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Conversion.....overated? Audio Interfaces
Old 3rd June 2009
  #451
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Slikjmuzik's Avatar
 

Duardo, I'm liking the way your head works brother.
Old 3rd June 2009
  #452
Lives for gear
Quote:
Originally Posted by Slikjmuzik View Post
Duardo, I'm liking the way your head works brother.
yea, he's very clear headed and looking at things fresh always helps too.

I admit to getting sidetracked sometimes and going off on tangents sometimes, even once in a while saying things that are just dumb.

He managed to point out clear obvious points very well, although sometimes when the points he responds too are taken out of context it changes their relevance, but he did get things back on track pretty well.

I'm impressed with his points about the high frequencies causing the a/d filtering to add audible side effects into the signal. While I doubt most of my analog gear could pass audio that high so strongly that it could cause issues with my a/d, it's certainly an interesting topic and I personally don't have enough information about it to say that he's wrong.

And I know he's right about the filtering being a significant part of the output quality of the conversion process. I just don't know what it takes as an input signal to make such filtering cause anomalies in the audio signal.

very interesting stuff...

Cheers,
Don
Old 3rd June 2009
  #453
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Slikjmuzik's Avatar
 

Quote:
Originally Posted by dkelley View Post
yea, he's very clear headed and looking at things fresh always helps too.

I admit to getting sidetracked sometimes and going off on tangents sometimes, even once in a while saying things that are just dumb.

He managed to point out clear obvious points very well, although sometimes when the points he responds too are taken out of context it changes their relevance, but he did get things back on track pretty well.

I'm impressed with his points about the high frequencies causing the a/d filtering to add audible side effects into the signal. While I doubt most of my analog gear could pass audio that high so strongly that it could cause issues with my a/d, it's certainly an interesting topic and I personally don't have enough information about it to say that he's wrong.

And I know he's right about the filtering being a significant part of the output quality of the conversion process. I just don't know what it takes as an input signal to make such filtering cause anomalies in the audio signal.

very interesting stuff...

Cheers,
Don
Interesting indeed. This is the kind of stuff I 'experience' when I am mixing, when I try to boost with a plug-in EQ, compress more than say 3-4db out of a signals dynamic range. I knew digital information just wasn't good enough for these tests. That makes total sense and I just could never describe it to Ethan or anyone else for that matter so that it made sense. It's just not what I do, I run a studio. - lol But yes, I'm liking his descriptions and the way he's introduced things to this thread that seem a whole lot more valid than some of these other tests that wouldn't account for the converters true use in the real world. This would probably be why I never saw a loss when running a file through a preamp and back in using the same inexpensive converter. Never saw a loss, however, I have specifically found much better results with a mix that has been started completely with the Aurora. I could never explain it, but I felt it when it came to the final stages of the mix.
Old 3rd June 2009
  #454
Lives for gear
Quote:
Originally Posted by Slikjmuzik View Post
Interesting indeed. This is the kind of stuff I 'experience' when I am mixing, when I try to boost with a plug-in EQ, compress more than say 3-4db out of a signals dynamic range. I knew digital information just wasn't good enough for these tests. That makes total sense and I just could never describe it to Ethan or anyone else for that matter so that it made sense. It's just not what I do, I run a studio. - lol But yes, I'm liking his descriptions and the way he's introduced things to this thread that seem a whole lot more valid than some of these other tests that wouldn't account for the converters true use in the real world. This would probably be why I never saw a loss when running a file through a preamp and back in using the same inexpensive converter. Never saw a loss, however, I have specifically found much better results with a mix that has been started completely with the Aurora. I could never explain it, but I felt it when it came to the final stages of the mix.

heh heh, I won't go THAT far, but I do acknowledge that he mentioned concepts that are beyond my current memory of how a/d conversion could introduce audible sde effects into the signal.

I won't say that it actually DOES happen, that isn't clear at all, but the fact that he mentions it has piqued my curiosity and I'll have to go back to my white papers and see if the filtering could be problematic in any current designs and what it would take from the source signal to make that happen.

I have a feeling that it would take something far more extreme than we'd ever do in our mixing, especially since we all know that in digital it is a very very bad thing to overload any inputs or overdrive any converters. But if there IS distortion somewhere in the preceding analog chain, which of course could introduce a lot of high harmonic content (some of it beyond human hearing), and if that content was passed through every component after that point and could somehow make the converter not behave well, that would be very interesting.

Cheers,
Don
Old 3rd June 2009
  #455
Lives for gear
 

Quote:
The question is can we hear a difference between high end converters and low end converters, one of which is a requirement for all of the work we do for distribution unless you're going only to vinyl.
Sure, I don't disagree that the differences can be very subtle, even between today's cheaper converters. My point was simply that, if we can hear a difference, we'd need to have the source to compare to to know which one was "better", assuming "better" means more accurate as opposed to more pleasing to our particular taste. And to really hear a converter "working" you need to make it work by feeding it a signal that hasn't already been, uh, worked.

Quote:
I suppose in the room there, if they're listening to a performance in real time and they switch an a/d d/a converter pass into the playback then they could hear if there's a difference but since the source material being live music would be ever changing it wouldn't really be scientific nor a true a/b test (which requires identical signal).
Yes, the tests I've been involved in that I've found to be most useful have been in a control room with an analog console or monitoring system, with a live acoustic source split off to separate A/D converters, run through the same D/A converters. Sure, it's not a perfect test, but no test is...and it was certainly helpful. One thing that was clear was that the difference between the analog source and any of the converters was much more obvious than the differences between any two converters...even when comparing cheaper ones to more expensive ones.

Quote:
But it was also to illustrate that if the actual converter inside a cheap sound card is actually as good as it seems to be then there's nothing to stop prosumer audio companies (behringer, m-audio, art, modern tascam, etc) from using those same converters with better analog circuitry around them to make very good converter boxes for retail sale.
You're right, there's nothing to stop them from doing it, and they're doing it all the time, sort of...at least, as far as marketing is concerned. E-Mu and MOTU both advertise, for instance, the "same converters" as Digidesign's 192, but if you even look at the specs they do provide they're not the same. The chips themselves are a very small part of the cost of the converter as a whole. Apogee got their start not making converters, but replacement filters that preceded the converter chips in the old Sony digital reel-to-reel recorders.

Quote:
While I doubt most of my analog gear could pass audio that high so strongly that it could cause issues with my a/d, it's certainly an interesting topic and I personally don't have enough information about it to say that he's wrong.
The audio doesn't have to be that high...most modern gear extends at least a bit above 20 kHz, even if it's only measured up to 20 kHz, and it's when you're up close to there that the artifacts of a converter are most likely to be heard. It was certainly more of an issue with early A/D converters than it is with today's oversampling and digital filters. The same holds true with the filters on the D/A side of things.

Quote:
He managed to point out clear obvious points very well, although sometimes when the points he responds too are taken out of context it changes their relevance, but he did get things back on track pretty well.
Yeah, sorry about that...I came to the proverbial party a little late and had a bit of catching up to do...
Old 3rd June 2009
  #456
Gear Guru
 
Ethan Winer's Avatar
 

Quote:
Originally Posted by Duardo View Post
we'd need to have the source to compare to to know which one was "better", assuming "better" means more accurate as opposed to more pleasing to our particular taste.
Technically this is true, but probably not necessary. If it can be ASSumed that a given high-end converter is acceptably transparent, and then an M-Audio or Presonus or SoundBlaster card is shown to sound the same or very similar, the point has been made adequately IMO.

BTW, I really appreciated your point before about needing a live feed with suitable HF content to fully test an A/D converter. That's a good argument for why a full mix played from CD is not a perfect test. However, using a 96 KHz Wave file as a source could solve that. (Or even a single live cymbal recording.)

--Ethan
Old 15th July 2009
  #457
Gear Maniac
 
hakim's Avatar
 

So what is the preferred oversampling rate for an ADC? My ADC is 24-bit and 64x oversampling and my DAC is 24-bit 128x oversampling but I am stuck with a sampling frequency of 44.1khz (fixed).
Old 15th August 2009
  #458
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AllAboutTone's Avatar
 

Tracks sound fine, however I would never use a convertor pre, high end pres are so much better, day and night. I realize this is sream audio but the laury are a little to soft for my taste, again its prob the mp3s
Quote:
Originally Posted by Michael Zick View Post
Here's a test. Everyone go to Songbird Sound on MySpace Music - Free Streaming MP3s, Pictures & Music Videos and listen to the first two songs on my player. The first was done on a 002 with no outside conversion, clock or pres. The second was done on a LavryBlue with Lavry pres.

Tell me which sounds better.
Old 16th August 2009
  #459
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Mr.HOLMES's Avatar
Why discussing over and over again?

Let your ears decide!

I was coming from Motu to RME and wanted to upgrade to Apogee.

So Motu sounded very harsh in the highs to my ears so I went over to RME later I was comparing RME to Apogee and the difference between these two companies was to small for me as I could invest into Apogee.

So in my opinion if you like to have good conversion not bad in any means and you want to go sure that the sonics you track are captured well (we did a test) buy a RME. Nothing is bad about them and you have ****ing stable drivers fast updates of them if something is going crazy. You can count on the RME-service within 1-2 working days even with the silliest question.

So yes you can have better conversion but this IMO goes up to very expensive units like Lavry etc....and I am very sure this is at the actual quality of conversion we have in 2009 much over equipped for the most hobbyists and small places like mine.

If a mastering house has such converters it makes more sense.

So we are talking again of the last 5% of sound and what for?
May 3-5% of the users on this board can afford a 6K converter.

Sometimes I ask myself don`t we have work to do?heh
Old 17th August 2010
  #460
Gear Addict
 

Quote:
Originally Posted by Ethan Winer View Post
Okay Mark, here are two files (1.5 MB each) of the same acoustic guitar performance, with the signal split to different converters after the microphone preamp. One was recorded through an Apogee 8000 and the other through a $25 SoundBlaster X-Fi sound card:

Clip 1
Clip 2

I'm sure you'll be able to tell me which is which, yes?

--Ethan
Clip 1 = Soundblaster
Clip 2 = Apogee
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