EHX - Big Muff Pi 2007  [schematic]

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EHX - Big Muff Pi 2007

Postby Bernardduur » 23 Dec 2007, 19:07

Today I got a 2007 EHX Muff in and yes, again, they differ from all the before models :)

So, for the persons who like to complete their collection, here's the schematic

Linkie

Transistors are BC550's; diodes are 1N4148's
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Postby analogguru » 23 Dec 2007, 21:39

It´s funny that after more than 35 years of BigMuff history it appears that the people at EH can´t stop to tweak around with this circuit....

But because it is Christmas I will tell you a "secret":
The 2007 Version is nothing else than "back to the roots" and the component values are the same as used one the first prototype(s) Triangle-Muffs which were build on perfboard. You have seen the guts ?

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Postby Bernardduur » 23 Dec 2007, 21:59

analogguru wrote:It´s funny that after more than 35 years of BigMuff history it appears that the people at EH can´t stop to tweak around with this circuit....

But because it is Christmas I will tell you a "secret":
The 2007 Version is nothing else than "back to the roots" and the component values are the same as used one the first prototype(s) Triangle-Muffs which were build on perfboard. You have seen the guts ?

analogguru


Cool!

The build quality was OK although I really disliked the solder used and the ribbon cable that connected the switch with the PCB; that was the reason it came to me as these points were damaged
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Postby bumblebee » 24 Dec 2007, 00:09

my favorite muff is the current (06 PCB) model, its probably the same as this.

i dont like the rams head,its muddy,or the russian,its weak and poorly made.
one fault i find with EH TH PCB's is that the trace is very thin and breaks easy if you wana mod it,my bmp looks more like its been built on perf with all the repairs ive done to the traces due to modifying it.

the SMD PCB's look and feel real good though!
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Postby Meanderthal » 25 Dec 2007, 05:07

Hey, this does look different. This is the new NYC version? I haven't seen those 0.47uf decoupling caps at the input and the in of the last gain stage before... interesting. I wonder if that's enough to tame the usual mud... probably for some amps... and all those 10k resistors remind me of the Russian ones... mid notch shouldn't be too extreme with those tonestack values.

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Postby Bernardduur » 27 Dec 2007, 12:17

I also wondered about the 500k log pot as the volume pot; would this change anything when compared to a 100k log pot there (as in all the other versions)??
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Postby bajaman » 27 Dec 2007, 12:30

I also wondered about the 500k log pot as the volume pot; would this change anything when compared to a 100k log pot there (as in all the other versions)??

It will roll off some more highs - less fizzy sounding :wink:
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Postby Bernardduur » 27 Dec 2007, 22:12

bajaman wrote:
I also wondered about the 500k log pot as the volume pot; would this change anything when compared to a 100k log pot there (as in all the other versions)??

It will roll off some more highs - less fizzy sounding :wink:
bajaman


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Postby Zztop128 » 03 Jan 2008, 16:08

I've a BMPi from 2004 and all pots are 100k, so it would be interesting to replace the volume pot with a 500k.... Another mod to do 8) 8)
But first I'm working on my LDO and SHO clone :D
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Postby patafix » 01 Feb 2008, 18:24

bajaman wrote:
I also wondered about the 500k log pot as the volume pot; would this change anything when compared to a 100k log pot there (as in all the other versions)??

It will roll off some more highs - less fizzy sounding :wink:
bajaman


I think it would be the opposite !!!!

As in guitars, the higher the value, the higher the output level and the highs.

Maybe I'm wrong ???
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Postby bajaman » 01 Feb 2008, 22:49

think it would be the opposite !!!!

As in guitars, the higher the value, the higher the output level and the highs.

Maybe I'm wrong ???

yes you are wrong - because you will unlikely be running the output level on full and the larger series resistance will roll off more highs in conjunction with the input capacitance of the proceeding stage.
Try turning your guitar volume 500k pot down to half way and listen to the loss of highs (unless you have a treble bleed bypass capacitor fitted to your poti). :wink:
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500K Volume

Postby Pippuz » 25 Feb 2008, 09:27

But this not change with other pedal in the audio chain?
It's not better to filter off some highs with a capacitor from output to ground?

Another question... I have a small clone and it have a 47ohm resistor between the - of the power jack and circuit ground..

can be this the definitive cure for ground loops problem?


bajaman wrote:
think it would be the opposite !!!!

As in guitars, the higher the value, the higher the output level and the highs.

Maybe I'm wrong ???

yes you are wrong - because you will unlikely be running the output level on full and the larger series resistance will roll off more highs in conjunction with the input capacitance of the proceeding stage.
Try turning your guitar volume 500k pot down to half way and listen to the loss of highs (unless you have a treble bleed bypass capacitor fitted to your poti). :wink:
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Re:

Postby Dirk_Hendrik » 25 Feb 2008, 22:37

bajaman wrote:your poti


Since when did you change over to German terminology !!?? :shock:
Sorry. Plain out of planes.

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Re: EH - Big Muff Pi ( 2007 model )

Postby bajaman » 26 Feb 2008, 01:26

Since when did you change over to German terminology !!??

:slap: :lol:
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Re: EH - Big Muff Pi ( 2007 model )

Postby Bernardduur » 22 Jul 2008, 14:45

YES! They do it again! The 2008 model??? Again one with changes from the 2007 model

Linkie

Transistors are BC550C's, diodes 1N4148's....... all caps ELCO's except for the tone stack which are ceramics

Sounds even worse :)
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Re: EH - Big Muff Pi ( 2007 model )

Postby AL » 29 Jul 2008, 20:02

Bernardduur wrote:Sounds even worse :)



:lol:
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EHX Big Muff, EC3003 REV_C Model

Postby Rocket Roll » 06 Oct 2009, 00:04

Just in case, here's the board:

IMG_0002.jpg
IMG_0008.jpg


Sound sample with a Strat: http://www.box.net/shared/s2gfkc0yit
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Re: EHX Big Muff, EC3003 REV_C Model

Postby cctsim » 06 Oct 2009, 19:47

I have this one too. Totally useless. I had to change all 1uF electrolytics to 0.1uF ceramics to remove all the excessive bass.
Now it sounds ok-ish.

The pcb is for sure not suitable for modifications, even with moderate heat I managed to damage it.

There are also a few electrolytic caps (2 220uF and one 2.2uF) that I have not seen in previews schematics.
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Re: EHX Big Muff, EC3003 REV_C Model

Postby bumblebee » 07 Oct 2009, 00:51

The schematic of this is already posted in this forum some place.
Thanks for the pics though, this is the onyl modern muff i dont yet own.

BTW, some of these come with a blue PCB.
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Re: EHX Big Muff, EC3003 REV_C Model

Postby cpm » 07 Oct 2009, 07:56

i dindnt have much problems when soldering on the board, not great quality, but not terrible.

some 1uFs must be changed into 100n definitely.
those 2 100R+220uF filters dc nicely
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