Tales from the Zonk Machine

[Jonaz]

All the Zonk Machine schematics I've seen have two parts that are different from the real-deal Zonk pictured here:



The supposed 3.3K resistor from the "Fuzz" pot wiper to ground in this picture clearly reads 33K. Also, the coupling cap on Q3's Collector reads .47uF in all commonly circulated schematics of the Zonk but the tropical fish cap in the above picture is obviously .047uF. Sure, there may have been variations in the circuit like so many other effects from this era but I can see how it can be misread very easily from 3.3K VS. 33K and .47uF VS. .047uF. Please help me confirm I'm not seeing things here!

Here's the updated schematic I drew up:



I was curious about this circuit so I built an NPN negative ground version using three OC140 NPN Germs for all three slots. The circuit is built on a fancy-shmanzy woodgrain-patterned board using miniscule eyelets, which was a pain in the neck to hammer into place. The transistor gains for Q1-Q3 are as follows: 70, 116, 97. Here's a gutshot:



Tips for other builders interested in the Zonk Machine:

1. Socket all transistors because you're likely to go through a bunch of them before you find some that work well.
2. The Zonk is very bright. Play around with the input cap and try values between .001uF and .01uF. Maybe even set up a three way switch to toggle between different values.
3. Definitely use a log/audio taper "Fuzz" pot. I used linear at first but it greatly limits the useful range of the pot. The name "Fuzz" is a bit of a misnomer as it doesn't really fulfill most people's definition of a fuzz control. It essentially adjusts the bias of Q2. The Sola Sound Tonebender Mk1, which is a topographically identical circuit (sans the 33K resistor), called this pot "Attack" which is a bit more appropriate IMO.
4. Set up an SPST switch to bypass the 2.2M resistor for nasty, all-out craziness!
5. Build it point to point on a fake wood board so you can pretend you're cool.

Sorry no sound clips on this one...

What do you guys think?

[bluesdevil]

Wow, first time I've seen a wood circuit board.Thanks for sharing your schematic. Will have to breadboard this one with the proper values to hear what it sounds like!

[jrod]

Awesome! Thanks for the report and your updated schematic. Very cool! 

[Curly]

thanks for the info ... I just got a couple of GGG's Zonk board, so this is on my 'to do' list.

nice board, btw ... I'll do something similar for a Buzzaround build, using G10 and eyelets.

[John Lyons]

What happens when the humidity goes up and the wood absorbs water vapor? 
Some fender amps had this problem.
Cool looking board and good information though.
Thanks for sharing.

john

[SonicVI]

doesn't look like real wood.

[R.G.]

doesn't look like real wood.

It's probably not. One of the suggestions from the early Tube Amp FAQ at GEO was to use materials like Formica and set terminals in them if you couldn't find the proper rubberized fabric/glass epoxy stuff to make eyelet boards from.

All the Zonk Machine schematics I've seen have two parts that are different from the real-deal Zonk pictured here:

It sure does help to have a real, unmodified one to work from... 

[Jonaz]

It's probably not.

Correct. It's faux woodgrain and from what I've understood, it's a great insulator.

It sure does help to have a real, unmodified one to work from...

In addition to the picture I posted above, here's another Zonk with a 33K resistor from the "Fuzz" pot wiper to ground. Also has a .047uF output cap.



Here's the schematic for this Zonk:

One of the suggestions from the early Tube Amp FAQ at GEO was to use materials like Formica and set terminals in them if you couldn't find the proper rubberized fabric/glass epoxy stuff to make eyelet boards from.

The amount of information on your site is truly staggering. I got my inspiration from Dumble amps which sometimes use woodgrain laminate boards.

[DougH]

What does it sound like? I breadboarded a zonk according to the circulated schematics and it sounded pretty much like a fuzz face to me. If it is bright, I kind of wonder why it would have the treble booster "attachment" available for it.

[Jonaz]

What does it sound like? I breadboarded a zonk according to the circulated schematics and it sounded pretty much like a fuzz face to me. If it is bright, I kind of wonder why it would have the treble booster "attachment" available for it.

Mine doesn't get as saturated as a fuzz face but it clips pretty hard. Good point on why the Zonk would/could need a TB addition. The Zonk HAS a severe treble boost already built in thanks to the miniscule input cap. The Hornby Skewes Shatterbox features a Zonk II and a Treble Booster in one box, where the TB side comes after the Zonk II side. The Zonk II is reportedly is very dark sounding on its own, so if I were to speculate, I'd say the TB goes better with the Zonk II. I'm soon going to build a Shatterbox to see if it that could be true.