[sdiy] Measuring Audio Sine Purity

[Jerry Gray-Eskue]

There is a lot of info on the web if you look for Measure THD, here is one
on how to use the spectrum analyzer to calculate THD and more.

http://dogstar.dantimax.dk/tubestuf/thdconv.htm

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Scott Gravenhorst
Sent: Friday, September 07, 2012 6:57 PM
To: synth-diy at dropmix.xs4all.nl
Subject: [sdiy] Measuring Audio Sine Purity


How would a DIY person measure the purity of a sine wave beyond using a
spectrum analyzer?  To give a figure of sine purity, of distortion (THD?) ?

Say you have an oscillator you built, it's supposed to be a sine oscillator
and you'd like to know just how pure it is.  What would you use?

I've used RMAA to analyze a wav file of a sine signal, but that doesn't give
purity numbers, it just gives the spectrum.  

Is there software that might be used with a good sound card? 
(understanding, of course, that soundcard artifacts will present themselves
in the results)

I imagine that there is expensive hardware, but that's out of the question
for me.

-- ScottG
________________________________________________________________________
-- Scott Gravenhorst
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