Monday, 13 January 2014

Creepy Fingers Doomidrive

Request, with thanks for forum member 'doomidrive' (just to confuse matters :o) for the pictures and information to allow us to do the trace.

A popular effects used by Hendrix and Page amongst others, here's the short but sweet overview:

A faithful reproduction of the vintage Univox Uni-Drive circuit with original NOS transistors and bottom control with some added modern improvements. 






54 comments:

  1. Volume 2 to output :)
    Should be good with BC550 I guess ?

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    1. Aaarrrgghhh! :o)
      Yes any NPN silicon transistor should be ok, I've read of people using 2 x 2N5089 for Q1 and Q2, and an MPSA18 for Q3 with good results in a Unidrive. It may be worth selecting them with a BCE pinout though to match the layout. The BC184L is mentioned in one datasheet as a replacement product for the 2SC859 which may be a good choice for the pinout.

      Smallbear do sell them though if you want the originals.

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  3. Ignore my last comment. It's verified!. I had an error that I'd rather not admit to!!..The sun is out here and it distracted me!.. Sounds exactly like the demo.

    Cheers mate!

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    1. So Vince, which trannies did you use, the original ones ?

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    2. Excellent, nice one matey :o)

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    3. I used 2 x 2N5089's (Q1 &2) and an MPSA18 for Q3. I used that combo in the Uni'Drive that I built but this has about 10 times the amount of drive than the UniDrive.

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  4. Incidentally, what sort of differences in sound does the trimmer give you? In the original that was a fixed 8K2 resistor

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    1. On further testing there is a very early note decay no matter how the trimmer is set. The trimmer doesn't seen to affect the sound much, just brings the sound in but doesn't seem to bias anything (in my build anyway). Maybe this needs a bit of fiddling with different transistors.

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  5. Doomidrive here. Sorry I didn't get back to you sooner.

    The pot values are:
    Volume - A10K
    Bottom - B250K
    Drive - B100K

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    1. Excellent cheers. For anyone who has already built it or started building it I think the Bottom will work fine with a 100K because it's just used as a blend between the two input caps and so it isn't hugely important, as long as it is "enough" or more. But I'll change it on the layout so that it's accurate.

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  6. I drew up my own vero and built my Uni-drive last year using NOS OEM transistors. it doesn't have anywhere near as much fuzz/distortion as the Creepy Fingers version. the stock one is more of a clean/dirty boost, but that CF version does sound very good in the clip.

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  7. just finished building this one and I like it a lot more than the original. I used NOS SC859's in it. the trimmer adjusts the amount of final gain and I like mine set to the maximum.
    the only difference that I made was to add a 1K resistor from Drive 1 to ground instead of directly to ground so it wouldn't completely kill the signal when it was fully CCW.

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  8. Oh boy. I've been waiting for a Unidrive or variant to pop up here for a long time! I don't think it could get better than the doomidrive!

    So I'm excited to build this one, but I have some reservations because I always feel weird copying the really cool small builders

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    1. DIY is DIY mate, I wouldn't have any reservations. Just don't build 10 and sell 9 :o)

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  9. I nearly bought one of these, but thought I'd go for the Creepy Face instead.
    This is defo my next build.
    I really need to buy some houses for these circuits.

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  10. Turns out that I've got everything I need to build one of these on hand! Well no 2SC859 but plenty of alternatives. I think I'll order some from smallbear just for fun

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  11. Thanks! This'll be a fun one! IVIark, sorry for the random off-topic question, I just build a dual OD of a Timmy+3-knob red snapper, and both sides sound great, but with both engaged and even with both gains rolled back there is a high-pitched whine, it's not un-useable, just annoying. Both sides sound really awesome, but I'd like to use both together without having to roll the gains way back. Any way around this? (Red snapper is first in the chain, I sed a Tayda KIA4558

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    1. Try a low value (maybe 47R to 100R) resistor in series with the supply to both effects and the same low value in series with the input.

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  12. *and a LM1458 for the Timmy. Is this an IC problem, or just too much gain & output? Anyone have any solutions? Thanks in advance!!

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  13. Sorry for the dual posts, my phone is being stupid!

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  14. Hi Mark,
    Haven't built this yet.
    From your schematics Bottom 3 goes to the negative side of 10uF.
    Is that a mistake?
    Thanks

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    1. No it's a Bottom control so the bass increases when you turn it up.

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  15. Sorry, Mark
    I must be a bit slow.
    Bottom 3 goes to the negative or positive side then?
    Thanks again for your quick reply.

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    1. Sorry Alex, I just noticed the layout. I knew I wanted it to go to the negative side but for some reason didn't. So yes the input goes to negative, thanks for the heads up I'll alter the layout.

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    2. Incidentally Vince, I know yours worked but definitely swap that round, it may solve that early gating you were having.

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  16. Thanks! I'll try that and report back. Do I need one to both effects' inputs? (Or the input to the jack?)

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  18. Hi Metalman,
    Forget my answer!
    I thought you were talking about another pedal.

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  19. Haha no prob! Did you see my previous posts? It was a question about a dual OD build, a Timmy + a 3-knob red snapper OD

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  20. I just hooked this up to my test rig and it sounds sweet, lots of gain. The trimmer doesn't do much. I used 2x 2N5088 and an MPSA13 But I am getting some high pitched oscillation, any idea how to fix it?

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    1. It's the nature of the beast with some gainy circuits, many of them are noisy for me when I breadboard. The noise should disappear when the circuit is boxed.

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    1. Exactly what is the trimmer's intended function?
      It appears to me to be some sort of feedback loop(?)

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  22. Welp, I finished boxing this one up and it's kinda too late to crank it but seems to sound great

    http://i825.photobucket.com/albums/zz176/Dub-T-123/Mobile%20Uploads/photo_zpsc8404b2f.jpg

    I didn't have a 47k trimmer, so I just fixed it at 47k. Transistors are 2SC828.

    I'm excited to play around with this pedal more tomorrow

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  23. And the money maker

    http://i825.photobucket.com/albums/zz176/Dub-T-123/Mobile%20Uploads/photo_zpse7e43a56.jpg

    This pedal is awesome! Super loud, low end is really tight throughout the whole range of the bottom control, and its super crunchy and clear with chords

    This will be the perfect addition to my board for an upcoming project. Thanks for the effort you guys put in making this layout!

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  24. simple distortion...without the weight / bass demo

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  25. How might i go about adding a mid control? I'm building for my friend and he seems paticularly adamant about it. btw, haven't begun yet, just don't want to disappoint seeing as we'd have to pay shipping back and forth between the US and Sweden if he didn't care for it without! :/ Is it possible or nonsensical?

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  26. i think im just going as is. the bottom control seems to have great range through frequencies, not just those in which it implies. haha. perhaps this is why i was neglected the answer to my question. thanks for posting this one. super useful circuit.

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  27. Hi there, I'm looking for some advice on this build.
    This my second attempt at building a Unidrive. The first was on I breadboarded, but it sounded awful.
    So I decided to build this one.
    I am pretty much a novice when it comes to building pedals, with just a woolly mammoth clone under my belt.
    I have built this pedal but cant get it to work, other than on bypass. No hiss, led or anything when switched to the effect. I suspect that my final wiring may be the problem. I have tried to wire up a power supply jack to the positive track and the ground track and a true bypass switching like so, http://img716.imageshack.us/img716/8838/3pdtledwiring.png, omitting the led connections.
    Effect output going to volume 2, Effect input going to drive 3, Jack output to output jack tip, Jack input to input jack tip, Ground to input jack ring, wired the rings together and to the negative/ground track on the board, Led negative to the negative/ground track.
    I'm at a loss to what I have done wrong, or what the problem may be.
    Can anyone help me out?

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    1. I usually use this offboard wiring (Actually its the same than the yours, but more complete), http://www.madbeanpedals.com/tutorials/downloads/StandardWiring_MBP.pdf


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  28. The riff starting at 0:39 is that by The Endless Blockade (1st song from Turning Illness...)?

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  29. Tried to read what I could but has anyone asked what a 2sc945 would be like in here? Only ask cos Tayda has them by the bucket load but imagine they're not gonna cut it.

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    1. I've got some 2SC945's basically because they were so cheap but have never tried them in this. Certainly worth a try though at the price they can be found

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    2. Thanks Mark. Sounds like it might be worth a shot for the $$$.

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    3. Man they ar CHEEEEAAAAPPP. I did some looking for pedals that use them and I came up with two. One - boss ce-3, and the second was someone that used them in a Kay fuzztone clone. So they might be good in a bunch of different effects. I would definitely give them a try.

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    4. They're worth getting in just for BCE pinout for when they are required and using 2N5088 or similar would be a pain

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    5. Hmmm. According to the datasheet from tayda they're EBC. So I wonder if it's just the Fairchild ones they sell or if they come in different pinouts, or if the datasheet is wrong.

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    6. Never mind. Im an idiot. They're listed as ECB, so if you turn them around they are BCE, and I miss typed it as EBC.

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    7. Ok built this using 2N5089s in Q1 and Q2 and MPSA18 in Q3 (had to twist legs) and fuck me its loud, but its also really good. Worth a build if you like em loud.

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