This is my version of the Zonk Machine, based on one of the early vero layouts. I added a switch for the input cap, which is possibly the most unoriginal mod known, and increased one of the input caps from 1n to 2n2.
I used an OC76 for Q1 and Q3 and an OC44 for Q2. I found this provided the best balance between noise and the aggression of the fuzz. It was very similar to using OC75s, but with noticeably less noise.
How does it sound? It's a nasty primitive fuzz with a lot of character - I really like it. The standard 1n input cap is not nearly as bright as you think it might be, but it wasn't entirely to my liking which is why I went up to 2n2. The 10n which is stock for a MKI is really meaty - again, perhaps more than you might expect if you have not tried a MKI before.
The switch essentially functions as a fat switch. 2n2 is good - 10n is about as much as you would want.
ORIGINAL ZONK MACHINE VERO LAYOUT
The image below is attributed to Graham and his seemingly endless supply of vintage English pedals on D*A*M forum Note the 25k Fuzz pot and the vero construction.
MY BUILD
That’s a cracker. I love Zonks but bloody hell is it difficult to find the perfect set of transistors. What sort of leakage do you go for? I’ve tested a few that have had a really leaky Q1 and others with quite a stable Q1 and Q2 and a really leaky Q3. Seems like witchcraft too me sometimes.
ReplyDeleteSacrifice a chicken on the rising moon and your Zonk will work out just fine.
ReplyDeleteFor something like this I don’t check measurements, I breadboard and use transistors that I know are leaky to start with. As I don’t mass produce pedals, time auditioning transistors by ear is not an issue.
I’ll measure a few of my OC76s when I get a chance and add to the post. Not sure if I have any OC44s left.
The last Zonk I did I used an OC75 in Q1 (HFE: 60-70/Leak: 200-300ua), an OC71 in Q2 (HFE: 80-90/ Leak: 800ua) an OC45 (HFE: 60-70/ Leak: 0ua). It sounds awesome.
ReplyDeleteAnother combinación I liked was with the OC45 in Q1 and the OC75 in Q3 But in this case the sound was less gated and a tad more noisy, but more stringy.
Just to share some information. My transistor selection was as follows:
ReplyDeleteQ1: HFE: 83/Leak: 250ua
Q2: HFE: 84/Leak: 320ua
Q3: HFE: 71/Leak: 210ua
Something worth to add, instead of 470k (R3) I used 220k and it biased perfectly. I love the Zonk!
ReplyDeleteSome great info there. Thanks very much 👍.
DeleteThese layouts both use a 220k as that's what's on the board that it's taken from.
DeleteYou are right of course. I didn't see that. I was just reading your Tone Bender MKI Component Table where the 470k was mentioned as a stock resistor for the Zonk Machine. :-)
ReplyDeleteTrue - I should update the table. Apologies if the previous comment sounded a bit short. Was in the middle of doing something else at the time I wrote it. :-)
DeleteThis resistor was changed a lot during the production time for biasing the pedal. In the Zonk and in the MKI, in some pics from the MKI you can seen a180k.
ReplyDeleteIn the Zonk it depends if is an early one or a late one. They change it according the transistor models used (and the pedals that wear OC71 the fuzz pot changed to 22k the same way, IIRC)
Think I still have a few more variations to add to the list ;-) I generally like to see photos, so I have an example as a reference.
DeleteI am currently building your modded layout and was wondering if you could help me with one step: I am using an 8-rows vero and wanted to add a third input cap at the bottom (1n-3,3n/4,7n-10n) by using an SP3T 3-way switch. Am I correct to assume that I just need to add another connection wire going from row 8 (5) to row 6 (5)? And secondly, input goes to lug 2 of the switch and then lug 1 to row 6, lug 2 to row 7 and lug 3 to row 8, or am I missing something?
ReplyDeleteA rotary switch? Have a look at the treble booster layouts with caps on a rotary switch or the beano boost with a simple SPDT ON-OFF-ON switch
DeleteIt sounds like you're on the right track - For a rotary, from stomp switch to rotary A. 1, 2 & 3 on the rotary to respective capacitors on the board. The capacitors are all linked to the base of Q1
DeleteThanks :-)
DeleteI meant a simple SPDT ON-OFF-ON switch, you are right.
Got it - and yes you are on the right track. Basically the same as the beano boost.
Delete