Modding an EHX to be more suitable for Bass?

[Scruffie]

Hey all,

Has anyone here modded the double muff to be a bit more suitable for Bass? I know it'd probably just be a few cap changes but a friend is down just for the day wanting it modded as he finds it to cut some bottom end on his bass and I want to order some caps that are in the right region incase I don't have anything else suitable to try out on the day for him.

Cheers for any info.

[fuzzo]

increasing the input cap I guess. 220nf in the normal version, creating a low pass filter with the resistor biasing the transistor base . I had one but one day....it died and I never know why, the EHX mystery !  

Anyway, I think with some mods that can really sound good with bass ! maybe reducing the gain , I don't think a bass really needs a lot of gain, just a kind of dirty crunchy tone.

If that can help you I've the factory schematic , nothing different compared to the 60's model , just two muff fuzz in serial.

[Scruffie]

Yeah i've got the schematic for the muffs and double muff, just wondered if anyone had some good reccomended changes and good values for the input and output, guess i'l just try 470nF being the next incriment up though, the output caps are fairly large anyway so they'll probably be okay, a diode change might help too, I find 3mm Red LEDs to be bassier normally.

Yeah i'm sure it will be good for bass, my friend already likes it, tbh I think he may have a bit of BUMS but i'm sure it can be tweaked a little for him, he'll atleast get the Blue LED he desperatley "needs"

Surely the EHX mystery can be solved... can't have a good effect go to waste!

[fuzzo]

The LED will reduce the gain and increase the volume .  Maybe tame the highs ?

[Mark Hammer]

Do not mistake over-enhancement of mids and highs for under-amplification of bass.

There is a  .022uf/1k2 network in parallel with 22k on the input.  The network gives preference to upper frequencies over bass.  Break that path so that everything has to go through the 22k and your friend might hear a better balance in tone, more suitable for bass.  You can break it by cutting the trace at some point or by lifting one leg of either of the two components (.022/1k2).

Apart from that little tweak, everything else in the circuit seems fine for bass.  Your friend may find, however, that rolling off some top end in the first stage might deliver up a better bass fuzz sound.  To do this, stick a cap in parallel with the first pair of clipping diodes.  Start with .01uf and work up (for more treble cut) or downward (for less) from there.

[Scruffie]

Aha, that's what that .022uF/1k2 network is doing, cheers Mark, that's probably where his complaint stems from and the cap in parrallel seems like a nice mod as I don't have to solder and can just jam it in there while playing to try.

Well I assumed it was fairly decent for bass in the first place, or why would he have bought it for bass! so that preference to upper frequencies is probably just niggling him at the top end.

[Scruffie]

Snipped them out this evening and it worked great Mark, thanks for the info, also gave it a really dark coloured tone on guitar which was kinda nice aswell but definitley removed some harsh top end on his Bass.

[Mark Hammer]

If a person had the patience, they could replace the 1k2 resistor with a 1k resistor and 25k variable resistor to vary the "treble advantage" at the input.  But glad to hear it worked ut nicely, though.