Monday, 4 March 2013

Vox Tonebender compact version

I was doing a request, and this one was so close to the one requested, so i thought i'd draw it up too. Mark has published this in the past and that one fits easily in B, but the one i'm posting now should be doable even in A... :) This also features a trimmer for nailing the bias just right for your transistors.

It may sound a bit thin to someone's liking, so upping the 4n7 for 10n, 15n or maybe even 22n would give you much more bass responce.

First up, the PNP version (this uses positive ground, so a inverter circuit as a addon, perhaps?):


And the NPN (to be daisy chainable):

Posted by at 08:21
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32 comments:

  1. Kinski7 March 2013 at 19:55

    Would this be the MK 1.5?

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    1. mirosol7 March 2013 at 20:53

      Nope. This'll be the original: http://youtu.be/vphRkUHMYwk
      +m

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    2. Kinski7 March 2013 at 21:04

      Will be finished in 15 min. Will report back.

      Delete
    3. Kinski7 March 2013 at 22:01

      Yep, works very nicely. First tone bender of any kind I ever built. I find it a bit thin compared to my fuzz face type builds. I had some NPN Germaniums that needed a home. This was perfect. Thanks!

      Delete
  2. Travis7 March 2013 at 20:28

    Verified

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  3. Kinski7 March 2013 at 20:47

    Almost done with the NPN version. Realized I'm out of 15uf caps. Any respectable alternative? Would a 10uf work? I've got a million of those....

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  4. Travis7 March 2013 at 21:29

    In the excitement of my first verification I forgot to say thanks for the great layout! Thankyou!

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    1. IvIark8 March 2013 at 00:56

      Congratulations on your first Travis, may there be many more in the future! :o)

      Delete
  5. Unknown3 April 2013 at 18:39

    This was my first build also...sadly I didn't have the correct parts so I substituted...unsurprisingly it sounds like junk (I was secretly hoping it would be magical...). I had to swap the 15uf for a 22uf, the 1K pot for a 10K, and only had some Si trannys (2N5089). Is there any other substitutions I could make to accomodate for a lack of "accurate" parts? I know I can drop the value of the 1K with some transistor bridging but I don't know how...

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    1. mirosol3 April 2013 at 18:45

      The 10K pot is the culprit. You really need 1K linear here to get a workign fuzz control. Just take two 470R (or 510R) resistors and solder those to the pot. First from lug 1 to 2 and secong to lug 2 to 3. That won't f up your taper too much...

      22µ is ok for 15µ. It should also work with any transistors (recently build one with BC301s and that was awesome). The 4n7 cap at the output - i'd recommend upping that to at least 22n.
      +m

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    2. Unknown3 April 2013 at 19:09

      Awesome, thank you so much!

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    3. Unknown3 April 2013 at 19:10

      I upped it to 12n from the get go as per your recommendations...I'll fix the pot first then mess around with the other parts.

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    4. mirosol3 April 2013 at 21:44

      No problem. Let us know if it lights up good :)
      +m

      Delete
  6. Unknown5 April 2013 at 19:48

    Ok! So I figured out what I messed up...misread the layout and reversed the electrolytics...and had one shifted down a row...argh. I definitely blew the caps so I swapped those and now the pedal sounds like a legitimate fuzz...but I think something else is damaged as there is a crazy, scratchy, hissy sound when I'm not playing. Any indication what might have gone south there? Now that I know it's working I think it's just a damaged component...of course it's just a tangle of wires and components...but this isn't signal interference :)

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    1. Unknown6 April 2013 at 15:12

      It's only in hindsight I realized how gross of a difference 10K to 1K is...I was thinking of how marginal ohm differences might be in lower ranges...9000 ohm difference is quite a bit. Well, at least it got me thinking! Almost have the circuit functioning but am having a weird fizzle out of the note at the end of decay...like something suddenly dying, a swallowing type sound.

      Delete
    2. mirosol6 April 2013 at 16:01

      2N5089s are known gate up quicker and simply differently than most other transistors. That could explain it...
      +m

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  7. Jarrett Trezzo8 May 2013 at 15:43

    Used some NPN OC140s I had, sounds nasty. I put the 4n7 and a 22n on a DPDT. Wanted to be able to get that digusting shred your ears fuzz with the 4n7 but the higher value is a bit more practical. I might switch it to a 10n though as the 22n is a little too bassy to my ears.

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  8. Alltrax744 July 2013 at 10:40

    I latelly built this one with AC176 NPN trannies, as per the layout except for the 15µf that i replaced by a 22µf
    It sounds absolutely awesome !
    Well balanced tone, no decay, no gating, behaves great with the guitar vol pot.
    I'm very happy as I haven't been very lucky until then with Ge fuzzes

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  9. souljah12 September 2013 at 12:08

    i built this one with bc301 as per miros and he is absolutely right they are nice and creamy, unfortunately i had to use higher hfe than i would have liked at 140 and 154 so i cant crank the fuzz or it starts to oscillate i will try with mp38's when they arrive but this is a great layout, small simple and incredibly effective, thanks guys!

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  10. Unknown7 June 2014 at 16:27

    hi, I built this and liked the fuzz but got some unwanted noise and radio interference when volume is lowered I tried to shield the wiring using a layout from another tone bender but get lots of hum now! anyone know a correct wiring for this?

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  11. Jeff23 September 2014 at 16:49

    I got this working, but have a couple issues: (1) I can't quite get up to unity volume, even with everything dimed. It seems like there should be more volume available. (2) I replaced the trimpot with an external pot, but I can't get voltage on the Q2 collector to go over 4.3v. Maybe this is related to the volume issue?. (3) If I turn down my guitar volume pot I get a quiet high pitch sound.

    The other change I did was swap the power and ground wires since I did the PNP version and didn't want to deal with a polarity adapter. I checked both ways (swapping wires, and not swapping but using a polarity adapter instead) and they seemed to produce identical results in terms of voltage and sound.

    Any ideas would be appreciated. Should I check other voltages somewhere?

    Thanks!
    Jeff

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    1. Zach23 September 2014 at 18:03

      Did you reverse the electrolytically too? If you're using a pnp transistor everything that has a polarity ends to be reversed, not just the power coming in. I would bet that's your problem. You might want to check the caps when you remove them to make sure you didn't kill them. If you made the pnp version then you should follow the pnp layout as it is not use the npn layout and reverse the power.

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    2. Jeff23 September 2014 at 19:31

      Thanks for the reply Johns. I followed the PNP version, including the cap orientation. I may be confused by the -9v for PNP vs. +9v for NPN, though. I understand how to wire up a board for traditional +9v power. But to get the -9v power supply my understanding was I could wire the enclosure and jacks like normal, but swap the ground/power wires. Or do I need to do my internal wiring different too?

      Thanks again!
      Jeff

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    3. Zach24 September 2014 at 00:34

      the internal should be the same, but what you can do, is make an inverter that will convert the +9V to -9V. if you do that then you wire everything the same to the inverter daughter board, and the follow the two new power connections to the correct location on the circuit board. the positive of this is that you can daisy chain this pedal too if you choose.

      Delete
  12. Jeff24 September 2014 at 01:57

    Cool, I'll look that up. Is that what everybody does to get from +9v to -9v then? Or is there another way that doesn't require a daughter board? I'm not too concerned about daisy chaining since I use a 4x4 power supply with isolated inputs.

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    1. Zach24 September 2014 at 03:31

      a lot of guys do that. you still need to worry since the voltage coming in is still going to be traveling as +9V into the effect unless there's a dedicated -9V output from the power supply. here's the address for the one you want to use from the site:

      http://tagboardeffects.blogspot.com/2013/02/ne555-voltage-inverter.html

      you can use either the ne555 chip or ICL7660s. if you use the ICL7660s make sure it has an "s" at the end, as the ICL7660 will not work as well and can give you problems. i would order a bunch from ebay, as the 7660s cab still be fairly cheap compared to the ne555.

      Delete
  13. Jeff24 September 2014 at 03:40

    Awesome, thanks so much. I'll give it a try. Though it still seems like reversing my wiring at the jack (assuming I am not using a battery) would produce -9v. I'll need to keep reading on this to get it sorted out.

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  14. XCBeast94420 January 2015 at 11:35

    Has anyone found any suitable Si transistors that would work in this circuit? I'd like to try this one out but I can't seem to get my hands on any tested NPN Germaniums for a less-than-crazy price... Any help would be appreciated! Thanks

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  15. veli30 July 2022 at 13:44

    With 1KC (antilog) pot is much better. The whole attack range is useful, smother transition from soft to full fuzz. Great circuit.

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