[sdiy] Frequency Counter Software

[James Patchell]

The jitter, I would say, is pretty normal.  Probably caused mostly by noise 
in the comparator.  I get about the same amount in my VCO's...I look at it 
this way...it adds to the warmth of the sound... :-)

At 02:43 AM 10/11/2005 +0100, Seb Francis wrote:
>To answer my own question ...
>
>I've tried a few different frequency counter / spectrum analyser / scope 
>softwares (hopefully 'softwares' is acceptable english ;)
>They all use FFT to get the frequency and don't seem to be very accurate - 
>they jump around by a few hertz even with a stable input.
>
>But thinking along different lines, I found this great little VST plugin 
>"C-Tuner"
>http://mitglied.lycos.de/moritz_48/Free-VST/cplugs11.ZIP
>
>In 'super-accurate' mode it measures to 0.1 cents.
>
>Testing with a soft-synth showed the expected 0.0 cent error
>Testing with my nord lead (digital) hardware synth showed a consistent 
>error of +0.4 cent across the whole keyboard .. I can live with that :)
>
>Interestingly when I hooked up my MOTM VCOs, although they tracked well 
>(within 5 cents across the whole keyboard - perhaps could be even better 
>if I bothered fine tuning the trimmers a bit), both the 300 and 310 showed 
>a jitter of approx 2 cents.  This is not my MIDI2CV converter by the way - 
>the jitter is still present even with nothing plugged into the CV input.
>
>Now I'm not complaining: this is probably much better than most other VCOs 
>(and actually one of the plus points of analog is the inaccuracy), but I 
>make my point again about MIDI2CV converter accuracy - what benefit is 
>there in having better than 1 cent accuracy if even a super-stable MOTM 
>VCO is not this accurate.
>
>Anyway, now off to tune my newly built Oakley 3031 .. which was what 
>started all this in the first place!
>
>Seb
>
>
>
>
>ryan williams wrote:
>
>>thats a good idea. I had been tuning VCOs by doing this:
>>run a soft-synth at some frequency. also output the MIDI value to your 
>>MIDI->CV converter. mix that with the VCO and listen to beats to get the 
>>offset correct. then go up 2 octaves and adjust the scaling, repeat. Sure 
>>this is a common method, but it shouldn't be too hard to make a frequency 
>>counter (did one with an 8bit uC once). A neat program would be something 
>>that plays a reference frequency mixed with the VCO output and displays 
>>the VCO frequency at the same time. I think I'll write this program. 
>>It'll be atleast 2 weeks though.
>>
>>-ryan
>>
>>Seb Francis wrote:
>>
>>>Hi,
>>>
>>>Can anyone point me in the direction of an accurate (and preferably 
>>>free) frequency counter software for windows.
>>>
>>>It seems to me that this would be a very accurate and easy method of 
>>>tuning VCOs (especially since my sound card is clocked from a dead 
>>>stable RME A/D D/A interface).
>>>
>>>Seb
>>
>>
>>
>

         -Jim
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