Pro Co FATRAT [schematic]

[Cub]

Thanks for that thorough review ! It's very interesting to read what somebody who knows the Rat circuit and sound so well thinks of these switches. Seems like it's not worth the effort for me to try and add these options to a build then, as I really like the classic stock sound already.

It took some digging, but I found your Bass Boost mod. Very clever ! Is it still either 180r + 15µF or 120r + 22µF. Or has your recipe changed over the years ?
Nearly all my attempts at mods to the RC filters with switches or Ruetz-ish (trim)pots just turned it from a Rat into something that isn't a Rat and not in a good way. Since your BB mod leaves the corner frequency intact, it's definitely something I'm going to try.

One mod to that section that I do like is based on our forum brother Moonwatcher's recipe of 49r + 2.3µF for the other RC filter. It lowers the corner frequency from the stock 1539 Hz to 1412 Hz.
Vintage/Whiteface Rat vs Modern Rat circuit question
The only difference is that I used a 51r resistor with the stock value of 2.2µF for the cap (1419 Hz). It's subtle and hard to put into writing, but it sort of goes from the stock "what a classic Rat ought to sound like" to "slightly more of what a classic Rat ought to sound like" if that makes any sense at all. It "ups the Rattiness" so to speak.

Love the increased volume and touch sensitivity of the LEDs in the Turbo. But when turning the gain up, I do miss some of that the fuzzy goodness from the classic pair of antiparallel 1N4148 diodes. I'll be experimenting with hybrid combinations for my next build and the best two or three options will go on a switch.
The Jam Pedals Rattler has a 1N4148 and a red LED in series on one side and a single 1N4148 on the other, the same recipe as the Asymmetric mode on the clipper switch for the Rat section of the EarthQuaker Devices Sunn O))) Life Pedal.
The Burn mode always was my favourite one on the Proco Solo, with two 1N4148 diodes series on one side and one red LED on the other. Two options for the same three components, It'll be fun to hear how they compare.

[ggbb]

It took some digging, but I found your Bass Boost mod. Very clever ! Is it still either 180r + 15µF or 120r + 22µF. Or has your recipe changed over the years ?

Those values would be a bit extreme IMO. I don't know whether that's something I suggested for max effect at some point in time or is someone else's take on the mod. I've pretty much stuck with my original design which you can find here (not my blog): https://marcuseffects.wordpress.com/201 ... -bass-mod/. The original image source for the RAT BB mod is no longer online - it moved to https://www.diyschematics.com/schematic ... sBoost.gif

[Cub]

Oh, I see. The values I found were for making it a permanent mod instead of making the sounds switchable.
https://www.diystompboxes.com/smfforum/ ... msg1062115

Good to have the values know safely stored in a folder and I can't thank you enough for sharing so much information over the years about the many different versions of the ProCo dirtboxes. They are some of my absolute favourite pedals in de world.

[thesmokingman]

Well, I finally bit the bullet and bought a FatRAT. Traced it and have added the details to my Multi-RAT schematic. The FAT switch mod is kind of interesting. This confirms p.eat's report but note the output JFET is a J109 in my unit. D4 is BAT41. Also worth noting is that the PCB layout is essentially a modified version of the original big box "filter" RAT PCB which was also used by original small box RATs as well as the Vintage and Whiteface reissues.

https://www.mediafire.com/view/4pdvsczb ... T.png/file

so no pcb pictures then?