# Percolation Station - Volume



## doublej (Jan 7, 2021)

Built the Percolation Station with 2N2907A and PN3565.  I am getting a real volume drop unless I crank the pedal well past noon - nearly 3 or so.  Is this normal for this circuit or could it be my choice of transistor replacements?


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## Nostradoomus (Jan 7, 2021)

Any Perc I’ve built has been pretty loud. You sure about the pin outs?


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## Betty Wont (Jan 7, 2021)

All the percolators I've built need both controls all the way up to beat unity gain with germanium diodes. Remove the diodes for much more volume at the sacrifice of the octave down.


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## doublej (Jan 7, 2021)

Nostradoomus said:


> Any Perc I’ve built has been pretty loud. You sure about the pin outs?


welp.....


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## Chuck D. Bones (Jan 14, 2021)

Biasing a Harmonic Percolator is hard enough even when you use the right transistors.  when you start subbing, be prepared to change R1 and/or R2.  It all interacts.  Any other parts that don't conform to the BOM?

If you want to get this sorted out and have a DMM, measure and report the voltages Q1-C, Q1-E and Q2-C.


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## doublej (Jan 15, 2021)

Chuck D. Bones said:


> Biasing a Harmonic Percolator is hard enough even when you use the right transistors.  when you start subbing, be prepared to change R1 and/or R2.  It all interacts.  Any other parts that don't conform to the BOM?
> 
> If you want to get this sorted out and have a DMM, measure and report the voltages Q1-C, Q1-E and Q2-C.


so I measured and here are the values

Q1-C = 1.30
Q1-E = 1.94

Q2-C = 2.81


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## Chuck D. Bones (Jan 15, 2021)

That's pretty close to what I measured on mine just now:

Q1-C = 1.34V
Q1-E = 1.80V
Q2-C = 2.83V

Unity on mine is between 2:00 and 3:00.  This is not a high-output pedal.


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