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Soundcard Problems 04: Im determined to run my SB Live! project at 44.1kHz. What exactly will the audio difference be?

For anything relating to music-making on Windows computers, with lots of FAQs. Moderated by Martin Walker.

Soundcard Problems 04: Im determined to run my SB Live! project at 44.1kHz. What exactly will the audio difference be?

Postby Martin Walker » Mon Jun 25, 2001 7:22 am

Since the internal engine is fixed at 48kHz, any recording made using the analogue inputs will be performed at 48kHz, whatever sample rate you choose in your software. It will then get converted down to 44.1kHz before being saved to your hard drive. It is possible to build a perfect sample-rate-converter (SRC) given sufficient processing power, but a more modest real-time version such as the one used in the 10K1 chip of the Emu APS and SB Live! will have a certain amount of 'passband ripple' - a series of several tiny bumps in the frequency response that are caused by the digital filtering. The Emu spec is designed to tolerances of +/-0.5dB, and this is what gives rise to the 1dB anomalies that some people have measured on the S/PDIF input of the SB Live! soundcard.

The digital input is also fixed at 48kHz, and once again passes through an SRC, which provides the very useful facility that you can mix digital and analogue input signals in the Creative mixer. However, recording through this makes it possible to hear the effects of the SRC without going through the A/D converters as well. When I compared a digital transfer through the SRC with the original file it was very close, but I could still reliably identify which was which - the original was slightly more transparent, and the SB Live! conversion had a slight harshness at the top end. For a consumer card of this price I would still rate it as very good quality, but not suitable for digital copying in a professional studio.
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