AS3320 VCF

ld · Joined: Sep 27, 2020 Posts: 2 Location: Amsterdam

Hello,

I am trying to breadboard a AS3320 VCF, and I have so far got to the point where I can hear music playing through the input and out the output. I also have been able to hear a basic sweep sound as I adjust the freq. ctrl. However, I haven't been able to get the resonance control to work, and the frequency control is quite noisy on one end of the spectrum.

My first question whether the input a CV control meaning it should be a difference in voltage across the pin? Or is it a current control, and I need some sort of vactrol to control it?

Here is my schematic so far attached. You can see the part I have in question is the pots. I also understand that the voltages should be -18 to +2 on the resonance ctrl. and +/-6V on the freq. ctrl. Can I achieve that by using a simple voltage divider? I tried making a voltage divider across the +/-12V, but even using equal value resistors, I couldn't get it to be +/-6V. It seems like the circuit itself is causing a load on the voltage divider which is messing up the values.

Any help on improving my schematic is appreciated. In particular, I would like to have pots that control the freq. ctrl. and resonance ctrl., as well as having a CV input. How do I combine the pot input and the CV input?

Thanks in advance for any help.

The schematic is here: https://imgur.com/a/M5XaRtv
(The forum wouldn't let me make an attachment? Is that because I am a new account?)

blue hell

ld · Joined: Sep 27, 2020 Posts: 2 Location: Amsterdam

Hmm, it looks like it is letting me attach in the reply, but not in the original post (I tried editing it again, no luck).

Anyhow, here is the schematic!

AS3320-schematic.png

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dslamnig · Posted: Sat Feb 06, 2021 4:21 am Post subject:

This is how I've done it. I cloned the Sequential Pro-One 3320 VCF almost literally, adding resonance modulation and V/Oct tracking. More on my page:

https://dslamnig.wordpress.com/content/electronic/3320-vcf/

3320_VCF.png

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