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Offline JD

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Question about pre-amp coloration.
« on: November 22, 2007, 01:44:18 AM »
Can you vary the amount of sonic coloration from a pre-amp by using different amounts of gain?

In other words, say I have a transparent recorder and a warm pre-amp and I need about 20db of gain. If I set the recorder to zero gain and add 20db with the pre will it be warmer than say adding 5db with the pre and 15db with the recorder?

Just wonder if this is something that can be played with to fine tune a pre-amp/recorder combination.
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Offline boojum

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Re: Question about pre-amp coloration.
« Reply #1 on: November 22, 2007, 02:31:08 AM »
I think that would depend a lot pn the hardware's tendency to distort at higher levels.  Better, IMO, to record a clean signal and tweak in post processing.
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Offline OOK

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Re: Question about pre-amp coloration.
« Reply #2 on: November 22, 2007, 06:03:00 AM »
IF I understand your question correctly.  Coloration doesn't really have anything to do with gain.  It has more to do with the signal traveling through a particular series of circuts.  Since each preamp thats out there has somewhat different circuts and or signal paths, that is what imparts a particular sound for a particular preamp.

Example the circuts in say a V3 are different than a SDmixpre.  Although they may do the same thing, different circut designs and layout along with different brands of circuts being used is what impart that sound for said preamp. 

Thats just my 2cents.  Peace and Happy Thanksgiving..OOK
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Offline guysonic

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Re: Question about pre-amp coloration.
« Reply #3 on: November 22, 2007, 09:48:59 AM »
TECHNICALLY SPEAKING, the more gain demanded from a preamp, the 'softer' it gets. 

While most are not going to hear this, and there are a few preamps without this characteristic (like my PA-24 series), I have noticed (very audible) a 'softening' with minidecks (MD, DAT, Flash) having only two mic input gain selections (hi/low or 0dB/-20 dB ATTEN) mic sensitivity choices. 

When these decks are in lower mic gain, the sound is crisp/clear, but in boosted +20 dB high gain mode, the single stage amp's gain is set too high to maintain extended frequency response, low distortion.  This is easily audible to me using Sony high resolution MDR-SA3000/5000 headphones.

The sound is NOT usually bad in boosted mode, in fact the Sony DAT minidecks sounded quite good in boosted 'soft mode' and might be useful in taming an aggressively 'harsh' sounding microphone input.     
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Offline JD

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Re: Question about pre-amp coloration.
« Reply #4 on: November 22, 2007, 09:56:22 AM »
IF I understand your question correctly.  Coloration doesn't really have anything to do with gain.  It has more to do with the signal traveling through a particular series of circuts.  Since each preamp thats out there has somewhat different circuts and or signal paths, that is what imparts a particular sound for a particular preamp.

Example the circuts in say a V3 are different than a SDmixpre.  Although they may do the same thing, different circut designs and layout along with different brands of circuts being used is what impart that sound for said preamp. 

Thats just my 2cents.  Peace and Happy Thanksgiving..OOK

So a signal traveling through a pre-amp is sonically the same regardless of how much gain is being used? Just the amplitude of the signal changes?
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Offline Lil Kim Jong-Il

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Re: Question about pre-amp coloration.
« Reply #5 on: November 22, 2007, 10:30:54 AM »
So a signal traveling through a pre-amp is sonically the same regardless of how much gain is being used? Just the amplitude of the signal changes?

For an ideal preamp, yes, but only for an ideal preamp.

In an actual preamp (those sold by every vendor everywhere), there is always some distortion, noise, and non linear response. 

The better preamps have distortion, noise and non-linear response below the threshold of perception within their intended operating range but it's always there.  Those preamps are refered to as being "transparent".  "Color" is audible distortions and non-linear response.  Some color is pleasing, other color not so much.

edit for clarity
« Last Edit: November 22, 2007, 10:33:14 AM by Lil' Kim Jong-Il »
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Offline DSatz

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Re: Question about pre-amp coloration.
« Reply #6 on: November 22, 2007, 01:17:40 PM »
It's remarkable how many different viewpoints there are on this subject, no? --including some that can't possibly be correct at the same time. "Coloration" seems to be like "resolution"--a (seemingly) common-sense term used with great confidence by many people as if there was general actual agreement about what it means.

There are many things that a preamp can do besides simply amplifying a signal--it can add distortion of various kinds; it can have a limiting or compressing effect (which creates distortion, too), and/or it can have non-flat frequency response, for example. There are preamps which do all of these things and more, which are hotly desired by some engineers. All I can say is that I don't go there; what boojum said above (especially the second part of his message) is exactly what I believe. Before I take a preamp out for live recording I put it up on the test bench and make sure that it has flat frequency response and that it can handle the expected signal levels without overload (soft, hard or in-between, I don't want it).

In the process I've come across one otherwise very good preamp (the Rane MS-1B) that as you turned up the gain, its low-frequency response rolled off more and more; a series of rather mediocre preamps (ART Tube MP) that can merrily pump out 25% THD before their overload LED decides to come on--or only 0.5% THD (which I don't consider audible), all depending on exactly how you set the (three!) gain controls. I've seen one "classic" "vintage" preamp (Telefunken V 72) with a boosted low-frequency response, which has an effect that some people would describe as "warm"--but you could just as easily get that effect by boosting any other preamp's response the same amount, so how much of a virtue is that, really? And I've tried two kinds of Aphex "Tubessence" equipment (a preamp and a parametric equalizer) which used a tube for coloration, but after listening for a while, I gained a real appreciation for how the original recording sounded without any of that.

I'm far from being a purist; I'm all in favor of any kind of signal processing that gives favorable results, any way you choose to define that. I'm fond of the old Carver "Digital Time Lens" which uses M/S techniques to produce some audiophile enhancements; they're especially nice on some X/Y recordings. And Peavey used to make an inexpensive rack-mount device called the "Tube Sweetener" which adds tube coloration in controlled amounts to any stereo signal. Both are fun to experiment with, and sometimes they're just the cure for what's wrong with a recording. As is careful equalization--a fundamental skill that deserves great respect.

But a clean original recording is always the best starting point. You can't remove the excess salt from a soup once it's been poured in.

--best regards
« Last Edit: November 22, 2007, 01:21:22 PM by DSatz »
music > microphones > a recorder of some sort

Offline Professor chaos

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Re: Question about pre-amp coloration.
« Reply #7 on: November 23, 2007, 08:09:21 AM »
i think that each pre amp varies. for example: as a general rule i think preamp sound better when run "hot" (alot of gain). however, i have an oade m248 and the sound gets distorted if i go past half way on the gain. but imho you get more out of a preamp the hotter you run it. this is something you could play with from set I to set II. change the gain setting on the pre and the recorder and see what you find out. see how your gear works best with the bands you tape and in the rooms you tape. good luck
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Offline Church-Audio

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Re: Question about pre-amp coloration.
« Reply #8 on: November 23, 2007, 10:11:06 AM »
Can you vary the amount of sonic coloration from a pre-amp by using different amounts of gain?

In other words, say I have a transparent recorder and a warm pre-amp and I need about 20db of gain. If I set the recorder to zero gain and add 20db with the pre will it be warmer than say adding 5db with the pre and 15db with the recorder?

Just wonder if this is something that can be played with to fine tune a pre-amp/recorder combination.
I think it depends on the preamp. I agree with some of what has been said here. I think there are reasons why some people like Neve.. And I also believe that not everything can be analyzed on a bench. There are some things going on that are " not measurable " with today's equipment. More then just distortion more then frequency response.

To answer your question. There are some preamps that once put into the signal chain change the sound of your recording with out needing to necessarily be asked to amplify anything. And there are some that are so liner that they can not be detected..

My self I prefer a preamp that adds something besides gain. I want warmth. And I also have to disagree that you can just "eq" warmth into your signal... If that was the case there would be a lot of guitar players that would have sold there tube amps and purchased line 6 amps. That simply is not the case you can add low end. But low end is not all that warmth is.. There is harmonic distortion going on that adds warmth and there are other factors.

 I think everyone is in a rush to convert everything into 0--1's but IMO there is a lot be said for a nice fat warm analog preamp in the front end of any digital recorder as long as it has some kind of desirable character and I am not just saying this because I make preamps  ;)
« Last Edit: November 23, 2007, 10:13:16 AM by Church-Audio »
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Offline Brian

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Re: Question about pre-amp coloration.
« Reply #9 on: November 23, 2007, 10:32:51 AM »
Can you vary the amount of sonic coloration from a pre-amp by using different amounts of gain?

In other words, say I have a transparent recorder and a warm pre-amp and I need about 20db of gain. If I set the recorder to zero gain and add 20db with the pre will it be warmer than say adding 5db with the pre and 15db with the recorder?

Just wonder if this is something that can be played with to fine tune a pre-amp/recorder combination.
I think it depends on the preamp. I agree with some of what has been said here. I think there are reasons why some people like Neve.. And I also believe that not everything can be analyzed on a bench. There are some things going on that are " not measurable " with today's equipment. More then just distortion more then frequency response.

To answer your question. There are some preamps that once put into the signal chain change the sound of your recording with out needing to necessarily be asked to amplify anything. And there are some that are so liner that they can not be detected..

My self I prefer a preamp that adds something besides gain. I want warmth. And I also have to disagree that you can just "eq" warmth into your signal... If that was the case there would be a lot of guitar players that would have sold there tube amps and purchased line 6 amps. That simply is not the case you can add low end. But low end is not all that warmth is.. There is harmonic distortion going on that adds warmth and there are other factors.

 I think everyone is in a rush to convert everything into 0--1's but IMO there is a lot be said for a nice fat warm analog preamp in the front end of any digital recorder as long as it has some kind of desirable character and I am not just saying this because I make preamps  ;)

great post.  i know my ears love me some even harmonic distortion from tube gear :)

although there is something to be said for the clarity of some high quality 24/192 ADC's. i firmly believe that with the right techniques and a good ear, you can get a digital mix or recording to sound "just as" good as a great analog mix or recording.  it's all about understanding how those 1's and 0's work and using it to your advantage.

Offline JD

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Re: Question about pre-amp coloration.
« Reply #10 on: November 23, 2007, 12:09:56 PM »
Lots of good feedback so far. I like the suggestion about running one set with the gain on the pre and one set with the gain on the recorder.

I have been running the Portico in front the 722 my last few times out and adding all the gain with the pre. So far, I'm loving the warmth the pre is adding, it sounds very realistic and seems to take that "digital edge" off of the recording. I was just curious that if I were to redistribute the gain from the pre to the recorder if I could lessen this warmth for when it might be overkill.
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Offline 108Ω

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Re: Question about pre-amp coloration.
« Reply #11 on: November 23, 2007, 07:40:36 PM »

Can you vary the amount of sonic coloration from a pre-amp by using different amounts of gain?


Absolutely.
Non-linearity in gain is a reality in amplifier design.
It is one of the design parameters that any good pre-amp designer would be engineering and carefully testing.
The best amps have overcome virtually all of the non-linearity.

The most typical form of this distortion is that bass response increases as amp gain is increased, BTW.
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Offline OOK

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Re: Question about pre-amp coloration.
« Reply #12 on: November 23, 2007, 07:53:52 PM »


 I think everyone is in a rush to convert everything into 0--1's but IMO there is a lot be said for a nice fat warm analog preamp in the front end of any digital recorder







Yep gotta agree with this comment.......I am really liking the sound of the portico 5012 pre....and the MMP....
I always thought it is better to have a box that does 1 thing great than several things good.....

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Offline guysonic

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Re: Question about pre-amp coloration.
« Reply #13 on: November 23, 2007, 08:02:57 PM »

Can you vary the amount of sonic coloration from a pre-amp by using different amounts of gain?


Absolutely.
Non-linearity in gain is a reality in amplifier design.
It is one of the design parameters that any good pre-amp designer would be engineering and carefully testing.
The best amps have overcome virtually all of the non-linearity.

The most typical form of this distortion is that bass response increases as amp gain is increased, BTW.

"The most typical form of this distortion is that bass response increases as amp gain is increased, BTW."

Found pretty much the opposite where increased gain decreases high frequency response, and sometimes also low bass depending on the feedback/gain configuration.
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Offline 108Ω

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Re: Question about pre-amp coloration.
« Reply #14 on: November 24, 2007, 11:36:31 AM »

Can you vary the amount of sonic coloration from a pre-amp by using different amounts of gain?


Absolutely.
Non-linearity in gain is a reality in amplifier design.
It is one of the design parameters that any good pre-amp designer would be engineering and carefully testing.
The best amps have overcome virtually all of the non-linearity.

The most typical form of this distortion is that bass response increases as amp gain is increased, BTW.

"The most typical form of this distortion is that bass response increases as amp gain is increased, BTW."

Found pretty much the opposite where increased gain decreases high frequency response, and sometimes also low bass depending on the feedback/gain configuration.

I'm old school and trying to keep it simple.
Functionally, virtually all traditional tube and transistor amps sound bassier at higher levels unless extra expense and design work compensates for this.  (Fletcher-Munson not considered)

Needless to say, newer devices play much differently.

In my day, we never used "Codecs", PA ICs, and DSP.

The basic idea still applies, however. Different gain levels often does change the coloration of a pre.
I'll stir the pot again, a bit, and say that this is even more true of transformer-based pres.
Again, newer designs will likely exhibit much less of this effect.
Particularly if the xfmr is of a quality design and properly sized.
 
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Offline 108Ω

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Re: Question about pre-amp coloration.
« Reply #15 on: November 26, 2007, 09:16:54 PM »

 But low end is not all that warmth is.. There is harmonic distortion going on that adds warmth and there are other factors.


QFT
Most people, at a gut level, see warm coloration as increased mid-bass response.
This can occur from uneven frequency response or by low-bass harmonics "thickening" the mid-bass registers, as well as other "distortions".
Harmonics, if they are even-order (2, 4, 6, 8 ) have a pleasing, sympathetic sound, not entirely unlike listening to a chorus.

The acoustic effect of uneven frequency response is very different from that of low-bass harmonics.
The gain level which you adjust to will likely affect how much of each is present.
The design of the amp will determine whether you can hear it, and how it will sound.

Perception and acoustic impact will always be your best guide.
Use your ears, as different mics and recording conditions will impact the way a pre amp reacts.
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