EHX - Big Muff Pi 2007  [schematic]

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Rocket Roll
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Post by Rocket Roll »

bumblebee wrote:The schematic of this is already posted in this forum some place.
There was one here, but now it's gone: https://www.freestompboxes.org/viewtopic ... 806#p31806

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bumblebee
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Post by bumblebee »

I have it if you need it,just PM me. Since I didnt draw it I cant post it up on the open forum without the guys permission. But I assume the guys still got it posted here, I don't see why he'd take it down.
I so dislike the modern digital world that I need to use semi-digital effects to emulate the analog world of cassette, VHS, and vinyl.

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Post by RnFR »

Rocket Roll wrote:
bumblebee wrote:The schematic of this is already posted in this forum some place.
There was one here, but now it's gone: https://www.freestompboxes.org/viewtopic ... 806#p31806
thanks! i couldn't find it! :x :D
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Post by maitregonzo »

Hello everyone,

I want to mod my big muff usa rev 3 because I use this one with my bass, the sound is very unsharp in low frequencies

bumbble be can you send me the diagram for the revision C 2008 vers.

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Post by bumblebee »

Nope, because I don't give out schematics of pedals that EHX are currently producing (my new policy).Sorry.

But I will tell you its here if you want it bad enough. *wink wink*
I so dislike the modern digital world that I need to use semi-digital effects to emulate the analog world of cassette, VHS, and vinyl.

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Post by maitregonzo »

I can understand you point of view.

anyway I don't want this diagram to make another clone or somethin'

I have 2 big muff the RI from 2008 and the black sovtek, and I wait for a bass big buff


I just want to use the RI as an experiment lab trying various resistor and caps settings using socket for easy removing.

your diagram is just an easy way to do that.

I never eared that EX blame customers that mods their BM, go see their forums and you will see by yourself that many topics subject are mod topic.


I want to apologize for all the english mistake that I make (I'm French)

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Post by bumblebee »

I know, almost all the Big Muff mods on EHX are mine anyways. :mrgreen: I'm an admin on the EHX forum incidentally. :lol:

Anyways, the 2008 diagram isnt mine, i didnt draw it, someone else did. It is on the forum though.
I so dislike the modern digital world that I need to use semi-digital effects to emulate the analog world of cassette, VHS, and vinyl.

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Post by devastator »

I've one of these "rev.C model" , the "stock" pedal sounds really boomy with a big midscoop and a lof of basses, I wasn't fan of that so I modded mine with the "sovtek" specifications and sounds better .

All caps are higher than 1Uf (even the ones with diodes) , some of them was 4u7 . Also The volume pot is 500KA, I'll change it for a regular 100KA.

But the PCB is really fragile :?

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Post by bumblebee »

All caps are NOT higher than 1uF, some are .47uF electros not 4.7uF. and thers TWO 2.2uF electro in it. Most caps are 1uF. In the diode clipping section stage 2 is 1uF then stage 3 is 2.2uF. And the way that woks in these two stages is the bigger the value the less boom. If you put 10nF in there it will be boomy as hell,its bad enough with 47nf. 1uF in these two stages prevents boom.

So, in the diode clipping section a BIGGER cap = LESS boom, not more!!!


And yes, EHX/Sovtek PCB's are of poor quality.



I have the schematic and the pedal and I can guarantee you this.

Funny, I say sovteks are boomy as hell and this pedal is nice and bassy but NEVER boomy.


It all depends on which pickup you play on, what guitar you use and what amp and amp setting you use.


I play Fender jaguars/Mustangs/jazzmasters into a twin reverb and this pedal is NEVER boomy, the only boomy pedals on my setup are sovteks (since modified highly) and all other muffs that use 47/50nF caps in the diode clipping stages like the majority of triangle muffs, which suck.
I so dislike the modern digital world that I need to use semi-digital effects to emulate the analog world of cassette, VHS, and vinyl.

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Post by devastator »

Yes I says mistakes , some of them are 0.47 (not 4u7). My bad.

But still, that version doesn't sound good to me, too much bass . Since I transformed it (I started with adding a midboost (ala Gilmour) in the tonestack , then I changed all cap values for the 100n and 22n with diodes) I like it ! (it wans't the case before).
And yes, EHX/Sovtek PCB's are of poor quality.
Not only PCB , the pots too. I changed two in my EHX pedals (wiggler and big muff).

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Post by bumblebee »

devastator wrote:Yes I says mistakes , some of them are 0.47 (not 4u7). My bad.

But still, that version doesn't sound good to me, too much bass . Since I transformed it (I started with adding a midboost (ala Gilmour) in the tonestack , then I changed all cap values for the 100n and 22n with diodes) I like it ! (it wans't the case before).
And yes, EHX/Sovtek PCB's are of poor quality.
Not only PCB , the pots too. I changed two in my EHX pedals (wiggler and big muff).

Your pedal sounds liek a nightmare to me as far as sound is concerned...but so long as you like it!

The pots used in the 1st green sovteks and some civil war muffs are excellent but the ones you are talking about are indeed very poor quality.
I so dislike the modern digital world that I need to use semi-digital effects to emulate the analog world of cassette, VHS, and vinyl.

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Post by deadllama »

I just got one of these today. Just wanted to report that mine also has BC550C's, and also has 1N4148 clippers.

In the process of adding a tone bypass toggle (a must for a Muff, IMHO) and bright white LED (just because I had one :P ) to my new one, I pulled the guts out of my older NYC RI Muff, a Rev. A board, and it's got 2N5088's and weird blue clipping diodes, and it appears to have some slightly different resistor values. I can trace it if anybody really wants me to. FWIW, I think the new one sounds much better.

EDIT: I forgot to mention that my new Muff has a blue PCB, too. I wasn't expecting that.

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Post by tommasomatassini »

Hi all,
that's my tracing for the EC3003 REV_C Model.

I hope you like it!
Tommaso
Attachments
Big Muff PI Ec-3003 ver_C .png

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Post by clintrubber »

tommasomatassini wrote:Hi all,
that's my tracing for the EC3003 REV_C Model.

I hope you like it!
Tommaso
Hello Tommaso,

Thanks for posting.

In case you're reading this, or anyone else that knows more,
how is the red C16 cap meant ? is that a changed value, or orginal ?

Need to have a look at mine, think it's a rev C as well.

Thanks

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Post by clintrubber »

clintrubber wrote:
tommasomatassini wrote: how is the red C16 cap meant ? is that a changed value, or orginal ?
Let me answer that myself,

I guess C16 will have been added to break the unwanted but not too harmful DC-path
from the collector of Q3 through R_8, P_tone & R_5 to ground, right ?

Bye

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