Wednesday, 1 August 2012

Vox Repeat Percussion

.. awaits comments asking what the bloody hell is that! :o)

I think a few people will like this, a really great sounding tremolo.  The 2N2646's are obsolete but still available from a number of places, RS, Farnell, Mouser and a few sellers on eBay.  They're not as cheap as the more common silicon transistors but definitely worth getting in for this. 




Original:




Modified to include a depth pot and altered values for more output.




Version with all of the above and a couple of extras including a Tone switch which switches the input cap to give you an option to prevent any low end loss, and a Fast/Slow rate switch.



152 comments:

  1. Mate you effing legend. I found that video on YouTube about a year or so ago, but I'd forgotten about the effect until now! Good one sir, will defo be getting my arse involved with this badboy tonight!! Thanks Mark! ;0)

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    1. No problem, I saw a faux pas and updated the layout and have also added a version with the additional switches I mentioned. The input cap switch may not be that important, better to just increase the input cap if you're experiencing any losses because you're likely to leave that in one position anway, but the rate switch should be a useful addition. But the options are there anyway, so make sure you've downloaded the latest versions above.

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  2. Will do sir thank you. Once I stopped behaving like a giddy schoolgirl, comprehension of the parts list set in. RS rockin it is! Will do what I can tonight though.

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  3. I'm hoping these are the same 2N2646 that the layout needs (as I've just bought 10), but at £0.92 a piece, these were seriously cheap in comparison to RS & Farnell;

    http://www.electronelec.co.uk/acatalog/2N2646_TRANSISTOR.html

    Had to pay £5 P&P, but you're still saving. Act fast though, they should only have 35 left in stock now. :0)

    Hope this helps.

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    Replies
    1. I just ordered 4 from Bulgaria! :o)

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    2. shit, i ordered 4 for £12 from fleabay :-(

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    3. I got 6 from electronelec. Plus i just to grab some other stuff too :)

      This one here is quite high on my list...
      +m

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    4. Over the last week i've spent over 500€ on parts.. Don't even want to check the receipts from paypal. I shouldn't be running out of basic stuff anytime soon...

      I think it's quite ironic.. I bet everyone starts out with just bare ammount of parts, and even all the resistors are ordered per pedal. Now, 59 builds later, my stash is wide enough to build anything right away - from scratch to finnish, but the list of designs i really want to build is just getting shorter and shorter.

      Maybe i should try to mod Tubescreamer to operate on 15 volts... :)

      Plus, Mark knows why i had to order so much stuff :)
      +m

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    5. Yes but it'll be all worth it in the end! :o)

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    6. I do think so. All hobbies cost money. And this one here isn't by far the worst i've had :)

      Just went outside to get a few small tools, like couple new spanners, some new pliers, long nosed lighters for heat shrink, couple bigger files and 1-13mm set of drill bits. Whoops. Another 50€...
      :D
      +m

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    7. Yeah like we were saying the other day, this is cheap compared to some hobbies. I wanted to buy a plane once! :o)

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    8. Im trying to compare the costs to buy the actual originals, suddenly it's all worth it :)
      And the feeling when you hold the finished boxed product is all worth it!

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    9. Uncanny! These three years past I've literally spent thousands on pedal parts & tools. Money I was supposed to use towards my PPL

      Ah well...

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    10. My cousin is doing it at the moment and is going on a flying holiday to the US to build up his hours. I really wanted my PPL but decided I couldn't be bothered with the fairly frequent renewals, so I thought about just getting NPPL so it was more relaxed but then decided I wasn't going to buy a plane unless I could fly to France and fill it with beer. So I had kids and became poor instead! :o)

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    11. Just pissed myself laughing. It's something I've wanted to do for years. Will do one day! I'll take you to France mate, we'll fill the plane with beer, beer & hot slags!

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  4. I wouldn't care but I've bought relays and transformers from Electron before but didn't think for a second they'd have any of these. Oh well.

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  5. So stoked to build this one! You rule Mark!

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  6. FYI fairly cheap at http://www.musikding.de/Active-parts/Transistors/Silicon-universal/2N2646::3029.html and the shipping is quite ok as well.

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    1. Just placed biggish order at musikding. Didn't even think they would have these.. Oh well. They are coming and i don't mind about the cost. :)
      +m

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  7. got some 2N2646's on the way :)

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  8. I knew this one would be popular :o)

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  9. Futurlec has some as well...

    http://www.futurlec.com/TransGen2N.shtml

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  10. Postman's just been, dropped off my trannies & this bad boy is VERIFIED. Sounds the tits, although the speed isn't as fast as on the video when the pot is maxed & the switch is in "fast". Do you know if different sized caps on the rate switch would make it any faster Mark?

    The depth pot seems to work backwards on mine too, but that maybe because of me also being a tad backward. I'm not really all that bothered by it to be honest, I'll probably leave it in one position anyways.

    Otherwise it's sweet & is a great effect, glad I made it & I'm glad you posted it, thanks matey. ;0)

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    1. Check it if you like;

      http://soundcloud.com/milkit-2/vox-repeat-percussion

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    2. Excellent stuff! Yes the cap value determines the rate so play around with lower values and see what you can get out of it. So do you think the depth pot needs swapping around?

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  11. I'm not so sure actually mate. At zero I get full effect of the swell & then from around 3 on wards (if increments are 10) I get a nice overdrive sound. I'd say it functions just fine mate, depends on how you prefer it to roll I guess. I'm happy with it as it is dude! ;0)

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  12. Sorry Mark, but it would appear that ibhsvecbeen talking shit about the pot. It works fine, I am an idiot!

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  13. & for some reason I can't type "I have been" properly! Shit I need a smokey!!!

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  14. I'm quite tempted to stick a few cap values on a rotary. Would all the neg sides of the caps go to common & from there to ground?

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    1. Yes if you connected all the caps from their own contact to the common and also connect the common to ground, then only the position selected would be in circuit. 12 position single pole should give you some versatility! :o)

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  15. Got my 2N2646's in the mail. Way too excited to build this!

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  16. Got mine today and built the circuit with mods. Really cool! Tremolo with an synth-like edge! Although i did couple little thing to the switches. I used 3 position two pol switches for both, and sticked 6n8 to the middle of tone switch, 82n to other end and 150n to the other. Pretty mean, as it overdrives the bass frequencies with 150n+6n8 :)

    For the rate pot, i first tried 2u2 in the middle and 3u3 + 4u7 for the others. That was way too slow for me, so i swapped the middle one for 1u. 5u7 (4u7+1u) is enough to keep it reeeeeeeaaaaaallllllyyyy slow with rate pot down, but 1u is killer fast with pot up.

    So. Three tonal setting and three different speed ranges.. Ah. This will get in a box real soon..

    Really worth of getting those special transistors :)
    +m

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    1. Yes it's well worth using those middle lugs to give you an extra setting with something like this. Do you think the 1u is as low as you'd go then for the Rate switch or would something lower be usable?

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    2. Probably.. I have elctrtolytics starting from 0,1µ, but 1µ is definitely fast enough (at least for me). I should build another circuit at some point, and i think i may try to start from 0.47µ..

      Current caps are soldered in to the switch, so i don't feel like swapping them. Guess i should breadboard that.
      +m

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    3. Well. It may take some time for me to back on the horse and start boxing my clones.
      http://mirosol.kapsi.fi/varasto/boxes_other/2012_08_unfinished_business.JPG

      Here's my currently unfinished builds. On the right, there are 20 bags of circuits waiting to be boxed, plus two unwired builds of The Boob Tube. On the middle, there's 9 boxes that are for something completely different (!), and on the right is my unfinished Madamp G2 (please english documentation is a horror, please. Too bad i don't read german too well...).

      Maybe a bit too many projects to be handled at once :)
      +m

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    4. Ha ha, and I thought I had problems with 2 or 3 to box! :o)

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  17. Anything I could temporarily substitute for the MPSA18? I've only got one

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    1. They can be quite high gain, and their low noise figure seems to make them good for this, but you could try 2N5089's or BC560Cs if you have either. Basically if you've got sockets then just try anything you have which matches the pinouts.

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    2. i haven't got the mpsa18 here with me either, but i used bc109c on my build and it worked just fine. i read somewhere that 2n5457 can also be used as a substitute? you can try them out if you have some.

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  18. So, decreasing the 100u electro will increase max rate?

    Thanks!

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    1. Nevermind. I tried a few values instead of the 10u electro (not the 100) and I think 3.3u gives the best rate range. I probably wont touch the depth knob...doesnt seem very useful...best at full.

      Haven't played with it too much yet, but I like it so far :)

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  19. BTW, put mine in a box yesterday and played with it for some time. Mine is pretty loud. Would say about 6-8dB over unity. Actually that's not too bad, as it makes nice sounding booster with 150n cap :) - Anyway, if someone's experiencing the same, it could be a good idea to take add conventional volume coltrol (or trimmer on a small utility board inside the box). Basic output to 100K (prolly a C-taper) pot's lug 3, new output from lug 2 and lug to ground.
    +m

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  20. Built this today with the rate switch mod (I used a 2u and a 4.7). I did not have enough switches for the tone mod. Sounds pretty cool to me. Think I will finally have the right trem. for Rem's "What's the Frequency, Kenneth".
    I have two questions.
    1. I still have some dry bleed through with the blend knob all the way up.
    It's pretty noticeable with the gain wicked up on my amp.
    What can I switch around to get full wet out?

    2.What does the tone mod do...and is it a "must do"?
    Thanks.
    J.D.

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  21. Built this up today with the original layout but used a 100n Input cap and wired a DPDT in where the the 10u normally goes. I'm gonna swap the 4u7 for something smaller, it's not quite as fast as I'd like. But other than that it's awesome! I love the one knob circuits!

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  22. Hey Mark,

    Another great pedal on the list now, already got all the parts in the post. But still being new to building I was wondering how you would change the tone switch into a tone pot instead?

    Many Thanks

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    Replies
    1. Mark is away for a week ;)

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    2. sar_ryder: You could add SWTC2 (http://www.muzique.com/lab/swtc.htm) to the output wire...
      +m

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  23. Just build this tonight.. everything's right, triple and quadruple checked the components, made sure there's no continuance in-between the tracks, everythings oriented and grounded right.. but all i get is a constant buzz sound (and very, very faintly behind it, the tremolo thump, which changes in rate when i adjust the rate pot, but no guitar). Any ideas on this one?

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    Replies
    1. Must be a bad joint somewhere. Can you probe it to see where the problem starts?
      +m

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  24. I'll reflow everything, I did check that, but will do again

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  25. reflowed and checked each connection, I have guitar signal now, still a drone buzz faintly behind the white noise, and no effect. I've built the v2 with the 2 switches. I've looked at the datasheet for the 2n2646, i'm wondering if it is being ground properly? bottom right hand part of the board (with the 33R and 47k, sw2-5, rate 1-2 & ground) seems.. strange, but I am a noob, so it is probably ok. Thinking of stripping this back to v1 or original..

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  26. I'm really determined to conquer this.. Buzz is gone (traced a bad ground), I get a dry guitar signal only now, effect on. I've socketed the transistors, check orientation and still no go. Interestingly, the dry signal is unaffected if I remove the transistors completely, or one at a time.. It is likely through my playing I've killed the three of them. I'm guessing the 2n2646 is the component that actually gives the effect - when I built and fired it up initially, I had it oriented the wrong way. How sensitive are transistors in the scenario? I'm going to buy replacements for the three tomorrow..

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    1. I placed it in reverse for the first time too. That won't kill it. But since my build of v2 works perfectly (louder than unity, but othwerwise perfect), i still think the problem lies in your build. Probe should give you a hint where the signal goes bad. It could be a faulty component too?
      +m

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    2. It didn't take me long, so yeah, I will get out the dmm and have a feel around, but I'll probably just rebuild.. Thanks for your help :)

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  27. rebuilt tonight v2 with mods, with all new components, switches etc, still dry guitar out with no effect. wahhh!

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  28. I have mine working good now. I swapped q2 for a lower gain 2n4401 and I get 100% chop (no dry signal bleed through). Have it boxed up with all the mods. Thanks for the great layout!

    JD

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  29. http://mirosol.kapsi.fi/varasto/boxes/RPTRDLX.JPG
    +m

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  30. This comment has been removed by the author.

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  31. Actually, what I really need and where I seem to be getting confused is with the off board wiring - I have for the whole 3pdt/true bypass thing down, and pots are pretty straight forward, but switches aren't that clear cut me, and I think hat where I've gotten caught in the last couple of builds. I'm a fast, visual learner, not seeing he off board wiring intricacies is like a missing piece of jigsaw puzzle. If anyone could give me a diagram or some pointers to guide me through that would be awesome :D

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  32. Also, apologies for my consistent crap typing, my iPad is very unforgiving :P

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    1. You could just easily ditch the switches and still have it per V2 specs. Here's what i would suggest:

      Tone: Take 4n7 cap and solder it below the 47n cap, so that it's other lead connects to row with Sw1-2 mark and other lead to row where it says depth 3. (rows 5 and 8 on the left side of the board - second column has space for it.)

      Rate: Take 2u2 or 3u3 electrolytic cap and solder positive lead to row that says Sw2-5 and negative lead to where the 100u cap's negative lead is - two rows up. So on the right side, last column, positive to row 5 and negative to row 3.

      Or if you can post couple of photos (top, bottom, outboard), i could check them out.. (my email is mirosol ät g mail dot com)
      +m

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  33. http://i1115.photobucket.com/albums/k543/jd_roost/VoxRepeatPercussionmodifiedII.jpg


    Hope that helps...Did not have much time.

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    1. Depth pot is in reverse, or it has to be viewed from top instead of bottom. But great work. Jeremy will be happy!
      +m

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    2. That is fantastic - i can't wait to get home after work and fix up where i've gone wrong. right away looking at it I can see my issues - i've got the ground at q9 running off to the mono plug ground instead of the switch, and i've got the depth pot wiring daisy chaning from the switch rather that the pot. will re-wire and see how it goes.

      Thanks guys - I really appreciate your help with this, i'll repost again and tell you how I went.

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    3. quick question - usually board grounds go to ground (like a jack), but this board ground goes to the switch and then back to the board.. is that right?

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    4. The way I Have been doing it is either running two or three grounds off the vero.Or one to the 3pdt (from the board)--over to the output jack lug and branched from there. The diagram was just to show you that that lug on the switch gets "grounded". It does not need to come directly from the vero.I have not noticed any performance gain by running everything it's own separate ground. Ground is ground in my book.

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    5. Keep in mind...I have only been building for a few months. The vets may have a better way to run their wiring.

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    6. Ground is common between all the points that need to be grounded. You can take two wires out from one ground hole on the board - take other to the switch and other to ... Hmmm..

      Check this out: http://www.generalguitargadgets.com/pdf/ggg_sw_3pdt_tb_gi_dcj.pdf

      All the grounds connect to each other.
      +m

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  34. Hmm..Thought I had the pots right (correct) if flipped and viewed from the bottom. #1 should be up top no? LOL oh well...should get him pointed in the right direction.I am learning as I go too.

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    1. http://4.bp.blogspot.com/-Eu1vuXVH3UM/TzGNIkeLuAI/AAAAAAAAAlM/h7re0CGH6A8/s1600/Pot20numbering.jpg

      I was partly wrong. It's the rate pot, not the depth..

      But i drew up this: http://mirosol.kapsi.fi/varasto/boxes_other/pots_switches.png
      +m

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    2. Printed...and filed in my "utilities" folder. Good stuff.

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    3. My pleasure :D

      I've had something like that on my wall for quite some time :)
      +m

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    4. That's awesome, very handy to have, printed and on my wall now as well. kudos!

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  35. http://i1115.photobucket.com/albums/k543/jd_roost/IMAG1197Small.jpg



    http://i1115.photobucket.com/albums/k543/jd_roost/IMAG1196Small.jpg

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  36. http://www.youtube.com/watch?v=jvmtGAOrMXE&feature=youtu.be

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    1. Still catching up on missed things while I was away, thanks for posting the vid, sounds excellent!

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  37. Ugh.. No 25k pots on Tayda, and local shop is too pricey. Is there any way I can modify the build to use a B10k or B50k for the 'rate' pot? I thought about using version 1 but I like the option to switch the rate. Thanks a ton for any help!

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    Replies
    1. Try 20K. That should be ok as is, with slight change in the knob behaviour. Or head over to Futurlec. :)
      +m

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  38. jgoulds I made the version one with a rate switch. All you have to do is put the 10u on a DPDT. I thought the 10u was way too slow though so I used a 4u7 for the slow mode and 1u for the fast mode. I think I'll increase the value of the 1u slightly to get a small amount of overlap in the two rate modes, but overall 4u7 and 1u are really good!

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  39. iI have a slight add on query for this one
    Would it be possible to add a rate led to this to indicate the speed?

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  40. have been wanting one of these for years! am in the midst of the modified II version. Thing is, just noticed you have the Depth 3 wired to the switch and also to the board at A8. How should I wire these wires exactly? Cheers

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    Replies
    1. All three points need to be connected so just wire to one, then daisy chain from that to the next.

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  41. Cheers for quick reply Ivlark. so Vero > Pot (Depth 3) to DPDT Switch.

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  42. Thank you! This is an awesome trem. 3u3 is the rate cap for me. I put another in series on a switch for double time. I am getting a boost in volume after the Kalamazoo. Any suggestions that can bring me back to unity or add a volume pot? Thanks again!!!

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  43. I finally got my 2N2646 from futurelec. It always seems to take a month for their oxcart to get to the US. Anyway, it worked right out of the box and it sounds amazing. With the switches, I was not able to get it into a 1590B, so I might try a 125B. I'm not the best at space management. Thanks for this and all the layouts.

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    1. This should fit in a 1590B quite easily, you should think about mounting the board upside down, that gives you lots more room.

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    2. My trouble was with those big capacitors hanging off the switches. They are bent almost flush with the bottom of the switch, but they take up a lot of room. It's no big deal. I am not one of the "smaller is better" crowd. You will never see me use a 1590A for anything - ever. I don't have that kind of patience. Take care

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  44. Built this a few days ago (modified version with switches). Sounds amazing! I used 4.7uf and 2.2uf on the speed switch (the 10uf was waaaayyyy to slow).

    Thanks for another great layout. Glad I bought two 2n2646 so I can build another one of these :)

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  45. Sounds like a random question, but could I add a switch to hook up a second pot for rate and still keep all the other mods the same? What I am hoping to do is use a toggle switch to go back and forth between two different preset rates. Would that work?

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  46. Thanks, guys! I just built this and it's an amazing little pedal.

    Had a little trouble with the 10u cap like several people here. 1u - 4u7 seems to work well. I tried .47u and it was not very usable at all.

    Here's a picture. I don't have it decal'd or anything yet, just finished building it.

    http://dl.dropbox.com/u/3078710/Vox_Repeat_Percussion.jpg

    The labels are vinyl tape and ink pen :p

    Skullz are some guitar knob cast offs that I put on it temporarily (all my normal knobs are knurled). Not sure if this pedal is "brutal" enough to leave them on. :)

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  47. Love this thing. Miro had a great suggestion on another thread that I built into mine (volume control). I also added a momentary soft touch spst for the double time stomp which makes this a cool live usable effect. Very funky at hi speeds. here are some pics:

    http://i1273.photobucket.com/albums/y413/glenncohen/_DSC0085.jpg
    http://i1273.photobucket.com/albums/y413/glenncohen/_DSC0079.jpg
    http://i1273.photobucket.com/albums/y413/glenncohen/_DSC0078.jpg

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    Replies
    1. How do you do your labeling / graphics? It looks killer!

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  48. This is a great pedal. I built one that worked great, so I decided to build up another and put it into a box with a fuzz factory. The second one works great but I have a ticking bleeding through into the dry signal. Anyone have any suggestions on how to deal with this?? I have switched my grounds all around a few times to see if that would work, but I'm not sure what else to try, because everything works great except the tick.

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  49. you could use a switch that grounds the output(when off), the switch drawing on this site shows you how to ground the input. i think it would be prety simple if you use a 4 pole switch, hope it helps. : )

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  50. Updated picture:

    http://dl.dropbox.com/u/3078710/Pedals/2013-01-19%2005.33.50.jpg

    I *love* this pedal.

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  51. Loving this pedal. Easliy one of my favorite yet, however I get a volume drop in the depth pot on the lower third of its travel to the point where its at zero I lose all signal. Am I right to assume that placing a 5-10k resistor leading to lug 1of the depth pot would correct this?

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    Replies
    1. Nevermind, I switched the depth pot wires.

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  52. Hi, soz noob problems, can any1 help. Am getting full 9v on base2 and .3 less on emiter and nothing on base1 and all my pot eyelet readings are 9v, this isnt right, any suggestions?

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  53. Hi All,
    having a frustrating noob problem with this one. Have finished the basic model, and I can hear the thump of the tremolo, and a small amount of guitar signal but no guitar/effect signal. have reflowed solder, double checked resistors, and replaced a dodgy 10uf electro, but still no joys, don't seem to be getting a signal from the input wire? Any ideas would be appreciated, as I say I can hear the thump of the rate pot loud and clear, but cant think of what to do next other than start again! This is just the board, jacks and pots, have not boxed it. Cheers

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  54. Hello again,
    Well managed to finish this one, after realising an embarrassingly simple fault! Anyway this is my first build with dc/led/toggle switches etc, and I love it it. My only problem is that when I plug my adapter in to the pedal there is quite a lot of noise, static/white noise. When I use just the battery it is nice and quiet, any suggestions, thanks in advance.

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    Replies
    1. Check you have good joints on the adapter and reflow if necessary.

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  55. I use 4.7k instead of 47k at the rate connection and don't need speed switches. Goes from sssssloooowww to super fast. That's from a schematic by analog guru.

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  56. Hi, just a quick question. Could I reduce the output, without adding a volume pot, mine is a tad loud, which cap/resistor would I change and to what value, thanks!

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  58. Has anyone done a layout of this circuit with the caps for the rate and tone mods on the tagboard, and using SPDTs instead of the DPDTs?

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  59. I just built the depth control version and the depth control is behaving weirdly for me. With full depth, the trem sounds great but cuts the volume substantially. As I decrease the depth my full signal is restored but the trem signal is quickly lost. Anyone else have this problem?

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  60. Hi guys,

    I need help with this. Effect is ok and present but...radio interference are also present...I can't get rid of radio signal...it is on when I max (or go to max) of depth pot. I use B50k for pot. Effect is cool but please help me get rid of this radio interference.

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    Replies
    1. I had this problem in one of my Repeat Perc builds, kinda liked it for a day, then decided to get it right. I fixed it by doing a star ground onto the metal enclosure: make sure all grounds connected at one point and making contact with metal box [I soldered a wire from star ground into one of the 4 screw holes in the box]. I used plastic jacks on this build so the ground on the in/out jacks wasn't grounded to the enclosure. Next build for this circuit, I used metal jacks & had no issues with radio.

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  61. I get a distinct 'pop' that is in-time with the rate knob. It makes this effect unusable at this point, does anyone have any idea why? I made the modified II version.

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  62. Hi,

    I ran into some weird issue with this one. I can't get it to act as tremolo, to go up and down with sound volume (don't know how to describe it but just to do what tremolo does). I get rate knob working, both switches are working but depth knob is somehow out ot sync. When I max pot I hear ticking (from switch and rate knob) and when I put it to min it just acts as volume pot. Like it can't take fx to put it together with guitar sound. I don't know how to describe it better but please help me I will provide all additional info you need.

    I have build v2 with mods as I indicated but also have added anti-hum mode (from madbeans forum) because pedal was humming too loud no it does not.

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  63. so i'm getting a bit of dry signal through (i built the original version with no depth pot- just a speed pot) I saw someone recommended using lower gain transistors for the mpsa18's and I tried that, but I'm still getting dry through which is killing the psycoaural effect from this circuit. sounds good and percussive just not as much as it should be.

    help please!

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  64. What are b1 and b2 on Q1? What happened to c?

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    Replies
    1. Ha, that's why the first line of the post was "awaits comments asking what the bloody hell is that!" :)

      It's a unijunction transistor and so a bit different from what we are all more used to. If you have problems sourcing these ones, I will be doing another tremolo at some point in the next week or so which is very similar but uses unijunction transistors which are more commonly available.

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  65. Bloody hell indeed.....I learned something new today. I was able to find the 2646, although they are a bit pricey. Can't wait to try 'em! Nice work, as usual.

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  66. well, I finally got around to building this thing, and now I wish I would've built it sooner! I built the modified one with the depth pot but without the switches, and at first I was disappointed with the results. building it part for part as per the layout, the only speeds I got were slow and slower. someone earlier in the posts mentioned the 47k from the emitter to rate 1&2 being 4.7k on the schematic over at fsb, so after reading all the posts over there and playing around a bit, here's what I came up with- 4.7k yields way more range in the rate pot. so much so that the 2N2646 on my build would lock open at the end of the pots sweep causing the effect to disappear. I tried several resistors and settled on a 10k. I also played around with the 10u cap value and ended up using a 4.7u in its place. the result, at least for my build, is a very useful range of speed that goes from almost too slow to almost too fast. I just thought I'd share my findings, since this thing does sound really sweet once its dialed in.

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    1. @atomicwombat: Thanks for posting this GREAT mod. After substituting a 10k resistor and a 4.7uF cap using layout #2, the very wide range of speeds are just as you describe. This makes the pedal much easier to operate since there is no need to add an extra rate switch. An excellent and unique sounding pedal. A recommended build.

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    2. Thanks for your mod! It's awesome. I already built 2, and both had the switch. With the switch you dont know at what speed you will be and there could be overlap. This works like a charm and saves space! The fastest pace is so fast now it's a whole other effect on top of the already great sounds. As stated above: Highly recommended!

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  67. just trying this as my first build, sounds sweet apart from a slight ticking in time with the rate.any ideas on a flashing rate led?
    thanks for the layouts they're TOP

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    1. I'm planning to try it. I think a using COSM 555 timer chip is the way to do it… take a wire from the lfo out to led via a resistor. The only way I can imagine would be to have a daughter board of sorts. Anyone here have a better answer?

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    2. I posted a solution for a rate LED mod w/image. It was posted below on January 4, 2015. Super simple add-on.

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  68. Hello
    I built this thing, It works, but I have a permanent hiss and a light alarm sound. What did I do wrong ?

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    1. Those symptoms could be explained by a tiny solder bridge between the gaps or a bad solder joint somewhere. Knife the gaps and look for suspicious looking joints.
      +m

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  69. Thank you for the super fast response !
    I'll check the solder.

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  70. Just made the mod II version (including mirosol's suggestions for cap values) and WOW! This one is definitely going on my board as soon as it's boxed up :)
    Thanks for the awesome layouts!

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  71. Hi there.
    Made the dumbest mistake ever. Drilled a hole too many for my fuzz factory-tremolo combo. So... I was thinking of adding a speed/rate blinking led. Does anyone have an idea how to do it?

    I keep reading things about a led between the collector of the q3 and +9. Can that be done with the 2n2646? I don't have a breadboard to try it yet, and have no idea what resistor I could use best. Anyone know how to?

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  72. To display the rate, I placed a LED between B2(Q1) and Rate 3 with the LED anode(+) connected to Rate 3. Depending on the brightness of your LED, you may need an additional load resistor (470R is the only one there).

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    1. Thanks So much for your reply!! Could not find it anywhere!

      I placed a led with the anode in the last hole of the row of B2. The cathode goes to a resistor (10k) and then to lug 3 of the rate pot. This does not have any effect, so I guess I'm doing something wrong.. Is it the value of the resistor that is not correct? Or should I place the cathode in the top row?

      Sorry for my late reply, I had this page open for days and did not refresh it apparently :s
      Thanks again. Also changed the cap on the switch to a 2u2 thanks to you. Sounds much nicer.

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    2. Maybe the 10K resistor is preventing the LED from lighting up? Try it without adding the extra 10K resistor. Here's a picture of what I did;
      http://llamamusic.com/images/Vox_Mod_20150104.jpg

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    3. Thank you! That's so helpful. I will try that tonight!

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    4. It did the trick :) Thanks so much! God, I have searched everywhere, found the questions, but never the right answer.
      Only have to get rid of the ticking noise (at least when the effect is in bypass)..
      Thanks for your help so far, on to the next and last issue :D

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    5. Glad the rate LED worked!
      BTW... don't spend too much time trying to get rid of the ticking. I've spent hours troubleshooting that and have even isolated and rewired the transistors on separate boards. So far... no luck.

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    6. Haha ok. I won't sweat it to much then... Gonna try to move some of the grounding around and give it up then if i have no luck.

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    7. I should clarify my last comment by saying that if it's ticking in Bypass Mode, by all means, troubleshoot it. That's an issue. I just can't get mine to stop ticking when the stomp switch is on.

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    8. Ah crap... hm, thanks for the heads up. Will definitely do that

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    9. Ok, update.. I replaced some of the grounding a few times. The weirdest was at the ' battery-lug' of the input... Made al the leds flash in sync.. Not good! haha

      Eventually what I did was: I grounded the circuit to the rate-switch (slow fast). That eliminated the ticking in bypass. In fact, when it's on it's barely hearable too, and that with a fuzz factory before it!

      Thanks for all the help!

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  73. Hi evrybody !
    just want to know by what can i replace the condensator 4,7 nf of the 3pdt tone switch…
    I've in my stock 3,3 nf & 1nf ! what can I do ?
    Thx

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    1. The closest one to it would make the most sense, but you will obviously affect the frequency response compared to using the 4n7. It will probably give you slightly more treble in that position.

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    2. ha ok !
      thanks for your quick answer !
      I've time for my project ! i'will buy in a next order !

      Franck

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  74. Hi,
    a good booster but nothing about tremolo… :(
    Any Idea ?
    My PCB look to be perfect ! I don't know why but nothing tremolo……… :(

    Franck

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    1. Just for information, when i take off the Q1 2n2646, it's result the same !
      The tone switch work fine but not the rate switch ! not any effect ! just boost the sound when I Inrush the effect ! do you think the 2n2646 could be burned ? but why ? Is anybody can tell me the direction or position of it because i'm not sure of me…
      Please help me… I can measure the values ​​and positions of the ic i somebody help me !

      Franck

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    2. all is ok, the 2n2646 was at reverse !
      The fourth stomp boxes work very good now ! if you want to see my work, it's finished !

      Franck

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    3. https://imageshack.com/a/6NXz/1

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    4. You have done a great job there Franck. That plexi top is great, good to see a tidy and interesting internals
      Well done

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  75. Hi guys,

    I know this build is from a while back but I've been tinkering with mine recently and got some very cool results.

    I built Version 1 (as above) but with a switch in place of the 10uF cap (DPDT On/On) allowing to switch between a 10uF and a 3.3uF. And in place of the 47K resistor joining Rate 1&2 to the emitter of Q1 I used a 33K.

    With this combo I managed to get speeds ranging from 90bpm at the bottom end when 10uF is selected and up to a very fast flutter (I'd say ~800bpm) when the 3.3uF is selected and maxed out. The really cool thing is that the combination of 10uF and 3.3uF has zero crossover and they meet perfectly at 250bpm.

    With a 4.7uF in place of 3.3uF I was getting about 50bpm of redundancy (4.7uF would bottom out at 200bpm) but 3.3uF bottoms out exactly where 10uF maxes out. I'm not sure if everyone can expect this or if it's just my good luck with the 2N2646 I purchases.. maybe it's even the 33K helping? I'm not 100% sure. I just know it sounds killer, has a huge range and has no redundancy.

    Anyway, perhaps that mod will work for someone else. I'm going to try building a second one for a friend and see if I can replicate it.

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