Op Amp Big Muff Mid Control

[squirrels]

Hey everyone, I built up an Op Amp Big Muff using the layout that uses the quad op amp as opposed to the two IC's. I didn't add the tone bypass (yet at least) and was wondering if it was possible to add either a mid control like the LSTR or a switchable Skreddy style mid boost to it. I am pleasantly surprised by this one, it plays fairly nicely with my OR15. I have a drilled 1590BB that has a four holes in it for pots already in it and a hold for an extra footswitch. I was hoping I could add a mid boost of some sort and make the tone bypass footswitchable. Any help would be appreciated.

Here is the layout used: http://tagboardeffects.blogspot.com/2012/01/ehx-ic-big-muff.html

I couldn't really find any info about this anywhere so I was hoping someone had an idea. Thanks.

[BetterOffShred]

I'm actually fixing to do the same thing with the split chip version using a uA741 and changing the tonestack to a Pharaoh style.  I believe you can just swap out the tonestack values and add the pot where you need it.  There's a Kit Rae pic that has 4 common big muff variant tone stacks, including the one with the mids knob.  

I may get to it Saturday morning.  I'll report back

I read up on the crown of horns, so I'm going to try and make a super muff with Pharaoh tone stack, which could be switchable using the switch from the forum  to a LSTR tonestack, and then rotary for 6 clipping options like Pharaoh supreme.  I hope it's that easy.  The sustain on the IC big muff is dope.  I'm not sure if the 150p or 330p paralleled with the clipping diodes sounds better so I'll probably socket that.  I think that's the only difference between '77 and '78 ICBM.   Hah.  ICBM ..

[BetterOffShred]

Yeah peep the Badascan thread in verified fuzz contributions.

[squirrels]

The tone stacks are different between the IC Muff and transistor model. I don’t think the Badascan mid control would work, would it?

[squirrels]

I think I’m gonna hold off on any type of midrange control. The tone bypass makes it much more usable through my Orange. Muffs and Orange don’t seem to get along very well. The Green Russian, Pharaoh and LSTR were the only ones that seemed to like my amp. The Op Amp seems to tolerate it but it sounds better with a little bit of gain. The tone bypass really sets it off and makes it totally usable. I’ll try to record a demo this weekend if possible

[BetterOffShred]

Yeah you're taking the output from Q3 and running it through a high pass and low pass adjustable with the 100k pot.. then into Q4

The opamp just takes it after the output of the uA741 and rather than running it through another gain stage it just heads right to the volume control.  In theory (we will see) you should be able to just transplant your new tone stack right there.   I already marked up a layout with my additions so I'll be attempting it this weekend :)  

[BetterOffShred]

Yeah I literally just removed the opamp tone stack and stuffed in the Pharaoh stuff, and it works great

Now I just have to hook up my clipping board and boost toggle and it's ready to slay.  

[traktop]

Just out of curiosity: What did you finally use for the tone pot? Pharaoh/lstr used 250k, but I found that It kind of suffered from the "frequency black hole" syndrome when the tone pot is at noon

[BetterOffShred]

That's exactly what I have found.  I have the tone caps socketed and their associated resistors, and I was going to test a few things out.  It may be just a matter of component values here to bring that up out of the mud.  I'll report back.  Probably won't mess with it till Saturday.

[rocket88]

That’s the main reason i prefer the mid switch, plus i find the switch does more.

[zosotone]

This muff it's amazing. Like other muffs it's a little bit scooped, so i added the tone bypass switch like the original IC but the habitual mid switch works fine here. You can add in parallel some caps with the 100n (next to tone 3) for less mid scoop sound.

[BetterOffShred]

I've been messing with Pharaoh tone stack values to beef the mids a little bit, but also have the tone stack bypass.  I agree it's one of my favorites.  I think it needs a boost, and definitely jettison the 100k to ground at the volume pot.. It's loud enough, but I like it to crush amps.