AS3320 Resonance Inputs

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Chris Willocks
Learning to Wiggle
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Joined: Mon Dec 09, 2019 1:09 pm

AS3320 Resonance Inputs

Post by Chris Willocks » Sun Mar 22, 2020 12:27 pm

Hi everyone,

I've designed a Eurorack AS3320 low-pass filter module and just have a query regarding the resonance input (pin 9).

As the input is current controlled and comprises a low-impedance summing node at a potential close to ground, would it be acceptable to assume that no external summing op amp would be required for inputting multiple resonance CV sources into it? This is shown below for illustration purposes:

AS3320 Resonance Inputs.png

The module has two resonance inputs; a standard normalised input from a pot on the front panel that controls the initial resonance level and another input that comes from an attenuated input socket that accepts a CV of between 0V to 5V.

Each input will provide a current of 75uA to pin 9 when fully open, which combined will provide up to 150uA maximum, as the input resistors are in parallel. I am aware that 100uA is the maximum from the datasheet, however I have read from other that up to 150uA should still be safe. The reason I chose 75uA is because this is what the Pro-One is also specified at and is enough to provide sufficient oscillation.

Hope this makes sense.

Many thanks,
Chris
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Chris Willocks
Learning to Wiggle
Posts: 12
Joined: Mon Dec 09, 2019 1:09 pm

Re: AS3320 Resonance Inputs

Post by Chris Willocks » Mon Mar 23, 2020 11:28 am

Anyone?

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windspirit
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Re: AS3320 Resonance Inputs

Post by windspirit » Mon Mar 23, 2020 5:14 pm

This would probably belong in the DIY section, you might get more answers.

Chris Willocks
Learning to Wiggle
Posts: 12
Joined: Mon Dec 09, 2019 1:09 pm

Re: AS3320 Resonance Inputs

Post by Chris Willocks » Mon Mar 23, 2020 6:33 pm

Sorry, I've just realised this.

Apologies. I'll post it in the correct section.

Thanks,
Chris

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