Testing a DAC absolute phase ?
Feb 20, 2011 at 8:50 PM Thread Starter Post #1 of 6

00940

Headphoneus Supremus
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At first sight, it'd be as simple as playing an asymmetric waveform generated in audacity (see attached one) and check with an oscilloscope the output of the DAC. Or am I missing something ?
 
 
 

 
Feb 20, 2011 at 9:43 PM Post #2 of 6
sounds like a plan to me
 
Feb 20, 2011 at 9:52 PM Post #3 of 6
Like many things, phase is relative.
Left phase relative to right phase.
Input phase relative to output phase.
 
Absolute phase relative to what?
 
An electric guitar has no phase.
The strings move side to side and up and down
though the speaker can only move in and out...
A kick drum could be said to have a phase...
But how do we know if they were recorded in phase or not..?
 
I think what you are getting at is the absolute phase of the recorded signal.
Your asymmetric wave form is probably the best indicator of the absolute phase.
 
Too bad I sold my scope years ago...that would be a fun experiment.
 
Feb 20, 2011 at 10:14 PM Post #4 of 6
 
Quote:
Originally Posted by Avro_Arrow /img/forum/go_quote.gif
 
I think what you are getting at is the absolute phase of the recorded signal.
Your asymmetric wave form is probably the best indicator of the absolute phase.

 
Yeah, that's what I meant. It's more a way to check my wiring inside a DAC than anything else.
 
As an OT, here's an interesting link about AKG headphones being always wired out of phase: http://recording.org/pro-recording-forum/17159-akg-headphones-usually-out-absolute-phase.html
 
Feb 20, 2011 at 11:21 PM Post #6 of 6


Quote:
Yeah, that's what I meant. It's more a way to check my wiring inside a DAC than anything else.
 


Build a little stereo to mono box like this. If the outputs are wired properly a mono tone comes through loud and clear. If they are not wired properly nothing comes through.
 

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