Saturday, 28 June 2014

EHX Small Clone

Modded to include a depth pot instead of the switch used in the original, giving you variable depth control rather than just two preset levels.  Not the best looking layout with too many links and cuts, but it's a means to an end, and it's hard to avoid when you have 4 ICs, 3 transistors and lots of interconnections, so I'm just happy that I managed to keep the size down.  21 x 28 will be a squeeze to get in a 1590B, but with only two pots and no other switches it shouldn't be a problem for most people.

I didn't have enough room to fit in pulldown resistors on the input and output and can't bring myself to add extra columns just to do that, so if you get any popping just add them to the stomp switch, 1M between input board wire lug and ground lug, and 100K between output board wire lug and ground lug. I may actually do it with surface mount resistors on the copper side of the board (the entire second row is ground).

Anyway, you all know what it is so no need to describe further.  Manufacturers info about the great sounding, and very well priced original.

The classic chorus! Analog chorus pedal popularized by Kurt Cobain. The finest analog chorus sounds: from clear, rich and dimensional to warm pulsating warbles, can be intensified with the Depth Control. Simple tweaks generate exciting doubling effects. Chiming 12-string tone, or Leslie-like warbles.






71 comments:

  1. Can't wait to build this. One problem that I noticed was that there are two Ic4's and no ic2's on the layout.

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    1. 2n5087 hmm pnp.. 2n4125 & bc558 theare work? :)

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    2. Yes they should work ok

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    3. damn the entire second row is ground :)
      yes work love this sound.. i have little angel & NYE edition and zombie. . next project ce-2 . :) thank for layout iviark,cheers
      you Rock. hahaha

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  2. This is cool! I'm in heaven with all the cool circuits you've been posting lately.

    Any chance of the Small Stone? Many of us may have ordered CA3080 recently to do the Janglebox so it would be perfect timing :P

    I also have a vintage (version 2) Small Stone if you need any info though it seems well documented

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    1. Hey Travis, where did you source your CA3080's? I'm guessing eBay, but did you find any particularly good deals? I'm about to purchase a bunch myself i think.

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    2. Sorry Sean I spaced on your post

      I can't find any cheap CA3080 or NTE996. Unfortunately I think we just have to pay the price for them :/

      Seems that they're used in some great circuits anyway

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    3. I get mine from Dr. Tweek:

      More expensive, but sound great with very low noise.
      http://www.doctortweek.co.uk/shop/article_533/CA3080e-%28OTA---Operational-Transconductance-Amplifier%29.html?sessid=HDxdJIHiEomJXrfjqWkXXEuX0G5zZbyH017U7z8TwjQPEyr2FlN2TCyvTSHN4DL6&shop_param=cid%3D41%26aid%3D533%26

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  3. Sweet!
    I forget the cap to socket but... ( I have an analog man chorus pedal)
    I think the 150p cap on pin 1 of IC3 is one to socket for the DEEP mod, put your favorite values on a toggle or even a 3P4T with several values for some good delay options
    Thanks IvIark! nice layout

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  4. ah here we go
    http://www.moosapotamus.net/wavy.html
    "Depth adj. switch:
    This is the 4-position rotary switch in the center. I replaced the 150pF cap that's on the CD4047 with two leads going to the switch. Now there are four different cap values that can be switched between. I used 33pF (mellow chorus), 100pF, 180pF, and 330pF (pitch bending wierdness). This allows for a huge range of sounds. My only complaint about this one is that there is a very audible "pop" when switching between settings. I edited the "pops" out of the audio clips, above."

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    1. Could you post a link for the rotary switch you used? I have one from Tayda (3 Pole 4 Pos. 15k), but I'm not sure if it would work. Thanks in advance!

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  5. awesome. so glad you did the one mark. can't wait to build it

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  6. Well it works. I forgot a cut. Actually a couple of cuts....OK I forgot ALL the cuts. Couldn't figure out the problem. I have a fool proof "shrink the pix, tape to tag and build" method. It's fool proof NOT idiot proof. I had to drill all my cuts AFTER completion of the board. LOTS of filing and digging. Anyway if anyone gives a shit it works. On to the CE-2
    jeff

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    1. Awesome, thanks for verifying Jeff :o)

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    2. Hey Jeff, what scale do you use or % of the pic? I usually use a fine sharpie and circle the points where the components go as a guide.

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  7. Hey Leo.
    I don't select any page scaling.
    I just 'copy image' then take it to excel and paste. Then 'grab' a corner and make it smaller several times to get the left to rt width very close. Then I use the side 'adjustments' to fine tune the width to exact size.

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  8. ah ok... that is a good idea
    thanks!

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  9. Hey Mark, I've just finished this and Rate 1 should be Rate 3, otherwise, it works backward with very low precision near the fast setting. In the tonepad schematic the rate pot is not numbered but you can check it in the board layout. I need to drill and paint the box, I'll post a pic when I have it boxed.

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    1. yeah rate 1 really needs to go to rate 3 or the sweep is reversed and acts like shit.

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    2. Sorry yeraym I missed your post, and thanks for the bump dexxyy

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  10. HI all,
    I worked it on a vero and once completed, it worked very well was able to get that warble sound as mentioned, I must thank Guitar FX Layout for this sweet deal.
    However I usually leave all my DIY on overnight to see if they can withstand the current (don't know why I do it) but I think it will also proof my build. I've tried it on the deep blue delay, mutton phasor, EA Tremolo, now with this one about 4 hours into leaving it on through the night, there was this fuzzing and crackling sound, I woke up to it and tried to play my guitar, no sound! Coming through the small clone at all. All the other FX were still working well. So could anyone shed some light upon this idiot what could have gone wrong? It worked well and now there is just no sound at all.

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  11. Will this work for bass guitar? I want to build a simple (not the CE series) chorus for my bass player. Any recommendations?

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    1. I built it and use it with my bass. I didn't have to make any changes at all. Works beautifully and sounds amazing, IMHO. I also added a switch to change the cap on the IC, I used the stock value and a lower value to get a mellow chorus. I love it, but the only problem is that if you flip the switch with the effect on you hear it. Check out the link near the top about how to do it.

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  12. Is there a way to include a dry kill switch on this circuit to make it onto a chorus/vibrato pedal?

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  13. Possible awesome mods?
    http://experimentalistsanonymous.com/board/index.php?topic=1578.0

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    1. you can do all of these on this layout, but it will require revision or you will have to find those parts and replace them with leads to a switch putting the components on switches like in the mod directions in the link.

      the first mod of adding a depth pot is already done. i built mine exactly as it is here, but put the 150pF cap on a switch with another value to change the rate. in one position you get the stock chorus, the second gives a mellow chorus. it sounds killer and still sounds like a small clone.

      if you really wanted a chorus/vib pedal i would check out the tri-vib layout here. it's a great sounding pedal and has that already. i think that if you did all of the mods in the link i think would change a lot of the character of the small clone. at least that's what i would fear.

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  14. I haven't built this yet but I'm about to get an orginal one and then build this to compare. I would like to do this mods on the one I build. I figured I would post it here if anyone else wanted to see them

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  15. Good call I'll check out the tri-vibe i was just searching mods for this circuit and thought I would post a link. I'm dying to build this I've never built a chorus and I would like to make one. I've looked into the pt2399 chorus circuits but I wanna try out this and the boss ce

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    1. no worries man. this was the first chorus i built, and there's something about it that makes me want to keep it stock, just having the rate knob makes it more versatile then the stock one. it might just be that since i'ma 90's kid, and i grew up with bands like nirvana that used the small clone as is, i just don't see a need to change it, that sound is just iconic to me. but, by all means go for it and see how the mods change it, it might make it better.

      here's the link for the layout:
      http://tagboardeffects.blogspot.com/2014/03/runoffgroove-tri-vibe.html

      the tri-vibe is a ROG designed circuit, so you really can't go wrong with it. i think that the it's more of a vibrator pedal that with a flick of the switch can become sorta phasorish or rotating speaker like. but it might be what you're looking for.

      i have a bunch of pt2399 IC's, but haven't done anything with them yet as they are notoriously finiky. for instance i want to build the little angle chorus, but if you check the forum it's known to not be such an angel. it's still on my list, but due to the difficulty with pt2399 builds i try to avoid them. i mean i think one attacked heath and he had to cut it in half for protection. lol

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  16. just wanna share my build :D im so happy with this and i will definitely use this for my gigs
    credits to the maker of tagboardeffects.blogspot.com, IvIark and mirosol!!!
    -vahnrondel from philippines

    https://www.youtube.com/watch?v=dpePntGB75Q

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    1. Great job, thanks for sharing the video

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  17. Just finished this pedal and it fired up first try. I'm wondering what the 100k trimpot does in this? I was nervus to play with it since the pedals working great! Thanks for another fantastic layout!

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  18. Does anyone have a list of correct voltages for this one? Debugging… Thanks!

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    1. I can check mine tomorrow. I'll have to remember to do it when i get home from work. is yours not working?

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  19. I'd like to second the request for working voltages. I built this the other day, but the signal is completely unaffected by the circuit. As in the by-pass and the signal sound the same.
    any ideas?

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  20. I had the same problem with the first board I built. It passed signal but didn't do anything to it. With an audio probe, I found no signal getting to Q3 at all. Pulled and tested Q2 and it was dead and open, and replacing it made no difference. I made a new board and was getting the same problem, except now I could get a little chorusing while I turned the depth knob or got it in just the right spot, almost fully clockwise.

    I took a utility knife and ran it over the tracks, then discovered I had lugs 1 and 2 on my depth pot reversed. Everything works great now, although I did have to add a dinky little Klon buffer board to eliminate the clock ticking noise I was getting at most rate settings. Before it's signed and boxed, I'm also going to add an LED between ground and pin 7 of the LM358 to show the rate. Here are the voltages:

    V+
    9.468

    2N5087 - Q1
    C 0
    B 3.07
    E 3.7

    2N5088 - Q2
    C 9.468
    B 3.93
    E 3.355

    2N5088 - Q3
    C 9.468
    B 9.425
    E 8.8

    4558 - IC1
    1 4.744
    2 4.74
    3 4.64
    4 0
    5 4.73
    6 4.74
    7 4.73
    8 9.468


    MN3007 - IC2
    1 8.8
    2 4.38
    3 4.25
    4 0
    5 0
    6 4.37
    7 4.03
    8 4.03


    CD4047 - IC3
    1 8.66
    2 0.18 VAC, 0.07 VDC
    3 7.15
    4 8.8
    5 8.8
    6 8.8
    7 0
    8 0.72 VAC, 0.23 VDC
    9 0
    10 4.16 VAC, 4.377 VDC
    11 4.17 VAC, 4.38 VDC
    12 0
    13 8.68
    14 8.8

    LM358 - IC4
    1 3.73VAC, 9.0 Hz with rate all the way up
    2 2.35
    3 0.85 VAC
    4 0
    5 4.28
    6 4.31
    7 0.54 VAC
    8 9.467

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    1. really, the klon buffer cured the lfo tick? that's pretty interesting. i might have to give it a try. my tick is only really noticeable at the extreme CCW. did you notice any tonal difference with the buffer vs no buffer?

      i haven't added the LED, but have been thinking about it even though i boxed it a while ago. plus it gives me an excuse to design and etch a new enclosure for it.

      i'll also check my voltages since mine worked from day one. they should be the same you have, but it might be something worthwhile for comparison sake.

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    2. Yep, the first one I built and boxed was a Centaur clone, so I use that to check the effects that work but act funky. My Rat clone with a 1K knob for the Ruetz mod also really likes the Klon buffer; without it, high gain settings make it squeal and whistle around 2.5-3K. Those into more experimental screechy-squealy stuff will love that one with true bypass.

      I didn't really notice a difference in sound beyond less volume drop with the buffer in place. It's still that sexy, watery analog chorus, just without the clock tick. It's good to have a buffer board or two laying around for just these kinds of effects.

      Unbuffered, my ticking went away with the rate turned fully clockwise. The chips are TI CD4047BE, ST LM358N, and JRC4558D from Tayda, and an MN3007 I got from a seller on AliExpress (ten chips for $8 shipped, whee!) As for the 100K trimmer, I noticed three distinct spots. About a third of the way from either fully CCW or fully CW, I'd get just a dry signal. Around halfway or just past 12:00, it'd abruptly start working. This was before I fixed the depth knob wiring and I don't want to mess with it now that it's working and sounds great.

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  21. Can someon post photos of a finished one? I am a newbie i really need to see.

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    1. What part do you want/need to see? I think I posted mine under the pictures thread in forum. If not I can take a pic and post it later.

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    2. Start on something easier than this one!

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    3. I need to see backside of the pcb to see the solderings. I checked the tutorial page in your forum but still some parts are not completely clear to me. Lines are bridges, squares are cuts. I get it. But what are those white dots on lines? "note double links in single dots" it says near same symbol. Didnt understand it.

      And another thing i found out, this one has less components than the one on tonepad.com. Did you stripped it down? I don't care as long as it sounds good tho.

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    4. ok. lets start from the beginning. taking a picture of the bottom of the board isn't going to help you, actually. typically when you have a link it starts in one place and stop in another. when you have a double link, what you have is a place where that link has another connection. so when you see the places where you have a blue circle with a white inside that is a place where 1 link makes another connection.

      this is not a stripped down version, from the tonepad version, this one has a mod for replacing a the depth switch with a depth pot. if this is your first build, or one of your firsts i would try something a little simpler. this is a very, and i mean very complex circuit to build on vero and not for the inexperienced or faint of heart.

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    5. Yes this is my first project but i already collected all needed parts 5 years ago. (all transistors, resistors, caps, board, pots, pedal box...)

      They were staying in my room in somewhere and i just decided to start doing it again. Sad but true. :D

      I just need to put em together correctly. Although I haven't build anything in the past, I ve read so much. I know about capacitors, diodes, resistors etc etc Lets say i know basic electronics. I also read about Millenium bypass thing, 3dpt switchings, DPDT switchings... What i have is DPDT one and i ll build a non-led/non-battery version.

      I just need to know a little bit more to not make a mistake and fuck it up :)

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    6. Btw, stock tonepad layout has depth mod pot, not switch. You can do a mod and add a switch, but stock one has a 10k-b pot for depth.

      I counted all components here and there again... 65 parts in tomepad.com, 62 parts in your version. 100k resistor connected to the output is missing in your version for example. I am clearly not the expert, but you claimed that your version is different than the one on tonepad.com by having the depth pot instead of depth switch...

      Thanks for clearing up double link thing tho.

      Since i have pre-holed board i ll stick with your version. I haven't successed to print the tonepad pcb thats why i stopped doing it.

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    7. Not sure how much it'll help, but here you go: http://imgur.com/a/3uaj4

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  22. Sorry, all my bad:
    "
    I didn't have enough room to fit in pulldown resistors on the input and output and can't bring myself to add extra columns just to do that, so if you get any popping just add them to the stomp switch, 1M between input board wire lug and ground lug, and 100K between output board wire lug and ground lug. I may actually do it with surface mount resistors on the copper side of the board (the entire second row is ground).
    "

    I should have read the description before directly jumping into schematics :)

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  23. thanks for the voltages mr Eriv Von Michigan. they really helped me . i had a bad 4047 switched it and the lm358 everything is dandy. after 6 hours building 2 hours troubleshooting its working now. im so happy cause today i made a clone.ha ha nirvana

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    1. Sweet!! Glad it worked! Sockets are our friends... a bad connection fried a 741 on my first opamp Big Muff build, so I always get at least two of everything for these projects just in case.

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  24. Has anybody added a tone contol mod?

    I'm considering the "wonderfully stupid tone control 2" (2nd picture): http://www.muzique.com/lab/swtc.htm

    Not sure where the best place to insert it into the circuit. Before or after the last opamp stage? Any suggestions?

    Link to schematic:
    http://www.6v6power.ru/inf/Chorus/Small%20Clone%20Analog%20Chorus.jpg

    I'll be adding a volume control too. (Replacing 10k at IC1 pin 6 with a pot)

    Thanks,
    Mike

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    1. you're going to lose a ton of output if you use the SWTC or any passive tone control. you will need to add a gain recovery stage after it to push the output back up.

      as to where you should put it ends up being up to you. if you put it at the beginning you'll shape the tone going into the chorus, if you put it at the end you're going to shape the tone after the chorus has done it's thing. if i were you and you really want a tone control i would breadboard the whole thing and see which way you like.

      i've didn't add a tone control on mine, mostly because i think it really sounds great on it's own and i do my toneshaping with other effects.

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  25. i cant make up my mind really, if to build or not, cause i have a ehx electric mistress :S
    pretty big project and its pretty cheap at stores to buy (thats a bit strange in my view)

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    1. the electric mistress is a flanger, while the small clone is a chorus. it's definitely a big build, but IMHO totally worth it. just take your time and you'll be well rewarded.

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  26. okey, i'll build one then, it does have some nice "Hemispheres sound" to it so just there for i build one :)

    here's a template for those you like to use in their comming build?
    just make changes if you use extra pot or a ON oFF ON or what you will choose?

    a bit bright, but will compensate for the coating.

    http://s1.postimg.org/xrehz6u8f/small_clone_template_1590bb.png

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    1. and it's ment to be used with white waterslide decal paper and cut to 3 pieces and slided on to box ;)

      i plan to paint my box in some kind of matte silver first.

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    2. Cheers Mark!

      it work very well with a chicken knob, this layout.
      point of knob points exactly at marks and swings nicely around ;)

      i might have to mention that i have gone over to build with PCB's, if available,
      but checks this site for tips etc, this site is the best happening since my sons birth ;)

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  27. Definitely an awesome pedal.Better than a stock one if. you fo the depth pot instead of a switch. ya sure you can buy a used one for 40-65 dollars but its an awesome build. i built mone in 5 hours . i did have some mistakes that took a couple troubleshooting rounds.this was my first mega build. on stripboard. its no different than a 20-30 component board. Just make sure you take your time. Triple check the cuts and links before populating. This is a fantastic chorus. Curt Cobain used one on several songs.

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  28. now i only need my of IC's to show up, so i can get started :)
    ebay are pretty slow, but you get good prices.

    http://s1.postimg.org/6o82rk2gf/IMG_0594.jpg

    http://s1.postimg.org/jtnkxnwbz/IMG_0584.jpg

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  29. I was wondering, on this layout it looks like the 2.2uF tantalum is connected to pins 6-7 on the LM358 when on the schematics I see it is connected to pins 1-2..Am I reading the schematics wrong or something? mine is not working yet btw...

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  30. Wow, this one sounds just insanely good! Best chorus I’ve ever heard. The Depth pot makes it so useful and versatile, awesome. I have built it yesterday and it works on the first try. :-) I have used a 125B enclosure and there’s still enough room for a battery.
    Thanks for this!

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  31. Can't wait to build this, but my problem is i've never had much luck finding reverse log pots for the Rate. can i use a linear pots?

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    1. You can use any pot law (linear, log, reverse log etc) with the right value resistance, and the circuit will work, but you'll most likely find that all the usable range of the control is bunched up at one end of the pot sweep with the "wrong" law, and it'll be difficult to dial in just the right settings. I'd say, go ahead and build using linear pots whilst you source the reverse logs.

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    2. ...or wire an "ordinary" log pot backwards - the rate control will work backwards, but with a reverse log taper.

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  32. I openend the enclosure yesterday just to put in a battery – I didn’t change anything inside, but suddenly my rate pot doesn’t do anything anymore. I can measure the resistance on the board as I turn the pot, so it seems it’s still connected correctly. With an audio probe I don’t get any sound at Q3 and IC4. Could it have anything to do with the 2n2 cap that is connected to Rate 3? I have used a tantalum cap here.

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    1. Puuh, found it … It was the 47nF cap at the bottom. Cold solder joint maybe. Soldered this one in again and bam … got the greatest chorus sound ever back :-) Thanks again for the layout!

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  33. Finished this one off and I'm getting pretty much the same sound out of it whether it is on or bypassed.
    Have compared my voltages to the ones listed further up and they are all very similar with the exception of B and E on Q1. My readings are approximately double.

    I'm currently suspecting that I've been suckered into buying some fake MN3007's from eBay. 5 for £2 did sound too good to be true.

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