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Ok: The 2n7000 is more aggressive/biting, but less overal gain and drive. SOUNDS FANTASTIC with a typical 4558 opamp though. Best choice IMHO.
As for the IRs, it sounds best with the stock chip and the 2272. The 2272 is a bit more hi-fi and clear, but the sag with the 2262 really makes it work.

Greetings,
I'm curious to whom has experimented with the Sparkplug and some of its easily tweaked values. I've built 2 now, and have them before me to mess with this weekend. One has 2n7000s which sound a bit more biting/aggressive and the IRs are a bit more spongy/greasy to me. They have the stock opamp in them, but I think a mosfet opamp would match this better, or even a BurrBrown. I'm going to check these out in the morning as the kids are asleep---

Has anyone messed with these yet?

Well, i removed the IR transistors and put in 2n7000s (matching pins correctly). Some noise (as expected) unboxed but pretty decent. So, I'll see if that helped. Even screwing in there before the transistors gave tons of noise. This is my first time using the large military grade transistors, so maybe I damaged them clipping the top? I dunno. I'll box this and I'm building another Sparkplug for my bro-in-law for Christmas. I'll compare the 2 if they work out: 1 with 2n700 and the other with the IRs.

Any idea-- the IRF transistors must've been the culprit. Pedal works perfectly, now boxed (and sounds awesome) with 2n7000. Weird? I know I double checked the pinouts to make sure. I can only guess I may have damaged them when i clipped them.
Thanks for the help!

Any idea-- the IRF transistors must've been the culprit. Pedal works perfectly (and sounds awesome) with 2n7000. Weird? I know I double checked the pinouts to make sure. I can only guess I may have damaged them when i clipped them.
Thanks for the help!

Well, i removed the IR transistors and put in 2n7000s (matching pins correctly). Some noise (as expected) unboxed but pretty decent. So, I'll see if that helped. Even screwing in there before the transistors gave tons of noise. This is my first time using the large military grade transistors, so maybe I damaged them clipping the top? I dunno. I'll box this and I'm building another Sparkplug for my bro-in-law for Christmas. I'll compare the 2 if they work out: 1 with 2n700 and the other with the IRs.

I built an audio probe, any links to how it works/how to debug with one?

Thanks!

i unpacked it again, and yes, it has a 'slight' feedback that is worse when I touch the transistors. Weird.
IC is the recommended 2262. At this point I think I'm going to undo all the wiring and redo it/reground. Unless you have something else.
(thanks Brian!)

Ok, just curious if there are any ideas.... I've built several Sparkplug v1s, and loved them. This rev1 is my first time building the update. So it works great OUTSIDE the box (rock it before ya box it!) with the exception of picking up a radio station. I box it and it immediately starts feedbacking this "WEEEEEEEEEEEEE" noise that gets worse as you turn up vol and gain. You can hear the guitar signal through the noise, but the "WEEEE" is pretty overwhelming.

I've unboxed and reboxed 3x now, also double check ground, solder points etc.... This is far from my first build, and I'm perplexed. Any ideas?

****I hope I didn't double post this****

Ok, just curious if there are any ideas.... I've built several Sparkplug v1s, and loved them. This rev1 is my first time building the update. So it works great OUTSIDE the box (rock it before ya box it!) with the exception of picking up a radio station. I box it and it immediately starts feedbacking this "WEEEEEEEEEEEEE" noise that gets worse as you turn up vol and gain. You can hear the guitar signal through the noise, but the "WEEEE" is pretty overwhelming.

I've unboxed and reboxed 3x now, also double check ground, solder points etc.... This is far from my first build, and I'm perplexed. Any ideas?