost-saving measure. Expensive
pre-amps will have more headroom because they are more powerful. It's a
cost/benefit trade-off. You cannot get adequate gain from a pro-sumer mixer
pre-amp to record very quiet sounds, but most people using them will not be
trying to record quiet sounds. When you jack up the gain on a pre-amp to
record a quiet sound, the pre-amp introduces a lot of noise near its maximum,
whereas a pre-amp twice as powerful (and probably four times as expensive)
would only be driven half as much to get the same gain, thus operating at its
most efficient and least-noisey range.

[Eeyore]

Chevdo wrote:

says...
Laurence Payne wrote:

If you pass a signal through ANY circuit distortion will occur.

National's latest op-amps have THD figures of -130dB.

THD isn't rated in dB, it's rated as a percentage across a particular frequency
band.

Stricly speaking I should have said SINAD but not everyone's familiar with that.

In this case there are so many zeroes after the decimal point I can't reliably
remember the figure any other way.

Graham

[Eeyore]

Chevdo wrote:

THD is a specific type of distortion,

It's total harmic distortion.


and certainly not all types of distortion are THD.

Obfuscation.


He was referring to distortion in the general sense of the term, in
other words, the signal not being perfectly reproduced and any difference from
the signal on one side of the circuit to the other referred to as distortion.
Not total harmonic distortion, just distortion.

Well ... it seems he didn't really know what he meant to me.

Graham

[Eeyore]

Chevdo wrote:

says...
Paul Stamler wrote:

some Mackies, in particular, have highish distortion levels in the
bus, summing and output amplifiers, so one needs to run those at
lower-than-usual levels to avoid the distortion.

They simply have inadequate headroom on the mix bus in a misguided attempt to
keep the bus noise down.

The inadequate headroom is what brings the bus noise into the picture

Low headroom in this instance is cause by running the bus too hot in an attempt to
keep bus noise DOWN.

The bus amp isn't required this way to have as much gain as it doesn't have to
make up a typical 6 or 10 dB signal 'loss' hence it can be quieter.

Graham

[Paul Stamler]

wrote in message
...

Actually the situation is quite simple. Once we switch to off-board
preamp rather than the built-in preamp of a mixer, we must remember to
dial the input trim all the way back to 'U'. Otherwise we will still
be activating the preamp on the mixer and lose some transparency of
the music.

Actually you don't understand what's going on at all.

Here is how most mixers are designed.

First there's an input jack, which is connected to an amplifier. That
amplifier has a GAIN or TRIM control, which controls how much amplification
it provides the signal -- a lot for a small signal, less for a larger
signal.

Then come things like insert jacks and EQ circuits, which we'll ignore for
the purposes of this discussion.

Then comes a fader. It does only one thing: it cuts down the signal level.
Always. It never boosts, because it can't. It's a passive device, also known
as a potentiometer. It decreases the signal level by a greater or lesser
amount.

Then comes another amplifier, which may or may not have any voltage gain.
Then come switches and panpots to steer the signal where you want it to go.

Then comes a summing amplifier, which mixes all the signals for that
particular channel together.

Then comes another fader, the master fader for that channel. Again, it cuts
the signal by a lesser or greater degree. It DOES NOT amplify.

Finally comes an output amplifier, which boosts the signal some and sends it
out into the world via the output jack.

There may be other bells and whistles (extra buses, monitor sends, etc.) but
that's the basic architecture of most of the mixers out there.

When a mixer's fader is marked "U", that means that when it's set to "U" and
the TRIM control is also set to "U" and the master is set to "U", the mixer
AS A WHOLE will have unity gain -- in other words, the amount of loss the
faders create will compensate for any gain the amplifiers provide. IF you
feed the mixer with the proper level and you have a good mixer, the
distortion will be low.

BUT -- and this is the crucial thing you haven't understood -- just having
the mixer's faders and TRIM controls all set at "U" is no guarantee of low
distortion, since you can put too hot a signal into it from an external
preamp. It's a good starting point, if your mixer's a good one, but it's no
guarantee. Conversely, just because the mixer's faders and TRIM controls are
NOT set at "U", that doesn't mean the distortion will be high. Again, it's a
matter of gain staging and the quality of the mixer.

Please go read about gain staging and how it works before you come back
again. You really don't understand what's going on yet.

Peace,
Paul

[[email protected]]

On Mar 4, 12:01 am, "Paul Stamler" wrote:
wrote in message

...



Actually the situation is quite simple. Once we switch to off-board
preamp rather than the built-in preamp of a mixer, we must remember to
dial the input trim all the way back to 'U'. Otherwise we will still
be activating the preamp on the mixer and lose some transparency of
the music.

Actually you don't understand what's going on at all.

Here is how most mixers are designed.

First there's an input jack, which is connected to an amplifier. That
amplifier has a GAIN or TRIM control, which controls how much amplification
it provides the signal -- a lot for a small signal, less for a larger
signal.

Then come things like insert jacks and EQ circuits, which we'll ignore for
the purposes of this discussion.

Then comes a fader. It does only one thing: it cuts down the signal level.
Always. It never boosts, because it can't. It's a passive device, also known
as a potentiometer. It decreases the signal level by a greater or lesser
amount.

Then comes another amplifier, which may or may not have any voltage gain.
Then come switches and panpots to steer the signal where you want it to go.

Then comes a summing amplifier, which mixes all the signals for that
particular channel together.

Then comes another fader, the master fader for that channel. Again, it cuts
the signal by a lesser or greater degree. It DOES NOT amplify.

Finally comes an output amplifier, which boosts the signal some and sends it
out into the world via the output jack.

There may be other bells and whistles (extra buses, monitor sends, etc.) but
that's the basic architecture of most of the mixers out there.

When a mixer's fader is marked "U", that means that when it's set to "U" and
the TRIM control is also set to "U" and the master is set to "U", the mixer
AS A WHOLE will have unity gain -- in other words, the amount of loss the
faders create will compensate for any gain the amplifiers provide. IF you
feed the mixer with the proper level and you have a good mixer, the
distortion will be low.

BUT -- and this is the crucial thing you haven't understood -- just having
the mixer's faders and TRIM controls all set at "U" is no guarantee of low
distortion, since you can put too hot a signal into it from an external
preamp. It's a good starting point, if your mixer's a good one, but it's no
guarantee. Conversely, just because the mixer's faders and TRIM controls are
NOT set at "U", that doesn't mean the distortion will be high. Again, it's a
matter of gain staging and the quality of the mixer.

Please go read about gain staging and how it works before you come back
again. You really don't understand what's going on yet.

Peace,
Paul

This is what I was worried about. And if this is true, I have no use
for a basic mixer. Mixing high quality preamps/effects with these
lesser amplifiers do not make sense. This is the kind of knowledge
that I was looking for. Thanks!

If the manufactures can build a mixer with only faders and not
amplifiers, then it will be the barebone mixer that I was
envisioning. Without the amplifiers, this barebone mixer should be
able to rival the best mixers in the world in turns of distortion.

But with these amplifiers, not even the longest FAQ can turn a budget
mixer into decent recording device like some people claimed.

[Laurence Payne]

On Tue, 04 Mar 2008 05:56:02 +0000, Eeyore
wrote:

Laurence Payne wrote:

If you pass a signal through ANY circuit distortion will occur.

National's latest op-amps have THD figures of -130dB.

Your statement is false. Such circuitry will not add distortion in any
meaningful way.

Which was my point, as you'd have discovered if you'd read on before
knee-jerking with a put-down.

Everything introduces distortion. Often it's negligible, and not
worth chasing.