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Mystery Signal
Audio playback spectrograms at 44100

Audio playback at the 44100 sample rate is important for MP3 music.  For the majority of computer users the 44100 playback is the only exercise their sound card gets.  So focusing on this particular mode of operation is a worthwhile endeavor.

The sound card's highest clean rate, typically 48000, was used as the capture input sink.  The source output sample rate was fixed at 44100.  This combination emphasizes and tests the performance of the DAC.  Below are the spectrograms of a linear sine sweep test signal.

This gallery is part of the Full Duplex DAQ comparison survey. 

Cirrus Logic CS4236B Sound Blaster Vibra16X

Sound Blaster 16 PCI Sound Blaster 128 Sound Blaster Live!

VIA 8235 SiS 7012 ESS Maestro 2E

Griffin iMic v0.06 Griffin iMic v3.00 Edirol UA-25

Only the Cirrus Logic CS4236B, Sound Blaster Vibra16X ISA, Edirol UA-25, and both versions of the Griffin iMic have clean noise floors when playing audio at the 44100 sample rate.

The Cirrus Logic CS4236B and the Sound Blaster Vibra16X ISA card have noise floor spectrograms that look almost identical.  This is because the Vibra16X is a half duplex card and the CS4236B was used as it's test sink.   Note that both the Vibra16X and the CS4236B utilized a source sample rate of 44100 which explains the lack of the linear sine sweep's folded aliasing (Nyquist bounce).

The Creative Sound Blaster 16 PCI, 128, and Live! all share some mild harmonic distortion.  The SB16 PCI and the SB128 look like they have slightly less folded harmonic distortion and sharper anti alias filter roll off.  This is surprising since the Creative Sound Blaster Live! is newer and more modern sound card.

The VIA 8235, SiS 7012, and ESS Maestro 2E have ENOB's of less than 3 bits and an extreme amount of harmonic distortion.  Audio playback at the 44100 sample rate is not recommended with these chips.

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