new Formant book arrived

[Tony Allgood]

>Maybe it doesn't lock. In OTA polygon filters with 1/1+s it does lock
>because of the "short" feedback loop that turns intopositive feedback.

I have used TL072s in a OTA based SVF in my polysynth. The original
circuit called for 1458s, which in my ignorance replaced with TL072s.
(Hey, I was 17... I didn't know about polarity reversal )They do lock
up, at power on only, and only one of the four in the synth, I don't
know whether its the same one. A quick sweep of the cut-off pot seems to
un-lock the stuck VCF. I really ought to change them to something
else... but after 18 years, I sort of gotten used to turning that pot
every time I power up. :-)

Regards,

Tony Allgood  Penrith, Cumbria, England

Oakley Modular Synth and TB3030:
www.techrepairs.freeserve.co.uk/projects.htm
My music: www.mp3.com/taklamakan