[sdiy] Cheap audio spectrum analyzer

[Neil Johnson]

Jean-Pierre Desrochers wrote:
> Do you know of a cheap audio spectrum analyzer I could
> buy to check 20-20khz frequency response on audio stuff ?

Define "cheap".

> That would includes sinus generator + analyzer in the same box.

Ok.

> I checked on eBay and most analyzers are RF band based and are
> so $$$$$ expensives. But 2 things:

You're looking for the wrong kind of thing.

> - I don't want to use analysis software on a separate PC
> - Any DIY projects with micro/graphic LCD would do..
> I want a standalone analyzer.

Well, for a complete standalone box I would recommend an HP Dynamic
Signal Analyser, such as the venerable 3561A, or something a little
more modern such as a 35660A.  Pros: all-in-one, built-in screen, will
do amplitude and phase response.  Cons: dynamic range ok but won't get
down to the very low levels of noise and distortion.

The next step up would be audio analysers, such as the HP 8903 or
something from Audio Precision.  While the 8903 does have a built-in
computer and can do sweeps, the display is 7-seg LED so you'll need a
pencil and some graph paper.  The Audio Precision kit needs an
external control computer, but can measure the very lowest noise and
distortion.

Again, what do you mean by "cheap"...?  What is your budget, and what
level of performance do you want to measure?

Neil
--
http://www.njohnson.co.uk