Hornby Skewes - Zonk Machine / Zonk II ( JHS )  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
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MoreCowbell
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Post by analogguru »

That unit is pretty messed up. the switch should be rotated 180 degrees, the resistor and electrolytic connected together, the yellow wire should be connected on the other side, and thee white to the common lug.

Let´s see how much money somebody is ready to invest in such a fucked up unit.

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Post by MoreCowbell »

analogguru wrote:That unit is pretty messed up. the switch should be rotated 180 degrees, the resistor and electrolytic connected together, the yellow wire should be connected on the other side, and thee white to the common lug.

Let´s see how much money somebody is ready to invest in such a fucked up unit.

analogguru
You forgot to mention that they sound like shit....which they do.

However, it's the first trace side shot I've seen. That, coupled witha few board pics that are out there should be able to generate a accurate schematic.

There are Shatterbox pics HERE.... the "fuzz" section of the Shatterbox is the same circuit as the Zonk II.


:?

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Post by Jonaz »

I originally made the following post at the diystompboxes forum but didn't get a very enthusiastic response. I think the people here might get something more out of it...

All the Zonk Machine schematics I’ve seen have two parts that are different from the real-deal Zonk pictured here:
ZonkGuts.jpeg
ZonkGuts.jpeg (61.7 KiB) Viewed 2305 times
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:
TheZonkMachineSchematic.jpeg
TheZonkMachineSchematic.jpeg (22.4 KiB) Viewed 2305 times
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:

Image

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. :roll:

Sorry no sound clips on this one...

What do you guys think?

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Post by RnFR »

good stuff! correct schematics should always be treated to an enthusiastic response! btw- i'm going to merge this into the Zonk thread.
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Post by SpencerPedals »

I have now seen wood paneling incorporated into a circuit. I can seriously die happy now. That is f'ing awesome!

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Post by royaltoots »

I was planning to build one of these, but was put off by conflicting online info, so yeah! thanks!

I was also considering fucking around with eyelets (just to make things more difficult!) for a new FZ-1 build - would you say they are trouble, or was it just the small size that made them a pain?

S

PS the Zonk II? It sounds pretty crap, don't bother.

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Post by Electric Warrior »

Jonaz wrote:I originally made the following post at the diystompboxes forum but didn't get a very enthusiastic response. I think the people here might get something more out of it...

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

Image

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!
confirmed. That picture is from David Main's blog. he posted a schematic at his forum: http://stompboxes.co.uk/forum/viewtopic ... e&start=10
your schematic is identical.

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Post by Jonaz »

I have now seen wood paneling incorporated into a circuit. I can seriously die happy now. That is f'ing awesome!
Ha Ha!! :applause: Really appreciate it!
I was also considering fucking around with eyelets (just to make things more difficult!) for a new FZ-1 build - would you say they are trouble, or was it just the small size that made them a pain?
The really small eyelets I used are Keystone #23 (Mouser part# 534-23) and the smaller they get, they easier they split upon hammering. If you're using eyelets, make sure that the flange of the eyelet is just a bit thicker/longer than the board material it gets punched into. Otherwise you'll end up with split ones. I bought my eyelet staking kit from http://www.turretboards.com but you can also get it from Mouser (part# 534-1721). I say that in the end it's worth it! It's really fun to wire it up the good ol' way, altough my favorite method is terminal strip. However back in the day, as witnessed by a bunch of early FX gutshots, you never see eyelets on things like this. The component leads went straight through the board.
confirmed. That picture is from David Main's blog. he posted a schematic at his forum: http://stompboxes.co.uk/forum/viewtopic ... e&start=10
your schematic is identical.
I completely missed that thread! Thanks for the link, there are some really nice pics in that thread. Very cool! Looking at the pictures it appears that some Zonk Machines came with 25K linear "Fuzz" pots. Might have to try that to see if things improve. At the moment, my clone is not overly gainy. It can definately break up and hard clip but not in a super saturated fashion like say...a Fuzz Face.

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Post by Jonaz »

I drew up another schematic of the one in the link that Electric Warrior posted. What's different in this one is: Q2 and Q3 are OC71, 220K Q2 base resistor, 1.8M output resistor and the "Fuzz" pot is B25K.

Image

To not confuse people by adding another schematic I want to say that this is simply a different Zonk version. Both schematics are verified as being real Zonk's.

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Post by Electric Warrior »

Jonaz wrote:I completely missed that thread! Thanks for the link, there are some really nice pics in that thread. Very cool! Looking at the pictures it appears that some Zonk Machines came with 25K linear "Fuzz" pots. Might have to try that to see if things improve. At the moment, my clone is not overly gainy. It can definately break up and hard clip but not in a super saturated fashion like say...a Fuzz Face.

I guess not. It woul be the same as setting a 50k lin fuzz control to 12 o' clock

have you seen this one? http://stompboxes.co.uk/forum/viewtopic ... nk+machine

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Post by Jonaz »

I guess not. It woul be the same as setting a 50k lin fuzz control to 12 o' clock
Yeah, you're absolutely right (now that I think about it!!!)

I had not seen that link either. Wow! Super pics! There's ones of a Shatterbox and a ZonkII in there as well. It's interesting to note how different some Zonks look on the inside. There's two different layouts that I've seen so far.

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Post by Electric Warrior »

make sure to check the zonk II/treble boost thread http://stompboxes.co.uk/forum/viewtopic ... shatterbox
great pics of Graham's Zonk II here: http://stompboxes.co.uk/forum/viewtopic ... ox+zonk+ii

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Post by Jonaz »

make sure to check the zonk II/treble boost thread http://stompboxes.co.uk/forum/viewtopic ... shatterbox
great pics of Graham's Zonk II here: http://stompboxes.co.uk/forum/viewtopic ... ox+zonk+ii
Thanks for posting the links. I now have an insatiable urge to build a Shatterbox!!! Arrggghhh...

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Post by Electric Warrior »

According to David Main the fuzz part of the one he analyzed sounded really bad (even called it the shit-yer-box).
The vero board one we analyzed had problems with oscillations when fuzz and boost were engaged at the same time. The fuzz on its own was very dark sounding..
Graham on the other hand reports that his zonk II is sounding great. Biffa (on this forum) got a great sound out of the circuit as well. it's probably all down to transistor selection.

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Post by royaltoots »

Jonaz wrote:
make sure to check the zonk II/treble boost thread http://stompboxes.co.uk/forum/viewtopic ... shatterbox
great pics of Graham's Zonk II here: http://stompboxes.co.uk/forum/viewtopic ... ox+zonk+ii
Thanks for posting the links. I now have an insatiable urge to build a Shatterbox!!! Arrggghhh...
I built a shatterbox for someone but the fuzz sounded v v bad, I should have trusted D Main's judgement! - but the tb side was nice.

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Post by Solidhex »

Yo

Rad! love the wood board and the turret stuff. I did a pcb layout on Guassmarkov's site for the Zonk Machine. http://gaussmarkov.net/wordpress/circuits/zonk-machine/ . Also applicable to the Tonebender MkI. It still have the 33K listed as a 3K3. My guess about the version with the 220K is that the OC71's probably don't have the gain/leakage needed to bias properly with the usual 470K. I found some pretty leaky ac125's sounded pretty good in my Zonk. Its a tight almost metal sounding take on that circuit topology. Can do some palm muted stuff decently but has awesome sustain too.

--Brad

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Post by sinner »

Is the search function here is broken? I cant find tread about it...

I revised my Zonk Machine layouts today, so it's good time to start one

Enjoy

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Post by Electric Warrior »

Search function works just fine: viewtopic.php?f=19&t=3367&hilit=zonk

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Post by sinner »

It's zonk II tread :idea:

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