Dino Flavored Big Muff...

[Fingolfen]

So now that I've got my Dimetrodon Distortion dialed in pretty much where I want it, I'm looking at the next Steggo semi-original design. I want to do a Big Muff with a 3 band EQ in place of the tone stack, and of course mess with the clipping stages (I think I want to stick with two for the time being). I'm hoping to start breadboarding a couple of ideas this weekend or next week. In that spirit, I was looking at the 3-band EQ on the Cold Turkey EQ, and I sort of had two ideas. For starters, I could lift the 3 band EQ out of that and drop it in the place of a conventional muff tone stack, or I could use the EQ circuit itself as sort of a "Bigger Muff" concept and add the clipping stages and sustain pot after the op amp in the input boost stage. The purist in me likes the former, but given the Cold Turkey is a pretty nice clean boost on its own, I'm really curious to see what adding a couple of modded muff clipping stages to it would do... I know... I'm going to need more breadboards...

... anyone done anything similar and have any "gotchas" I should be looking out for?

 

[phi1]

You could also consider the tone job circuit for the eq (it can be simplified to fewer op amp stages but keep the filter values). I’ve built the tone job, not the cold Turkey, so not sure wxactly how they compare, but similar concept with different filter values

 

[jesuscrisp]

As someone who was involved in a similar concept recently:

• I hate Big Muff clipping options, most of the time you'll wish you just stuck with the stock silicon diodes. Or at least I do, unless it's on bass because it seems if something sounds horrible on guitar it tends to sound good on bass.
• Adding an active 3 band EQ can give you good results. However, instead of that you might consider just doing a Big Muff with a T notch filter instead of the usual tonestack as seen in the link below, but add a pot between the cap and ground so you can determine the amount of scoop. Then do the rest of the muff and add on a 2-band Baxandall (for most guitar pedals the one from the BB preamp works great), maybe with a small gain recovery stage or buffer before.
  http://www.muzique.com/lab/notch.htm (calculate the mid scoop frequency as outlined in the article, don't be afraid of big steep scoops, you can dial that back with the mids/scoop knob after all.)
• 3 band EQ in front of a muff I'm not sure about. Unless you're doing low cut or boosting mids up front, I don't see it working great for a muff and it sort of "swallows" a lot of the tone that goes into it.
• At this point I might as well rant about the Cold Turkey: 2M2 bias resistor for a 4558 is too damn high, the output stage reeks of copypasting stuff and leaving in crap that's not supposed to be there and A500K volume knob just begs for bad output impedance. WHY?

 

[Fingolfen]

I've played with a few silicon and different transistor options, I may end up focusing more on the transistors than the diodes...

The 3 band EQ wouldn't be in front of the clipping stages, even on the Cold Turkey style build - it would still be in the middle - I kind of got the idea when I was looking at the Bigger Muff circuit diagram from Free Stomp Boxes. It appears to be using the op amp for the input and making the tone control active...



I'll check your link - the mids scoop + 2 band is an interesting idea...

 

[jesuscrisp]

You could also take a look at the Thorpy Fallout Cloud which has a transistor based Bass and Treble EQ and add a mids gyrator EQ or even some parametric EQ on top if you want to vary the mid frequency ...

 

[cdwillis]

I mentioned a few weeks ago that I had built a muff on a breadboard with a Fender style tone stack replacing the muff tone control. It's still on the board. Most of the values are Triangle/Hizumitas, but the clipping diodes changed to red LEDs. The idea was to have more than enough signal to work with from the lossy passive EQ.

I'd have to double check, but I think I used a 100k slope resistor, 220pf/100nf/47nf caps. The treble and bass pots are 250k linear and the mids pot is 50k linear. If you turn up the mids up real high the treble and bass controls become less effective. It sounds massive, but I'm not sure how well it would hold up in a band mix.