I'm messing about with the Big Muff circuit on my breadboard right now. This is something that came out of it that I thought was really cool sounding. It's the second stage of a Big Muff with a couple of component values changed and a pot added to control the diode clipping. It goes from slightly dirty boost through to nice gritty clipping. I've tried it with BC208, BC107, BC238 and BC547, sounds nice (nasty) with all of them. Si diodes are good, Ge create too much volume drop really.
I'll wait for someone to pipe in and tell me that all I've done is re-invent the "Blah Blah Whatever Fuzz", in the meantime I'm having a little dirty fun with it.
(http://i210.photobucket.com/albums/bb292/frequencycentral/MuffMinor.jpg)
A nice beginner circuit!
The Sola Jumbo Tone Bender was essentially a Big Muff Pi without clipping diodes in the 2nd transistor stage. Over the years, I've suggested to people who were looking for interestng mods to their basic BMP build to simply lift the diode path on stage 2, but this seems like it might yield more interesting flavours by varying the degree of clipping, vs boosting produced in that 2nd stage.
Nice work.
Thanks Mark, yeah it would make a nice beginner circuit wouldn't it. I was breadboarding really to see what mods I will make to a BM when I eventually get round to building one, I really wanted to try switchable Si/Ge diodes, but I've ruled that out now due to the volume drop with Ge, though I may add the pot I used here to reduce the clipping. I also wanted to see what difference changing some component values would make, and generally understand what does what in the BM. This is just a bit of fun that came out of it.
Question: Oh boy here we go with the questions again
The pot you added, It only effects the degree of clipping right? Not the gain of that stage.
Does it change the diodes clipping headroom?
Glen
Quote from: biggy boy on April 14, 2009, 12:51:40 PM
The pot you added, It only effects the degree of clipping right? Not the gain of that stage.
Does it change the diodes clipping headroom?
Yes it affects the degree of clipping. Clipping does reduce volume by it's very nature, so the more clipping is dialled in the less volume, so increasing the clipping requires you to increase the output volume (Boost pot) to maintain the signal level. The Clip pot reduces the amount of signal reaching the diodes, so with the pot at maximum resistance the diode have very little to clip, so the signal is 'almost' clean. The circuit can provide simultaneous clipping and boost with both pots maxed out.
Thanks Rick
By the way I'm still working on that Tremolo Issue I'm having with my Valuecaster setup. I'm going to try a different aproach.
Mark!
How would this setup on a big M sound compare to the Voodoo distortion mod you helped me with last week.
Would it sound much the same when they are both dialed up to max gain?
Just wondering if it would be worth making a big muff, but if it sounds the same then I wouldn't see the point in making it, there too many other porjects one could work on.
Quote from: biggy boy on April 14, 2009, 02:10:31 PM
By the way I'm still working on that Tremolo Issue I'm having with my Valuecaster setup. I'm going to try a different aproach.
It must be the cheap 'value' tubes you're using.......?
(http://www.muzique.com/schem/muff.gif)
Quote from: biggy boy on April 14, 2009, 02:10:31 PM
Thanks Rick
By the way I'm still working on that Tremolo Issue I'm having with my Valuecaster setup. I'm going to try a different aproach.
Mark!
How would this setup on a big M sound compare to the Voodoo distortion mod you helped me with last week.
Would it sound much the same when they are both dialed up to max gain?
Just wondering if it would be worth making a big muff, but if it sounds the same then I wouldn't see the point in making it, there too many other porjects one could work on.
The secret to the BMP sound is that it is clipped twice, but the first clipping is reasonably significant. Enough that the second clipping imposes almost a fixed signal level with very little dynamics.
Is adjustment of the amount of clipping in the first stage going to be noticeably different from simply adjusting the "Sustain" control? I don't know. On the other hand, if you were to install a bypass cap on the Sustain pot, such that turning down the Sustain would still result in
potentially high drive from the upper mids and above (though lower drive from the bass end), that could be interesting. Varying the base-to-collector resistor in Rick's design, in tandem with a compensated ("bright cap") input sensitivity pot, might offer greater sonic variety for a modest investment. For the moment, I'll suggest 2200pf as a starting value for the compensating cap, and let your easrs dictate where to proceed from there.
It's worth playing about with the value of the 47K resistor in this circuit. Removing it completely gives loads more gain, but you lose the clean boost facility. Maybe I'll try lowering the value (the BM is 33K) or making it switchable. It does look quite like the though Muffer doesn't it?
Yup--aside from clip control, and the age-old coupling cap question: 1uf or 0.1uf? Look, Jack basically presented this as a useful snippet from an existing design, so I don't think there is any real question of originality, so no reason you shouldn't come up with a few useful tweaks around the edges.
Reminds me of this... which I really like.
(http://www.diystompboxes.com/analogalchemy/sch/easydrive.gif)
Yes it affects the degree of clipping. Clipping does reduce volume by it's very nature, so the more clipping is dialled in the less volume, so increasing the clipping requires you to increase the output volume (Boost pot) to maintain the signal level. The Clip pot reduces the amount of signal reaching the diodes, so with the pot at maximum resistance the diode have very little to clip, so the signal is 'almost' clean. The circuit can provide simultaneous clipping and boost with both pots maxed out.
[/quote]
Is the ratio of gain to clip close enuff that this could this be handled with a dual ganged pot to keep the signal steady?
Quote from: bluetubes on April 18, 2009, 10:38:28 AM
Is the ratio of gain to clip close enuff that this could this be handled with a dual ganged pot to keep the signal steady?
Well firstly, the ratio of that 'Clip' pot differs with Si vs Ge diodes. So it is diode dependent. I didn't consider it a problem that changing the Clip pot requires changing the Boost pot, as it's pretty universal in dirt pedals that an increase in the gain control will require a decrease in the volume control to maintain unity. I figured it would be something that would be set and forget as guitarists with multiple dirt pedals tend to leave them at the preferred settings and use different pedals for different amounts/shades of dirt.
Did you try using 4 Germanium diodes, instead of two? That should up the output.
Quote from: azrael on May 14, 2009, 12:10:54 PM
Did you try using 4 Germanium diodes, instead of two? That should up the output.
I never did. I presented this idea as a circuit snippet, and incorporated the clipping pot into a BM I built recently. I'll breadboard it up again and check it out with 4 Ge as you suggest, it's easy and fun to breadboard!
Quote from: frequencycentral on May 14, 2009, 06:27:35 PM
Quote from: azrael on May 14, 2009, 12:10:54 PM
Did you try using 4 Germanium diodes, instead of two? That should up the output.
it's easy and fun to breadboard!
Yikes breadboarding scares me!!
I find it too easy for me to get wires crossed and parts in the wrong place when I breadboard.
I get myself all confused, then I spend lots of time trying to figure out why it doesn't work.
I tend to just build known working circuits. I'll mod that circuit to my liking or leave it as is.
I then go right to a pcb and skip the breadboard stage. If it works great if it doesn't then I set it aside. I have a small pile of boards in my basement :icon_eek:
Cool, I tried it today, and It gets nasty and thick, kinda like the fuzz section of a Brassmaster! I likes.
Quote from: frequencycentral on April 14, 2009, 11:52:01 AM
I'm messing about with the Big Muff circuit on my breadboard right now. This is something that came out of it that I thought was really cool sounding. It's the second stage of a Big Muff with a couple of component values changed and a pot added to control the diode clipping. It goes from slightly dirty boost through to nice gritty clipping. I've tried it with BC208, BC107, BC238 and BC547, sounds nice (nasty) with all of them. Si diodes are good, Ge create too much volume drop really.
I'll wait for someone to pipe in and tell me that all I've done is re-invent the "Blah Blah Whatever Fuzz", in the meantime I'm having a little dirty fun with it.
(http://i210.photobucket.com/albums/bb292/frequencycentral/MuffMinor.jpg)
probably a stupid question and if it is I plead ignorance :P
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
Quote from: Derringer on May 15, 2009, 04:37:18 PM
probably a stupid question and if it is I plead ignorance :P
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!
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.
Quote from: frequencycentral on May 15, 2009, 05:11:58 PM
Quote from: Derringer on May 15, 2009, 04:37:18 PM
probably a stupid question and if it is I plead ignorance :P
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!
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.
Quote from: Derringer on May 15, 2009, 04:37:18 PM
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
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."
:icon_mrgreen:
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.
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.
The Big TOOB Muff
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
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?
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.