Muroidea Bass Boost Mod

[VanWhy]

Probably a dumb question but I'm looking at the Rat Bass Boost mod for my Muroidea. I haven't heard this one yet, but it sounds pretty cool. The "More Bass" mode is likely overkill. Either way, I just want to run it by the forum before I do it.

So, as my understanding, it looks like you just you would be connecting the toggle switch from the left side of R3 (560R) to the positive side of C2 (4u7). (R7 and C6 on the ProCo Rat schem/mod pic)

Am I right so far?

The other question is, I don't need to populate C2 and R3, then, correct?

 

[jwin615]

Looks good from my house, but I think maybe you would populate the board components since it's an on-off-on? But it's the same values.
Also, the RC combos have basically the same corner frequency? 59-60hz
Putting another filter in parallel probably wouldn't do much. Resistance would half and capacitance would double, same frequency.
Okay, now I'm confused.

 

[jwin615]

Maybe a junk mod?

 

[Nostradoomus]

have you tried chuck's contour mod? I prefer it to messing with those filters if you wanna bring in more lows, or messing with the 3.3n/1.5k tone stack

 

[jwin615]

I modded an EL Ache (EQD LIFE) PCB several weeks back aiming for more bass and less nasal honk and it came out well aside from I need to tweak the tone control as it's bunched really bad with the A taper.
I can list the val changes if you want to ponder them.
Haven't done a build report as I need to get back to the jfets before wrapping it up... The one feeding the octave isn't quite right. But the rat side just dooms.

 

[VanWhy]

have you tried chuck's contour mod? I prefer it to messing with those filters if you wanna bring in more lows, or messing with the 3.3n/1.5k tone stack

Interesting... this is the one right? https://forum.pedalpcb.com/threads/so-this-is-where-i-am-with-my-pandora.1601/#post-11782

So, I see it done to the Pandora's Box. The question then is, how do I add this to the Muroidea? Looks like C5k pot (pin 3?) with 47u and 22r still in between R3 and C2?

 

[Nostradoomus]

yep! ground pin 1 and 2

 

[Feral Feline]

That's the exact mod in the OP, by Gord Tranter ("GGBB" in Jwin615's linked DIYSB thread), that I implemented in my Filigree Siberian Hamster. Works great!

Follow the schematic, ie populate the main board and the switch and its components are added to the main circ.

I liked the EXTRA BASS mode, plenty of extra BASS-OOMPH on my upright when I gigged it.

 

[VanWhy]

yep! ground pin 1 and 2

Awesome. Thank you. And thanks @Feral Feline
I got 2 cool options. I'll have to decide which one to build. Or screw it, build one with each mod

 

[Nostradoomus]

if you have a breadboard and some jumper wires you can try em pretty easy

 

[VanWhy]

if you have a breadboard and some jumper wires you can try em pretty easy

For sure. Breadboard is step 1. May try a C1k pot.

 

[Nostradoomus]

that'll basically just be a partial rotation, go higher if you have it. I used 10k on mine and just went halfway and back

 

[jesuscrisp]

Just keep in mind you're letting more bass through at the gain stage, meaning you get a very flubby low end on a pedal that is already known to fuzz/fart out at high gain settings. If you want more bass but keep the response, you'd have to add an EQ stage after clipping.

 

[Nostradoomus]

Just keep in mind you're letting more bass through at the gain stage, meaning you get a very flubby low end on a pedal that is already known to fuzz/fart out at high gain settings. If you want more bass but keep the response, you'd have to add an EQ stage after clipping.

I have not done a 308/OP07 etc comparison and I should... but I have had great results with 3130ez and MCP6241 opamps, little more mid range and no flub to be heard of. The 6241 especially because it's cheap and plentiful (for now)

 

[Nostradoomus]

(I haven't hit the circuit with a scope yet though, to be fair lol)

 

[VanWhy]

I have not done a 308/OP07 etc comparison and I should... but I have had great results with 3130ez and MCP6241 opamps, little more mid range and no flub to be heard of. The 6241 especially because it's cheap and plentiful (for now)

That is another thing I wanted to try is a 3130 chip. Out of curiosity, what do you use for a compensation cap for that one?

 

[mckillacuddy]

I have not done a 308/OP07 etc comparison and I should... but I have had great results with 3130ez and MCP6241 opamps, little more mid range and no flub to be heard of. The 6241 especially because it's cheap and plentiful (for now)

How do you power the mcp6241?

 

[lowpitch]

That is another thing I wanted to try is a 3130 chip. Out of curiosity, what do you use for a compensation cap for that one?

I'm not Nostradoomus but I'll answer anyway 30p works fine ime although the datasheet says it needs a 47-56p comp cap for unity gain stability. You can up it to 150p, 220p or higher if it's too bright for your taste. With a 30p comp cap this chip sounds very different from the LM308 and OP07. More gain, more cut, upper midsy/trebly, wild. I personally love it.

 

[Nostradoomus]

How do you power the mcp6241?

I just threw it in the existing circuit on a whim, haven’t tested it extensively at all but it works and sounds fine. Gonna do some more poking around when I’m off work today.

 

[Feral Feline]

That MCP6241 is completely off my radar.
I searched my HD for it and came up empty.

I'm into weird esoteric parts (mind, not well-known hype-overblown unobtanium),
and I've got nary a document/schematic/mention snippet of this thing existing.
I collect odd info and yet...

Completely off the radar — so how did you come to learn of this IC, @Nostradoomus ??