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Mudbunny: Scoop/Flat/Boost mod

Started by make_fast, April 07, 2016, 05:54:23 PM

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make_fast

Just ordered my first few PCBs and am going to get started on the Mudbunny soon.  I've read a few different builds in other places and was looking at adding a  Scoop/Flat/Boost Mids switch (I think I got this idea from the tagboard site).  From what I can tell (limited knowledge here), varying the capacitor in the high pass filter portion of the tonestack (which I think is C10 on the PCB) would accomplish this.

In my mind, I should be able to take wires from C10 and offboard a switch to incorporate a couple of additional capacitor values there.  I'm not exactly sure how to do that.

Could I just solder the wires in at C10 and then run an On/Off/On with the center poles having the wires and the 3n9 across the center (I'm planning on a green russian) with additional capacitors on either "on" setting?

I searched and found other similar questions, but all the links to pics on how to accomplish this were gone or they referenced threads I couldn't find.

edit:  Just saw the Tech Help subforum, this may be more appropriate there, but I can't figure out how to delete this one.

midwayfair

Download Duncan's tone stack calculator. Play with the BMP tone stack section. You'll learn a lot more than someone just giving you a couple capacitor values.

Also AMZ has multiple articles on this.

make_fast

#2
Thanks, I'll try out the calculator - I have looked at AMZ and reading through there is what got me down the rabbit hole of adding options.  I don't need capacitor values (I plan on socketting and messing around with it before settling on values), I'm trying to figure out what I need to do, physically, to offboard that capacitor to the switch when I eventually box it up.

I think the On/Off/On switch should work (with caps soldered across the poles)

thesmokingman

I believe the first time I saw this was in a skreddy pedal of one stripe or another. you should look at those schema as well.
once upon a time I was Tornado Alley FX

pryde

Skreddy p19 is an example of flat to mid-boost EQ (just switching in a parallel cap to the existing tone cap). As Jon said the duncan calculator is your friend.

Lubdar

Also if you look at the BYOC muff project, they use a rotary switch to select different frequency response options for the tone stack.
(--c^.^)--c

make_fast

#6
Quote from: Lubdar on April 07, 2016, 09:02:26 PM
Also if you look at the BYOC muff project, they use a rotary switch to select different frequency response options for the tone stack.

That's exactly the kind of option I wanted to introduce.

My question (from the start) is how do I wire that.  If I did something like this with an On/Off/On, the "off" position would give me the 3n9 (I believe) and in either of the "on" positions it would bring in the other capacitor in parallel.  Is that accurate?

Jebus

Quote from: make_fast on April 08, 2016, 12:37:22 PM
Is that accurate?

Yes. You could also do it with just on/off/on SPDT -switch like this (sorry for the Paint art ;D):


make_fast

Quote from: Jebus on April 10, 2016, 07:57:30 PM
Quote from: make_fast on April 08, 2016, 12:37:22 PM
Is that accurate?

Yes. You could also do it with just on/off/on SPDT -switch like this (sorry for the Paint art ;D):


I didn't even try with paint, you get my "scrawled on the back of a scratch sheet of paper".  I had thought about the SPDT, but I don't have any on hand.