Big Muff Pi: Adding Parallel Coupling caps - can I run them through a switch?

[Enoch0)))]

I have a Black Russian Big Muff Pi

I've added some larger caps parallel to each coupling cap to give the pedal some more low end (yeah, the Muff already has lots of low, but this is for a special application)

The stockers are all .1uf, I've added additional .1uf caps parallel to each, but might change those to 1uf.

My question is: To effectively disable the additional parallel caps, do I need to run each through a switch, or would switching just one (say the last one) effectively create a bottleneck and give me the same effect as switching them all?

Basically I'd like to find a way (if possible) to switch all the additional caps on and off as simply as possible and with the least amount of switches possible.

On the other hand, maybe someone can tell me if I'm going about it all wrong. I basically want a switch that adds tons of low/heavy to the pedal. Is this the right way of doing so?

Can anyone help? Thanks in advance!

Schematic:http://www.premierguitar.com/Stream/...age_Type=image

Layout: http://www.premierguitar.com/Stream/...age_Type=image

[Mark Hammer]

Simplest and least problematic approach is simply to alter the tone control. It already provides a bit of a mid-scoop. You ll get a sound that feels more bottom heavy if you shift that scoop over a bit.

R19 and C11 form a lowpass filter with a rolloff starting around 400hz. C10/R18 form a highpass filter section with a rolloff starting around 1850hz. You can monkey with those rolloffs to get a different EQ which will downplay the mids you select, making the unit seem more bottom heavy.

Take a look at the AMZ site for some nice tutorials on how to do that. AMZ Lab Notebook & Guitar Effects

[Enoch0)))]

Wow, excellent! Thanks Mark, that sounds like what I'm looking for!

I also think I answered my coupling question last night while tinkering with the muff. I added a DPST switch in series with the last two coupling caps that I added. Switching them on/off makes almost no audible difference. I may try it with the first two or maybe the first and last to see if it makes more of a difference. I'll try messing with the tone section as you suggested as well.

Thanks again!

[loudthud]

It should be possible to switch a bunch of stuff at once using P channel JFETs. It would be helpful to know what the low end rolloff actually is in the stock pedal. Maybe you actually need to boost the lows above flat response to get what you want. Ever tried running a graphic EQ before or after the Big Muff?

[Enoch0)))]

It should be possible to switch a bunch of stuff at once using P channel JFETs. It would be helpful to know what the low end rolloff actually is in the stock pedal. Maybe you actually need to boost the lows above flat response to get what you want. Ever tried running a graphic EQ before or after the Big Muff?

I like the JFET idea, I may try that. I haven't tried the graphic EQ, but I'm sure that would easily do the trick as well. For the most part the reason for these mods is just to hot-rod the big muff for fun.

Another issue may be that my guitar (tuned to drop C) isn't producing anything low enough for the extra coupling caps to make a difference. I'll try playing a bass through it and see if switching the extra coupling caps in and out produce a more pronounced effect.

Thanks for the suggestions!

[Mark Hammer]

The unit IS generating gobs of bottom. The reason why you don't hear it is because it generates gobs of gobs of mids and top end. Tweaking the tone control circuit will push the mids into the background and make the existing bottom end seem huge. That's how the Univox Superfuzz and Shin-Ei FY-2 work. It's all in the scoop.