mybud
Well-known member
- Build Rating
Though I've never seen or heard one in the flesh, so to speak, I'm a bit of a Supro fan by proxy, I guess.
A collaboration between our esteemed constituents Dave (@szukalski) and Chuck (@Chuck D. Bones), this emulates the Supro preamp (rumoured that) Jimmy Page used on the first album. Quoting from Apocalypse Audio's website to be exact, 'the preamp section of the legendary amp used by Page and supposedly Hendrix, done up NPN germanium style.' I began by breadboarding Dave's circuit, as below:
I tried different JFETs (5457, 113, 201) because I thought I'd used up my all original 4393s. But then I found a couple stashed in a safe place for later (sound familiar?) and we were under way. I subbed the 10k trimmers Dave calls for with 100k's because I still find JFETs somewhat finicky and didn't want to chance them not biasing on the Vero version. Likely over-cautious on my part and no critical reflection intended on their circuit design.
A/B'ing them revealed some slight tonal differences. Breadboard version lets more bass through, which I prefer, but I used sockets for all the transistors on the Vero one so that I can swap the JFETs out to see if this is dependent on the Hfe and IDSS of the breadboard ones. It may well be so; time and further testing will tell.
The finished article wastes some space because despite my best efforts it's orientated horizontally, so opposite from the breadboard's vertical layout. Not my smartest move, so I had to keep my head and follow the schematic very closely. Had to make a couple of cuts this morning and rewire the gain pot to rectify my errors with this different orientation but now it does its thing according to plan.
It's sufficiently different from @Robert's Repro fuzz to merit a shot if you like the Supro sound in a box. I prefer using it with the gain low but there's plenty of fuzzy goodness and gain available to suit what you need. YMMV, naturally.
So hats off, Dave and Chuck, for a new venture into Supro territory.
Thanks for reading as ever and happy building, y'all.
A collaboration between our esteemed constituents Dave (@szukalski) and Chuck (@Chuck D. Bones), this emulates the Supro preamp (rumoured that) Jimmy Page used on the first album. Quoting from Apocalypse Audio's website to be exact, 'the preamp section of the legendary amp used by Page and supposedly Hendrix, done up NPN germanium style.' I began by breadboarding Dave's circuit, as below:
I tried different JFETs (5457, 113, 201) because I thought I'd used up my all original 4393s. But then I found a couple stashed in a safe place for later (sound familiar?) and we were under way. I subbed the 10k trimmers Dave calls for with 100k's because I still find JFETs somewhat finicky and didn't want to chance them not biasing on the Vero version. Likely over-cautious on my part and no critical reflection intended on their circuit design.
A/B'ing them revealed some slight tonal differences. Breadboard version lets more bass through, which I prefer, but I used sockets for all the transistors on the Vero one so that I can swap the JFETs out to see if this is dependent on the Hfe and IDSS of the breadboard ones. It may well be so; time and further testing will tell.
The finished article wastes some space because despite my best efforts it's orientated horizontally, so opposite from the breadboard's vertical layout. Not my smartest move, so I had to keep my head and follow the schematic very closely. Had to make a couple of cuts this morning and rewire the gain pot to rectify my errors with this different orientation but now it does its thing according to plan.
It's sufficiently different from @Robert's Repro fuzz to merit a shot if you like the Supro sound in a box. I prefer using it with the gain low but there's plenty of fuzzy goodness and gain available to suit what you need. YMMV, naturally.
So hats off, Dave and Chuck, for a new venture into Supro territory.
Thanks for reading as ever and happy building, y'all.
