Duo Vibe and Grease Gun

[midwayfair]

CJ's cool little vibe/phaser/filter effect. I modified it to have a rate LED, and made some adjustments to use a super bright LED (though in the end I probably would have been fine with the regular red LED). I also used an on/off/on switch for the mode, so it has a mode that's just the two wobbletrons in a row.

Sounds pretty cool. The "big cap" mode, which I labeled filter, is very unusual, sort of a cross between a filter and phaser effect, and I think the project is worth a build just for that mode.

Literally the only thing I would have considered changing about this is to change the output buffer to a gain stage and have an output trimmer or volume control. On lower depth settings, I have a very small volume drop, though it's at unity otherwise.

I wasn't sold on the knobs, but cream was just wrong, the enclosure wasn't "white enough" to use refrigerator white, and chrome didn't look right.



Brian's Grease Gun, with a germanium transistor and a pair of OA126 diodes.

When I moved it from the breadboard to the PCB, I made some changes to the coupling caps -- the output cap was overkill, and there seemed to be something wrong with the decoupling cap after Q1 -- it was 2n2 in the original, but there was only a very tiny bit of signal coming out of there, even though the calculator says that it should pass most of a guitar. I ended up just using 100nF for every coupling cap in the circuit and it's a very dirty boy now.

Finally, in addition to the germanium transistor in Q2, I also decided to just use a BC549C in Q1 because the input impedance was bellow 500K, so there was no benefit IMO to using the (more expensive) MOSFET. Incidentally, the joke on the enclosure about magical germanium is a nod to there being almost no difference in sound here between the BC549C and the germanium in Q2 and that the OA126 diodes have the same Fv (and thus sound basically the same) as the 1N914s called for.

I'd recommend this one with the caveat that you should be prepared to try a couple different values in place of that 2n2, and to think of the pedal as more as a roleplayer.

What's it sound like? Kinda greasy. No, really. The treble cut on the tone knob is fairly deep, and the feedback diodes are a little spongy sounding, and it also gets pretty dark on lower gain settings. It sounds really cool pushing the yellow channel on my Hot Rod Deluxe, and it also sounds pretty neat stacked after something else into the rhythm (blackface) channel on my Imperial. I know Brian plays an AC30, so I suspect that the tone knob's extremeness is very friendly with a cranked vox.

[Leevibe]

Nice work Jon. I love the paint on the Duo Vibe and the knobs go with it fine! Magical germanium is hilarious!

[peAk]

awesome as usual!

[culturejam]

Great builds, Jon. Your feedback on the circuits is appreciated.

[neiloler]

Did you notice the output being only fairly boosted at highest levels? I noticed on my build that I get unity about 1 or 2 o'clock, and even when cranked, the boosted signal isn't amazingly high compared with my bypassed signal. Am I off my rocker?

[m-Kresol]

Nice work Jon. I especially like the finish on your duovibe.
I hope I'll post my reports soon. My duovibe worked rather fine (very subtle effect, probably a bad choice of LED and/or LDR) but isn't working since I boxed it. I didn't get around debugging yet. The greasegun doesn't even have a bypass, but i just tried today in the morning after finishing rather late at night. Has to be a minor mistake, I hope.
EDIT: It was a minor mistake. I didn't fully plugged it into the amp, because I just quickly grabbed a 90° plug which got stuck on the corner of my amp. Is the grease gun supposed to be very subtle as well? On full gain I get only little distortion. Since I have a klon clone, I don't need another medium-gain overdrive. Have to give it a proper try though

[jubal81]

Snazzy. Two thumbs up.

[rullywowr]

Looks good man!  Like the art.

[gordo]

I botched my DuoVibe board but picked up one from a member sale and have spent a bunch of time with it this evening and I'm surprised it doesn't get more love around here.  Not crazy about the square wave setting but the triangle sound at mid depth and slower rate is kind of "Gilmour" in my rig.  It's very subtle, and that seems to be what I like about it.  It's not a univibe and it's not a phaser.  Pretty cool.  Mine, unfortunately, will look far more utilitarian than yours.  Nicely done Jon.

[midwayfair]

Did you notice the output being only fairly boosted at highest levels? I noticed on my build that I get unity about 1 or 2 o'clock, and even when cranked, the boosted signal isn't amazingly high compared with my bypassed signal. Am I off my rocker?

That's probably about right. It shouldn't be too much louder than something like an electra distortion.

[neiloler]

Haha, I noticed in playing around with it last night that the treble pot wasn't working, some weird solder bridge or cold solder joint thing with the solder points. Reflowed them and now I'm in business. Thanks!