Noob Q about modding Clean Boost for Mids Control

[DrummerMan]

Hi All! I am new here, and on the noob end of the spectrum when it comes to electronics. I'm a decent solder monkey and have done a few kits, modded some stuff and wired plenty of guitars but many aspects of whats actually happening in there often eludes me. This is all to say, forgive me if I ask a dumb or ignorant question, and if your answer needs to be "you need to go back and study more before bothering us", I won't be offended in the least. Ok, now onto it...

I am not entirely sure of the protocol surrounding this, as this is a question about a certain "clean boost" that we're not supposed to post schematics about. I'm not sure whether or not I'm allowed to even name it, but lets say originals can be controversially very expensive and they're sometimes gold, sometimes silver, with black goop all over the PCB. Do we all know what I'm talking about? (Not trying to be cute here, just want to respect the etiquette of this forum and the people who run it).

I have built the GGG clone of this pedal already once and use it, as well as the EHX version, in my studio frequently for post processing of lots of different kinds of audio signals and I love it for that. What I wish, though, was that it had control in the mids, both for boosting and cutting. I know i could throw an EQ before it, but I would like to see if there's some elegant way to do this within the unit. I was thinking about how the Swollen Pickle basically makes the Muff much more useable in this respect and I was wondering if there's some point in the circuit of this Clean Boost where that's possible. I've seen plenty of mods allowing in more bass, but I haven't seen any reference in the circuit to anything specifically taming or allowing more mids where, say, I could replace a resistor with a pot or change a cap somewhere.

So, question 1) Do you know of any existing mods that specifically deal with boosting or cutting mids on this circuit, preferably in the saturated signal only?

Question 2 is where my ignorance really starts to shine through.... There is a Parametric EQ stombox that I have the schematics to. If there's not a simple mod for this, would it be possible to take the MIDS section from that EQ and basically inject in somewhere in the signal path of the Clean Boost? Again, I would prefer to do this in the saturated signal only. It's an active EQ as far as I can tell, btw, so the section in question has an 14 pin IC receiving +-9v, if that makes a difference.

I'm happy to experiment and can breadboard it out, but I just thought I'd see if anyone can point me in the right direction or let me know of anything glaring to avoid.


My initial goal would be to make a mono stompbox version of this out of whatever experimentation I need to do here, and to that end, I've got some ideas about alternative signal routing that I want to ask about to make this unit more functional to my specific needs, but I think I'll wait on those until I see if this first part can be accomplished.

End goal would be to then make a 2 channel rack unit that I can use with my recording setup.

Thanks. Appreciate your time and thoughts!
-Geoff

[vigilante397]

First of all, welcome We're friendly people here, and while reading is a great method of learning, asking questions is another one, so nobody (hopefully) on this site will tell you to "go back and study before bothering us."

Second of all, we are allowed to talk about the Klon, but the rule has been explicitly stated that we are not to post the schematic on this forum. It is my understanding that this is out of respect to the wishes of Bill Finnegan.

Third of all, and I hope you forgive me for asking, do you read schematics? ElectroSmash does excellent breakdown analyses of pedals, and they go through the Klon very thoroughly, including the tone control, which is in the feeback loop of the second half of the second op-amp. They even go so far as to give you formulas for frequency. So adjusting your mid controls can be as simple as adding another filter into the feedback loop or modifying the frequency of the filter already in there.

I hope at least some part of this made sense and was helpful, if not then I (or any of the many people here smarter than me) can answer further questions. Good luck!



P.S. I'm a drummer man myself DW Design Series with Sabian AAX cymbals. I'm more talented on the drums but more passionate about guitar

[DrummerMan]

Hi there! and thanks for your friendly response!

To answer your question, yes, I am able to read a schematic, though slowly and, like I mentioned, I don't always understand what everything's function is. I had read Electrosmash's analysis but the formulas are where my brain starts to get a little fuzzy so maybe I'll spend some more time studying those to see if they'll make sense to me and see if there's a way to get a mid control filter in there that doesn't necessarily affect the highs at the same time.

I started to like the idea of an actual Para EQ band in the circuit so I could really tailor the Freq and Q to each specific situation. Is this an idea worth exploring? Or does trying to add something like that in automatically open up a huge can of worms?

Thanks again!

[vigilante397]

It's definitely a can of worms, but if can of worms is what you're shooting for then there's no reason you can't add a full 6-band EQ to the circuit, if that's what you feel like doing. You would have to do it carefully in order to not mess of the treble control, which is part of what makes the Klon's distinctive sound. It's already has more mids than something like a tubescreamer, which is why I would guess there aren't a lot of notes already on modding a Klon for mid control.

One thing I failed to consider in my first reply was that you mentioned you really only want the mid control in the dirt side of the pedal, so you may even want to leave the treble control alone and change the filter in the feedback loop of "U1B." That would be a good place to put a tone control that only affects the gain side of the pedal. You may even want to tweak the values in the feedback loop of that op-amp (do you own a breadboard?) and see where that gets you.

[DrummerMan]

That OpAmp Gain stage looks like an interesting place to start. Yes, I've got a breadboard and it looks like there's no way to avoid starting with that. Thanks for all your advice so far. It's been really helpful. I don't know if I'll be able to get around to this before I leave town in a week and a half (likely not) but I'm going to try and get the parts so that I'm ready to go when I get back in early March...