Harmonic Percolator - make one!

[pinkjimiphoton]

no worries bro, sorry if i came across with a tude, just trying to help man!!

hope ya get it sorted out!! 

[Paul Marossy]

no worries bro, sorry if i came across with a tude, just trying to help man!!

hope ya get it sorted out!! 

No problem. 

[digi2t]

OK, here's the skinny...

I've got it on the breadboard. I'm pretty much faithful to the plan(s). I'm using a 2SB176 in Q1, and a PN2222 in Q2. I spent the day trying different trannies, and these two are the cat's ass. Using 1N695 diodes, including a third on the input side, as per the original layout.

The 1K/2.2uF combo to ground on the collector of Q1 is a real kill joy. It really mellows things out, but that's not what I'm here for.

220K is fine between B and C of Q1, but Q2 didn't wake up until I up'd the ante to a 1.5M resistor between it's B and C. Even a 1.2M works pretty well.

I replaced the 20K to ground on Q1's collector with a trimmer. The harmonics really start slapping me in the face when I got down around 4.6K. Far cry from the 20K or even 91K stated on some drawings, but kind of fits in between with 2.7K I've seen on a drawing.

Input cap is a .047uF. Q1C to Q2B cap is .01. I added another .01 between Q1C to ground, because Radio Moscow was sending me the word of God.

The biggest ass kicking was the 1uF cap. I tried a Tant., and an electro, but with a Nichicon Muse bi-polar, the low end bark scared the crap outta me.

If I crank the amp just enough, I feedback harmonics just about everywhere.

Video tomorrow. I'm just too stone deaf right now.

[pinkjimiphoton]

i may have to build it up with your mods...i have a feeling i'll like 'em!!! 

[Jazznoise]

Wow, you guys are certainly outdoing yourselves. That thing sounds amazing, Jimi, I'd consider that feat beer-worthy.

What digi2t is saying makes me think the 91K resistor is more of a current establishing thing than a voltage thing. A factor of 20 of a difference certainly doesn't correlate to what differences we're hearing of. Does Vc or Ve change much with your biasing, digi2t?

[Pyr0]

^ digi2t - Interesting. What did you use for the resistor in series with the last 1N695, 2k7 or 4k7 ?
I've a couple of those Nichon 1uf non-polar caps, must try it out tomorrow along with the resistor values you mentioned.

thanks

[pinkjimiphoton]

thanks chris, a cyber-toast to you, bro.

i can't wait to hear what dino comes up with...he can take some amazing circuits, and make them UNBELIEVABLE, lol!

[digi2t]

^ digi2t - Interesting. What did you use for the resistor in series with the last 1N695, 2k7 or 4k7 ?
I've a couple of those Nichon 1uf non-polar caps, must try it out tomorrow along with the resistor values you mentioned.

thanks

1K for the resistor in series with the diode. I took that from some gutshot pics of an early original. Here are some numbers from mine;

2SB176 hfe = 115, 0.15mA leakage (Peak Atlas meter)
PN2222 hfe = 190 (TO-92 cases are quieter than the metal heads.)

With the trimmer at around 20K on Q1 collector to ground, at 9.09v supply voltage I can easily get the widely posted voltages of;
PNP 2N404A

E 1.61 v
B 1.46 v
C 1.46 v

NPN 2n3565

E 1.62 v
B 1.93 v
C 2.49 v

or with a tweak,

Q1    E 1.51  B 1.42 C 1.36
Q2    E 1.51  B 2.09 C2.33

but, I found that if I dial down to around 6.8K, and bring the Q1 collector to around .5v, I hit this sweet spot that gives me a slight octave bloom at the end of the notes. Sounds just as raunchy as the higher voltages, but with a little extra mustard. I mean, I've seen drawings that go from 91K, all the way down to 2.7K here. That's why I decided to throw a trimmer in here, and play with it. When you're dialing down, you can hear it getting louder, but obviously, you have to be careful not to go too far to ground.

I tried it with a .022 input cap, and harmonically it does pop more with single coils, but with the humbucker, I lose the grunt. Sticking with the .047 for now, but I might try a .033 to split the difference. Turning down the volume does clean up a lot, and with the neck single coil, I get a real Tele type snap twang. So much so, that I need to dial down the tone a tad.

That's it for now. Video tomorrow. Bedtime now.

[Mark Hammer]

Thanks for your diligence, Dino.  Much appreciated.

Let's compare the "consensus" drawing against other devices:

HP-1 has....2 transistors, 2 pots, 2 diodes, 5 resistors, 5 caps.

Fuzz Face has...2 transistors, 2 pots, no diodes, 4 resistors, 3 caps

Jordan Bosstone has....2 transistors, 2 pots, 2 diodes, 5 resistors, 4 caps

Fuzz-Rite has...2 transistors, 2 pots, no diodes, 4 resistors, 4 caps

Amazing what one can do with so little, eh?

[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.

[pinkjimiphoton]

paul, don't give up man.
it sounds to me like you need to do a continuity check. i've had a lot of problems like that too lately, and have found it usually to be a resistor that's open, particularly if it's standing...it makes enough of a contact to complete the ccct when ya whack it, but is maddening to find.
i've had it happen on a few builds now, including the ross distortion i built a week ago. nothing made any sense, voltages seemed right, and wango...it was one stupid end of one resistor that fell apart as i was de-soldering it to check..on the ross, there's a pot, a cap and a resistor for the gain pot, so it had to be one of the three, and sure enough, that was it.

so check it out man...i KNOW you will find it, and it will be something so freekin' stupid you won't think of it...that happened to me with a few ccts now..

tayda 1/4 watt resistors aren't too sturdy..

[DougH]

This sounds really good. From what I remember, this is pretty much what mine sounds like. (Been a while since I used it.) There's that smooth fuzztone when you crank it up that just oozes harmonics. I remember it responded well to just playing without picking, just sliding my left hand fingers around the fretboard and it kept going. Also, the whole overdrive->clean thing it does when you turn down your guitar or the "harmonics" control is well represented here. Nice demo!

[pinkjimiphoton]

thanks doug!

it is exactly like what you describe...and you almost can't get dissonant harmonic feedback with it. nice box!

[Mark Hammer]

Paul, your frustration is starting to sound like those TV sitcom scenes where someone experiences, um, er, "masculine" problems. 

"I don't know what's wrong.  This has never happened to me before...ever....I swear!"

[Morocotopo]

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.

[pinkjimiphoton]

hey mark,
ever notice how those commercials always are tinted blue?

[DougH]

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

[Mark Hammer]

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.

[DougH]

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?

[pinkjimiphoton]

his and hers, platonic fun? what the heck do ya need the blue pill for then? 

my world looks more...ummmm....purple, anyways..