This week on the Breadboard: The Emerald Green Overdrive

Well whaddaya know?? I stuck a 2N1308 in Q2 and now it all makes sense! It sounds really good. I steer away from them because I have such rotten luck with them usually. I think it's done.

Cheers!
 
I wonder why Bjørn decided we needed a treble boost at one end of the Voice knob? We already have a Treble control. Could we make Voice into a straight Bass control and make Treble work better? Could we just keep the extra brightness of Voice on full and just use the Treble control for, well, treble control?
 
I just built this circuit on @szukalski 's "Tunbridge" board that he ginned up for @HamishR.

What's hilarious is that Dave had already made a version of this board called the "Cladair". (Check post #15 of this thread)
I think we're whipping poor Dave too hard, he's cranking out PCB layouts left and right........ :ROFLMAO:

Anyway, the Tunbridge board was put together for @HamishR . I had a nice chat with James via DM about this circuit.
I have to say, I spent about 6 hours yesterday auditioning Ge trannies and dialing it in.
I was really surprised at how different models of Ge trannies made such a profound difference in how this pedal sounds.
I tried a couple that made it sound like absolute ASS. I almost shit canned the build. I'm glad I kept pushing on because I've got it right now where it's pretty darn close to the Skreddy circuits.

Dave mentioned he had a hard time biasing the JFETS. So even before I started the build I decided to add 3 Trimmits.
I used SMD 5457's for the JFETS. I read through this thread maybe 10 times and was able to glean that Q2 should be around 6v.
So I wound up biasing Q1 to 4.6v, Q2 to 6v and Q3 to 5.6v.

For Q3, after going through a bazillion Ge transistors.....(ok that's an exaggeration, I don't have that many Ge trannies heh)
I wound up back at the single 2N3108 that I had. It was one from a batch that I got from SmallBear and the "reject" from that batch because it had such low gain. It measured 25 hfe on my Peak but very low leakage. So I decided to give it a try and it was the best sounding of the bunch.
Go figure......

I also removed and jumped R17 in Chucks schematic. So technically I guess this is the Emerald Green Distortion.

I think both the Bass and Treble knobs work great with the specified tapers. The Gain knob can go from a total clean boost at one end to a sputtery fuzz on the other end.

What's neat as a boost is that you can go from clean to almost treble booster or any shade of dirt into the boost as you move the gain knob from total clean (about 8 o'clock on my build) then in increments of adding dirt. There's a TON of output. This is a loud pedal.

This is not my favorite Juhls circuit but it's earned at least a place on my shelf.....:)

The trimmers I used was 20k for the 12k spots and 5k for the 2k spot. This pic shows my final biasing. Just judging from the dial positions for the JFETs I suspect that the original 12k resistor would have been fine.

IMG_8627.JPG

Green knobs because....it's like Emerald yo.....
IMG_8628.JPG

Big shout out to @Chuck D. Bones @HamishR and of course @szukalski for pulling this all together!
 
Nice board, nice build! I like the color scheme ;)

HFE = 25 is WAAAAY out of spec for 2N1308. I hope you didn't pay too much for it. :LOL:

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But seriously folks, this circuit is very forgiving for HFE & Iceo (leakage). Still, there are some Ge trannys that will sound better than others. I used to install sockets on the PCBs, but now I just audition them on a breadboard. I prefer to select the biasing resistors on a breadboard as well
because once the bias is dialed-in, you'll never need to change it.
 
Chuck D. Bones said:
Nice board, nice build! I like the color scheme ;)

HFE = 25 is WAAAAY out of spec for 2N1308. I hope you didn't pay too much for it. :LOL:

View attachment 112401

But seriously folks, this circuit is very forgiving for HFE & Iceo (leakage). Still, there are some Ge trannys that will sound better than others. I used to install sockets on the PCBs, but now I just audition them on a breadboard. I prefer to select the biasing resistors on a breadboard as well
because once the bias is dialed-in, you'll never need to change it.
Click to expand...
Yah, it was the order where I bought a couple of AC127's and one of them was dead. Of course I didn't realize that for 6 months....heh.
And we're talking SmallBear, of course I paid too much :ROFLMAO:.

Definitely this circuit takes some auditioning to find the best sounding Ge. I tried some GT404b's, MP36a, 2N3104, 2N3106. This was my last 2N3108 and I didn't have a plan to use it due to the low gain. But man it sounds great in this pedal! The trimmers definitely are helpful for us non-bread boarders. Which begs the question, why am I even on this forum hahahaha. Its my grand plan to learn how to breadboard via proximity........:)
 
You're not alone. I can't work out bread boards - yet. I thought I was doing pretty well, what with designing my own Vero layouts and being able to draw rudimentary schematics. But so far breadboards have defeated me!

I tried over 1/2 a dozen 2N1308s in this circuit, of varying HFE and leakage. They all sounded much the same. I was surprised at how little difference there was.

Glad you got there Michael!
 
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