Human Gear - Animato  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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Crowella
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Post by Crowella »

Very weird bump but I thought I'd make a sneaky suggestion to those playing at home/have one of these. I spent a fair while wondering how on earth to reduce some of that noise floor. There was a very prevalent hiss in the original and even the ones I started making had a bit of the same hiss too (even when the guitar/bass is muted).

Well, doing some looking around and some tinkering, I thought I'd throw a 2k2 resistor (or something small in that range, feel free to tinker) between the 102/103 and the supply after the trim. The result? A tiny bit of a more treble response, maybe the tiniest dip in gain (oh hey, there's a nice trimpot there to fix that) and substantially less noise.

Why this wasn't done to begin with, I don't know and admittedly I never spotted it many years ago when I was reverse engineering it. I even reopened the original to see if I had missed something and nope, even the original had it omitted.

Basically, these are the articles I have to thank.
https://sound-au.com/articles/cmpd-vs-darl.htm
https://www.electronics-notes.com/artic ... y-pair.php
The bypass resistor is included to aid the switch-off process. Without the resistor in place, there is no discharge path for the base emitter capacitance. Including it enables the charge stored in this capacitor to dissipate and this aids a faster turn-off.

It is good design to include this resistor, but if speed is not an issue then the resistor can be omitted, but unless cost and component count are being reduced to the minimum then it is wise to include it.
:popcorn:
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BurgerCrisis
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Post by BurgerCrisis »

Funny the things that turn out to be big muff clones!

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tommymariot
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Post by tommymariot »

Hi Guys, I have some issue with my version. I have a lot of noise with the guitar/bass muted. it's something like an helicopter. What could it be?

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Ichabod_Crane
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Post by Ichabod_Crane »

Something about the ground?

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Jarno
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Post by Jarno »

Have you tried a different power supply (battery?)?
"It crackles....., but that's ok"

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Post by tommymariot »

I didn't tried yet with battery. I used several commercial PSU (Boss, one spot....) and my laboratory PSU. This pedal is really noisy. After some debug I found that the treble booster section is ok, not so much noise. The Big Muff section is really noisy but I cannot understand why. I built another one but with 2n404 and Mpsa06 and this one have more noise the the first one.

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