This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Friday, June 19, 2015

Vox ToneBender Mk I

You might look at this and think, "Gee, it's just another Fuzz Face," when in actuality, this pedal pre-dates the famous Dallas Arbiter stombox. (This is different from the Sola Sound ToneBender Mk I, as the Sola Sound has 3 transistors.) It was made in Italy for Vox and sounds like a Rangemaster and Fuzz Face combined, due to its smaller input and output capacitors. This is also the same circuit as the D*A*M 1966 Italian Tone Bender. I've added a 10k trimmer in place of the stock 8.2k resistor to dial in the bias for Q2 (a 20k trimmer might give you more tweakability), but on the PCB there are pads for a resistor in place of the trimmer if you prefer to go that route. Also, I've added a pull down resistor at the input, and polarity protection and power filtering. Note that this was originally built with PNP germanium transistors and was positive ground. The perf side of the layout reflects this, while the PCB side reflects negative ground for use with NPN transistors.




13 comments:

  1. I have this built up now using Germanium AC128s.

    This part in the description confuses me:

    Note that this was originally built with PNP germanium transistors and was positive ground. The perf side of the layout reflects this, while the PCB side reflects negative ground for use with NPN transistors.

    I am using the PCB layout.

    Pedal is very quiet with no fuzz. Should I switch to NPN transistors? If so, any suggestions?

    Thanks, and happy holidays!

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  2. Hi Ryan,
    Yes, I believe that you should be using an NPN. Your ac128 is a PNP which would work if you made this using the perfboard layout above. The PCB version needs an NPN. Good luck.

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  3. I can verify this one. Built with AC187K NPN transistors.

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  4. Hello!
    I just finished building the perfboard version. no dice. all i get is the same sound as when the circuit is bypassed. it's baffling...
    Anyone have an idea?

    Thanks in advance!

    Chuck

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    Replies
    1. figured it out! it was b/c i've been testing it with a negative ground test box (duh!) this thing sounds rad! thankyou for this awesome blog!!

      Chuck

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  5. what happend if I use a 10 uf or any other value instead of de 47uf cap?

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  6. The 47u cap is for power filtering. I wouldn't go much lower than 22u if you're substituting. 100u is another common value for power filtering caps.

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  8. Do those extra power filtering caps change the values of the other caps and affect the sound, or are they there for providing constant power through the line?

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    Replies
    1. Doesn't affect the sound. Just smoothes the power to make it more consistent

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  9. Hi!! The resistor in the lug 3 of the fuzz pot is 47k or 100k? Thanks buddy!

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