Sound Blaster 32 measurements

Measurements are made 12. August 1997 using SB32 Ct3600 soundcard (uses CT2502 codec) and Nakamichi T100 audio analyzer. The masurements were made using set of frequencies available from that analyzer (for every half octave) and the frequencies available in Finnish HiFi Magazine Test CD which had all test signals available in WAV format in it's CD-ROM track.

Measured results

Microphone input frequency response

This microphone frequency response is quite awful for anything else than some little better than telephone quality audio recordings.

Output frequency response

This frequency response is measured from line level output.

Line output frequency response

The frequency response is very flat from 40 Hz to 20 Khz. In frequencies below 40 Hz the frequency response starts to drop a little bit (it has dropped 3 dB at 20 Hz frequency). So lowest bass frequencies are a little bit attenuated.

Using SB32 as audio recoder

Frequency response of the card input and output. The measurements are made so that the audio is recorded with the soundcard and played back. The chart shows the real signal levels measured from the card output (maximim level I got with the settings used during this test was around -9 dBV which is quite typical signal level used in home audio systems).

Combined recording and playback frequency response

This frequnecy reponse look quite much like the playback frequency response. There is a little boost (around 1 dB) at highest frequencies, but in general the frequencye response is quite good for computer soundcard.

Other performance details

Noise levels in line output:

All signal outputs in card turhed off using mixer and volume at maximum: -88 dB(A)
All signal outputs in card turhed off using mixer and volume at minimum: -95 dB(A)
Normal operating settings: -80..88 dB (A) (depends on actuial settings)

When I measured the soundcard I found out one strange thing: the balance setting could not be set exactly to the center position. At the center posistion there was 2 dB difference in volume levels between the audio output volumes of left and right channels (this means that the balance can't be set exactly to the center ! I don't know if the problem is in card hardware or in mixer software).

I also measured the distortion characteristics of the soundcard. The THD at 400 Hz frequency for record+playback is 0.02 %.

Tomi Engdahl <[email protected]>