Pisound + RPI3 noise floor

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.

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.

Hello Stuzer,

Thanks for the information.