"Muff Minor" - the wheel re-invented?

[tackleberry]

I soldered 3 ge diodes in series fw and reverse and there is almost no vol drop compared to the LEDs I used. They are on a switch so its ge/LED/ or no clipping. I used the "saturation" control from AMZ but used a 1k pot vs the 10k AMZ says to use. Very easy to dial in a little or alot of clipping. This is built into the jiggle side of a DoubleD pedal.

[Derringer]

probably a stupid question and if it is I plead ignorance

but FC ... have you tried this configuration with a mini tube? Did it work well / poorly ?

I'd imagine you'd have to take the BM route and AC couple the diode(s) to the anode to keep the HV off the grid

I never did.........do you think I should? I think I'll have to try it now! And no I don't think its a stupid question - I'm curious now!

why not ... see what happens

just make sure the components can handle the voltage

do it up!

[Gus]

What are you using as an input source a guitar direct(high output or low output pickups) or after a buffered effect?   What feeds the circuit input is a part of the gain math.

Parts to keep in mind for the gain. Collector and emitter resistors.  C to B resistor (DC bias part and AC feedback) other parts cap coupled C to B (AC feedback)and the series input resistor to the base.  The guitar adds to the series input resistor.  Jacks Muffer has more guitar interaction because of no series input resistor.

[frequencycentral]

but FC ... have you tried this configuration with a mini tube? Did it work well / poorly ?

I just tried something similar with tubes. A couple of back to back 1n4148 in series with a cap between grid 1 and plate of a submini pentode (5480). Nice crunch actually. Then I cascaded two pentodes and did the same with each one. Interesting. The cap value determines the frequency range of the clipping. There is mileage in this idea for tubes, though I'm not sure at this stage if it's any different to just adding a clipping diodes to ground after the plate's decoupling cap, as in my Red Star Drive: http://www.diystompboxes.com/smfforum/index.php?topic=71350.0 I'll experiment some more with it though.

Here's a direct link to the Muff Minor schematic, as my Photobucket is down at the moment: http://dl.getdropbox.com/u/967492/Muff%20Minor.JPG

[Derringer]

cool man

thanks for reporting back

Having the diodes between plate and grid definitely clips the signal differently than having them go from signal to ground post gain.
How different does it sound? Only your ears can judge.

I know that it sounds different with transistors at least.

Maybe try running just one diode, so that only one side of the signal gets clipped like in a bass fuzz ... see what that does.


Now it's coming full circle. "Let's apply tube concepts to solid state technology"

now we're geting into "Let's apply solid state technology to tubes and see what happens."



awesome man ... so cool that you're trailblazing with these mini tubes for the rest of us!
Soon enough I'll try my hand at them.

[frequencycentral]

Yeah, I tried Ge diodes too, and single diodes, and back to back Ge/Si. Briefly tinkered with LED, but I guess their forward voltage is too high. I think the capacitor in series defining the frequency is really interesting, I tried 0.0047uf, 0.1uf and 1uf. Basically the smaller the diode the more bassy. I'm going to have to develop this idea, it's pretty cool getting dirt with just one tube stage, it's a different kind of dirt compared to just overdriving the following stage. I used a pentode but it will work with triodes too. It would be interesting to have a rotary switch to select the diode 'flavour' and another rotary to select the value of the capacitor. It might be interesting to copy the Big Muff topology using two dual triodes - first stage just boosting, second and third clipping, then a tonestack and gain recovery stage.

[Derringer]

The Big TOOB Muff

[Derringer]

you know ... having the diode + cap in that configuration also makes a nice and easy "switch on distortion/fuzz" "switch off overdrive" capability. It sounds like you're getting plenty of drive/dirt out of simple stages.

Maybe this is the precursor to some simple two channel designs?

again dude, thanks for reporting back with your analysis

[Gus]

This is textbook biasing with a added AC feedback path and that is OK.

  I see an possible issue with it that I posted about before.

The input is kind of like a FF input and inverting opamp a summing junction.  Part of the gain control is the 470K and AC feedback in parallel  divided by the input source(the 47K and whatever is before it)  The source will cause an interaction with the circuit.  The Muffer has more of an interaction not having the 47K

The signal feeding this will need to be big enough to clip this stage does it work with weak single coils is it over powered with a bass?  Would you want to add a small gain stage before it to boost and buffer the input and remove this interaction or do you want to keep the input interaction?  If you add a boost think about the output resistance of the boost and remember to use that as part of the gain control.  Or do you want a 10K with a 50K pot as the series input resistance?

[frequencycentral]

Gus, I only tried this circuit snippet with humbuckers, and it was good. I hear what you're saying, though my approach to electronics is more based on tinkering and listening than maths and theory - if it sounds good it is good. It would be interesting to see if it gets developed by someone more knowledgable than myself (hint hint), it's really just a 5 minute breadboard job. Though it's so like the Muffer that maybe it's not worth it. One good thing that's come out of it is Derringer suggesting that a similar clipping method be applied to tubes, which has interesting possibilities.