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Building your own stompbox / Re: Grow Your Own Guitar Pedal Finish, Chapter 2
« Last post by bluebunny on Today at 08:25:52 AM »Mr Stephen speaks wisdom. 

SMF for DIYStompboxes.com!
The voltage at V- (pin 5) is four diode drops below
ground, which, for the 2181, is approximately -2.85 V.
Since this pin connects to a (high impedance) current
supply, not a voltage supply, bypassing at pin 5 is not
normally necessary.
Could you, please, confirm resistor values asked before (see schematic at https://www.diystompboxes.com/smfforum/index.php?topic=113930.msg1167164#msg1167164), resistors R2, R4, R5 and R6. They seem as 1k to me (if photograph colors are right), not as 10k as shown on original schematic.
> I've drawn the tone stack already, but with your values it does nothing
You must model the tube output impedance. Else C9 has nothing to work against. The simulated power source would pull Hoover Dam out of the river, and laughs at a mere 10nFd.
Link
I also think C9 could be much bigger to give a strong effect (100nF may be too much).
Because of scaling (which I can't figure out) it looks like a small slump, but is >20dB above 2kHz.
Almost all the action of Tone happens at the right end of slider.
cool!
your site helped me get an octave down effect using cmos chips salvaged out of old organs working. thanks!