Rat pedal mod?

Discussion in 'Effects [BG]' started by phangtonpower, Jan 20, 2013.

  1. This should be an easy one for you guys. I'm trying to mod my Rat for more bass. I've already done the Ruetz mod, changed the opamp to an LM308 and it sounds good, but I would like to add a little more bass. My rat is one of the ones they made right before they moved to china similar to this one....

    I want to try and change the input cap to maybe .47uf to bring out the bass more. Problem is I'm not sure which cap. I'm not really good at reading schematics, so if anyone can circle the one I need to replace in the picture above that would be awesome. Also any advice to bring the bass out more would be appreciated :)
  2. Anybody?
  3. taurus1


    Sep 13, 2006
    Vancouver B.C.
    I'd love to know too, I have an old Turbo Rat that I use with blend, I'd like to mod it for more bass as it lacks it bigtime as is.
  4. Projectile


    Feb 5, 2009
    The input cap is already plenty big enough for bass. That's not where the low frequencies are getting lost. The easiest way to make a RAT better for bass is to do the Ruetz mod, but it sounds like you've already done that and still need more low end. The Ruetz mod sets the LF roll-off to around 60Hz and we can do even better. You could double the size of the 4.7uF capacitor to around 10uF (the one series with the 560ohm resitor). This would move the roll-off down to 28Hz, which would let most of your low end through.

    That being said, I find that the main problem with distortion pedals is not that they don't let enough bass through. Rather, the problem lies in the fact that they generate a lot of high frequency harmonics that drown out the low frequencies. The best solution in that case is to add a clean blend circuit, or use a clean blend pedal. If you just want a bass boost, you could add a simple lowpass RC filter to the clean blend signal so that you would just let through the low frequencies in the blended signal, but I usually find it's not necessary.

    The final option would be to add a bass boost circuit to the output stage instead of a clean blend, but that's a lot more complicated and requires a good deal of circuit design knowledge to implement well.

  5. Interesting... is it possible to add a clean blend feature on the RAT?
  6. I didn't think anyone was gonna respond.

    Anyway I kinda gave up modding the rat itself. I tried my RC bass booster in front of it and there it was. I don't really want to use the booster just for the rat so I'm building another booster and tuning it to the range I'm looking for. I'm going to fit it into a wah pedal that I've turned into a an expression pedal and looper. That way I can turn the booster and the rat on at the same time