JSH / Jen Fuzz

[Mark Hammer]

My son gave me a 60-drawer parts bin unit he wasn't using anymore, so I started sorting semiconductors this past weekend.  During the sorting, I came across a pair of BC238B transistors and a BC239C, which rang a bell.  I looked it up and sure enough, that's what the JSH / Jen fuzz required.  Seeing how easy it looked, I whipped it up on a a smallpiece of perfboard in an hour and fired it up.

Not bad.  It's a Fuzz Face variant with an extra gain stage up front.  Phil Bryant has schematics posted for both the Jen and JSH, and they're identical.  Do note, however, that Phil has an error in the JSH redraw he has posted:

You can see that he has the 150k resistor going to the emitter of the 2nd transistor, when that emtter sdhould be going to ground, and the 150k should be going to the base.  I found out it was in error "the hard way".

Much like a lot of distortions, the unit doesn't really need the clipping diodes, but they add some extra sizzle.  I found it never really cleaned up much, even at minimum gain, but that may well be because of the substantial output level it has.  I'm assuming that even at min gain there is more level than can sneak past te diodes cleanly.  I stuck an SWTC control on mine, using a 50k pot and a .015uf cap, providing a still pretty hot output (even though the pair of 50k pots cuts amplitude by at least half) with lots of tonal range.  the trannies I used were in the low 300s for the first two and 450 or so for the 3rd.  Everything else was as per the drawing.  I imagine the thing could be easily built with some low-to-medium gain NPNs (3904, 2222, 4401, C828, etc) for the front pair, and a 5088 or MPSA18 for the 3rd transistor.  It,s not as zany as a Jordan Bosstone, but clearly more intense than a Fuzz Face.  And, as I say, plenty of output to survive addition of any of a variety of passive tonestacks.

[jrod]

Cool! Thanks for the build report. I have been curious about this one.

I've wondered if "JSH" was a typo and should actually be "JHS" for John Hornby Skewes.

So, there is a mistake in both schematics posted? The 150K should connect to the base of Q2 like in this schematic ?

[Mark Hammer]

That's correct.  The resistor on the emitter of Q3 is variously shown as 22R or 220R.  I used 220R, and while 22R might deliver even more gain at that stage, frankly I'm not looking for it.  I may experiment with a 2k pot instead of 1k this evening, just to see if I can get something milder out of it.

It's not like I need another fuzz, but I have this big hulking rack panel I salvaged from the tech lab at school, musta been 20 years back, that has been compelling me to throw together these simple circuits.  It has 16 columns of 3 holes drilled in it, so I figured I'd build myself a "3-knob universe" with virtually every conceivable 2 or 3-knob distortion in it, a single in and out, and a pushbutton sequential switch to select which one I want.  Some things, which normally only come with one or two knobs (e.g., original 2-transistor Muff Fuzz, Jordan Bosstone) are modified to be 3-knobbers, with adjustable gain and a tone control added.

One distortion at a time, the empire is accumulating.

[LucifersTrip]

I was also confused why mark explained the error in Phil's schematic, but had the exact same hookup in his...and they're not exactly identical since the 22 R is 220 in Phil's.

The schematic jrod linked to:


...is almost identical to the one I used:


...which has the 22 R like Phil's JSH you posted and a .015 cap before the 47K R instead of a .01
And of course all the caps in the schematics you posted have .1 caps instead of the .015/.01's

[Nasse]

Neighbour boys had a band and both guitarists had those Jen fuzzes. I think they let me have one for few days (though I almost had had fight with one band member) test ride and it was really good, better what I had then. Big tonebender style box but black wrinkle finish, and perhaps chicken head knobs too.

[Mark Hammer]

I was also confused why you explained the error in Phil's schematic, but had the exact same hookup in yours. Also, they're not identical
since the 22 R is 220 in Phil's.

The schematic jrod linked to:
...is almost identical to the one I used:
...which has the 22 R like Phil's JSH you posted and a .015 cap before the 47K R instead of a .01
And of course all the caps in the schematics you posted have .1 caps instead of the .01/.015's

I used what I believe is RG's original drawing, as it appeared in Jamie Heilman's archive. That means 100nf caps rather than .01uf.  Use of a 220R emitter resistor and a 238B in the 2nd position makes it kind of a blend of the two.  Betcha this could sound nice with a Big Muff style tone control.

[LucifersTrip]

I was also confused why you explained the error in Phil's schematic, but had the exact same hookup in yours. Also, they're not identical
since the 22 R is 220 in Phil's.

The schematic jrod linked to:
...is almost identical to the one I used:
...which has the 22 R like Phil's JSH you posted and a .015 cap before the 47K R instead of a .01
And of course all the caps in the schematics you posted have .1 caps instead of the .01/.015's

I used what I believe is RG's original drawing, as it appeared in Jamie Heilman's archive. That means 100nf caps rather than .01uf.  Use of a 220R emitter resistor and a 238B in the 2nd position makes it kind of a blend of the two.  Betcha this could sound nice with a Big Muff style tone control.

I'll definitely pull mine out again and experiment. I don't remember the sound. The schematic I used was simply titled "Jen Fuzz" and the others "III" so I'd guess those'd be later versions or corrections. Also, just realized the Jen III vol pot is 100K instead of 50K

[Mark Hammer]

Not one of those where-has-this-been-all-my-life distortions, but worth monkeying around with.

[Gus]

http://www.diystompboxes.com/pedals/3tran.JPG

something like that circuit