# Favorite Rat Mods?



## MightySmallElectrons (May 14, 2020)

I’m getting ready to build my 3rd Muroidea pedal and am curious if you have a mod that you think makes this classic even better and why?


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## Nostradoomus (May 15, 2020)

I usually lower the 4.7uf cap down to 1uf to get rid of the farty compression sound but other than that I love them stock or Turbo spec.


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## Chuck D. Bones (May 15, 2020)

Nostradoomus said:


> I usually lower the 4.7uf cap down to 1uf to get rid of the farty compression sound but other than that I love them stock or Turbo spec.


There are two 4.7uF caps.  Are you talking about C2 or C7?


I like the BASS mod and increasing C8 so the entire range of the FILTER control is usable.


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## MightySmallElectrons (May 15, 2020)

Chuck D. Bones said:


> There are two 4.7uF caps.  Are you talking about C2 or C7?
> 
> 
> I like the BASS mod and increasing C8 so the entire range of the FILTER control is usable.


What’s your preferred value for C8?


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## Nostradoomus (May 15, 2020)

Chuck D. Bones said:


> There are two 4.7uF caps.  Are you talking about C2 or C7?
> 
> 
> I like the BASS mod and increasing C8 so the entire range of the FILTER control is usable.



Sorry C2 tied to the 560 ohm resistor and DIST pot.


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## Chuck D. Bones (May 15, 2020)

MightySmallElectrons said:


> What’s your preferred value for C8?



6.8nF or 10nF


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## Nostradoomus (May 15, 2020)

I’ll play with that to make up some of the pre opamp bass signal lost by lowering C2. I don’t really notice too much oomph gone with the corner frequency moved up to 260-ish Hz. It definitely doesn’t bottom out anymore and that was my only real issue.


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## phi1 (May 15, 2020)

Put a 1k or 500ohm pot between R5 and C3 as a “voice control” like a zendrive has. Maybe experiment with removing R3/C2 with this mod. R5/C3 cuts bass below 1.5kHz. The voice knob allows you to choose a lower frequency (though you lose some gain when you turn the voice knob down for lower frequencies). On the rat, R3/C2 adds some bass back in, but at a much lower gain than R5/C3.  A bass knob like chuck mentioned will also allow some similar results. 

I did this voice mod on my DRV (in built reports), after trying a bass knob first. Chuck added lots of great info to that thread, including some simulation graphs of the different mods. The DRV circuit is very different from a rat, but the voice knob should still work on the rat. For example, instead of 47R/2.2uF, the DRV has 470R/220nF. Same 1.5kHz cutoff, but 10x less gain at this stage (because the DRV has the boost circuit first).


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## HamishR (May 17, 2020)

I like Chuck's mods - esp the bass pot. I also like a lower value gain pot but suspect I might be alone on that. I have no use for crazy amounts of dirt except in a gatey fuzz.


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## benny_profane (May 17, 2020)

Chuck D. Bones said:


> There are two 4.7uF caps.  Are you talking about C2 or C7?
> 
> 
> I like the BASS mod and increasing C8 so the entire range of the FILTER control is usable.


What is the ‘BASS mod’ ... I’m guessing it’s in addition / complementary to increasing C8?


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## Chuck D. Bones (May 17, 2020)

benny_profane said:


> What is the ‘BASS mod’ ... I’m guessing it’s in addition / complementary to increasing C8?


https://forum.pedalpcb.com/threads/so-this-is-where-i-am-with-my-pandora.1601/#post-11782


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