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Discussion Starter · #1 ·
I give you a process which works on Maudio cards with cooledit.


- Encode a sin wave in a wav file with cooledit.

- In the Maudio panel, reroute the WaveOut 1/2 on the Monitor mixer.

- Setup Cooledit to record the Monitor mixer


- Play the wav file with Foobar2000 or Winamp with the renderer you want (Directsound, waveout, ASIO, Kernel streaming).

- simultaneously, record the Monitor mixer channel under Cooledit

- When the recording is finish, do an FFT to see the noise added to your origin sin wave.


Thats all :).


ALL THIS PROCESS IS DONE IN THE DIGITAL DOMAIN. Thanks to this, you can see exactly the impact of kmixer.


Some FFT are here :

http://www.homecinema-fr.com/forum/v...01232&start=61


Under IE, click on the "zoom" icon at the bottom right when the mouse cursor is on the picture to magnify it.


FFT 1 : the original sin wave (1000 Hz)


FFT 2 : the mpg1 layer II used for the test (too complicated to explain why)


FFT 3 : Directsound renderer (see the noise !)


FFT 4 : ASIO renderer (no noise added :) ).


FFT 5 : Reclock renderer @ 75 Hz (for PAL DVD)


FFT 6 : Reclock renderer @ 72 Hz in order to correct the PAL speedup on PAL DVD (the goal was to verify that the correction was really a 4% speed slowdown, which is the case). NTSC DVD owners are not concerned :)


Bye.

Emmanuel
 

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Discussion Starter · #2 ·
Note : the soundcard used is a Delta 1010.


Tests all done with WinMe and wdm driver v5.10.00.27 . I will verify with XP and v5.10.00.0031 or v5.10.00.0029 very soon.
 

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Discussion Starter · #3 ·
this process should work for every multichannel audio cards having a hardware mixer implemented on then :


when the wav file is played by foobar with directsound, the kmixer corrupts the audio stream. This audio stream is then sent to the audio card harware mixer (because of the setup used in Patchbay / Router panel) and the new audio stream ouputs by the hardware mixer is recorded by cool edit.


That why you can see the noise added by the kmixer on FFT 3.


Thanks to this it is possible to generate tests wav for blind tests :


- wav n°1 : generated by foobar + directsound (=> corrupted)

- wav n°2 : generated by foobar + ASIO (=> not corrupted)


Then, both wav have to be played with foobar + ASIO during the blind tests. For the moment I have no opinion on the result of such tests. I will do real double-blind tests with good headphone and PRO headphone amp (with XLR connections) in a few days.


Emmanuel
 

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Discussion Starter · #4 ·
I did a test with XP and Maudio lastest driver v5.10.00.0029 (previous FFT were obtained with WinMe)


The results are now OK (no noise) for directsound and Asio.


So the noise on FFT 3 seems to be more a pb of WDM audio not fully compatible with WinME than a kmixer problem...


Sorry for this wrong information.


Emmanuel
 

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Interesting, though I still dont see what all the fuss is when practically all of the noise generated is below any noise floor in all but the most rediculous systems. Are there that many people listening to SACD on 10,000 dollar systems using a HTPC?
 

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BTW, the monitor-mixer recording method you have used didn't work well in my case (Audiophile). IIRC I couldn't get bit-perfect recordings when using kernel streaming or ASIO.
 

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Discussion Starter · #11 ·
KiKeG, I have XPpro+SP1 and WDM driver v5.10.00.0029 installed.


All your measurements are very insteresting :
http://www.kikeg.arrakis.es/measurements/


Can you explain a little more the process used for :


- Comparison of 16-bit analog output with and without kmixer resampling in M-Audio Audiophile 2496


and


- Digital measurement of 16-bit kmixer resampling from 44.1 to 48 KHz
 
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