Mudbunny/Gruntbox Mids Control Pot

[bigmufffuzzwizz]

I have a bunch of gruntbox pcbs but I really wished they had the Mids control pots like the newer mudbunnys. Looking at the schem I realized its super easy but there's no value listed for the pot in the mudbunny pdf. Wondering what value you guys used?

[bigmufffuzzwizz]

While I'm at it, does this look correct to do a tone stack lift?

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[CRBMoA]

That's where I put the last one I hacked.

[bigmufffuzzwizz]

What about a mids pot? 25Kb? 100Kb?

[henryadams]

Hey, I am using a 25kB. Different values will change not only the mids, but the tonal response of the whol shebang, I think. Check out this site for an explanation: http://www.muzique.com/lab/tone3.htm

[Bored]

What about hacking it into the existing Mudbunny etchable layout?
I've been on a bit of a BMP kick lately and want to try a new twist.

[bigmufffuzzwizz]

What about hacking it into the existing Mudbunny etchable layout?
I've been on a bit of a BMP kick lately and want to try a new twist.

Yes of course that's possible. It's gonna require 2 trace cuts on the board and soldering a few extra wires to the bottom of the board but nothing too hard or crazy. If you follow the schem I posted above, this is how you would do the tonestack lift. For the mids knob, I recommend changing R18 to something more like 3.3K. Your notice a way bigger sweep in the mids with that change! Also jumpering the first 3 transistors emitter resistors is adds a big bunch of gain to the circuit, but nothing unusable!

Here's an example for the single sided mudbunny tonestack lift.

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[Bored]

awesome thanks! I'll have to test it out on the Tonepad layouts as well... I've got a couple of those floating around as well.

Thanks again

[Bored]

What about hacking it into the existing Mudbunny etchable layout?
I've been on a bit of a BMP kick lately and want to try a new twist.

Yes of course that's possible. It's gonna require 2 trace cuts on the board and soldering a few extra wires to the bottom of the board but nothing too hard or crazy. If you follow the schem I posted above, this is how you would do the tonestack lift. For the mids knob, I recommend changing R18 to something more like 3.3K. Your notice a way bigger sweep in the mids with that change! Also jumpering the first 3 transistors emitter resistors is adds a big bunch of gain to the circuit, but nothing unusable!

Here's an example for the single sided mudbunny tonestack lift.

I'm wiring this up and had a question... what happens with lug 2 on the Tone pot? In your lift drawing you show it cut... so do I leave lug 2 on the tone pot empty?

Thanks!

[bigmufffuzzwizz]

I'm wiring this up and had a question... what happens with lug 2 on the Tone pot? In your lift drawing you show it cut... so do I leave lug 2 on the tone pot empty?

Thanks!

I'm glad you looked it over cause I definitely made a mistake on that diagram. Only do the first trace cut next to lug 2/lug 1 going to the switch. If you do the second trace cut you won't get signal in regular mode when the tonestacks added.

So the cut before R19. Lug 1 goes to R19 pad, Lug 2 goes to any pad connected to Q3 collector/R15. Lug 3 of the switch goes to tone knob lug 2 or the pad of c12. I haven't tried this mod yet but I know others have.

[bigmufffuzzwizz]

I'm doing some more research to make sure mine matches the others examples out there. I noticed that without that second trace cut after tone knob lug 2, the tone stack won't be *completely* lifted.

I've found this schem --> http://www.generalguitargadgets.com/pdf/ggg_bmp_tbp_sc.pdf and it looks slightly different. With his tonestack lift he fully bypassed it and replaced it with a 150k resistor. To do this you would need a DPDT and you would do the 2 trace cuts like I posted before. IIRC, when Dcountry did his GBOM muff project, he stated if you do the tonestack lift the 150K will help keep the volume at a unity setting. He said to socket that resistor and experiment.

If your up for some adventuring in experimenting, then give my original suggestion a try(in the post before). If it doesn't work properly or sounds bad, then you know what to do. Cut the trace after lug 2 of tone pot and change switch for DPDT. I can make an easy wiring diagram w/ DPDT for you if you can't figure it out.

I highly recommend this addition to your muff. On the BYOC muff I built, the tonestack lift is the setting I leave it on. Tell me how it works for you. I gonna try both methods on the next muff I build, hopefully soon!

[Bored]

I dont know that I want to lift it... just wanted to add the mid control pot.

[bigmufffuzzwizz]

Not sure what layout your using, but you take the HPF resistor (R18 in the mudbunny/gruntbox) and connect that to a 25kb pot wired as a variable resistor, then to ground. You'll get a much better sweep if you change R18's value to somewhere 1k-3.3k range.