[sdiy] Cheap audio spectrum analyzer.. finally..

[rsdio at audiobanshee.com]

Are you sure it's using an FFT in that mode? As the videos show, it's possible to do the whole process in the time domain. If the scope has a rectifier mode, you'd get a clean line instead of a solid shape for the envelope.

Brian


On Oct 27, 2015, at 12:10 PM, Tim Ressel <timr at circuitabbey.com> wrote:
> I have used the 35660 extensively. It is an excellent box for its age. It has a mode where you feed a chirp through the DUT and it magically smooths out the FFT results and gives a clean line. Very nice!  Wish I had one.
> 
> On 10/27/2015 10:28 AM, Jean-Pierre Desrochers wrote:
>> I finally decided to go for this:
>> 
>> HP 35660A (with option 001 memory installed)
>> http://www.sglabs.it/public/SgLabs_HP%2035660A.pdf
>> 
>> It was not cheap but around one third of eBay's mean prices
>> for those working condition HP testers..
>> and the dealer was 1 hour car ride from my home.
>> I think it's a good investment.
>> Ooooff !
>> 
>>> Le 2015-10-26 11:18, Neil Johnson a écrit :
>>>> 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