[sdiy] That 2180 with modular cv??

Neil Johnson neil.johnson97 at ntlworld.com
Tue Jun 28 22:20:25 CEST 2011


Dave wrote:
> Realistically, how much thermal noise does a 100K resistor generate,
> and is it important in a unity gain circuit, with typical synth CV
> levels?  If we're talking micro volts of noise in a CV path, does
> anyone care?

Each 100k resistor will generate 6uV of thermal noise.  Not much of an 
issue in CV circuits, but possibly quite noisy in the audio path once 
you sum up all those 100k resistors.  As in many things in life: "it 
depends".

It seems particularly odd to use a high-quality VCA and low-noise 
op-amps, and then spoil all that "quality" that you've paid for with 
poor passive component choice.

Neil
-- 
Synth DIY 2011 -- www.diy.synth.net/uk
Homepage -- www.njohnson.co.uk


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