BMP Mods help

[jbeasley]

I just finished a BMP GGG Tuned version.
I love the smooth fuzz of it but I want to make a few mods and I'm not sure where to start.

1. More Midrange fuzz / less trebbly fuzz
2. A little bassy square-wave grind in the mix
3. More and Tighter bass/low mids

I'm trying to make a more dimensional sounding multi layered fuzz that's octavia-ish in nature.  Maybe a "Grit" knob to add square wave distortion.
Are there any schematics in existence that I can use?

Alternately, I have the AMZ double and triple tone mod schem so I think I can mod the tone stack easily but I'm new to this pedal stuff and not sure which diode, etc will give me a little bit of square wave distortion in the bass frequencies...

Any ideas?

This is my first build but I'm not new to schems, soldering or components as I've done my own guitar/cab soldering and schems for years. 

[bumblebee]

http://www.ehx.com/forums/viewthread/117/

Any of these can be adapted to any version of the big muff.

If want some more specific I can draw it for you but your description is a little vague IMO.

You want more bass, is your muff woofy/boomy...like it has tons of bass but it isnt useable?

What ever you want I can help you with.

I really dotn get what you are wanting exactly from no 2 and 3. I think I know what you want in no3 as it sound like you are complaining the common complaint about big muffs.

Did you mod the version you built?
Link me to a schematic,NON PDF! Do a Adobe grab in the PDF and upload it.

[jbeasley]

Thanks Bumblebee!

The schematic I used was the General Guitar Gadgets BMP GGG Tuned Version.
I would link to the schematic but his projects/kits schematic section is "closed for sabbath" and he does not give permission to host his schems on another site.

I can say that it almost identical to the violet rams head edition schem:
http://www.pisotones.com/BigMuffPi/psst/BMP_versions.htm

The differences being that in the one I built (The GGG Tuned)
- the 39k resistor in the tone stack of the Violet is replaced with a 100k
- the first resistor going into Q2 from B+ is 15k instead of 10k as in the Violet
- the transistors (Q1-Q4) on my version are NPN 2N5089

What I'm trying to achieve is a bit of hard and granular type distortion that blends with the fuzz, more midrange and tighter/thicker and more usable bass. 

My ideal fuzz pedal would have the following mods:
1. A three band adjustable tone stack (Bass, midrange, treble) + deepen and tighten the bass so that it's not so soft and flubby.  (Would it make sense to bypass the existing tone control and use an eq pedal for this instead of adding a 3 way tone stack?)
2. A "Grit" control that adds and subtracts a harder, more granular, type of distortion (squarewavish) to the already existing soft and smooth, staticy sounding fuzz.
3. A resonance knob secondary to the "grit" control that changes the primary resonant frequency of the "grit" so that the hard grind sounds bassy or midrangy depending on the setting of this control.

Does that make more sense?  I know my descriptions are a bit nebulous, I'm trying to explain in more clear terms.  Ultimately I'd love it if these options were adjustable with external pots but I realize that may be a tall order.

[bumblebee]

I can show you how to fix the bass problem easy enough.
And you could put a three way toggle in that goes from stock to scooped to flat tonestack.
You could also put in a pot to control the mids.
Having collector resistors of 10k on all four Q's  and emitter resistors of 100R on Q1-3 and 2k on Q4 is ideal IMO. It sounds fuzzier,smoother and higher gain.
There's 5 specific caps that you would want to change from 100nF to 1uF to fix the bass problem.
You can also change the pF caps, put them on a 3PDT or 3 individual SPDT's o to switch between stock values and 100pF on each. This will bring out the high frequencies of the pedal.

I don't really know what to do about getting a true square waveform from it sorry.....

Have you read about clipping etc on some websites?

If you need I can draw a schem doing the 3 way tone switch,mids pot, bass fix, and high freq filter toggles if you like.
This may solve at least part of your problems.

Using the 3 way tone stack toggle in combo with the original tone pot and mids pot, the high frequency toggle/s would give you a lot of tonal options.

You should also download the duncan tonestack calculator to simulate frequency responses to different values in the BM tonestack. Its a tool i cant do without these days. Just google for it.

There's also a lot of mod info on the web if you google it. Take what you want from me and others and combine it all to make what you are wanting, a super muff by the sounds of it.

I have done a lot of BM mods but they are all pretty regular,I don't like changing the overall muff character, I just like to voice it to my liking and adjust the frequencies/tonestack etc.

The bass problem in big muffs is this pedals main issue IME and .1uF caps just don't cut it as coupling caps in the majority of positions. Nor do they cut at in the clipping section. These two sections should have at an absolute minimum of 470nF! 1uF is perfect IME.

[jbeasley]

Thank you bumblebee.
I'll definitely look into your suggestions and formulate a plan.

I also just found a pedal that encompasses some of the sound and functionality that I'm looking for; it's the ZVex Mastotron.
It has more of a buzzy, gritty, grinding fuzz as apposed to the BMP fizzy, staticy fuzz.  I'd like to have the ability to dial in/out both types of fuzz if possible and change the resonant peak of the buzzy fuzz to make it sound more bassy or midrangey.

[bumblebee]

Th mastotron is just a woolly mammoth, one pedal I have spent a lot of time with, with a subs switch and input impedance pot (2 very nice mods),other than that and the fact that it uses 2n2222 and is smd its identical.

The BM and WM are very different pedals. I can (and have done) get a WM to sound like a big muff (not 100% obviously but very close) but cant get a big muff to sound like a WM. Go figure.

[jbeasley]

Bummer, so just sub'ing 2n2222 resistors in the BMP won't give it more grind?  Hmmm, maybe I need to make a Mastotron in addition to adding the BMP mods you already mentioned.

As far as the mods go I don't think I would ever use a mid-scooped fuzz as I already don't like the lacking mids already.  A midrange control would be CHOICE!  I'm not sure which resistors are the emitters and collectors...

If you have a schem for the bass mods and midrange control handy I'd love to have them.  I'd hate for you to go out of your way though, that seems like a lot of work to draw it out for me.

[bumblebee]

I only have to add a couple of things to an already existing schematic.
Give me till tomorrow and I'll do it for you. I'll just use that violet RH schem as a basis since its close to what you are using.


BTW,the 2n2222's wont change much.

Looking at the schematic you have, the collectors are at the top the base in the middle and the emmiters on the bottom, collectors go to9V+ emiters to GND.

[jbeasley]

WOW, that's awesome of you, I can't wait!
I'm not sure how I can repay you but let me know if there is anything specific you are looking for, I just might have one laying around.

[bumblebee]

Actually, this would probably suit your needs, plus there's other options:
http://www.muzique.com/lab/tone3.htm

What I was gonna draw for the mid control was basically the same as the first diagram anyways. I'll still upload a schem with which caps to change for nice bass response.

This one works too:

[jbeasley]

Thank you,
That resonance control on AMZ was exactly what I was looking for!
I'll definitely change out the caps for the increased bass response too. 
The only other thing I'm hoping to achieve is a more clear sounding granular type of distortion that I can dial in/out.
I'll see how these mods sound first, maybe the resonance control from AMZ will render another mod unnecessary?

[bumblebee]

Modified Schem PM'd to you!

[nbabmf]

The AMZ Presence control is fantastic.  So, so, SO versatile.  It allows one trick pony pedals get along with a variety of guitars and amps that would otherwise be too muddy or even not meaty enough.