# Distortion 250 gain



## BuddytheReow (Mar 1, 2021)

Would changing the distortion pot from 1mb to, say, 100kb do to the sound? I forgot to order a 1mB pot, but I have others.


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## BuddytheReow (Mar 2, 2021)

Bump. If I lower the pot value, would that increase or decrease the total gain in the circuit?


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## benny_profane (Mar 2, 2021)

Without scaling the feedback resistor, you would be essentially lose some of the lower end of the gain sweep of you reduce the gain pot value.

The gain comes from a non-inverting op amp. The gain calculation is:





Gain = 1 + (Rf/R2)

For this circuit, R2 is the GAIN control with the 4k7 series resistor. In the stock configuration, Rf = 1MΩ and R2 = 1MΩ + 4.7kΩ.

*Stock values:*
Gain_min = 1 + (1MΩ/(4.7KΩ + 1MΩ)) = 1.5 (3.5dB)
Gain_max = 1 + (1MΩ/(4.7KΩ + 0MΩ)) = 213 (46.5dB)

*With a 100kB pot:*
Gain_min = 1 + (1MΩ/(4.7KΩ + 100kΩ)) = 10.55 (20.5dB)

If you wanted to sub the gain pot, you'd want to scale the feedback resistor. Also, you'd want to consider the series resistor and cap to preserve the frequency response. You'd have to scale the series resistor regardless so you could maintain the Gain_min behavior anyway.


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## scheffehcs (Mar 2, 2021)

I just built one and like many other people,  I didn’t like the B1M. The bulk of the gain comes in only in the last 10% of turning it up. I imagine the problem would be there with the B100k too. You might want to try using a C taper if you can get one, either 100k or 500k.


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## scheffehcs (Mar 2, 2021)

https://forum.pedalpcb.com/threads/distortion-250-problems.5020/


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## delackattack (Sep 28, 2021)

scheffehcs said:


> https://forum.pedalpcb.com/threads/distortion-250-problems.5020/


I tried the 100k and it helped significantly but still some sputtery nonsense going when you hold a note or palm mute


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