[sdiy] VCA distortion - bad

[Jim Patchell]

	You need to limit the signal at the input of the CA3080 to about 
10mV...so you need to let us know what your input voltage is...but, with 
the values you show...200K-220, 10 volts would attenuate down to 10mV. 
(the attenuation ratio of 200K to 220 ohms is about a factor of 1000).

	Several people have posted analysis of the OTA recently...mine is here:

http://www.silcom.com/~patchell/SecretsOfOTAs.pdf

	Another list member also wrote a very nice article on the OTA...I am 
sure he will post his url himself...I hope (since I can't rembmer it, 
lost all my bookmarks).


Michael Ruberto wrote:
> I am using Bernie Hutchins' 3080 VCA circuit in my processor but I am 
> getting distortion causing my triangle waves to become flat on top. I 
> have changed the input resistor from 100K to 200K compared to the 
> electronotes version of the circuit. should I have also changed the 220 
> ohm bias resistor following the input resistor? is there some 
> calculation to determine these values?
> the only other thing I changed from the original design was the feedback 
> resistor in the output amp, I don't have 560K so I used the closest I 
> had - 470K. I greatly appreciate any advice...
> 
> ~M
> 
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