D*A*M Forum

Ok, ok.
So I had been tracking one of these beasts for quite a while.
The extreme rarity of these makes the few online descriptions I found not very reliable.
The small consensus I picked up was that this was some sort of Big Muff clone and also the fact that it is called the "Fuzz & Sustain" must have added to this myth...

Well I can tell you that without a doubt, this is not anything like any Muff I have ever heard.
Lets go to the different controls first.
The "Blend" knob does exactly that, it blends in the wet and dry signal.
The "Sustain" knob is actually some sort of gate for the fuzz tone.
There really is no decay at all, the gate is either open or closed and the "Sustain" knob controls how long that happens.
"Volume" is well, volume.

The Fuzz sound itself it pretty wild. It seems to me like it is some sort of synthesizer-based fuzz.
Where the guitar basically triggers the synth which then kicks out the fuzz tone. I actually have another fuzz that is like this, the PAIA Roctave.

Overall the Jen is pretty nuts.
It sounds almost digital, but with that late 70s(?) technology it also has a cool organic punch to it.
and Forget about dynamics and long singing solos, this thing is for purely evil, crunchy heavy tunage.

I honestly can see why there are very few of these floating around.
I'm sure there weren't that many people who would have been into this sound when the pedal came out.
It's definitely unique though and something I am happy to own.

clips thanks to Em!



ok, enjoy the porn!

LOVELY pedal Ed!! Not something I have seen before - getting a bit outside my time frame - though I do have a few JEN peds - clips??

Graham

Graham wrote:LOVELY pedal Ed!! Not something I have seen before - getting a bit outside my time frame - though I do have a few JEN peds - clips??

Graham

Yeah, I'm not sure when exactly these were made?
(maybe Bart has an old Jen advert hiding away somewhere?)
I do believe that these are from the late 70's/early 80's though.

whenever it is from, this thing is pretty intense.

also, I have had a few PMs asking if I can post a pic of the trace side of the board.
I can, but the pots are bolted on kind of weird, so I have to find my ratchet set.
give me a couple days and I'll get it poppin'///

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man, I would love to have the Flanger and Phaser from the series:

that's a handsome box ed, some nice designs on those pedals.

edkoppel wrote:Yeah, I'm not sure when exactly these were made?

Isn't that IC code F8248 week 48, 1982, with F the plant in Korea where it was made?

The UA757DC is a variable gain stage (well two) that is usually used for a radio AGC (automatic gain control) circuit. I wonder if something is wrong with yours, as I would guess that there should be some range of gains available. Still very different than a big muff inside.

sir h c wrote:The UA757DC is a variable gain stage (well two) that is usually used for a radio AGC (automatic gain control) circuit. I wonder if something is wrong with yours, as I would guess that there should be some range of gains available. Still very different than a big muff inside.

I forgot to mention the trimpot on this inside does change the sound of the fuzz.
It almost tunes it or something. I didn't want to mess with it too much though, because it took me about 20 minutes to get it back to where I liked it.
So maybe that is where the variable gain is utilized?
but none of the knobs change the gain setting at all, and the guitar volume knob acts the same way as the "Sustain" knob on the pedal and simply opens and closes the gate earlier or later.

it definitely a cool pedal though, even though it is a little 1 dimensional.
I honestly have not heard any other fuzz pedals that sound like this.

Just taking a stab in the dark I'd say that the trimmer is a bias setting and it sets a sweet spot
for the operating point of the IC. I'm curious to see what's going in in there.
Or possibly a bias that sets a threshold for the gate..."Sensitivity"...
(Yeah, I'm one of the guys who PMed ed to take some trace pics. )
Ed, The guitar is AC voltage. Strum a big chord and you are creating a small voltage
that is opening up the gate. The Sustain knob may be a variable gain control but it acts the same
way if the gating is happening later in the chain of events. So guitar and the first gain stage
(likely the sustain pot and related bits) may well be before the gated circuitry and both affect the
envelope of the gate.

Jen used other people's circuits so this is most likely something we've seen before, but maybe
not. Pics when you can get to it pretty please.

here you go!
(also updated the first post with pics of the other IC and Transistor)