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Real life experiences with external summing (ITB)?
Old 23rd May 2006
  #1
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Real life experiences with external summing (ITB)?

Hi!

For some time now I've been curious about external summing, I mean digital tracks have been tracked to the DAW and instead of letting the DAW do the summing job you convert the signal back to analog, sum the material and convert the material again into a stereo mix track. This is of course very much dependent on a good A/D/A chain and a good analog summing unit, so I just wonder, have you noticed any improvements in sound quality when summing outside? Can you say that you "win" sonic performance based on this approach in practise?

According to my theories this is one of the main advantages (besides tape saturation) with tracking analog and then converting the analog stereo mix to digital format, it might very well be a very important aspect related to conversion quality as a critical component of the recording process, at least as long as the bit precision ITB is rather low...

Have you read about any good "DIGITAL" summing plug-ins? It would be fun to hear a difference between a song tracked with an RME Fireface summed ITB and the same song tracked with an Apogee Rosetta and summed externally...
Old 23rd May 2006
  #2
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norman_nomad's Avatar
It´s my opinion that the benefits of summing have almost everything to do with the characteristics of the makeup gain amplifier.

I´m not in the camp that thinks digital summing is fundamentally flawed... summing boxes should be called 'audio transformer boxes'...

The closest thing to a 'digital summing' plug I could think of would be the color-tone pro plug.
Old 23rd May 2006
  #3
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amost's Avatar
 

Okay...this is not a slam at all seriously, just a curious observation but you have like 585 posts here & you haven't ever come across this topic here? Other than Digi vs. The rest of the World this is like one of the top flamefest battle subject/arguments here isn't it...or I thought. Might be I focus on the wrong things for sure.
Old 23rd May 2006
  #4
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Quote:
Originally Posted by amost
Okay...this is not a slam at all seriously, just a curious observation but you have like 585 posts here & you haven't ever come across this topic here? Other than Digi vs. The rest of the World this is like one of the top flamefest battle subject/arguments here isn't it...or I thought. Might be I focus on the wrong things for sure.
Whatever... Your post was not of any help.
Old 23rd May 2006
  #5
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Quote:
Originally Posted by norman_nomad
It´s my opinion that the benefits of summing have almost everything to do with the characteristics of the makeup gain amplifier.

I´m not in the camp that thinks digital summing is fundamentally flawed... summing boxes should be called 'audio transformer boxes'...

The closest thing to a 'digital summing' plug I could think of would be the color-tone pro plug.
I'll check out that color-tone pro plug... Thanks for the help!
Old 23rd May 2006
  #6
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amost's Avatar
 

Sorry guy no offense intended, I knew it was a a bad idea. I'm curious the same as you. Personally I like the idea of sending the digi mix out into a nice console with lots of analog toys with somebody who knows how to use them. That said there's blindfold tests that have been done of ITB/OTB mixes that have fooled some good ears I'm sure.
Old 23rd May 2006
  #7
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Quote:
Originally Posted by amost
Sorry guy no offense intended, I knew it was a a bad idea. I'm curious the same as you. Personally I like the idea of sending the digi mix out into a nice console with lots of analog toys with somebody who knows how to use them. That said there's blindfold tests that have been done of ITB/OTB mixes that have fooled some good ears I'm sure.
Great! Thanks for your input! I've read that quite many seem to do it that way... I think I'll give my analog mixer Mackie 1604-VLZ Pro a chance. So far I've been using it only for monitoring purposes, but who knows, maybe it sums tracks much more nicely... I'll try that tomorrow...!
Old 24th May 2006
  #8
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Rainbow - you've made it very clear that you don't like the sound of your keyboard once it's been recorded, and have been blaming the converters and looking for high end converters etc, etc, etc ...

Well - now we have another piece in the picture. You've been monitoring through a Mackier mixer? Has it occurred to you that this might be the fly in the ointment?

Knowing your preference for extreme high fidelity, I very much doubt that you will enjoy summing through more converters and the Mackie.

From what I can tell, your Tyros has unbalanced -10 analog outputs, and your RME has balanced +4 inputs. You may possibly need a dual DI box to correctly connect your keyboard to the RME a/d. To judge the d/a, you would need to connect directly from the d/a to your monitor amp - hopefully balanced to balanced.

If the Mackie is inserted at any point, you aren't giving your converters a fair hearing.

Excuse me if i've got this wrong - but you have posted a lot of words and i'm still trying to figure out where you are coming from.
Old 24th May 2006
  #9
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mixerguy's Avatar
Quote:
Originally Posted by Kiwiburger
Rainbow - you've made it very clear that you don't like the sound of your keyboard once it's been recorded, and have been blaming the converters and looking for high end converters etc, etc, etc ...

Well - now we have another piece in the picture. You've been monitoring through a Mackier mixer? Has it occurred to you that this might be the fly in the ointment?

Knowing your preference for extreme high fidelity, I very much doubt that you will enjoy summing through more converters and the Mackie.

From what I can tell, your Tyros has unbalanced -10 analog outputs, and your RME has balanced +4 inputs. You may possibly need a dual DI box to correctly connect your keyboard to the RME a/d. To judge the d/a, you would need to connect directly from the d/a to your monitor amp - hopefully balanced to balanced.

If the Mackie is inserted at any point, you aren't giving your converters a fair hearing.

Excuse me if i've got this wrong - but you have posted a lot of words and i'm still trying to figure out where you are coming from.

TRUE, TRUE!!!

Old 24th May 2006
  #10
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GYang's Avatar
OTB is meaningful only with very good converters, great summing gears, proper cabling between all gears and high quality outboards involved in the process.
Unfortunately compromises on any part of the chain can make OTB mixes less desirable and whole OTB vs ITB issue losing real purpose.
Even if everything is OK, still engineer can fukk up the mix either way.
Old 24th May 2006
  #11
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tunasafedolphin's Avatar
 

I must be in the mood to answer threads I usually wouldnt tonight...

I've done blind A/B tests with summing before, MANY of them in fact. Most recently I summed something ITB, then via an SSL G back into the box, then via an SSL G to Ampex 1/2 inch.

Obviously the 1/2 inch made a massive difference, especially in the image. Interestingly enough, the SSL bounce was obvious to me. I actually expected it wouldn't be all that different, but it most certainly was.

I prefered the SSL bounce to the SSL-Tape / ITB bounce. My guess is that the tape machine was a bit out of whack and henceforth took that bounce out of the running...

Most importantly, although the SSL bounce and the ITB bounce were different, I'm not sure if it was enough of a difference to even apply to the average consumer.


-Christian

P.S. - All A/D/A conversion was done via 192's clocked to a Big Ben.
Old 24th May 2006
  #12
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Quote:
Originally Posted by Kiwiburger
Rainbow - you've made it very clear that you don't like the sound of your keyboard once it's been recorded, and have been blaming the converters and looking for high end converters etc, etc, etc ...

Well - now we have another piece in the picture. You've been monitoring through a Mackier mixer? Has it occurred to you that this might be the fly in the ointment?

Knowing your preference for extreme high fidelity, I very much doubt that you will enjoy summing through more converters and the Mackie.

From what I can tell, your Tyros has unbalanced -10 analog outputs, and your RME has balanced +4 inputs. You may possibly need a dual DI box to correctly connect your keyboard to the RME a/d. To judge the d/a, you would need to connect directly from the d/a to your monitor amp - hopefully balanced to balanced.

If the Mackie is inserted at any point, you aren't giving your converters a fair hearing.

Excuse me if i've got this wrong - but you have posted a lot of words and i'm still trying to figure out where you are coming from.
Thanks for your reply! It HAS accured to me... I have monitored both directly from my Fireface and from my Mackie mixer (in reset state), just in case I would notice a difference. When I calibrated the mixer levels properly I couldn't hear a difference and I really tested this very thoroughly, so since it's more practical I've been using the Mackie as a monitoring desk and that has worked great so far, I'm not going to change that... I think I will find external summing to not work better, just like you think... But I'll give it a try today just for the fun of it...

It's true that I have a preference for extreme high fidelity, so I need a better connection and a better converter. That being said, I still want to know if analog summing without additional processing can improve the sound quality in practise...
Old 24th May 2006
  #13
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H-Rezz's Avatar
 

Quote:
Originally Posted by GYang
OTB is meaningful only with very good converters, great summing gears, proper cabling between all gears and high quality outboards involved in the process.
Unfortunately compromises on any part of the chain can make OTB mixes less desirable and whole OTB vs ITB issue losing real purpose.
Even if everything is OK, still engineer can fukk up the mix either way.
Very true, i agree with everything you wrote GYang ....... this is what my testing resulted in as well .
Old 24th May 2006
  #14
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Quote:
Originally Posted by tunasafedolphin
I must be in the mood to answer threads I usually wouldnt tonight...

I've done blind A/B tests with summing before, MANY of them in fact. Most recently I summed something ITB, then via an SSL G back into the box, then via an SSL G to Ampex 1/2 inch.

Obviously the 1/2 inch made a massive difference, especially in the image. Interestingly enough, the SSL bounce was obvious to me. I actually expected it wouldn't be all that different, but it most certainly was.

I prefered the SSL bounce to the SSL-Tape / ITB bounce. My guess is that the tape machine was a bit out of whack and henceforth took that bounce out of the running...

Most importantly, although the SSL bounce and the ITB bounce were different, I'm not sure if it was enough of a difference to even apply to the average consumer.


-Christian

P.S. - All A/D/A conversion was done via 192's clocked to a Big Ben.
Interesting...!
Old 24th May 2006
  #15
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Mark Cattano's Avatar
 

Rainbow

FWIW, I just got my D2B hooked up last night, and, yes, to my ears, there is quite a difference between ITB and analog summing. At first listen, my mixes sounded DEEPER. Depth is the only word to describe it. I had clarity. I had width. But now I have DEPTH, and I'm damned happy about it. Someone else here posted something that rings in my head now; "The difference is maybe 5% better, but I like that 5% a lot!"

Mark Cattano
Magneto Studios
www.heedmusic.com
www.myspace.com/markcattano
Old 24th May 2006
  #16
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Quote:
Originally Posted by Mark Cattano
Rainbow

FWIW, I just got my D2B hooked up last night, and, yes, to my ears, there is quite a difference between ITB and analog summing. At first listen, my mixes sounded DEEPER. Depth is the only word to describe it. I had clarity. I had width. But now I have DEPTH, and I'm damned happy about it. Someone else here posted something that rings in my head now; "The difference is maybe 5% better, but I like that 5% a lot!"

Mark Cattano
Magneto Studios
www.heedmusic.com
www.myspace.com/markcattano
Well, theoretically it makes sense. The clock jitter will make the summing process dirty, with ITB summing that will result in for instance instrument decay that is blended together into mud. When the separation is there you will experience more depth because the instrument decay can be better perceived.

Thanks for your input and I'm glad that you'll experienced some improvements in your sound!
Old 24th May 2006
  #17
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nathanvacha's Avatar
 

Quote:
Originally Posted by Mark Cattano
Rainbow
FWIW, I just got my D2B hooked up last night, and, yes, to my ears, there is quite a difference between ITB and analog summing. At first listen, my mixes sounded DEEPER. Depth is the only word to describe it. I had clarity. I had width. But now I have DEPTH, and I'm damned happy about it. Someone else here posted something that rings in my head now; "The difference is maybe 5% better, but I like that 5% a lot!"
Well, I still mix itb right now, but I think the point of mixing analog is (aside from outboard integration) not so much a "better sound through higher fidelity" improvement as a "better sound because there are naturally occurring flaws" type of thing. It's not more-perfected, it just sounds better.
Old 24th May 2006
  #18
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dim light's Avatar
 

I've done some test myself;
Attached Thumbnails
Real life experiences with external summing (ITB)?-digi_anal_sum.jpg  
Old 24th May 2006
  #19
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RKrizman's Avatar
 

Quote:
Originally Posted by RainbowStorm
Well, theoretically it makes sense. The clock jitter will make the summing process dirty, with ITB summing that will result in for instance instrument decay that is blended together into mud.
Um...no. But thank you anyway, Dr. Science.

-R
Old 24th May 2006
  #20
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Quote:
Originally Posted by RKrizman
Um...no. But thank you anyway, Dr. Science.

-R
You're welcome, Dr. Idiot.
Old 24th May 2006
  #21
I think this says what i think, perfectly from Bob Katz on this thread:

https://www.gearslutz.com/board/showthrea...ons+for+paul+f

or read below for the excerpt:

Quote:
Originally Posted by innesireinar
It started last week when I and a friend OM had one of the boring discussion analog/digital. After hours of discussion where everyone has remain in his position I promised to link him the Digido site. After two days he called me saying "your guru (you) is stating that analog is better" - And I "maybe this article is old" - "no, is updated 2005".
I went to read the article and I've only stated a discrepancy about your words between the PSW thread and the article, because on PSW you said that analog is far from perfect, works that you have received in your mastering studio done in digital, with the add of good analog outboard sounded better than those done mixed on the desk.
Therefore I'd like to have a your definitively point about that."

"Oh. Yes, time has marched on, in my opinion.

In another thread here on Gearslutz, introduced by Charles Dye, called "Favorite Analog Summing", I think I've covered my opinion. Here's another take on it, I guess it's a rehearsal for a rewrite of my article!

In the past (say, through 1990), in my writing, it was a fight against cumulative quantization distortion and grunge, and the use of low-quality plugins and digitgal processors----and that made full analog mixing and processing much more attractive than digital mixing and processing. Now, today, it's the opposite, digital processing has come a long way, if you don't abuse it.

So today, if you wish to mix outside the box, you have to balance the loss of transparency that comes from passing the signal through low-resolution D/A/D converters (unless you spend the money on the best converters) against the supposed advantages of totally-analog-domain processing and mixing. And these advantages, in my opinion, can now only be justified when using a superb analog console whose coloration adds a desirable color (e.g., space, depth, definition) that cannot be obtained any other way. But even that color that, say, an API console can give you, can be obtained without the full console. And the tradeoff is probably less than going through the entire console to mix. For example, mix digitally in the box, use lots of good analog outboard for your prime signals, and possibly send the entire mix through a single pair of superb D/A converters and a pair of API modules and into a single pair of superb A/D converters to capture the mix, or a 1/2" tape machine. The "magic sprinkle" that the API pair add to that mix can produce a final mix with a unique combination of transparency and color that can sound superior to the use of 24 or 48 or however many "cheap, low-class" converters feeding a full API console.

I've objectively tested the premise that there is no problem with the digital summing mechanism (e.g. Pro Tools "infamous" summing bus) by simply taking a pair of good analog modules and putting them on a digital summing bus. If the sound gets WIDER and CLEARER with simply a pair of analog modules added to a digital sum, that makes it clear that most (if not all) of the "improvement" people attribute to analog summing is NOT due to the summing but rather to the desirable character of the analog gear they are using.

In other experiments, conducted by Linn Fuston, he demonstrated equal performance with some analog summers, and worse with many. I can confirm that the transparent analog summer which does not objectively degrade the sound, is very rare. A client sent me a matched gain and pan mix done with the Dangerous 2-bus versus digital mix in the box, and objectively and subjectively, there was nothing special about the Dangerous Mix. If anything, it sounded a little vaguer and less clear. In my opinion, it did not add any desirable distortion. I performed the listening tests blind on the client's files.

In another test, a client sent me a mix done with the Sumo with its converters versus in the box. The Sumo was EXTREMELY transparent. The two mixes were virtually impossible to tell apart, blind or sighted. But there was absolutely no advantage to the SUMO. In both cases, no analog outboard was used to "complicate" the test.

In my opinion, the bar on the digital side has been raised so far. There is still plenty of analog "processing" that sounds superior to digital processing, but summing is NOT one of those processes. So unless you have a virtually-totally-transparent analog summer or one whose losses are made up by its character (e.g. API), then I would currently recomend ITB digital mixing combined with lots of good character-providing analog outboard.

Does this help make clear my current thinking?
__________________
Bob Katz DIGITAL DOMAIN http://www.digido.com
"There are two kinds of fools. One says-this is old and therefore good. The other says-this is new and therefore better."

No trees were killed in the sending of this message. However a large number of electrons were terribly inconvenienced.
Old 24th May 2006
  #22
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Quote:
Originally Posted by mahasandi
I think this says what i think, perfectly from Bob Katz on this thread:

https://www.gearslutz.com/board/showthrea...ons+for+paul+f

or read below for the excerpt:

Quote:
Originally Posted by innesireinar
It started last week when I and a friend OM had one of the boring discussion analog/digital. After hours of discussion where everyone has remain in his position I promised to link him the Digido site. After two days he called me saying "your guru (you) is stating that analog is better" - And I "maybe this article is old" - "no, is updated 2005".
I went to read the article and I've only stated a discrepancy about your words between the PSW thread and the article, because on PSW you said that analog is far from perfect, works that you have received in your mastering studio done in digital, with the add of good analog outboard sounded better than those done mixed on the desk.
Therefore I'd like to have a your definitively point about that."

"Oh. Yes, time has marched on, in my opinion.

In another thread here on Gearslutz, introduced by Charles Dye, called "Favorite Analog Summing", I think I've covered my opinion. Here's another take on it, I guess it's a rehearsal for a rewrite of my article!

In the past (say, through 1990), in my writing, it was a fight against cumulative quantization distortion and grunge, and the use of low-quality plugins and digitgal processors----and that made full analog mixing and processing much more attractive than digital mixing and processing. Now, today, it's the opposite, digital processing has come a long way, if you don't abuse it.

So today, if you wish to mix outside the box, you have to balance the loss of transparency that comes from passing the signal through low-resolution D/A/D converters (unless you spend the money on the best converters) against the supposed advantages of totally-analog-domain processing and mixing. And these advantages, in my opinion, can now only be justified when using a superb analog console whose coloration adds a desirable color (e.g., space, depth, definition) that cannot be obtained any other way. But even that color that, say, an API console can give you, can be obtained without the full console. And the tradeoff is probably less than going through the entire console to mix. For example, mix digitally in the box, use lots of good analog outboard for your prime signals, and possibly send the entire mix through a single pair of superb D/A converters and a pair of API modules and into a single pair of superb A/D converters to capture the mix, or a 1/2" tape machine. The "magic sprinkle" that the API pair add to that mix can produce a final mix with a unique combination of transparency and color that can sound superior to the use of 24 or 48 or however many "cheap, low-class" converters feeding a full API console.

I've objectively tested the premise that there is no problem with the digital summing mechanism (e.g. Pro Tools "infamous" summing bus) by simply taking a pair of good analog modules and putting them on a digital summing bus. If the sound gets WIDER and CLEARER with simply a pair of analog modules added to a digital sum, that makes it clear that most (if not all) of the "improvement" people attribute to analog summing is NOT due to the summing but rather to the desirable character of the analog gear they are using.

In other experiments, conducted by Linn Fuston, he demonstrated equal performance with some analog summers, and worse with many. I can confirm that the transparent analog summer which does not objectively degrade the sound, is very rare. A client sent me a matched gain and pan mix done with the Dangerous 2-bus versus digital mix in the box, and objectively and subjectively, there was nothing special about the Dangerous Mix. If anything, it sounded a little vaguer and less clear. In my opinion, it did not add any desirable distortion. I performed the listening tests blind on the client's files.

In another test, a client sent me a mix done with the Sumo with its converters versus in the box. The Sumo was EXTREMELY transparent. The two mixes were virtually impossible to tell apart, blind or sighted. But there was absolutely no advantage to the SUMO. In both cases, no analog outboard was used to "complicate" the test.

In my opinion, the bar on the digital side has been raised so far. There is still plenty of analog "processing" that sounds superior to digital processing, but summing is NOT one of those processes. So unless you have a virtually-totally-transparent analog summer or one whose losses are made up by its character (e.g. API), then I would currently recomend ITB digital mixing combined with lots of good character-providing analog outboard.

Does this help make clear my current thinking?
__________________
Bob Katz DIGITAL DOMAIN http://www.digido.com
"There are two kinds of fools. One says-this is old and therefore good. The other says-this is new and therefore better."

No trees were killed in the sending of this message. However a large number of electrons were terribly inconvenienced.
Very interesting... I think it's pretty clear that the signal will degrade when doing external summing, the question is only, what kind of damage do we like more, the noise artifacts due to calculation errors or the noise artifacts mostly as lost signal? I am currently experimenting with this in my studio...
Old 24th May 2006
  #23
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Jason Poulin's Avatar
 

Quote:
Originally Posted by dim light
I've done some test myself;


Anal-06-sum


is that a wav file?




Jason
Old 24th May 2006
  #24
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RKrizman's Avatar
 

Quote:
Originally Posted by RainbowStorm
You're welcome, Dr. Idiot.
If you wish to spend your money on the wrong gear which won't fix your problems, that's fine. But I'd hate for the general populace here to accept your false notion that jitter screws up ITB mixing. It's when you go out of the box to external summing devices or analog processors that jitter becomes a factor, and in which case the deleterious effects of the jitter will become permanently imbedded in your tracks.

-R
Old 24th May 2006
  #25
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RKrizman's Avatar
 

Quote:
Originally Posted by RainbowStorm
the noise artifacts due to calculation errors
Which noise artifacts are those?

-R
Old 24th May 2006
  #26
Rainbow... the "jitter" comments are unscientific, and just plain untrue. We should clarify that for folks that are just getting into this conversation. Do a search here and there are plenty of valid reasons to do external summing, though. (pleasing distortion).
Old 24th May 2006
  #27
wait, correct me if i'm wrong - but i thought jitter occurs between two digital devices that are not in sync via word clock.

which means jitter would not occur ITB, nor would it when going from A/D/A or D/A/D

i am not a doctor.
Old 24th May 2006
  #28
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RKrizman's Avatar
 

Quote:
Originally Posted by Ricey
wait, correct me if i'm wrong - but i thought jitter occurs between two digital devices that are not in sync via word clock.

which means jitter would not occur ITB, nor would it when going from A/D/A or D/A/D

i am not a doctor.
Interesting theses, um, Mr. Science. But wrong about the A/D/A or D/A/D thing.


Sincerely,

Dr. Idiot
Old 25th May 2006
  #29
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Here is my simplistic understanding of the whole ITB vs OTB debacle:

Digital mixing and summing is mathematically precise, and boring. 2 + 2 always = 4. An audio signal panned dead centre will produce two identical cloned tracks, left and right, that are bit accurate.

Analog is all about electron flow through components. Electronic components are made to tolerance - and 1% tolerance is considered very good! So with analog summing - 2 + 2 might equal 3.999 or maybe 4.111 - or thereabouts. It's going to vary with the temperature, and your AC voltage on the day/night. It's going to vary from one end of the board to another - electrons are cunning little things.

So quite apart from the noise and distortion (which might also sound good too), you are going to get a very different "assymetrical" sound with analog summing. This is going to feed your two ears with slightly different signals, which you are going to percieve as increased width and depth.

This effect could be faked with digital trickery if somebody could be bothered. I've suggested this at KVR to the plugin wizards, and generally was dissed. Aleksy from Voxengo was very understanding, and he says he incorporates assymetrical code into some of his plugins to get this analog effect.

Personally - I always want the choice, and I wouldn't like to see imperfections built into DSP unless it was clear it was an effect, and could always be turned off. But I think it's a very palpable effect, and probably a major reason why analog summing can be perceived as sounding better.

Then there is always the gain structure effect. An analog box just might sound better because the gain is cranked a little compared to your ITB mix ...
Old 25th May 2006
  #30
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Purtty kewl explanation you got there Kiwiburger.




Hey, am I allowed to write "kewl" or is that like "rawk"?
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