Another Muff based fuzz build

[trad3mark]

Hello all,

I'm working on a Muff based pedal at the moment. It's got a bunch of little tweaks to fit my own taste, but i'm having some rather odd occurrences throughout the build... So it's basically a cross between the Violet Big Muff and the Tone Wicker Muff. So there's about 9 electrolytes on it, which looks so random in a muff. Anyway, I was trying out all sorts of different values for things. Everything from transistors to gain resistors. The thing i'm most confused about is to do with the diodes though.

I couldn't help but try out some germanium diodes in there. It did make for a much smoother fuzz, but can anyone explain to me why there was a volume drop of about 50%? and is there any easy way to compensate for that, without having to do anything drastic?

sadface,
N

[Jero]

That's just one of the characteristics of germanium diodes. Not much I can think to do about it. Maybe add a simple boost, with trimmer, before them. That still might not even work though.

[moose23]

You could adjust the gain recovery stage (final transistor stage) after the tone section for more gain/volume.

Is the schematic for the germanium muff on freestompboxes? checking that would help I'd imagine.

[Teej212]

germainum muff isnt really like the bmp at all. its the muff fuzz with germ trannies, and the EHX germainum overdrive. and for the volume drop i think the best option would be just to add a boost after the fuzz section, but it might be hard to do without changing the sound of the muff a little bit

[bubstance]

germainum muff isnt really like the bmp at all. its the muff fuzz with germ trannies, and the EHX germainum overdrive. and for the volume drop i think the best option would be just to add a boost after the fuzz section, but it might be hard to do without changing the sound of the muff a little bit

Correct about the Germanium Muff, but there really isn't a need to add an extra boost stage to the Muff when you've already got a makeup gain stage that you could easily tweak to get more output.

Or, to get a raise in perceived output, swap out the tone stack caps for some different values. You can find which ones give flat mids and go from there, or you could even replace the whole thing with a James-style stack for better control. All will raise the perceived output level.

But on a serious note, germanium diodes in a Muff are actually almost useless. They really don't change the clipping at all (not even really "soften" as people claim) 'cause everything is basically turning into a square wave anyway at that point of saturation. The only real difference is that lowered level at which the clipping starts, but since it's getting into squarewave you won't really be able to see that point where it all starts to curve (which is what germanium would cause it to do). You can get that softer sound by using FETs instead, in this case.

[eatyourguitar]

you could just add resistance in series with the diodes and cap. and try messing with the 560pf caps. I think 100pf sounds good too if you just keep the 560pf on the last one. bubstance is right that all diodes clip to make square waves and you achieve the same amount of clipping with compensated volume going in and out. but thats in a perfect world. germanium does sound different. even two different types of silicon diodes sounds different from each other. I can hear a change in sound between poly and ceramic caps. others claim there is no difference. but most of what you are hearing is not the difference is silicon/germanium... it is just a result of much lower forward voltage and how it affects what passes from collector to base. one is 0.7Fv and the other is 0.3Fv. if you stack two germaniums end to end(in each direction), you will have 0.6Fv. if all clipping is the same, they should sound exactly the same. please report back what you find and if it sounds the same as silicon.

[Teej212]

Correct about the Germanium Muff, but there really isn't a need to add an extra boost stage to the Muff when you've already got a makeup gain stage that you could easily tweak to get more output.

true, but theres only so much gain you can get out of the transistor recovery stage from tweaking the values of the resistors connecting to the emitters and collectors. if its at 50% of the normal volume i wouldnt expect to be able to get such a large volume increase out the pedal.

[bubstance]

Not necessarily, but I also doubt that it was 50% volume reduction. I've heard of around 25-35%, but 50% seems a bit much. I bet you could get close to 20% more output if you really goose that recovery stage, and then adjust the volume settings accordingly.

In response to the original query, that's just what germanium does. It'll cut your volume, but you can always just up the volume knob; there should already be plenty of output from a Muff.

[trad3mark]

ugh....

just thought i'd point a few things out there. Firstly, it's not a clone of the actual EHX Germanium muff. It's based on a combination of the Tone Wicker and one of the earlier ones. It just has germanium clipping diodes. It's not on any site, and my schematic isn't wrong. When you swap in silicon diodes, volume is just fine. Its only with the germaniums. As for the clipping, yes, all diodes do go for a square wave, but to different extents. For example, an LED will clip far more harshly than germanium diodes. If you want to look at the extremes, a triode used as clipping has only a very soft clipping curve on it, but something like a MOSFET or OpAmp will be ridiculously square. Case in point, look at the clipping characteristics of the MOSFET on beavisaudio's FKR.

As for the option to add boosts or anything like that, no. just no. There is a gain recovery stage, and i'm squeezing as much as i can get out of it, with some odd value metal film resistors to get as much out of it as i can. That took ages to figure out, but 3 pots later, and i'm there. I'll try a resistor in parallel though. That completely slipped my mind.

[moose23]

I'm not overly familiar with the germanium big muff, my bad for suggesting taking a look at it. I did get where you were coming from with the design of this pedal. Presume you're aware that leds in a big muff circuit boost the signal so maybe leds in the second clipping stage and germs in the first could help with the volume issue and still give you some of the germ sound you're talking about? I've not tried germs in the muff circuit at all but leds in the second gives a nice boost without altering the sounds much. I'm just throwing suggestions out there btw not definite answers to your question.

[eatyourguitar]

I'll try a resistor in parallel though. That completely slipped my mind.

actually I was suggesting resistor in series from C to B. maybe 10k up to 500k in series with the cap and diode pair, in any order. maybe try it with a 500k pot. at 500k it should sound like the diodes and cap are removed from the circuit completely. resistor in parallel might work but I think it just lets more negative feedback through. the problem you are having is caused by too much negative feedback. 10k would be a good starting point.