meet The Fuzz Ovation (1969 ovation standalone preamp fuzz)

[pinkjimiphoton]

couldn't have happened without marcos-munky and especially rob strand...
we took the fuzz section of the old ovation 9000 series stand alone guitar preamps, and made a standalone fuzzular out of it. one knob, unless ya feel it needs a volume.
its weird. its hip! its now! its 50 @#$%in years ago!

anyways, we found what i believe to be mistakes made by ovation engineers on the board, and the onboard fuzz, tho cool as an icing on the cake for other fuzzes, by itself was brittle, thin, no sustain and sounded like POO. i suspect it was designed for ge, and switched to silicon with no circuit tweaks when it became available. the original unit uses two bc109's and sounds absolutely horrible, like all the other units i'd tried over the last 40 years or so.

while dicking with it yesterday, i discovered that q2 was only really biasing if i used a reverse beta bc549 instead.. decent-ish tone, decent-ish balls.

so i said... hmm to my self.... hmmm, self, i wonder if they @#$%ed up and it was supposed to be a pnp for q2? so i popped one in.
then another.
then a shit load of different ones. every single one FIRED.

so... one mystery solved.

so next i had a play with gains..... i tried various q's from about 20hfe ge's to about 600hfe 5089's. there's a definite sweet spot... right around 100hfe is about the most you can push it with the original part values. it actually works best with LOW GAIN GERMANIUM TRANSISTORS, between 40-120hFE to work and sound the best... as soon as ya pop in a ge npn and a ge pnp, it comes to life and sounds freekin pretty damn good!

build one, and use some of them crappy ge's that are no good for anything else... i think this should help dispose of them!

i ended up going with a house numbered low gain npn outta an old thomas organ, can type dealio for q1, and an ac125 pnp for q2. both have hfe's around 65. very sweet and fuzzy with a very tubey overtone.

i also modified the cap values on three of the caps.. made them all 100n. the 100n's are SUPPOSED to be 1N, but to me, they were too thin and drecky sounding, too little bottom end to bias properly. 100n gives 'em some beef!
may have some mods for this coming soon, so stay tuned. on mine i shorted out R9, just to get a smidge more gain out of it.

the vero here is so ya can mount it on the back of a 50 or 100k board mounted 16mm pot if ya bend the legs around slightly.  you may be able to use a 9mm mini. mounted on the back of the vero if ya do it carefully, ya can probably squeeze it in a 1590a, but a b is an easier gig.

the jumoer next to q1 could be replaced with a pot, 1-5k, and a big cap, say 10u-47u for a gain control i think.. maybe just make the fuzz a little softer. i haven't tried it yet.

but anyways... props to the guys for helping me ressurect the original unit and come up with this:

schematic




verified veroboard layout



will get video asap for it. special thanks to Rob Strand, who spent many a bleary eyed late nite into morning with me, and marcos-munky, for drawing up the original circuit from the picture of the fuzz "card".

really cool little fuzzular. DIY or DIE! not for commercial use!! we three claim it as abandonware!! lol

[Mark Hammer]

A local fellow slipped me a box of various ancient germanium transistors yesterday and asked if I could make him something "60s-ish".  This might be the ticket.  Thanks, fella.

[pinkjimiphoton]

it sounds so much better with the ge instead of the original si, i'm gonna mod the board in the original unit. i suspect they messed it up, and was designed for an npn and a pnp, and at some point they just stuffed 'em with 109's.

socket it and audition the q's til ya find the proper pair. i think it will be worthy mark!!
and again, hats off to
rob strand and
marcos-munky
without whom, i'd still be staring at this behemoth wondering how/why it can possibly work.

[Rob Strand]

I wonder if sticking a small cap across the collector and bass will help the silicon.

[pinkjimiphoton]

maybe, ya mean q1? or both, rob?
it would make for a slightly quieter fuzz probably, but silicon above 100hfe in it really sounds horrible. the ge just biases itself and pretty much perfectly in the gain range that those transistors commonly had back then.
worth a try!

i'm thinking the q1 gain pot won't make a lot of difference, be more like a volume control than a fuzz pot i think. i was kinda thinking fuzzface, but its not an e follower.

i am thinking two of these in series would make one hell of a fuzztone!

[SpencerPedals]

This project lacks a demo with a crazy hat.  I feel like it's heading in that directly soon, though.

[pinkjimiphoton]

hahahah yeah, it does. maybe tomorrow or friday if i get a chance bro!

[pinkjimiphoton]

i tried a literal crap load of transistors tonite in it, and yeah, the low gain rules the day. as long as the first one's npn and the second pnp its hip. like a nice overdrivey fuzz. you only really need the one knob.

i think tho i may have drawn the pnp wrong, the collector should be on top, no?
with the ge's .... sometimes its hard to tell the diff. and sometimes, they have a better gain for fuzzes backwards. depends on how leaky they are i guess. anyways...

[Rob Strand]

maybe, ya mean q1? or both, rob?

Probably with trying both.  If you have am Si and a Ge side by side you could tweak the caps to push the Si closer.   Might be totally useless but it's worth a try.

[pinkjimiphoton]

the fuzz doesn't really need it, its not hissy or super noisey. it may make it a tad less harsh tho. i'm going with just GE on the pedal version, in the amp i went si/ge and its a good pairing.
cuz its in parallel in the amp, it needed a little more balls... but if ya go above about 200hFE it sounds thin and farty and strident. the 3906 is a compromise, but give it juuuuuuust enough balls to be louder when the fuzz is cranked up. in the pedal, it don't need it

[pinkjimiphoton]

this thing is the weirdest freekin circuit i've ever freekin seen.

its had me and rob strand scratching our heads for weeks trying to understand how some of the stuff in the preamp this was lifted from can even work. seriously.

anyways, i was dicking around with it tonite and decided the 50k pot gotta go. its just not worth freekin' being there, its more of a damn switch for all intents, and doesn't really affect the tone enough to merit keeping.

that said,...
an
A500k pot is almost kinda cool, if you wire it as a variable resistance with just 1 lug and the wiper... as you mess with the resistance, there's spots in the sweep where it acts like a compressor, and squashes your attack and then swells in... depending on the transistors you used. very sick. not super great sounding, but ok for some sick leads, and not annoying if the piss flanged out of.

i ditched that pot entirely. i also found i liked a diode clipper at the end of the circuit, with a bat41, cathode to ground, and a 1n60ge with anode to ground. loses some volume, but gets a nice squishy overdrivey sound thats really tough to beat. especially when ya read this next part...

this was designed to be a parallel fuzztone with a preamped signal. weird, right?

i'm seriously wondering, after messing with this for weeks if they were freekin high on acid, geniuses, morons, or what... cuz in the original unit it phases against the signal and gets a fairly wide range of sounds.

this thing is WEIRD. i thought it was supposed to be a pnp in q2 and an npn in q1... but i somehow got that backwards. i think. sorta. i don't understand this @#$%ing thing AT ALL and it makes no sense whatsoever to me.

but i've got it running now, and sounding like a nice old-school overdrive/fuzz

for q1,
2n2905A.... pnp, si
https://www.onsemi.com/pub/Collateral/2N2905A-D.PDF
ready?

hfe 166
uF 663mv

reverse beta... c to ground
voltages, 9.26v b+
e  1.54
b   .70
c   0.0


q2, 2n5088 , npn, si
hFE 522 <close to the original bc109 in the original unit>
uF 672mv

ALSO reverse beta, c to ground
e 1.95
b   .57
c  0.0

gives a really nice, warm fuzzy overdrive with much more common parts.

this is a really weird circuit. i will try and get video of it soon.

anyways.. thats the update for now. i'll try n re-jig the layout and schematic accordingly.

i'd love to hear thoughts on why the hell this thing would be so completely different from the original unit, which had two bc109e's and .001u caps other than the 330n input cap... and it sounded like utter ass.

i'm gonna have to reopen the dang headpiece and try the different transistors out and see if it suddenly comes to life like it did tonite messing with it.

peace.

[SpencerPedals]

Any luck with a demo yet?  Pretty curious about the sound of this semi-mystery circuit.

[Kevin Mitchell]

I'm curious about that hat.

[pinkjimiphoton]

gotta gig last nite
godda gig 2 nite
@#$%in car brokedown on the way home last nite, something major in the front end
so not gonna be for a bit, but i won't be going anywhere after tonite for a few days, so i will get a video asap.

its a weird circuit. it can run all kindsa q's. but the original had 2 x bc109e's and sounded horrible.

the standalone i tried the same compliment, didn't work well. tried every thing i had, hard to get a truly useful decent fuzztone. messing with plug-n-play resistors i figured out a few combos that kinda worked, but nothing great.
eventually i found if i mirrored two high gain npn's, like 5088's it would kinda work.
i had one nos q i'd never tried, no idea if it was npn or pnp. just plugged it in to see what it would do, and bingo, suddenly it really came to life.

i was like... wtf. cuz when i checked the q's in my meter, q1 was a pnp and q2 was an npn, but the weirdest thing was both were reverse beta'd according to my meter.

with leaky ge, pnp or npn both work in either position, but with both q's backwards, this thing screams.

before i'd been testing it thru the preamp it came from which i think colored the tone in a positive way. yesterday or whateve was straight into the princeton,  so i could hear what the circuit itself was doing.

very weird. if you've followed the ovation standalone thread, you'll see its the most maddeningly confusing circuit to figure out. everything is weird, and nothing much makes sense. this is supposed to be a "parallel" fuzz as designed, so maybe they made everything freekin backwards for a reason.

anyways, stay tuned.

funny hat optional.

[SpencerPedals]

@#$%in car brokedown on the way home last nite, something major in the front end

Blues licks it is then...

(sorry to hear about the car)

[pinkjimiphoton]

1440.00$ later i don't have, so yeah, most definitely. time to sell some fuzzboxes n shit.