# Propolis volume knob or trimpot



## Kroars (Jan 10, 2022)

Hoping one of you gurus can help confirm: Would I be correct in thinking that I could either replace R17 with a 500k trimpot or replace with a 500k linear pot for volume control on this board?

Thanks!


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## thesmokingman (Jan 11, 2022)

It is based on the kay fuzz tone ... you should be able to google a schematic for reference


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## fig (Jan 11, 2022)




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## fig (Jan 11, 2022)

I'm guessing it's the 100KΩ @ the OUTPUT?


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## thesmokingman (Jan 11, 2022)

the 100K on the kay fuzz tone is more or less the 330K R17 of the propolis (corrected)

now let's get specific ... the propolis is bleeding off more signal to ground than the kay fuzz tone and lowering R17 would continue to do that. Placing a trimmer there wouldn't be a very effective volume control as there is always a signal path to the output with 0R resistance

The more traditional route would be a volume control like the fuzz face where the pot is a voltage divider going from bleeding all signal to ground (0R to ground, 500K in series with signal) to passing all signal out (500K to ground, 0R in series with signal) ... in order to do that you'd need to place such a pot on the output and remove R17 (which would be parallel to whatever resistance to ground the volume control presented)


and since we're being thorough and you may get curious ... go watch a video of a kay fuzz tone if you're wondering why union tube got rid of the rocker-based tone control


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## fig (Jan 11, 2022)

Well explained sir!


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## Kroars (Jan 11, 2022)

thesmokingman said:


> the 100K on the kay fuzz tone is more or less the 33K R17 of the propolis
> 
> now let's get specific ... the propolis is bleeding off more signal to ground than the kay fuzz tone and lowering R17 would continue to do that. Placing a trimmer there wouldn't be a very effective volume control as there is always a signal path to the output with 0R resistance
> 
> ...


Thank you kindly!


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## Bobbyd67 (Jan 11, 2022)

I just added a 100k pot to the output of the pedal. Like in this build

https://docs.pedalpcb.com/project/Gnat.pdf
Works great and at full volume you get a stock bumblebuzz build. On the flip side you can't get a volume boost that way, just attenuation.


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## Big Monk (Jan 11, 2022)

thewintersoldier said:


> @Big Monk would say why not both? 😬



And don’t you forget it Holmes.


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## thesmokingman (Jan 11, 2022)

If you didn’t remove r17


Bobbyd67 said:


> I just added a 100k pot to the output of the pedal. Like in this build
> 
> https://docs.pedalpcb.com/project/Gnat.pdf
> Works great and at full volume you get a stock bumblebuzz build. On the flip side you can't get a volume boost that way, just attenuation.


not that this fuzz is capable of so much more than unity, if you didn't remove r17 before adding the pot then you actually made it less loud when the volume is full up because you added 100K of parallel resistance to that 33K resistor ... for what? 24-25K effective resistance? from my previous post, lowering the value of that resistor effectively lowers the volume ...


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## Bobbyd67 (Jan 11, 2022)

thesmokingman said:


> If you didn’t remove r17
> 
> not that this fuzz is capable of so much more than unity, if you didn't remove r17 before adding the pot then you actually made it less loud when the volume is full up because you added 100K of parallel resistance to that 33K resistor ... for what? 24-25K effective resistance? from my previous post, lowering the value of that resistor effectively lowers the volume ...


Well the stock pedal is a lot louder than the unity guitar volume in my experience, that's why I made one with a volume attenuator. Also R17 is 330k not 33k, so I don't know if that make more of a difference in the overall volume drop I would be getting at max volume on my 100k pot. I got 3 builds here so I will remove one r17 from one of them and compare it ^^.


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## thesmokingman (Jan 11, 2022)

Bobbyd67 said:


> Well the stock pedal is a lot louder than the unity guitar volume in my experience, that's why I made one with a volume attenuator. Also R17 is 330k not 33k, so I don't know if that make more of a difference in the overall volume drop I would be getting at max volume on my 100k pot. I got 3 builds here so I will remove one r17 from one of them and compare it ^^.


well look at that ... 330K ... probably shouldn't look at the schema on a phone ... the parallel resistance math still holds up ... 76K probably enough to prevent loss but certainly much less than 330K


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