Saturday, November 12, 2022

JOHN HORNSBY SKEWES: Hybrid Zonk Machine (Modded)

Similar to the previous Zonk Machine, this has a MKI switch for a larger input cap.  Have had this on the breadboard recently, and decided to jump to a vintage-style veroboard.  

There are of course more differences between a MKI Tone Bender and a Zonk than just an input cap, but for convenience's sake, the input capacitor gets you pretty close.

MODDED JHS ZONK / MK1 HYBRID - 0.15" VERO LAYOUT


HYBRID ZONK ON THE BENCH

Some minor changes to keep some mojo caps on the board.  12n instead of a 10n input cap, as I got a reasonable deal on 100x 12n caps.  10n tropical fish are sometimes expensive....   same for the 100n, went for something larger, which will have almost no impact on the sound, but not a common value, meaning substantially cheaper.

OC76 for Q1 and Q3.  Q2 is an old silicon glob top from Fairchild.

HYBRID ZONK MACHINE ON THE BENCH



FURTHER ZONK HYBRID READING



Voltages supplied by Acid Fuzz

Trimmer set to about 152k.  Here are the voltages at ~70°F with a 9V battery:

1/2 "FUZZ" Full "FUZZ"

Q1:  
        C -8.98V   -8.95V
        B -.707V   -.715V
        E -.656V   -.676V

Q2:    
        C -7.16V   -3.632V
        B -.643V   -.672V
        E -0.1mV  -0.1mV

Q3: 
        C -7.99V   -7.51V
        B -51.7mV  -51mV
        E -0.1mV  -0.1mV


2 comments:

  1. Is there a big difference soundwise between the Hybrid Zonk I and the "normal" Germanium Zonk I?

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    Replies
    1. I’ve only got the ones that I’ve made myself to use as a reference - frequency response is the same, as the only difference is Q2 and a trimmer.

      There are definitely differences to the texture. I found the silicon is actually more touchy to bias correctly - which I wasn’t expecting. It has more of the Velcro type gated tone.

      The germanium one has a more useful range over the sweep of the fuzz (bias) pot. Although it did take a while to find a transistor that did this.

      They’re both good.

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