How to mod caps of a Big Muff (Op amp) to use for bass?

gigimarga · February 24, 2008, 04:49:49 PM

Hello,

I had built long time agp an Big Muff (op amp version) from here: http://gaussmarkov.net/wordpress/circuits/big-muff-pi-op-amp-version/.
A good friend of mine wants very much one and, as i didn't use it very much, i want to make him a surprise and give it to him.
The problem is that he's a bass player and i don't know how to modify it (mainly on the input/output caps i think...) so he can use it on bass.

Did someone else do these mods and can help me?

Thx a lot!

gigimarga · February 25, 2008, 12:55:37 AM

petemoore · February 25, 2008, 01:08:47 AM

FAQ

petemoore · February 25, 2008, 01:15:54 AM

Caps block DC from passing through them, and can attenuate AC by imparting increasing resistance as...frequencies get lower and approch DC [the 'lowest frequency = no frequency' misnomer].
Stick one of those in the SP [signal path] and [HP Filter cuts lows].
It works differently than if placed from SP to Gnd [LP Filter cuts highs].
[or other DC reference,
depending on value, frequency content...etc.
My first post was better !

petemoore · February 25, 2008, 01:16:54 AM

Caps block DC from passing through them, and can attenuate AC by imparting increasing resistance as...frequencies get lower and approch DC [the 'lowest frequency = no frequency' misnomer].
Stick one of those in the SP [signal path] and [HP Filter cuts lows].
It works differently than if placed from SP to Gnd [LP Filter cuts highs].
[or other DC reference,
depending on value, frequency content...etc.
My first post was better ^
It would double post on me right now...lol.

gigimarga · February 25, 2008, 01:38:40 AM

Thx for your answer...because i don't speak english very well my posts are unclear...the question, detailed, must to be:

1. it's enough to modify only the input/output caps?
2. if the answer to question #1 is yes, which values would be good (or almost good...i have built him a modified fuzz face and he was happy only when the input cap becomes 10uF from the standard 2.2uF), because i can't test the mods on a bass?
3. if the answer to question #1 is no, which other parts of the Big Muff must to be tweaked to use it with bass?
4. it is useful to bypass the tone stack?

Thx a lot again!

gigimarga · February 26, 2008, 12:44:05 AM

lowstar · February 26, 2008, 03:23:16 AM

if you want to make your bass player happy, change the caps and resistors to "russian green big muff" specs.
that is the muff most coveted by most bass players, including me. sometimes bigger is not better, coupling caps that are very big between the stages sometimes mush up the sound, especially with bass. tonepad has a nice document with schematics that show the differences for three different muffs (stock, NYC triangle, green russian) that will provide you with all the info you need.
or, you could mod it to jumbo tonebender specs, which means lifting the second diode clipper pair. that also cleans up the sound a lot, and the jumbo tonebender is also a much coveted piece of gear when it comes to bassists (check on talkbass.com for instance).

cheers,
lowstar

gigimarga · February 26, 2008, 11:17:37 AM

thx for your answer lowstar...the only problems it's that i have the bif muff's version with op amps

...and it don't looks as any other version...anyway, i will study the caps of the russian version!

lowstar · February 26, 2008, 11:45:26 AM

Quotei have the bif muff's version with op amps

whoa !!

i was reading too fast and skipped that (important) part !

whole different story then. sorry !

cheers,
lowstar

News:

How to mod caps of a Big Muff (Op amp) to use for bass?