photonic juergulator rev 1

[Bret608]

Hey Jimi, I had some fun revisiting this last night after reading about your Q1 experiments. I had a 2n1305 at about 50 hfe in there originally, then swapped it last night for a 2n281 (AC128-like) at about 35 hfe. Believe it or not, this made a difference and it now sounds better! If I can get ahold of an even lower-gain germanium will try it out as well. Before, it always seemed to have this hint of mis-biased sound going on. Now it finally sounds like the one in your epic Juergulator video clip. 

[pinkjimiphoton]

if ya read uncle beavis's stellar runoffgroove site, check his article on the harmonic jerkulator.

he too found it sounded better with lower gain transistors, tho nowhere near as low as i've gone.... 18hfe sounds @#$%ing KILLLER... but it's really the balance between the transistors... that's what's nice about the juerg, you can kinda dial it in.

i've found with all the knobs up around half way, on the neck and middle of all my strats, i get these insane octave up/downs at the same time in certain ranges... the more i play with it...

but to me, it seems LOUDER with a LOWER GAIN transistor.

i think, and going out on a limb here, that by putting a smaller signal into a cranked stage, you get a bigger tone than you do by overdriving the base of the second stage. it can amplify much more linearly i think before it hits the rails and cracks.

if ya overdrive the base it's a much different sound... a lot more compression. it's more open, cleaner, and louder if ya don't... probably why some fuzzfaces are so much more dynamic than others.

[GGBB]

Jimi et al:

Sorry if this is a dumb question - is it possible to use a silicon NPN flipped instead of a PNP for Q1?

I have no low gain PNPs either germanium or silicon.  I know I should, as I am surely missing out on germanium fuzz awesomeness, but for now I don't (until the urge is no longer resistible).

Another possibly dumb question - does hfe matter independently of how you set the bias and gain (esp. AC) of the transistor?  I *think* I know the answer to this is YES!, but I want to hear it from a fuzz expert.

My only fuzz is a high-gain silicon BC108C unit that I liked a lot at one time but it no longer sounds the way I remember building it and does not move me so I feel the need to fill the void - and I really loved the clips of this one.

[pinkjimiphoton]

gord... you can use a pnp si for q1, it may not react the same tho.

if ya wanna pm me your snail mail, i can send ya a couple of low gain ge's.

buy a bum a cup of coffee for me someday.

the bias will affect the gain and vice versa i think... you should be able to compensate for either tho, this circuit is pretty forgiving. you may LIKE it with high hfe;
more octavey fuzz that way, for sure, and more compression.

[GGBB]

gord... you can use a pnp si for q1, it may not react the same tho.

if ya wanna pm me your snail mail, i can send ya a couple of low gain ge's.

buy a bum a cup of coffee for me someday.

the bias will affect the gain and vice versa i think... you should be able to compensate for either tho, this circuit is pretty forgiving. you may LIKE it with high hfe;
more octavey fuzz that way, for sure, and more compression.

Thanks for the generous offer Jimi but I bit the bullet and have ordered a small assortment of Ge PNPs.  It'll probably be a few weeks before they arrive.

[Bret608]

Hey Jimi,

I get on a Percolator kick about once a year. I'm wondering--do you think tantalum vs. a regular electro would make a difference in sound for the 47uf that connects the two emitters via the positive leg? I know it makes some difference in the "stock" percolator circuit, good or bad I'm not sure.

Cheers,

Bret

[pinkjimiphoton]

hi bret,
i have no idea, really. i would suspect it may be a little tighter not being an electro, but i never tried it. i am still slowwwwwly getting stuff unpacked in my workshop, so it'll be a while before i can really get to tinkering again.
check it out if you have one, and please let us know your results!
rock on brother
peace
jimi

[M4X lee]

Hi Jim, i've been working on the pedal that you made,wanna ask ya whether which transistor is swapable with GE PNP HFE 52, cuz the country that i live in doesn't have that model.Thx

[pinkjimiphoton]

pretty much any ge pnp will work.

hell, they can both be npn, pnp, whatever. it should still work.

to my ear, sounds best with one ge and one si,  but it doesn't really seem to matter which is which. socket and stuff transistors til it sounds good.
some transistors sound better reverse beta'd.

yes, HORRORS!! doing that is AGAINST THE RULES, but this is a FUZZBOX. rules need not apply too much when seeking inTENtional distortion.

so use whatever you can get in your country.  odds are it will work. even silicon/silicon or ge/ge will work. i've built percolator/jerkulator/juergulators with all ge, all si, all npn and all pnp and they ALL work and sound pretty much the same... tho to me, the all ge sounds smoothest.

sorry if it seems like i'm dodging your question, but honestly, just install two sockets and have at it until you're happy. i tend to do that with every box i build. good luck,and thanks
for the interest in the juergulator. ya may wanna use the search function, as i updated this project a while back to the rev 2 standards, more gain,  works with pretty much any transistors.

[roseblood11]

Interesting circuit!
I'd really like to know how this compares to the Catalinbread Karma Suture, which was released shortly after this thread started. Does anybody have a schematic fr the Catalinbread?

[pinkjimiphoton]

i haven't seen one, but would love to. it better not be the identical circuit, cuz then i may be an asshole. i believe i put no commercial use on everything i've ever done.