[sdiy] what opamp for "warmth"? (I know, I know...)

René Schmitz synth at schmitzbits.de
Tue Apr 4 13:04:14 CEST 2023

On 03.04.2023 23:18, Neil Harper via Synth-diy wrote:
> i know this is going to be controversial, and I'm grabbing my popcorn..
> i have a digital effect that I'd like to "warm up" in the last dry/wet 
> mixing and output buffering stage. So wondering if there's any choice 
> of opamp that might give some favorable non-linearity quality to the 
> output sound. Would be running them with a single supply +9V.
> as for what specs constitute "warmth", I'll leave that up to you.. :)
The warm vintage opamp: Philbrick K2-W


In my understanding "warmth" comes from open loop circuits.

Means low order distortions. Preferably second order than third.

A feedback opamp doesn't naturally have that.

At least not while its in the linear range. Clipping usually means 
higher order terms as well.

Could be worth also trying this before the input of your FX.

OTA is open loop, with a bit of bias you can get second order.

FETs can be used open loop (or with just a small bit of negative feedback).

CMOS gate as opamp. (Low loopgain)

Opamp with nonlinearities (Diodes etc.)

Or use a tube.




synth at schmitzbits.de

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