Big muff Low pass mod

[beanondabass]

Hi all, I'm looking for some help and advice!

I have a desire for a big muff type fuzz, where the low end is let through clean and fat and the top end of my signal ONLY is effected by the fuzz. I play a stingray which has lots of deep low end that either gets cut or becomes woofy with fuzzes and distortions and I would like to try this avenue. Also the synth like sound that this might acheive is appealing. If this can make my bass sound like the fat synth from Tyler's Igor I'll be very happy )))

I have a nano q tron with a low pass knob and I love how this makes the bass sound, I just wish I had different top end effect other than the swirling wah sounds from that, so I want to add it to a big muff.

I would modify an original EHX one but I only have the Nano big muff and I'm struggling to work out what is where so I have a custom one that some guy on Ebay made. Here's the schematic:

My question is: Where woud the low pass go? from where to where? ALso any ideas what kind of values do we think for the resistors and capacitors for it?
I'm imagining the LPF to be like a tone pot, but instead of the capacitor leading to ground it goes into the clipping section, and the low frequencies to pass the clipping and to return to the circuit later.

I have no idea what I'm doing but to take a punt I'm thinking to go from before C3 and returning the LPF resistor after C12?

Any advice and knowledge appreciated! Cheers TBers!

 

[bholder]

Sounds worth a try. Can't help with your questions, but subbing to find out - would love a LPF mod for my Big Muff Deluxe (not the bass version).

 

[moles]

It's not muff based at all (I don't think-?), but I really think you'd like the Fender Trapper Distortion. It's out of production but probably attainable for cheap.

Downsides: Is big. That right hand side channel has a midrange boost to it that may or may not be useful.

Having said that it's got the crossover blend thing you're looking for.

 

[ChristoMephisto]

This page might help you break down the BMP

ElectroSmash - Big Muff Pi Analysis

Circuit, List of Materials / Parts List, Input Booster Stage, Shunt Feedback Common Emitter Stage, Input Booster Voltage Gain Calculation, Input Impedance Calculation, Input Booster Frequency Response, Clipping Stage, Sustain Circuit, Clipping Amplifier V

www.electrosmash.com

 

[beanondabass]

Thnaks for the replies guys, I gave it a go!

So I wired a 250K pot from the left leg of C3 to the right leg of C12 and it worked! (sort of)

With the pot on 0 ohms, I get like 99% dry signal (But amped up by the pedal, sounds kinda cool tbh (might just be because its pushing my amp a little though)) and on 250K there is definitely a fat layer of bass with the fuzz. The tone seems to affect it, I'd rather it ignored it but its sounds good in the middle range of the tone selection. So much so I just wired it up with a 250K resistor across these 2 points.

...Then I couldn't fit it in my nano big muff box... and I don't like the purple blank one it came in. Sooooo...

I fixed my nano BMP, wired it the same (just by a guess, couldn't find an exact schematic but there's only 2 1uF caps on it so took a punt) and luckily it worked!!

Sounds good, bass has some nice meat to it and my guitar chugs more.

On a p bass there's probably not much need for this, but on my stingray the treble also pops through a little differently which I like.

Happy days!!!

 

[beanondabass]

Thnaks for the replies guys, I gave it a go!

So I wired a 250K pot from the left leg of C3 to the right leg of C12 and it worked! (sort of)

With the pot on 0 ohms, I get like 99% dry signal (But amped up by the pedal, sounds kinda cool tbh (might just be because its pushing my amp a little though)) and on 250K there is definitely a fat layer of bass with the fuzz. The tone seems to affect it, I'd rather it ignored it but its sounds good in the middle range of the tone selection. So much so I just wired it up with a 250K resistor across these 2 points.

...Then I couldn't fit it in my nano big muff box... and I don't like the purple blank one it came in. Sooooo...

I fixed my nano BMP, wired it the same (just by a guess, couldn't find an exact schematic but there's only 2 1uF caps on it so took a punt) and luckily it worked!!

Sounds good, bass has some nice meat to it and my guitar chugs more.

On a p bass there's probably not much need for this, but on my stingray the treble also pops through a little differently which I like.

Happy days!!!

Correction, the tone doesn't affect the LPF, I just had it to quiet to notice properly. Sounds perfect, just as I wanted! I might experiment with a switch to go to default if i want, and/or a capacitor/HPF for a guitar mode of some sort perhaps.