Saturday 15 June 2019

Vox Tonebender Mk. III w. Treble and Bass Boost

A rare tonebender variant made by Solasound
for Vox. Info, pictures and schematic HERE




14 comments:

  1. This is an intense fuzz unlike any other I've built. It's not an MK3, but a boost>tone>fuzz. The switching setting is also unique. I settled on BC337's at about 300hfe, after trying some hotter tranistors that just made it a noisy mess.

    100K for the treble/bass worked fine.

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  2. Hello, fuzzhead!
    Can you post a bigger layout image, please?

    Thank you a lot!
    Radu

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  3. I’ve just built this. I’ve got sound on both sides of the switch. A cool fuzz tone and a clean tone. Just wondering what the switch is supposed to be doing. None of the controls affect the clean side.
    Cheers.

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    Replies
    1. Just fixed up a bit of wiring and now the T & B control is working on the ‘Clean’(Boost?) side. It is under unity, though. Any way it can be made louder?

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    2. I don't remember if the volume was below unity in my clone....long time ago I built this... Not sure if you have a build issue at Q1 but you can try a smaller value for the 1,8k at the emitter of Q1. But since Q1 acts as a pre amp in fuzz mode you will more gain in circuit with a smaller value...

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    3. Try a jumper instead of the 220k before volume as a test. Does that at least get you louder?


      It may change the tone in a way you don't like. There's another Tone Bender with the same arrangement, and I read about changing the 220k for a 68k and the volume pot with a 250k

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    4. Yes!. Forget my suggestion about the 1,8k resistor. When Alex mentioning the 220k resistor before the volume control, I now I remember I replaced it with a jumper.

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  4. Yeah, I built it straight up with the jumper instead of the 220K.
    The Volume has no effect on the Boost side. Is that how it is supposed to be?
    Is this how the original was?

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    Replies
    1. Yes, thats how the original worked. Odd but true.

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    2. Ok, cool. I've only seen a couple of pics of the original unit and couldn't find any sound clips or videos.
      I'll try and adjust the 1k8 resistor as you suggested. Cheers:)

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    3. That did the trick!! I actually end up setting it for a nice slightly fuzzy edged overdrive. Fuzz side still sounds great!
      Cheers fuzzhead, keep up the great work 8-D

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  5. Just adding a note here for my own future reference... "Each unit will be branded with the 2N2926 type number and will also be color coded to identify the A-C beta range into which it falls. Segregation of the betadistribution into the five groups is provided, though it is not a requirement of JEDEC registration"

    Brown 35-70 Hfe, 36 typical
    Red 55-110 hfe, 62 typical
    Orange 90-180 Hfe, 115 typical
    Yellow 150-300 Hfe, 155 typical
    Green 235-470 Hfe, 215 typical

    The paint dot is on the top of the transistor."

    The transistors in the thread on the DAM forum have green dots. The Jerms video of this thing sounds great.

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