Hi,
I'm using the CS4272 codec to convert to and from digital. I've attached a picture of the noise floor. The red line is the signal going through the analog filters and the CS4272. The black line is just the analog filters. As you'll see, there's a crazy 30dB/octave increase in the noise starting at 10kHz.
I've tried a bunch of stuff, but it seems right now I have a very interesting noise generator instead of a good sounding codec.
I'm posting this in the hopes that someone will see the noise floor graph, remember when they had a similiar problem, and go "oh ya, it was this!"
Any help would be greatly appreciated,
Steve.
I'm using the CS4272 codec to convert to and from digital. I've attached a picture of the noise floor. The red line is the signal going through the analog filters and the CS4272. The black line is just the analog filters. As you'll see, there's a crazy 30dB/octave increase in the noise starting at 10kHz.
I've tried a bunch of stuff, but it seems right now I have a very interesting noise generator instead of a good sounding codec.
I'm posting this in the hopes that someone will see the noise floor graph, remember when they had a similiar problem, and go "oh ya, it was this!"
Any help would be greatly appreciated,
Steve.
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Looks like noise shaping to me. Pretty extreme though - with the CS4382 the increase in noise only starts at 30 kHz, and in the WM8770 this must be beyond 48 kHz. I guess the CS4272 uses a conventional 1-bit DAC, maybe not that fast, and has to do fairly heavy noise shaping to achieve the specified SNR. It's not like you'd hear it, but admittedly it doesn't look too great and one might want to do some lowpass filtering.
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