[sdiy] good for VCAs?

[Fernando de Izuzquiza]

Hi Mike,
Thank you very much for your help.
Couple more questions:

- It would be possible to switch between lin and expo response? Can you tell me how?

- In case of using 66k5 at the cv input we have unity gain at 10V cv.
We will have some gain at say 12V cv? (I think the SSM2164 can perform 100dB attenuation plus 20dB
gain)

- I believe a fast audio and control response is very desirable. I was surprised that the OP07 was
0.3V/us only.
Offset voltage and slew rate are always a trade off? Is the OP275 a good middle point?
slew rate: OP07 is 0.3V/us, LF353 is 13V/us, OP275 is 22V/us
offset voltage : OP07 is 10uV, LF353 is 5mV, OP275 is 1mV


Thanks again!
Fernando
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f
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> De: eq927 at freenet.carleton.ca
> Fecha: Tue, 19 Nov 2002 02:34:40 -0500
> Para: fdi at ran.es
> CC: synth-diy at dropmix.xs4all.nl
> Asunto: Re: [sdiy] good for VCAs?
>
> Hi Fernando,
> The design can be used as is. It would be a good idea to put a resistor
> of a few hundred ohms on the audio output to ensure stability when
> driving cables - output configurations for accomplishing this were
> discussed on the list a few weeks ago. It can handle +/- 12.5 V max on
> the audio input, it is DC-coupled as shown, and  can process audio or
> DC. You might want to add additional 100K resistors for multiple CV
> inputs. For best results use a low-offset op amp like the OP-07 for the
> op amp that processes the control voltage. The CV input is set up for
> +15V as shown - it will give unity gain with 10 V if you replace the
> 100K CV input resistor with a 66K5 resistor (or use 68K).
> Regards, Mike
>