Octave up fuzz simple build

[pinkjimiphoton]

i believe these peeps will ship world wide, and have an astounding selection of available, affordable parts...

http://www.mouser.com/

[vendettav]

ah well teh shipping is gonna cost 45 euros.. that's quite a lot!

[DougH]

hmmm...just found the ousb!..(octave up sick box)..has anyone actually built it off that handrawn schemo?.

Yep, build it you won't be disappointed it's probably the most aptly named pedal ever. It goes from about as clean an octave up as you're going to get to pure fuzzy octave madness.

Yup, me too.

Lotsa fun, that one.

[Mark Hammer]

Well, since I have come to trust Doug's taste, I put an OUSB together last night and fired it up.  I had to miss the first few minutes of the Daily Show, but it was worth it.  Doug's right (as is Gus, obviously).  Fun circuit.  Certainly does the fake sitar on the bridge pickup well enough (Jawari might be out of a job).

I did a few things different than the original schematic, but not terribly so.  I put a 680pf cap in the feedback loop of that first gain stage to keep the frizzies out.  Between that, use of a 5532, and the gating action of the series diodes, it's actually a pleasingly quiet circuit.  I also put a 4k7 fixed resistor in series with the gain pot so it wouldn't have any no-gain zone.  Probably should make that 2k2.

The octave is not strong, though it clearly sounds octave-ish.  I'm thinking that replacing the 10k input resistor for the (ostensibly unity-gain) inverting stage with a fixed-resistor/trimpot arrangement might be helpful to adjust gain for maximum octave.  I might consider making the .47uf cap in the output switchable for a better sitar-drone sound.  Maybe a switch between .1/.047 and the stock .47, just to have some bass cut.  It might also be wise to do that with a DPDT toggle and swap the 100uf cap on the ground leg of the gain stage for a smaller value like 2.2uf to cut some of the bass.  In retrospect, 100uf is bigger than it needs to be.  You can probably use a value as low as 10uf without any bass-penalty.

At higher gain settings, the circuit caves in on itself, with the output gradually blooming.  I've gotten that on my FY-2 fuzz and Scrambler when they are pushed hard by a booster stage of some sort.  I don't know why that happens, but it is interesting and, if properly controlled. musically useful.  I wish I understood how it happens.  Not sure the gain pot really needs to be 100k because the cave-in on mine seems to max out when the pot is around 50k or so.

All in all, though, yes a fun circuit, an simple build.  Good ROI on this one.  Thanks for the recommendation, Doug.   Now to get back to the Supertube I started two nights ago.

[slacker]

I simmed the OSUB and posted some thoughts about the cave in here http://www.diystompboxes.com/smfforum/index.php?topic=69289.0 don't know if that's all there is to it.

Couple of good mod ideas in there as well.

[Mark Hammer]

I completely forgot about that thread.  Ironically, the mods I made and suggested here were the identical mods I suggested (but never did) 3 years ago.

I'm going to have to try that trimmer balance thing to see if it helps the octave, though I'm not sure I left myself enough room on the piece of perfboard.

Thanks for reminding me! 

[slacker]

No problem. I was quite surprised I managed to find it.

[Gus]

It is good to read people have had fun with this circuit.   Yes things can be changed but it is what I named it.  Players that have used my build often like after they understand how sensitive it can be to gain and guitar volume setting.

Simple low parts count circuit

[novakram]

Sorry to drag this thread up, but does anybody have a verified vero for the ousb?

Gus - no problem with your hand drawn schematic, I'm sure, but I can't translate it to vero!

Thanks