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Hi All,
I'm trying to calibrate EMU-0404 USB sound card. The result is quite unexpected. Can I just get a quick opinion about whether this looks right. Can anybody share his calibration results for EMU-0404 USB? Thanks.

George

 

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The low frequency end would probably smooth out if the IR Window was extended, if you look at the Impulse Response graph it shows the windowed portion of the response so you can see whether it is covering the whole response until it drops into the noise.

The high frequency noise would typically be a sign of poor sampling clock stability, which I wouldn't have expected from that card. Try running it at 44.1k instead of 48k in case there is resampling going on.
 
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Thank you John. I've made some progress. First my levels were wrong. The EMU 0404 has analog potentiometers for adjusting input and output levels. With some trials and errors I found a combination of EMU and Vista levels that works. Here is the result:



Then I borrowed another EMU 0404 to compare the sampling accuracy. So it looks like my Emu is defective. Here is the good one:

 

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They do show different reconstruction filter responses, but I'm not sure I would say the card was defective - bear in mind the scaling, the ripple on your card is only 0.1dB. Variations in filter response of that sort are more typically seen when operating cards at different sample rates, worth making sure they were set up identically and also worth looking at the response on a broader scale to see what the trend is - your card looks like it might be running at 32kHz, but difficult to be sure looking at such a narrow amplitude range.
 
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The sample rate on all measurements is the same - 41.4 kHz. Basically I unplugged the first unit and plunged in the second. My understanding is that the scaling is the same for the second and the third screen shot - 0.1 dB. Only the levels are different - 73 to 83 dB. Since they were taken without any change in the computer setup the difference in levels is mainly caused by the position of the analog level controls.
 
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