DEMO Atomizer Half 'Cock (Harmonic Percolator)

This post contains an audio or video demo
DGWVI

DGWVI

Well-known member
Build Rating
5.00 star(s)
I built this for a friend's birthday gift. He's incredibly fond of the @Aleph Null Peacock I'd given him, but had brought up wanting a standalone version of the Percolator from that circuit, and has always loved the Atomizer graphics, so here's this guy

Mods are (resistor values taken from the Peacock)-
  • R1- 470k
  • R2- 150k
  • R4- 33k
  • R5- Jumper
  • C2- toggle between 22n and 220n
  • C3- 2.2u
  • C4- 22u
  • C5- 2.2u
  • Diodes are an infrared LED and UF4007
  • The harmonics pot has an 8.2k between lug 1 and ground
  • Transistors are 2n5087 and 2n7000

On its own, the Percolator in the Peacock sounds amazing, but a bit too thin for everyday use, and I wanted to give him something he could stack with the full Peacock, so I increased the size of all the caps. Still does the clang, but also offers up a lot more wool. He primarily plays an electro-acoustic, and this take on the Percolator plays a lot better as far as microphonics go, so hopefully he'll be stoked on this. I dig that it can go from an overloaded console type of drive to totally overblown. Used the C-Buffer because I'm fond of it.

I did have a chance to compare BS170 against the 2n7000, and I wouldn't have thought so, but the saturation characteristics are fairly different,, with my preference being for the crunch of the 7000. The BS170 has more of a kind of brittle attack that sounds cool, but not quite what I was wanting with this one.

Kudos again to @Aleph Null for his awesome work on the Percolator topology. My favorite thus far 🤘🏻😻

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The demo sounds mean! That cap swap is like night and day. The graphics are fun!

I found some correlation between R2 and splattiness. The larger R2, the harder you hit Q2, and the splattier things get. You might be able dial it in or out by adjusting that value.

Now you've got me wanting to develop a five knob percolator: input, output, pre-bass, post-treble, and a splat or clipping symmetry control. I'll throw an extra mosfet boost in front so you can make it cave in completely.
 
Aleph Null said:
The demo sounds mean! That cap swap is like night and day. The graphics are fun!

I found some correlation between R2 and splattiness. The larger R2, the harder you hit Q2, and the splattier things get. You might be able dial it in or out by adjusting that value.
Click to expand...

I've got an Antithesis board I was gonna do up in this fashion, so I'll play around with that resistor too. Was thinking I might also throw the transistors on a switch

Aleph Null said:
Now you've got me wanting to develop a five knob percolator: input, output, pre-bass, post-treble, and a splat or clipping symmetry control. I'll throw an extra mosfet boost in front so you can make it cave in completely.
Click to expand...

Dibs on a board or two if'n you have some made up 🤘🏻
 
Aleph Null said:
Got this on the bread board now. I'm up to five knobs: lows, fuzz, highs, clang, volume. Gonna see what happens if I apend a Push-Me-Pull-You and if I can get an octave blend working.
Click to expand...
Here's the Antithesis / Karma Suture with the relevant component changes. I left the feedback caps stock
 
I tried the Push-Me-Pull-You and, while I like the sound of the two circuits together, there isn't any advantage to putting one inside the other. In fact, putting them together causes a large volume loss and I don't think the blended tones are that exciting. I'd rather make the PMPY into it's own full-featured circuit.

That said, I'm up to five knobs. Do you think I should add a diode switch? Would you use it?
 
jcpst said:
Those are some great tones, makes me think of turn-of-the-century no-wave a la Ex Models
Click to expand...
Saw these guys with the Locust and Plot to Blow up the Eiffel Tower back in like '03. Everyone killed. Still one of the wackiest shows I've been to- the crowd didn't seem to know what to expect from anyone but the Locust, and then it didn't even seem like most people actually appreciated them 🤣
 
DGWVI said:
I'm not big on diode switches - I'll find one setting I like (usually the loudest) and stick to that
Click to expand...
Maybe I'll do the layout to accommodate diodes and then recommend leaving them out. There should be plenty of space left in a 125B for three or for diodes if other people want them.
 
Aleph Null said:
Maybe I'll do the layout to accommodate diodes and then recommend leaving them out. There should be plenty of space left in a 125B for three or for diodes if other people want them.
Click to expand...
What about something like VFE's diode blend or One of AMZ's warp controls?

I do like the diode blend in the Karma Suture/ Antithesis, and feel it's got a decent range through its travel, and breaks up the binary of compressed vs loud that a switch would offer
 
I tried a warp control before I tried the PMPY. I felt that the Clang control was doing something similar and in a more interesting way. I liked the diode blend on the Karma Suture as well, but it felt like I couild acheive the same thing by adjusting the volume and fuzz controls. I'll give the blend another shot before I start laying out the PCB.
 
DGWVI said:
Saw these guys with the Locust and Plot to Blow up the Eiffel Tower back in like '03. Everyone killed. Still one of the wackiest shows I've been to- the crowd didn't seem to know what to expect from anyone but the Locust, and then it didn't even seem like most people actually appreciated them 🤣
Click to expand...
That sounds like a great show. I think it was around ‘03 when I saw Ex Models and The Locust, but at separate events. It seemed like there was so much good noise coming out back then. Or I’m just old and out of touch. 😆
 
Aleph Null said:
I tried a warp control before I tried the PMPY. I felt that the Clang control was doing something similar and in a more interesting way. I liked the diode blend on the Karma Suture as well, but it felt like I couild acheive the same thing by adjusting the volume and fuzz controls. I'll give the blend another shot before I start laying out the PCB.
Click to expand...

Have you messed with soft clippers in the feedback loop of either stage?
I haven't, but I imagine it could be interesting. Probably up the clanginess to nigh unusable
 
I'm using negative feedback in the first stage as a tone control. I'm using a potentiometer in the second stage to adjust bias, that's the clang control. It sounds to me like it effects the symmetry of the clipping, but I think it's doing other things too. All that to say, all the feedback loops are in use. I've got a few more hard clipping/warp arrangements to test before I call it done. I sense is that adding soft clipping one of the feedback loops would just make it sound like a Big Muff.
 
Ok. I've tried every version of the warp control that Orman has on his site as well as a few variations that I came up with. I can't get diodes to do anything interesting in this circuit. They just cut output and treble...and maybe you get a little more saturation. I'm going with five knobs and loud as hell.

P.S. Thank you for begin so gracious about me hijacking your thread.
 
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