MI Audio - Crunch Box  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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hako
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Joined: 10 Jun 2009, 21:04
my favorite amplifier: fame gta-15
Completed builds: TSs, BORs, Zendrive, DLS, Microamp, EH Boost, OSQ, Thor, MXR-401, Formula5, Professor Tweed, Peppermill.....
Fender 5E3, 5E2, TAD JTM45....
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Post by hako »

Hi,
euronymous0001 wrote: i wanna know if you also relocated the clipping diodes to the feedbacl loop of ICa or you retained it as it is, after the 2u2 cap to ground. tnx :D
i did (most of) these mods too, and i relocated the diodes. I did even more, i made the diodes switchable.
I originally used bean´s vero (Krunk) and I changed:

R5 -> 560K
R7 -> 15K (or trimpot/pot for presence control)
C3 -> 47p
C7 -> 22n
IC1 -> OPA2134

2PDT - removing (original) red LEDs + adding whatever clipping stuff in fb-loop of IC1A or vice versa.....

Increasing C4 (as mentioned before) added too much bass for me, so adjust to taste or add another switch for bass boost.
This beast rocks, best tones from crunch to higain.....

Have fun,
Heiko

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roseblood11
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Post by roseblood11 »

An interesting mod is to use a 2pdt on/on/on switch for the clipping diodes. One pair in the feedback loop, one pair to ground, and in the middle position of the switch both together...

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michael_ibrahim
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Post by michael_ibrahim »

rocklander wrote:one of the guys at nzguitars.com opened up his version of this.. loving the 'goop' :lol:
Thank you! Thought you'd appreciate the joke.

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lukatosh
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Post by lukatosh »

would be any noticeable changes if the gain pot is alternate between the 100 k-B and a higher value( 250k-B, 500k-B or even 1M-B) by using a 4PDT?

my idea is to alternate between crunch and high gain modes like the carl martin plexi tone...

Excuse my bad english :P

Thanks!

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Roast7
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Post by Roast7 »

Hi
After all, the volume and gain pots are Audio or log?
Regards
DL

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TubeHugger
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my favorite amplifier: JCM800
Completed builds: BIG muff green version
JCM800 tube Preamp in a box
steampunk kitten ("original" recipe tube overdrive pedal)
angry kitten tube amp (5W EL84 evil little gainer)
JCM800 2204 replica amp
wampler triple wreck clone
reezafratzitz clone
Bsiab III
Crunchbox clone
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Post by TubeHugger »

no one warned me how addictive pedal building is :cheers

first build to fire right up :D

we don't have LM833 here.
used 4558D instead.
sounds killer.

might do a video this weekend :hmmm:
Attachments
captaincrunchguts.jpg
captaincrunch1.jpg
"JMP it's a good place to be" - Big Bob

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