My tests over kmixer effects, Seem to be none... Options

[KikeG]

I've been doing some tests over kmixer effect, both using standard waveout and directsound, connecting my TBSC digital output to my Audiophile digital input, under WinXP (no SP1), and I'm sure that with a single stream at 48 KHz, with the TBSC mixer volume at max, the kmixer doesn't touch a bit of the audio stream, it's sent bit-perfectly to the output of the card. At 44.1 KHz I can't be so conclusive, since the TBSC resamples everything to 48 KHz and I've had some problems to test it the same way, but according to my analog measurements in loopback mode of Audiophile output, there is no trace of signal degradation over the 44.1 KHz played data.

...So it's very possible that this kmixer sounding worse than ASIO or k.streaming is our old friend mr. placebo entering into scene again.

Anyway, I'll do some more tests in the future.

This post has been edited by KikeG: Jan 16 2003, 09:42

[KikeG]

I used WinXP pre-SP1. As I said, at 48 KHz, I used the digital output of the TBSC connected to the digital input of the M-Audio Audiophile 2496. I set the volume of the TBSC wave slider in the mixer at max. I played several signals I generated with CoolEdit Pro 1.2a in 16 bit mode. First, a 1 KHz at -1dB and another at -60 dB dithered sine that showed no digital or analog distortion artifacts, or amplitude changes when recorded. And second, and more important, a series of single pulses with known amplitude (data values) , that showed exactly same data values after recorded. For a more thorough test, I will record a musical singal and the proceed to compare bit-by bit the signal, using EAC wave comparator, but I don't think there will be any difference. The result was the same with waveout or directsound.

Note that if the output of the mixer wave slider of the TBSC is not at max, all I've said doesn't hold. Digital distortion artifacts appear and the recorded data is no longer equal to the played data.

As I said, with 44.1 KHz I couldn't use a digital comparison, since the card resamples everything to 48 KHz and when I did the test, due to some operating limitations with my Win98SE, I couldn't have a reference of the output of a hardware resampled 44.1 KHz wave file without kmixer effect, to compare. Now I have, so I will try so make a similar test with 44.1 KHz data.

Alternatively, I used analog output and input of the Audiophile, connected to each other (loopback configuration). The recording was done in 24 bit mode, with AP mixer disabled, and I played several test signals both in Win98SE (without kmixer effect) and in WinXP (with kmixer effect), and all the analog measurements I did with several 16 bit dithered signals generated with CEP (dynamic range, frequency response, distortion) were the same the same, I didn't appreciate any differences. I this case of 44.1 KHz I'm almost sure that the data is not altered, but since I can't make a digital copy, I can't prove it 100%. But even if the kmixer does something, it doesn't reflect into high precision analog quality measurements so I can conclude that, at least, it won't be audible.

I don't have any DTS decoder available to check if there's a problem here, but as I said, I'll make some more tests and try to get more conclusive results when I have time.

Now, could you describe how did you do your tests? Maybe you card internal mixer was the one that was altering the data played?

This post has been edited by KikeG: Jan 17 2003, 12:04