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Mutant Clap DIY Calibration Stupid Question
MUFF WIGGLER Forum Index -> Hexinverter Electronique  
Author Mutant Clap DIY Calibration Stupid Question
Sorry, probably a stupid question, but I'm trying to calibrate my Mutant Clap. I'm at Step 1 (Calibrating offset null) from the build tips doc. Where should I put the second probe from my multimeter, in order to test the voltage at the test point?

Would like to know this myself as my kits are in route and I thought the same thing..
You can use the lower pin of the Default Accent selector header, I discovered. I'd been trying to use the middle pin of the same header, but that's not connected to ground, as I had assumed.

My voltmeter isn't very accurate in the mV range. Hopefully yours will be better.

you can also clip a crocodile on a ground lead of a socket or the LM7805 ground, then you got a free hand!
Thanks for the tips, guys. I ended up fine-tuning by ear, as my voltmeter isn't very accurate. I think I got it to work though.

I'm struggling with this step now myself. When I turn the "offset null" trimpot, I'm only getting between about 3.6v and 4.8v on my multimeter, and that's only in the very far counter-clockwise direction; most of the range just has the value stuck around 4.8v. I've checked the boards for soldering mistakes & don't see any. The manual says this should be -100mv, so I'm way off.

Toneburst, how do you tune this setting "by ear"? What are you listening for?

I'm assuming there's something wrong with my build, since those testing values are so far off. Any ideas? I may try replacing ICs next, I guess?

EDIT: My LM13700 was plugged in backwards very frustrating -- it seems to be toast. ordering another one now; I should have known to keep more than one on hand!
Can anybody tell me if there is a 'Factory' setting for the Reverb volume? Just received a Mutant Claps, it looks like it is a DIY build, very nice at that. It all works fine, sounds good, but the reverb seems to be a little hot. I was just curious if there was a particular setting like 4v p-p or something. Knowing this is based on a 909 I looked at the 909 service manual but didn't see anything, so this might just be akin to the mutant clap circuit.
So I had a lot of trouble calibrating my mutant clap. Multiple attempts and never got anywhere. However tonight I finally got it dialed in and it's a different module. Way to better. Anyway, thought sharing my experience might help someone else, so here goes.

1. Did offset first
2. Module was turned on (took me awhile to realize this)
3. Rev Dec was fully up as it says
4. Black was connected to the lower accent jumper (thank you for that suggestion!!)
5. I couldn't get to -100, closest was either -120 or -80. Ended up going with -120

Then I moved on to the rev volume. This was super frustrating. With the rev dec at half way and the sustain at zero I had no noise. Also had everything else turned off. Anyway, after a while of going one way or another I finally gave up, couldn't hear anything (whereas previously I just had really loud noise). I finally gave the offset a little turn counter clockwise (maybe a quarter turn) and voila, got it!!

So advice is this a) don't give up, the module is so much better once dialed in b) get the offset as close as you can c) get the other trimmer close to the middle, the. Finally d) readjust the offset trimmer.

Hope this helps others
Oh - when I started my offset was reading 12V
Hello everybody,

I can't seem to have any reverb at all on my diy mutant clap module.
Anybody had the same problem?


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