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In Reply to: Re: Not that I can tell posted by drwkng on February 1, 2007 at 01:11:59:
The normal IMD test signal consists of 70 Hz and 7000Hz, which is what is displayed on my graph and also the results you linked to.Your results are weird because they are not showing these fundamentals.
You must have changed Rightmark options to measure IMD using 11kHz and 12kHz signals. This is not the standard way to measure IMD as per EIAJ.
Incidentally, I noticed that you results show a significantly higher noise floor between 100-500 Hz, indicating that you do have some issues with power supply noise.
Try measuring again after changing the settings in Rightmark.
Follow Ups:
is because any harmonics of 11 and 12kHz are higher than Nyquist (assuming 44.1kHz sampling rate) hence the test will give artificially good results for any soundcard.
they are not at 44k. they are 96k. in fact lynx performs better at 96k than 44k
and they appear to be significantly better than yours at 96k (3dB lower noise floor, which means the noise level is half that of the lynx, plus lower THD and IMD). The only area where the L22 wins is frequency response (since the 1212M is slightly aggressive in it's low pass filter).This is not surprising, because the 1212M has a number of design advances over the L22 (slightly better DACs, noise insulation from the PCI bus, and better clock). To my ears, this translates to a slightly better sound as well.
The reason the 1212M is cheaper is not because of quality, it's economies of scale. Lynx is a small company, and the L22 uses expensive FPGAs. E-MU on the other hand is using the 10K2, the design cost has been fully amortised through the high volume sales of Creative's consumer cards. E-MU is probably leveraging the production efficiencies of Creative as well.
o.k. i'll try and see.
and it seems that Rightmark has been configured to generate test signals at 19 and 20kHz for IMD.This is a silly way to measure IMD, because it's so close to Nyquist it's unlikely to result in any measurable harmonic distortion.
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