Originally posted by vintagekiki
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2nF capacitor between g1 and cathode
Connect a capacitor between the g1 (or anode) and cathode of the preamp tube and measure the cutoff frequency, and listen to guitar sound with and without 150pF.
LP cutoff frequency varies with source resistance. You should be able to calculate it yourself for a given circuit.
Effective source resistance between plate and cathode is typically only around 40k, so the cutoff frequency will be much higher than in my example with 300k.
And yes, I know how a 4kHz LP filter changes the sound.
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