hi guys, i've been reading about the harmonic perkolator for a while, have heard a bunch of demos that all sound ridiculously different, so decided to go with tim escobedo's harmonic jerkulator, as every thing i've tried by the man (except the wobbletron) has been bloody amazing. as usual, i made it on vero, but it's such a basic circuit you can almost do it point to point inside a box.
i tried every combo of npn/pnp transistors i had kicking around, and for the pnp used a russian mp16b ge of which i got a lot of 50 off evilbay recently for 11 bux shipped, and for the npn's tried everything from a 2n3904 to a mpsa14...ultimately settled on a tin can NTE 128 silicon (the nte "replacement" for a 2n2270). the two best sounding transistors in the npn slot were the mpsa14 and the nte 128...so close i a/b'd them both about 50 times before deciding on the 128.
this is a REALLY nice sounding pedal, i was absolutely surprised how good it sounded, and how much closer to the video demo steve albini did of the real harmonic perkolator..
very phat, rich, well designed, and it indeed does seem to generate harmonic feedback when you're intentionally feeding back...i couldn't get a discordant harmonic feedback happening no matter how i set the amp. that impressed the hell out of my newbe @$$.
so anyways, as i had such good luck with it, i decided to up my vero layout of the pedal for anyone to use if they want. i had it smaller, but forgot the 22u electrolytic, and had to actually tack it on sideways to the strip side of the board!! ooops...but hey, it works, and i fixed the vero layout.
it's a TIGHT layout using film caps like i did, but it worked out well. i stood the resistors up wherever possible, and can just barely fit all the components on an 8 hole x 8 row vero. but it can be done.
i recommend socketing the transistors so you can play around with them...you can get lost for a couple hours here if not careful, anyways, you've been warned!
hope someone finds this useful.