Something like this have probably been done before... Yes, Fuzzdog added a 3-band Marshall style tonestack to a Rat a while ago. Oh, and there is Idiotbox Blowerbox, a Rat tuned for bass with less gain with a James tonestack....
This one is quite similar to the latter but has more gain on tap and are tuned for guitar. The James tonestack have Matamp/Orange values but can be tweaked witch Duncan Tonestack calculator. Oh, and there is a diode switch for assymetric SI/MOSFET clipping and symmetrical LED clipping.
I've been obsessed with Rat variations lately & I think I have the parts...Going to start building this one right away. Thanks for posting!!!!
ReplyDeleteQuestion on this one...If I go with something other than an LM308 - do I need the 33pf on pin 8? I built this last night and need to test a little further today but wondering if that was my issue. Tried slotting an OP07 and TL071. OP07 seems like circuit is muted (I've been using these as drop in's for LM308 but it didn't work well in this circuit). TL071 seemed to work but it was late and I had the volume really low. Going to test more today....
ReplyDeleteThe 33pF cap is only necessary for the LM308 (or other op amps that requires an external compensation cap). OP07 or TL071 don't need it...however it will work just fine with it so no harm there.
DeleteNot sure if your issue is the op amp? Is your J FET legit? have you checked your solder joints and bridges?
Thanks for the quick response (and all you do on this site)!
ReplyDeleteI've had issues with fake JFET's so I'm testing out a variety just to see. Bad/bogus parts have been an issue lately. I'll post later today with an update. I plan to do a shootout with your MOuSeFET (I love that pedal) once it's up-and-running. Thanks again!
I got it up-and-running and was able to turn my amp up a little. LOL. I think it was the J201's. I replaced with 2N5457. Still using the TL071 (for now) but this thing roars! The LED clipping on this thing is really good & really loud. The BS170 seems to tighten up the bass and reduce noise (but it still functions without it). The distortion pot really drives this one & I'm not getting any squealing with this thing max'd out on all settings (but it's loud). I plan to compare this against a handful of other Rat pedals today (and still testing op amps) but this may be a contender for favorite Rat as is. Great work!!!!!
ReplyDeleteHey Fuzzhead, What value swaps would you recommend for tuning for bass. A Blower Box with more gain just sounds like to much fun to be ignored, lol.
ReplyDeleteMatt
Hey Matt!
DeleteTo come closer to Blowerbox spec, do the following cap subs:
33nF to 100nF
22nF to 10uF
4,7uF's at column 4 and 13 to 10uF.
Awesome, Thanks
ReplyDelete