Author Topic: Karate Shop Volume Mod  (Read 455 times)

btml

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Karate Shop Volume Mod
« on: July 08, 2021, 02:01:27 AM »
I'm a beginner and this is my question.
I have an old KS board from before I had kids that I am just getting around to enclosing.
I noticed there is a revised build document showing a new master volume knob. I want to include this feature but noticed some values are different in that area of the circuit. I'm wondering how you arrive at the values from a design standpoint.
The original shows 1M resistor(R10) shunted to ground at the output, and the revision has a 50kA in the same place acting as a voltage divider.
The cap immediately upstream from there went from a 100n(C7) to a 1u(C6).
These are the only changes I can spot to the entire circuit.
The cap is 10x different, the resistance to ground is 20x different.
My understanding is that the cap is there to block DC from the output and also filters low frequency AC; the frequency depending on the value of resistance to ground. So if that is 'tuned' to the new resistance, that makes sense. What I don't understand is why the resistance to ground had to be reduced that much.
I had a hard time getting the original circuit down to the same level as dry signal without losing the effect- so did the output just need to be tamed?
If there's a math reason for the resistance change, or whatever else, I'm curious to learn it.

Cheers!