Did the BMP Mid mod

I added a switch to my Big Muff Pi reissue.

Stock its tonestack values are as follows:
0.0033 and 27k for the Treble side
100k Tone pot
0.01 and 27k for the Bass side

Plugging this into the Duncan Tonestack Calculator, it has a slightly less mid scoop than the "original" values (though I guess they varied over the years).

My switch changes things further. I now have the following values...

"Stock" mode:
0.0032 (0.001 and 0.0022 in parallel) and 27k for the Treble side
100k Tone pot
0.01 and 27k for the Bass side

"Mid boost" mode:
0.01 for the Treble side
100k Tone pot
0.0032 for the Bass side

The boost adds a good deal of juice to about 1000 Hz range, making the bottom seem less and helping a lot with clarity (I know, its a fuzz, so clarity isn't always wanted). I really like the stock mode for old, dark and muddy Black Sabbath type fuzz and the mid boost mode for all sorts of stuff... the mid boost mode is really cool.

I'm pretty happy with the mod switch, but the ribbon cable EH uses to connect the 3PDT switch to the board is a bit flimsy, so if anyone is planning on modding their BMP RI, be careful when you remove the jack and pot nuts and pull the board back. Too many flexes and the wires mays snap.

I forgot to mention... I just drilled a big jumbo enclosure for my 5E3 in a box pedal.

I've got the AC adapter jack, footswitch, output jack, LED, and pots mounted.

I have two input jacks and a channel jumper switch mounted as well.

The controls are exactly like a 5E3, with a 1M volume pot for each channel, a 1M Tone pot, and as far as the pedal goes a 100k Level or Output pot.

I'll be using the Fetzer Valve concept and recreating every exact triode in a real 5E3 with 2N5457 JFETs. the output section I may model after the "Professor Tweed's" output stage (which is sorta based on the tweed Princeton's 6V6 stage), minus the NF of the 5F2 of course.

I wanted to make a dual stage SHO as well as the Les Luis, but I'm missing one or two parts for either one. When I find enough time I will be fixing my 2x10" 50w dual channel amp build as well.

dont make the les luis it sucks compared to a super duper.

interesting mod, johnny. can you think of any tunes that would give an example of what it sounds like? i just picked up a bmp. instant love! can't believe it took me 28 years to try this pedal.

dont make the les luis it sucks compared to a super duper.


The Super Duper is two SHO circuits... I actually have most of the stuff for that. I was going to build the LL anyway, but the dual SHO was next on the list. I didn't really care for the clips I've heard of the LL, but after a heated debate I am going to build one. If it doesn't sound good in-person, I'll give it to a buddy.



interesting mod, johnny. can you think of any tunes that would give an example of what it sounds like? i just picked up a bmp. instant love! can't believe it took me 28 years to try this pedal.



Stock it can get a lot of old '60s and '70s sounds. Some Hendrix type of filthy fuzz, some Black Sabbath, and Pink Floyd. It can go from mild sustain and slight fuzz to wild and filthy.

It was also used on the first few Smashing Pumpkins albums in the '90s with a JCM800. It's a real smooth sounding distortion when used like they did.

With the mid-boost mod, it sounds a little tighter, brighter, and clearer. Sorta like the Red Llama in some ways. Still whooly, but slightly different.

Hey Johnny:

That looks like half of the Cornish Mid Hump mod that 11Gauge just helped me with. I'd say if you like what you have so far, do the other half, and I promise, you won't be disappointed. I've always loved the Big Muff, but now...hooo baby, I can't get enough. Here's the thread (http://www.tdpri.com/forum/burnt-fingers-diy-effects/198759-another-question-modding-big-muff-pi.html):

Enjoy.

Hey Johnny:

That looks like half of the Cornish Mid Hump mod that 11Gauge just helped me with. I'd say if you like what you have so far, do the other half, and I promise, you won't be disappointed. I've always loved the Big Muff, but now...hooo baby, I can't get enough. Here's the thread (http://www.tdpri.com/forum/burnt-fingers-diy-effects/198759-another-question-modding-big-muff-pi.html):

Enjoy.



IDK if I want to swap the coupling caps.

The reissue has 1uF before and after the Sustain pot. Going from 1uF to 0.01uF is trimming a lot of the fat... I like the whooly thickness... then again I also like flexibility...

Damn you HenryAdams, now I'm going out to the garage to use up another DPDT switch HAHAHA!

IDK if I want to swap the coupling caps.

The reissue has 1uF before and after the Sustain pot. Going from 1uF to 0.01uF is trimming a lot of the fat... I like the whooly thickness... then again I also like flexibility...

Damn you HenryAdams, now I'm going out to the garage to use up another DPDT switch HAHAHA!

BTW, I left the coupling caps stock. It wooly when it needs to be. Do it! Do it now!

Cool thread, sounds like a cool mod. Not to deviate JohnnyCrash, but how does that Duncan Tonestack Calculator work? Be easy, I'm not a electronic genius...lol

BTW, I left the coupling caps stock. It wooly when it needs to be. Do it! Do it now!



I did it. Dude, you weren't kidding. I really like all four modes now.

On my NYC RI the stock caps were 1uF and 0.47uF. I kept that for stock mode and the switch puts in 0.01uF's instead.

I had a few problems. First, the traces on the NYC reissue SUCK. A few pads lifted and broke from their traces - the traces on these things are very small and the copper is very thin. Second the ribbon cable attaching the 3PDT switch's PCB to the main PCB snapped off. Too many flexes and too thin of wire. Finally, way back when I first cracked her open the 100k sustain pot croaked.

I ran some short jumpers to fix the lifted traces. I had to solder new wires for the whole 3PDT switch. The 100k pot I'd already replaced, but all I had was a solid shaft. The only extra knob I had for solid shafts was a Fender black skirted (or are they witch hat) knob. To make matters worse, the only other mini DPDT switch I had today was slightly smaller than the one I used for the mid-boost mod.

The outside matches the inside - ugly. HAHA! Its got two choco-cake knobs, one Fender skirted knob, two mismatched switched, and now a few scratches... it all adds to the character :smile:



Cool thread, sounds like a cool mod. Not to deviate JohnnyCrash, but how does that Duncan Tonestack Calculator work? Be easy, I'm not a electronic genius...lol



It's a program you can download. It has typical tonestacks setup in it (platefed BF Fender, cathode follower Marshall, Big Muff, etc). You can replace the values of resistors, caps, and pots and it will show you the frequency curve.

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The Cornish mod with the smaller couplers is cool. Being a child of the '80s I like the smaller coupler with the stock mid-scoop a lot. I like the stock setup as well - real vintage sludge. both mods made this much more flexible (especially the Cornish coupler mod)!

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PS
The build quality of the NYC RI sucks... if you plan on modding one, beware! If you plan on leaving it stock, it should be OK though.

PS
The build quality of the NYC RI sucks... if you plan on modding one, beware! If you plan on leaving it stock, it should be OK though.[/QUOTE]

Yep, I burned out a bunch of traces as well on my NYC RI...I definitely never want to have to crack that thing open again. But given how much I now the love the thing, I don't think I'll ever need to. Rock 'n roll...

Yep, I burned out a bunch of traces as well on my NYC RI...I definitely never want to have to crack that thing open again. But given how much I now the love the thing, I don't think I'll ever need to. Rock 'n roll...



Same here...

With the smaller caps switched on it's a great general purpose fuzz box. Still clear enough for chords, bright enough for palm muting, and crunchy. In stock mode it's great for that thick single note type stuff. The mid-boost is still useful, but I am VERY glad you talked me into the other mod!

It is very flexible... gotta say, I still find the stock mode great for a lot of stuff too... but now it's like having 2 pedals in 1.

I'll only ever need to crack the enclosure for future repairs - this no longer needs ANY mods... it sounds AWESOME. Thanks for the nudge HenryAdams!