Pisound + RPI3 noise floor

#1

Hi everyone,

I’m currently doing some tests to evaluate Pisound + RPI3 self noise in the following setting:

  • Input: IN jack, mono recording (nothing connected for this test)

  • FS: 192 kHz

  • 24 bits

  • Gain potentiometer set to the minimum

I noticed some emerging noises:

  • 1 ray @ ~31kHz

  • Increasing noise from 48kHz up to 96kHz. The noise floor is around -74dB @ 48kHz and -45dB @ 96kHz.


Pisound + RPI3 noise floor FFT

I tried several power sources and different test environments but those noises are always present on my signal.

Are those noises normal?

Many thanks by advance for your help.

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#2

Just google noise of delta-sigma modulator. The ADC is delta-sigma type, so yeah, it uses this type of modulator which has that shape of noise spectrum. The most audio converters are delta-sigma type.

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#3

Hello Stuzer,

Thanks for the information.

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