Harmonic Percolator - make one!

[wavley]

I just wish someone would explain what the deal is with people holding hands in two separate bathtubs. I don't get it...

They're not holding hands.  They're transferring the soap...securely.  It is slippery, after all.

Well, that's no fun... Which is kind of my point. What's so fun about sitting in 2 separate bathtubs?

I'm assuming it's because they're married and she's saying "Get that thing away from me, I thought we were past this, I got you a second bathtub am I going to have to get you a separate bathroom? Please stop taking those stupid pills."

[Mark Hammer]

Well, that's no fun... Which is kind of my point. What's so fun about sitting in 2 separate bathtubs?

Well, for one, you can count who made how many "bubbles" accurately.  
For another, nobody has to be the one to sit with the spigot jabbing them in the back (been there, done that).

But I get your point.  There are things possible with bench seats (and a little Johnny Mathis) that are not possible with bucket seats.  

Okay, let's get back on track from frothy bins to fuzzy boxes.

[Paul Marossy]

Still haven't got this thing working. I have the transistor voltages & Hfe's in the ballpark with a 2N1108 and a 2N2222, and I've got the oscillation almost under control except when controls at max, but it doesn't sound anything like pinkjimiphoton's video. No creaminess or sustain at all. Just a very mild overdrive, IF I strum the strings hard. I messed with the emitter resistor on Q1 and the resistor between C & B on Q2 too. So far, this build has been a complete utter failure. Why is it that these simple little circuits never $%&*(@+ work for me? I must have lost my touch.  

EDIT: Not sure if those "snubber" caps I added are helping or hurting. Will try removing the one on the output pot tonight and see what that does. I don't expect to have much luck at this point.

Paul, are you using a breadboard? Those things eventually fail, the contacts become intermittent/faulty. I recently suffered like mad trying to debug some circuit, till I realized it was the freakin´breadboard! Had to retire it.

No breadboard, this is on perf with only Q1 socketed.

[pinkjimiphoton]

paul, just for s-m-g's, try turning q1 around 180 degrees. i don't know why but for some reason, it seems to work with some ge transistors, particularly if they're leaky as hell. in some circuits, you can end up getting what you describe when it's in the circuit, even if your meter says it's the other way around..in fact, i had that very problem on mine when i was trying transistors...the one i have in q1 is probably in BACKWARDS...at least from what my meter read.

can't explain it, but sometimes it seems to be just the way it f'n is... keep us posted bud!! you'll get it!!

[digi2t]

Alright, here's another installment of the "Hen's Tooth Cafe". Spotlight on the HP circuit. First, I'm going with a Russian MP16A, gain of 43, zero leakage. Then, my trusty 2SB176, 112 gain, 0.1mA leakage. I prefer the 2SB176, especially when I roll off the volume. The MP16 is way too ice-picky clean, whereas the 176 is a tad smoother. I did try a Russian GT402V as well, and it was VERY close to the 176 sound wise. Unfortunately, since the collector is part of the casing, the 402 attracts more noise. In a pinch though, you might want to try a 402. It's not too bad, and might be easier/cheaper to get. Might be alright when boxed. I used it in my Gemini Fuzz with pretty good results.

PN2222 in the Q2 slot. I tried a bunch, but this one seems to be the best compromise between gain, and noise. I recommend plastic cases over metals ones, because I found that metal caps (BC10* etc) act as antennas, attracting more noise. 

1N695 diodes, including one to ground on the input side. 1K series resistor for one of the diodes. 100pF cap to ground on the input side.

0.047 input cap. This one seems to cover the most amount of ground between single coils and buckers. If you're using buckers exclusively, might want to try a 0.022.

0.01 cap between the two trannies, including one from Q1C to ground. 150pF cap to ground on Q2C, or else you'll get AM talk radio, all day long.

Both emmiters are  going to a 47uF electro to ground (normal, not Tant. Didn't have a Tant on hand).

On the output of Q2, I'm using a Nichicon Muse 1uF bi-polar. I just don't know what it is about this cap, but it pops, where all other 1uf (bi, electro, metal film, whatever) seem to be a bit flat.



220K FB resistor for Q1, and 1.5M for Q2 (rather than 750K). 750K just didn't cut the mustard for me here. I've seen numbers ranging from 737K, all the way to 3.9M here (Sardonic Albinator). Use your ears.

The 20K resistor to ground for Q1C is a 25K trimmer. I start at about 1.2v on Q1C, but if I move it down to 0.5v, I get a bit of octave bloom on the tail end of the notes. It's subtle, but there. Anywhere between 0.5 to 1.3 volts on Q1C is pretty happy ground. Again, use your ears. Actually, if we examine the Ge side of the Gemini III fuzz, you'll notice that the 91K resistor is a 100K trimpot as well, though it uses a Ge NPN here. I must admit, with a single Ge booster bofore it, the Gemini sounds pretty damn fine, but doesn't clean up 100%. Always a bit of fur around the edges. The Si side of things cleans up glassy clean. Here's the Gemini III schem, for those of you that want to ganger the Ge end of it. Ohhh Harmonic Percolator... I seeeee yoooou!



OK, popcorn's ready, on with the show.... Mustang-o-caster, into the breadboard, into an Ampeg G-212 pushing 2 x 12" Texas Heats. Touch of reverb on the amp.

Oh yeah, on a lark, I stuck a 2N2907 metal can in the Q1 slot. My hand just fell on one, so I thought, "What the flux, lets give it a whirl".
That was just down right stoooopid.... in a good way.
Same set up as the before, with the Q1C voltage at 1.0v. It won't clean up like the Ge when you roll off the volume, rather, it becomes a very mild chunky overdrive. Quite nice actually, think Bad Company "Rock Steady" chunk, but milder. But, crank the volume back up, and it's a freakin' monster. I tried it with my Korina Explorer, with the G-212 volume at 4, which is pretty loud on a G-212. I thought the bloody thing was going to jump out of my hands and beat me senseless.

I think I'm going to need therapy after that one....

[Kesh]

I have some low gain NPN so am going to attempt to reverse the whole circuit, that is a PNP in the high gain slot and positive ground.

[pinkjimiphoton]

dino, you NAILED it again bro...sounds freekin' great!! mine is a little bit "tamer" cuz i'm snubbing it some...
gonna have to build it as per your instructions. what a sound!!
love!!!!

[Paul Marossy]

paul, just for s-m-g's, try turning q1 around 180 degrees. i don't know why but for some reason, it seems to work with some ge transistors, particularly if they're leaky as hell. in some circuits, you can end up getting what you describe when it's in the circuit, even if your meter says it's the other way around..in fact, i had that very problem on mine when i was trying transistors...the one i have in q1 is probably in BACKWARDS...at least from what my meter read.

can't explain it, but sometimes it seems to be just the way it f'n is... keep us posted bud!! you'll get it!!

I've already tried reversing Q1, with multiple transistors. Same results no matter what I do. 

[digi2t]

I have some low gain NPN so am going to attempt to reverse the whole circuit, that is a PNP in the high gain slot and positive ground.

Huh! That should be interesting. Post results please.

dino, you NAILED it again bro...sounds freekin' great!! mine is a little bit "tamer" cuz i'm snubbing it some...
gonna have to build it as per your instructions. what a sound!!
love!!!!

Thanks bro. It's a really flexble circuit. A different cap here or there, or a slight change in the bias, can make a difference. Really, I never gave the Pukealator much thought, but I like it. With just the guitar's volume, you can go from glass clean, to gritty, or all the way to a Muff type roar. Interesting little circuit, I must admit.

Thanks to Mark for stirring up the poop-a-laka on this one. 

I'll whip up a schem and vero for this one later.

@Paul - Oscillation.... hmmm. If I pull the 47uF to ground on the two emitters, it will go into oscillation. Maybe you've got a bum cap? I'm using a normal electro. Check it out.

[pinkjimiphoton]

dino....

i was lazy, so didn't whip up a new layout, just modified my old one with ms paint... the diy layout file got corrupted, glad i got the pic to redo it with.


anyways...not so concerned with the physical layout, but does this look right to you with the values?
that nichicon cap is 1uf, not .1uf, right?

the other values look right?



you really seem to have nailed it well, bro!!! damn you, now i gotta build another one!!! 

[LP Hovercraft]

Cool thread!  I can recall being giddy at the sound of the Percolator driven by Puzzle87's So-Simple Compressor.  I used 2N404, 2N3565, 1n34a, and panasonic dark red film cap in the 1uF slot, but I doubt whether that cap makes too much difference in the overall sound.  I will second the notion that it will do a subtle octave down when pushed hard.  I'm wondering if that has anything to do with the second harmonic amplification touted in the sale literature?

[Paul Marossy]

@Paul - Oscillation.... hmmm. If I pull the 47uF to ground on the two emitters, it will go into oscillation. Maybe you've got a bum cap? I'm using a normal electro. Check it out.

I'm using a pair of 22uF in parallel because I ran out of 47uF caps. You think 3uF would send it into an oscillation hissy fit? At this point I'm willing to believe just about anything...

[Kesh]

dino....

i was lazy, so didn't whip up a new layout, just modified my old one with ms paint... the diy layout file got corrupted, glad i got the pic to redo it with.


anyways...not so concerned with the physical layout, but does this look right to you with the values?
that nichicon cap is 1uf, not .1uf, right?

the other values look right?



you really seem to have nailed it well, bro!!! damn you, now i gotta build another one!!! 

you have obscured the e11 to b11 jumper.

as it is +9V goes through R3 and then nowhere.

[digi2t]

Cool thread!  I can recall being giddy at the sound of the Percolator driven by Puzzle87's So-Simple Compressor.  I used 2N404, 2N3565, 1n34a, and panasonic dark red film cap in the 1uF slot, but I doubt whether that cap makes too much difference in the overall sound.  I will second the notion that it will do a subtle octave down when pushed hard.  I'm wondering if that has anything to do with the second harmonic amplification touted in the sale literature?

I have 1uF Panasonic metal films, and I did try one. It sounded a tiny bit darker. Just enough for me to say "dull". The Nichicon Muse BP is my choice. I do have some 47uF tantalums coming, so I'll try one when I get it. I think it might have a tough time knocking the Muse off the mountain though.

I tested the forward voltage on various Ge diodes that I have. 1N34, 1N60, and 1N270's all came in around 0.33 to 0.37v on my DMM. The 1N695's come in at 0.26 to 0.28v. I might try some BAT43's in here for shits and giggles.

Here is a vero of what I have on the breadboard right now;



I must apologize to PyrO, I misread the resistor in series with the diode, and told him 1K. It's 10K that I'm using here. I did an A/B test between 1K and 10K, and found that with 1K I was getting a bit more sustain, but didn't get as glassy a clean up when rolling off the volume. 10K is the opposite, better clean up, tad less sustain. I've seen 4.7K spec'd here, so as always, use your ears.

[Mark Hammer]

One of the things I like most about it is that I feel absolutely no need to incorporate any sort of treble cut control so that I can play clean and bright and then turn the Percolator on without slicing my head off.  It cuts through just enough to be heard, but has no graininess or fizz; just muscle.

Now, the one I just sold a guy yesterday nailed all the muscle well, but lacked the occasional sub-octave that my own manages to get.  So what do the rest of you get in the way of occasional sub-octave, and do the things you do to get some of the octave-up bloom get in the way of the sub-octave?

[inductor]

I'm using a pair of 22uF in parallel because I ran out of 47uF caps. You think 3uF would send it into an oscillation hissy fit? At this point I'm willing to believe just about anything...

I would say probably not, but I fiddled around with this cap while prototyping. The only way I could get mine to squeal was a low value e-e cap and then it was mostly motorboating.  I did try a 100uf cap but iirc it was less gainy. I tried a high gain & high leaky pnp it became icepicky.

[inductor]

So what do the rest of you get in the way of occasional sub-octave, and do the things you do to get some of the octave-up bloom get in the way of the sub-octave?

The ones I make have lots of suboctaves. I'm guessing its something to do with the gain/leakiness.
I'm waiting for some parts and I intend to try piggy backing higher gain 2n404's (to get lower gain) and see what it sounds like.

[digi2t]

One of the things I like most about it is that I feel absolutely no need to incorporate any sort of treble cut control so that I can play clean and bright and then turn the Percolator on without slicing my head off.  It cuts through just enough to be heard, but has no graininess or fizz; just muscle.

Now, the one I just sold a guy yesterday nailed all the muscle well, but lacked the occasional sub-octave that my own manages to get.  So what do the rest of you get in the way of occasional sub-octave, and do the things you do to get some of the octave-up bloom get in the way of the sub-octave?

Quite honestly, I've yet to get any sub-octave, except when I induce feedback. Depending on the note/chord, it might go up, or down, but always adhering to the root. The octave bloom on decay generally occurs at lower (read "sane") volume levels, with a Q1C voltage of between 0.5v and 0.6v.

Maybe if I up the Q1C voltage, I'll get sub-octave? Or, I'll try a 100K trimmer, in place of the 91K above Q2, but it'll probably just tone down the gain more than anything else. Shades of the Gemini III fuzz here. I'll try it tomorrow. Could be that the 2SB176 just isn't leaky enough? 

Just for information, these are the voltages from the Gemini III / Percolator section. I realize that it's using two Ge trannies here, but the PNP collector seems to be set close to the same voltage that I'm running.

Q2- AC128 (Q1 in the HP)
E=1.547v
B=0.946v
C=0.769v

Q3- AC176 (Q2 in the HP)
E=1.547v
B=1.586v
C=1.672v

[pinkjimiphoton]

dino....

i was lazy, so didn't whip up a new layout, just modified my old one with ms paint... the diy layout file got corrupted, glad i got the pic to redo it with.


anyways...not so concerned with the physical layout, but does this look right to you with the values?
that nichicon cap is 1uf, not .1uf, right?

the other values look right?



you really seem to have nailed it well, bro!!! damn you, now i gotta build another one!!! 

you have obscured the e11 to b11 jumper.

as it is +9V goes through R3 and then nowhere.

point noted, space that out!! will delete this.

here's it corrected...not the whole layout, just jumper put back in.

i'll let dino do his own layout, his always rock!



this is fixed, but not previewing right...the original layout was deleted, wtf?

[digi2t]

Takes time for Photobucket to update. It'll change, don't worry.