Reply 60 of 84, by stamasd
Consumer level audio (sound cards, MP3 players, etc..) will output 0.447V peak, so 40mV will be about -20db below peak. This is […]wrote:
Working on getting some measurements in... I have a few problems with the test setup.
1. Many audio cards give me an output signal that's too low for some reason for my oscilloscope to process correctly... it sees the signal as being only 40-50mV for some reason, despite the sound being loud and clear when I commect headphones instead.
Consumer level audio (sound cards, MP3 players, etc..) will output 0.447V peak, so 40mV will be about -20db below peak.
This is very normal.
Maybe, but my laptop output's is about 10x that (I did some preliminary tests with dosbox before moving to real sound cards).
With several real cards, the signal is just enough to display (barely) but not large enough for the DSP to apply the fast Fourier to it.
It's off to disk I go,
With a bit and a byte
And a read and a write,