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Converters and imaging ?
Old 26th January 2007
  #1
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DeadPoet's Avatar
Converters and imaging ?

Hi,

I just read a comment on the difference between two sets of converters (Alesis HD24 and XR24) and one of the arguments was that the better converters have better imaging..

I'm willing to believe this, but I was wondering HOW could this be ? I mean, if the signal fed to two sets of D/A's is identical and the connection from the D/A to your speakers is identical as well, how could a stereo signal have different imaging ?? I suppose D to A has no crosstalk, or does it ?

Educate me !


Herwig
Old 26th January 2007
  #2
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Levi's Avatar
 

The imaging has to do with the amount of digital jitter that is going on internally with the converters. The less jitter you have, the less smearing of the sound, thus, better imaging, tighter low-end, clearer hi-end, etc.
Old 26th January 2007
  #3
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funka's Avatar
 

I gained a better stereo imaging with the aurora16 compared to my previous ADI 8DS, and I also think it is a jitter/clock matter.
Old 26th January 2007
  #4
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Ethan Winer's Avatar
 

Herwig,

Quote:
one of the arguments was that the better converters have better imaging ... HOW could this be?
I don't buy it either, no matter how many people insist that an A/D/A can affect imaging. Here's my explanation:

www.ethanwiner.com/believe.html

--Ethan
Old 26th January 2007
  #5
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Windtaken's Avatar
 

Quote:
Originally Posted by Ethan Winer View Post
Herwig,



I don't buy it either, no matter how many people insist that an A/D/A can affect imaging. Here's my explanation:

www.ethanwiner.com/believe.html

--Ethan
Hi Ethan, I just finished your article and it's really interesting. Cool stuff
Old 26th January 2007
  #6
Here for the gear
 

Imaging & jitter opinions on MOTU products

Does anyone have some real world experience with MOTU converters and their quality? Two in particular I am interested in are Ultralite and 24 i/o

fanks
Old 27th January 2007
  #7
Lives for gear
 

I believe it, especially after upgrading my HD24 to the XR version. My drums tracks seem to sit better in the mix from the very start, much better depth, clarity and space. Everything sounds better with the upgraded A/D/A convertors, especially when compared to my older interface, the Presonus Firepod. I haven't read Ethan's article yet, but from what my ears tell me, the convertors make a huge difference.
Old 27th January 2007
  #8
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Levi's Avatar
 

I'm with over-man... imaging was definitely better, panning was more "friendly," eq'ing and placement in a mix was less tedious... can't tell you much else except my ears, and those in the room with me, say that there was a big difference. By the way, nothing else changed about my setup... room, monitors, etc. all stayed the same, so I know there was a positive, audible difference.
Old 27th January 2007
  #9
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Dave Peck's Avatar
 

I have had first hand experience with some well-designed comparison testing of converters. For a few years, part of my job involved performing these tests on a weekly basis. The experience made it clear that when a converter is performing in a less-than-transparent manner, one of the first things to be affected is the accuracy of the stereo imaging.

The tests were perfomed in professionally designed rooms with acoustic characteristics similar to a good mastering room. The speakers were Avalon Eidelons, known for their ability to reproduce imaging accurately. The tests were performed using first generation analog recordings of acoustic sources using minimal mic techniques which captured realistic acoustic imaging. These included vocal choir, orchestra, and grand piano.

The analog signal was sent to a custom A/B switch device which passed the analog signal directly to the power amps and speakers in one position, and sent it to the converter under test in the other position. The converter was used in A/D-D/A pass-thru mode, meaning the analog signal was converted to digital, looped from the DIG OUT to the DIG IN and converted back to analog. It was then sent to the power amps & speakers.

Thus, switching the A/B selector would reveal any differences between the direct analog signal and the same signal after being subjected to A/D and D/A conversion. This was not a test to determine if one converter sounded subjectively 'better' than another, it strictly revealed if the converted signal sounded the same as the analog signal or if it sounded different in any way.

The results - It was clear that most converters exhibited some kind of inaccuracy in the stereo imaging. Switching between the direct analog signal and the converted signal would frequently cause the stereo image to instantly widen or get more narrow. Sometimes there were other differences as well, but most converters had trouble with the imaging. Only a few converters actually sounded identical to the analog source with no imaging shift. It is important to note that these were often not just subtle differences that could only be detected by a 'golden ear' audiophile. Using this type of test setup, the differences were clearly audible and the results were repeatable.

DP
Old 27th January 2007
  #10
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Windtaken's Avatar
 

So Dave...now you've got me curious!

Which were those few converters that sounded identical!
Old 27th January 2007
  #11
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deuc647's Avatar
Honestly, over man and levi hit it on the head with those comments, i have a rosetta 200 and the 24XR and the first thing i heard was clarity, and i dont mean subtle clarity i mean wide open clarity. I think a lot has to do with the converter chip(AKM). I find myself using a lot less EQ and compression to make thing fix in a mix(mixing has got a lot easier ). If someone is gonna buy a new HD24 or a XR i would not even look at the regular and save for the XR. Im gonna have mine sent to jim williams in feb to be modded, hope it improves it even more
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