Big Muff Opamp Verolayout

Gila_Crisis · September 24, 2007, 02:27:31 PM

so, i've done a layout for the Big Muff opamp version (1977)
here it is:

it's not yet verified, so if someone could take a look would be nice

it's based on this schem: http://topopiccione.atspace.com/pjimages/EHBigMuff1977.pdf

alteredsounds · September 24, 2007, 02:45:37 PM

Excellent, ty

Gila_Crisis · September 26, 2007, 07:04:07 AM

i found a little mistake, so pay attention!!!!

R6 must go to foot 1 of the 4558, not to foot 2!!!! otherwise the rest is correct!

robidor · September 30, 2007, 02:46:29 AM

Wait, the pots are all linear?

...And Gila, how the hell have you built a Woolly Mammoth? If it's, uh, sensitive, PM me.

Gila_Crisis · September 30, 2007, 06:32:52 AM

yep the pots i think that they are all linear, maybe you can take a log for the volume

stopstopsmile · September 30, 2007, 06:39:43 AM

gila, i am in learning mode. what is the point of the resistor across the volume pot?

bluetubes · September 30, 2007, 08:51:45 AM

I'm no expert, but I think the resistor across the Linear pot is to make it act more like a "log" pot. Linear pots for Volume just don't sound right to our ears as a logarithmic pot would. So the resistor is faking it.

Gila_Crisis · September 30, 2007, 04:43:54 PM

oh well this is a question i can't reply

i just followed the schem!

The Tourist · October 01, 2007, 02:08:58 AM

awesome, might give this a go sometime. Thanks for making this, I've been hoping for a perf or vero layout for a while.

paperhouse · October 04, 2007, 11:31:58 AM

thanks! where are you guys ordering your vero from? is there a perf layout of this somewhere? preferably of the tone bypass version. i love my original tone bypass op-amp but i would like to build one so that i don't have to worry about my vintage one.

robidor · October 04, 2007, 12:43:06 PM

Hey hey, you can get your vero at the store right here ('swhere I got mine).

For the tone bypass, don't you just put a SPST switch right before the tone section? The link to the schem that Gila put up there doesn't work, and I can't remember where the tone section starts, so sorry I can't be more specific.

Gila_Crisis · October 05, 2007, 05:32:30 AM

pay attention in the layout above there's a little mistake.

this one should be right:

Gila_Crisis · October 05, 2007, 05:37:43 AM

here you find the schem with and without tone bypass

http://analogguru.100free.com/193/schematics/EH_BigMuffPi_OP-78.gif

http://analogguru.100free.com/193/schematics/EH_BigMuffPi_OP-77.gif

Gila_Crisis · October 07, 2007, 10:09:23 AM

PAY ATTENTION!!!!
i build it and it works, BUT to make it work right just look that on the layout it's missing a 820k resistor that goes from foot 3 of the 741 to the +9V!!!!!

s.r.v. · October 07, 2007, 11:18:38 AM

instead of the jumper? are opamps numbered like:/
1 5
2 6
3 7
4 8

Dragonfly · October 07, 2007, 11:58:54 AM

Quote from: s.r.v. on October 07, 2007, 11:18:38 AM
instead of the jumper? are opamps numbered like:/
1 5
2 6
3 7
4 8

nope...in the layout, the 741 is flipped around (the "dot" on the opamp is closest to "1"), so its....

5 4
6 3
7 2
8 1

Dragonfly · October 07, 2007, 12:10:40 PM

I drew up an "easy fix" for it. theres already space on the board as long as you put the (R18) 820K "over" a jumper....

Gila...I'm only gonna keep this "fixed version" posted for a short while (a day or two)....so if you want, just copy it so that you don't need to "re-work" the original....

Gila_Crisis · October 07, 2007, 06:12:22 PM

thank you dragonfly!! this is the same i've done on mine!!!!

btw here's a corrct one (there was a second mistake, C7 is a 150pF not 150 nF) THIS IS A VERIFIED LAYOUT, i built it and work nice!!

Gila_Crisis · October 08, 2007, 12:07:46 AM

here a pair of pics of the pcb

Dragonfly · October 08, 2007, 12:11:21 AM

I pulled mine now so no one gets confused.

Thanks for the hard work Gila.

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Big Muff Opamp Verolayout