Monday, 19 May 2014

Electro Harmonix Clone Theory

Request for this nice sounding chorus/vibe pedal.  Thanks to Scruffie for his schematic.  It will fit in a 1590B if you want the aggravation, but a 125B would probably be a better choice.

The effect needs a 15V supply so you can either use a standalone 15V adapter if you have one, or build the included power daughterboard which with double the supply and then uses a regulator to reduce it to a stable 15V.

The schematic was based on a mono version of the old MN3007 Clone Theory, but this is the manufacturers information about the current XO version:

This recreation of the original 1970's Clone Theory is re-known for its very edgy chorus. Stereo outputs provide lush chorus and vibrato with a sparkling wash and liquid elegance.

CLONE THEORY, one of the most lush, deep and warm CHORUS/VIBRATO ever made, now in stereo. The CLONE THEORY’s depth and rate controls swing from one extreme to the other, giving the user an entire realm of possibility for tone.

[20th May: re-jigged slightly reduced the number of links, no corrections were made so the first layout posted should still be good]

and here's the stereo daughterboard for those wanting the option


  1. You can bet I'm building this asap. I'm going to be seeing Peter Hook in Toronto in November, I may just build him one of these!

    1. That's spooky, my dad used to work with Peter Hook

    2. Awesome, please let us know if you can verify it. I bought one of the new ones and its just not the same.

  2. The description says it has stereo outputs. Any chance of a layout with the optional second output? Thanks.

  3. This is the mono Clone Theory as per the original '70's version - I have one, and it's far better than the stereo re-issue.

    1. Thanks for that Alan, I didn't realise the original was mono, I thought they were all stereo. I've added a stereo daughterboard should anyone want to try that, but I'd only be building it mono anyway.

    2. Thanks for that Mark. I only run choruses in stereo, so now you've given me (us) the option. If I get to building it, I'll let you know how the stereo daughterboard works out.

  4. Would this one be ok to add a rotary switch for the 560p cap for other delay times?
    Not sure if that is really needed on this but wondering

    thanks MARK@!

    1. I'm no expert on the 4047 and so have no idea if that is right, or what affect the 22K resistor has on the time, or even whether this kind of mod would be worthwhile anyway. If you want to test it I'd recommend just socketing the cap and trying a few different values to see if you get something useable. Then add those values to a switch when you know what you like.

  5. Thanks Mark.
    What is the best sub for the LM1458 chip?

    1. Try any dual opamp, another RC4558P, TL072, NE5532 etc, but you should be able to pick them up cheap as chips from lots of sellers on eBay.

  6. want build this,but dont have 1458 ,

    1. It's only an LFO so using the 1458 isn't compulsory. Try any other dual opamp like TL062, TL072, JRC4558 etc

  7. What is the Ch/Vib pot supposed to do ?

    1. it lets you blend in or out the dry signal with the chorus... chorus is wet and dry together, vib is just wet.

  8. When I posted about the original Clone Theory being a mono effect, I should have pointed out that it does have a dry output, so that you can have a dry/wet split, but I think that it's just daisy chained from the input.
    The Ch/Vib pot pans between a wet dry mix for chorus, and a wet only signal for pitch modulation.

  9. Hello again wonderful community :) has anyone verified it yet? i'm about to etch a PCB of this and test it, today hopefully! at least if it works we can tell if the schematic is correct (in case we're not 100% sure about the schematic) :)

    1. Others have built non-vero versions based on this schematic, so the schematic is verified.

    2. The only query really was the two 680p caps which were marked as 412 on the original. They may be a lower value (412p) and so you may want to socket those so you can test 390p or 430p caps in those positions.

    3. Shouldn't 412 stand for 4,1n rather than 412p ?

    4. It would suggest it with the usual cap numbering convention but Scruffie said on diystompboxes that 412p caps do exist and that value would make more sense. 4.1nF would roll off a lot of high end. It is also more in keeping with the older Clone Theory schematic which used 680p's in these positions.

    5. definitely 412p. i verified it for scruff on both my vintage units.

  10. Ok thanks, I should have read the thread first :)

  11. anyone built this with success? are we sure the schematic is 100% correct? i just pcb built it and all i get at the output is a tick tick tick (following the rate), no guitar sound... messed around with the trim pots and nothing happens. i have a CD4047 with a cut and a dot on the other side. pin 1 is on the cut side or dot side? :D

    1. *tried both 9V and 15V with no difference...

    2. Scruffie said he has compared it to the factory schematic and it was correct, and I definitely trust him when it comes to things like this so I'm assuming the schematic is fine.

      I've never seen a CD4047 with a cut AND a dot, but my first instinct would be that the dot is at pin 1. My first instinct has been wrong in the past though :o)

    3. thank you for the fast reply on this one mark, i checked out my wiring again and i had an external jumper on the wrong hole :) now it works fine, but the ticking sound following the rate is still there. i tried the 4047 with the cut as pin1 and i think it's ok, although i've subbed the 2N4302 with a BF244 (taking care of the pinout) do you believe this could be related? thanks a lot for all the help!!!

  12. guys, the pedal needs to run at 15v, but that means you need an 18v supply. it's actually a 36v center tapped... less noise that way for some reason. if you run this with a 15v supply it will not work right and the regulator will overheat and burn out eventually. it will also be noisy as fuck. when i built my original vero from cathexis's layout, i bought an 18v adaptor off ebay, and the thing was so noisy it was unuseable. i thought it was the pedal... tried everything, couldn't get rid of the noise.
    once i hooked it up to my pedalboard's 18v regulated supply, noise was gone.

    you can definitely use a switch to change between cap values to make it flange more, double, hell, you could probably get it to echo a little bit.

    the original unit was mono.... there's an effect output, which is a blend of wet and dry (set by the chor/vib pot) and a dry output which is simply a second jack connected to the input.

    if ya wanna go thru the hassle of a slide dpdt for the chor/vib-flange/vib switch, there's a "notch" where you get a completely different almost "flanger-ish" sound... you can also get this messing with the bias for the BBD.

    for the 1458, use any low-noise dual opamp and you should be fine. i would reccomend ne5532 or tl082 etc... 4558's will also work, but tend to be a bit hissier. would definitely socket and experiment for best tone and least noise.

    really glad scruffie did a proper trace... what has been on the net prior to this has been wrong. it's similar, but not quite... more like a modified small clone than clone theory.

    if your build is a little below unity you may wanna add a smallish buffer-boost, i found the foxrox style fuzzface-wah one to work well if modified to give a small signal boost... i just used a trimmer on mine.

    i may give this layou a shot down the road, bought a pcb from scruff's bud. nice guy, he threw in a bbd and the FET, too!!

    this is my favorite mod pedal of all time... the only chorus i ever liked (other than the old yellow mxr stereo chorus) and i really reccomend wiring it like the original.... the stereo mod, if it's like the one from the earlier versions just didn't sound right.... i actually disabled it. if run in "stereo" with one wet and one dry amp, this thing is un-believable... especially if ya like playing with feedback.

    thanks for yet another awesome layout guys. ;)

    peace ouy

    1. Thanks for all the awesome info Jimi!

    2. I'm not terribly bright...

      Jimi says "guys, the pedal needs to run at 15v, but that means you need an 18v supply. it's actually a 36v center tapped... less noise that way for some reason. if you run this with a 15v supply it will not work right and the regulator will overheat and burn out eventually. it will also be noisy as fuck. when i built my original vero from cathexis's layout, i bought an 18v adaptor off ebay, and the thing was so noisy it was unuseable. i thought it was the pedal... tried everything, couldn't get rid of the noise. once i hooked it up to my pedalboard's 18v regulated supply, noise was gone."

      The layout text says "The effect needs a 15V supply so you can either use a standalone 15V adapter if you have one, or build the included power daughterboard which with double the supply and then uses a regulator to reduce it to a stable 15V."

      I'm having trouble reconciling these two statements. Using a 9v supply through a doubler to 18v then through a 15v regulator.. is that significantly different from what Jimi is talking about ("if you run this with a 15v supply it will not work right and the regulator will overheat and burn out eventually") or is that method likely to produce the same issues?

      Also, I have no idea what "36v center tapped" means :(

      Would an 18v wall wart through a 15v regulator be the best option? If so, would it be as simple as running the +18v through the "I" leg of the regulator, providing a GND connection for "G," and pulling +15v out of "O"? I have no idea which components on the posted daughter board are strictly related to the voltage doubler and which are not.

      Forgive my stupidity. Some of this I take to like I was born to it, and some of it just refuses to make sense to me :/

    3. No I'm not sure either. The MN3007 can take 15V and the original may have been designed to have specifically that, I don't know. That's the schematic I did that layout from at the end of the day, but the ICs can also work at 9V so even if it didn't sound as good, you should get something out of it and I can't see anything in this circuit that would make it only work with a specific power supply. No bi-polar requirement, funky grounding or anything else that may make alarm bells ring.

      Are you getting anything out of it?

    4. Post your voltages mate including the daughterboard voltages if you've used it and including the voltages you're getting at the regulator pins.

    5. Thanks for the info. I was getting ready to take a stab at it and wanted to make sure I understood what I was getting into :) I'll let you know when I get it put together, though.

    6. Alright, so after a small period of "fuck this shit, I can't build anything right," I finally got around to building this. Can you see what an asshole I am? Fail, fail, fail, and then what do I pick to get back on the horse? This big-ass circuit.

      Well, I built it and, what do you know, the damn thing worked perfectly the first time I fired it up. Go figure.

      Substitutions (all of which are terribly minor, but I'm having a moment here so bear with me):

      MC1458 instead of LM1458
      JRC4558D instead of RC4558P
      2N5458 instead of 2N4302 (as suggested on the layout)

      I also did not use the daughter-board, but instead powered it directly with a regulated 15v power supply. Works great. I even touched all of the chips and transistor after running it for about 45 minutes to make sure nothing was getting hot (yeah, I know, sort of a "caveman" troubleshooting step, but I'm sort of a caveman, so there you go...)

      Not sure I really know what's going on with the Vibe/Flange switch, but I do hear a difference though my ears aren't sure what to make of it. I need to jam out loud for a while and figure it out.

      My trimmers are set at center. I can figure out what "Gain" does. I'm a little timid about messing with the "Bias" or "Cancel," however. The effect is quite strong, so my favorite settings have the Rate and Depth set very very low and the Chorus/Vibe set all the way to Chorus.. so it's possible I need to tweak something there. I'll do so after I box it so that I don't have pots and such flopping all over the place.

      All in all I'm pretty freakin thrilled to have this built and working.

      Shazam, indeed.

    7. Awesome, so more success than with the Little Bastard Chorus then :o)

    8. On a scale of 1 - 10, 10 being works perfectly first time, the Little Butthole Chorus would get a -suck.

    9. hi guys, sorry i missed this earlier... 36v center tapped means 18v-0-18v transformer. that runs to the board and is regulated DOWN to 15v from 18. you always get some loss via heat with regulators, they need to be run at a slightly higher voltage than what they put out... that's why with a charge pump circuit, you "double" the 9v to "18-ish" then regulate it down.
      on my original, 18v goes to one part of the circuit, 0 goes to ground, and 18v goes to another part... i'd have to open it to see just where again. but i had to replace the transformer in one of them a while ago, so i measured the voltage. it was kinda wired almost like a tube amp power supply.... 2 18v supplies (one for circuit, one for lfo i imagine) each regulated. kinda cool.
      glad ya got it working ;)
      the sweet spots for the trimmers are where ya get a good balance between chorused/dry... but ya can get some almost phasey tones or flangerish ones at some points. if you're getting chorusing, your bias is good... if getting any distortion, play with it just a little bit. where ya hear the least distortion is right.

  13. How sensitive is this circuit to having exact resistor values? Some of these are a bit off from the standard values I stock.

    1. Nothing is ever so precise with these that exact values are needed

  14. Finally got this working but not without some changes. I wasnt getting 15v to any of the ICs .. I didnt use the power board cuz it wasnt giving me 15v either . After eliminating the 470r , I finally had 15v to the 4047 but not to the other 3 ICs. I added a jumper wire from the + of the 470uF to the rail that supplies the 3 ICs.
    Seems perfect.

    1. Top man, I've missed out a link. I'll correct it (and may as well remove the 470R too) and tag it. Nice job

  15. k - have the voltage doubler working by adding a electro cap

    1. Where? Between the 9V input and ground?

  16. between the output of the 7660S and ground before the regulator

  17. If there is a volume drop the 390k resistor can be changed with a 470k or 500k trim (as variable resistor). The 330k resistor near the 2n5458 can be swapped with a 500k pot (wired as variable resistor) in series with a 50k resistor, it's like a Delay Time control to add or reduce more depth to the vibrato/chorus.
    Right now I'm trying to figure out the best way to add to this vero the feedback mod as suggested by Paul Nelson.

  18. Hi, Maybe a newbee question but I've build this vero and won't get no sound. Checked for bridges but there are none. Don't know either where the ground from the charge section should go to. Had it attached to the ground rail of the main frame but didn't work. Changed the LM1458 in LM358 and a 2N5458 for the 2N4302 transistor. Couldn't get a 160K res so i changed that for a 150 K. Help me plsz guys

    1. All grounds, onboard and offboard need connecting together. Did you add the omitted link to the left of the two trimmers between the 1u and 100n? If that is all correct then post all your IC voltages which should point to the problem area.

  19. I did add that link. Made all links and cutts like the layout above. I'm checking resistor values now and will post the IC voltages later. Thnx for replying so fast!

    1. My DMM going nuts on me. I have some correct values from the resistors and some don't. Didn't check them as they came in by post, but they were nicely labelled.
      Got my son getting new ones for the questionable values.

      The IC Voltages are as following:

      IC1 ( RC4558P)
      1: 1.33
      2: 8.9
      3: 6.05
      4: 0
      5: 1.42 and diminishing
      6: 13.79
      7: 13.79
      8: 13.84

      IC2 (MN3007)
      1: 13.85
      2: 13.85
      3: 4.75
      4: 0.88
      5: 0
      6: 0
      7: 9.2
      8: 9.27

      IC3 (CD4047BE)
      1: 14.18
      2: 0.52
      3: 14.16
      4: 14.20
      5: 14.20
      6: 14.20
      7: 0
      8: 0
      9: 0
      10: 14.20
      11: 0
      12: 0
      13: 14.23
      14: 14.23

      IC 4 (LM358N)
      1: 8.2 - 6.2 (changing values)
      2: 4.77
      3: 7.1
      4: 0
      5: 8.5 - 6.2 ( changing values)
      6: 7.1
      7: 14.21
      8: 14.3

      IC Power supply (7660S)
      1: 9.35
      2: 3.96
      3: 0
      4: -0
      5: 0
      6: 4.92
      7: 4.32
      8: 9.35

    2. what i said was this.... you never ever wanna feed a regulator the same voltage it's putting out. the circuit needs 15v to run, but you need 18v .... you'll lose a couple volts in heat from the regulator. a center tapped means you have 18v-0v-18v.... 36v,ct (center tapped) that way you're feeding the lfo and the circuit each with a stable and separate 18v (to be reduced to 15v by the regulator - there should be two, really... one for each tap)
      by using a voltage doubler, yeah, you can get close to 18v.... from a 9v supply, but not a lot of current. i suspect if you're having problems, you may wanna split it off to TWO charge pumps, and have one run the audio, and one the lfo. should help with the ticking issues, and ensure there's enough current to run the audio part... not sure what it draws, but charge pumps only put out maybe 100ma, and pretty sure this is drawing close to that... which may be part of the problem being faced by some of the builders.
      start with your trimmers about half way up (if it passes audio) and start with the bias control for the bbd... there's a narrow "notch" where it works. once ya have chorusing, you can fuck with the rest of it til it sounds good.
      hope this helps a little...

    3. Did you include the link I omitted from the original layout between the 1u and 100n on the left?

  20. Hi, I just built this one with the power supply daughterboard as per the layout. Checked for shorts, yet I'm not getting anything whatsoever.
    I noticed that even after replacement, the voltage regulator (78L15) instantly gets very hot when engaged. Might this be a trail to the problem?

  21. Just got this wired up today. Powered with 2 9v's and 7660 daughterboard, and also built the stereo daughterboard. It seems that almost everything works as it should- the cho-vib blends the dry in and out, the flange switch changes the voicing, and depth gives a more dramatic effect, sort of, except I can only get "motion" of the actual chorus sound if i twist the Depth pot back and fourth manually, as if the wave is stationary "stuck". This being my 1st build using a BBD I wish to know if this issue would be contained to just the LFO or if the 4047 isn't tick-tocking as it should. I've made no substitutions except for the 2n5458- I have an MPF102. I've tried j201 and 2n5457 but all tis seemed to change was how noisy the pedal was. I was very meticulous prepping, populating, and assembling; since completed I've double and triple checked my pinouts, Electro polarities, wiring and jumpers, checked solder and track cuts/seperation, cannot find a fault in these, though I can't conclusively rule any of these out... Im using a 2n7000 Millennium Bypass, but don't believe the problem is caused by this... ANY insight into what the issue may be, or maybe someone else encountered this problem? Any help at all would be much appreciated!

    1. What voltages are you getting on all the IC and transistor pins, particularly the LFO IC (IC4)

    2. This comment has been removed by the author.

    3. SORRY that was IC1... doing 4 now

    4. IC4 P1)15 P2)1 P3)9.5 P4)0 P5)3.5 P6)9.5 P7)2.5 P8)14.5
      IC1 P1)8 P2)2.5 P3)1.2 P4)0 P5)1 P6)2 P7)8 P8)15
      IC2 P1)14 P2)6.5 P3)1.5 P4)1 P5)1 P6)6.5 P7)4.5 P8)4
      IC3 P1)5.6 P2)6 P3)5.9 P4)15 P5)15 P6)15 P7)0 P8)0 P9)0 P10)6.5 P11)6.5 P12)0 P13)5 P14)15
      I beleive those are the approximate readings... the analog Voltage meter im using is kinda boo-boo...

    5. After getting fed up with my old meter I went out and got a decent DMM. Still getting chorus sound only when manually twisting Depth pot. Chorus/Vibe pot blends dry in out as should, flange toggle changes voicing appropriately (I think)
      Heres what Voltages I'm getting all pots fully CW and gain trimpots at as close to unity as i could tell, 2 fresh tested 9v batt power, pots and switches tested too... hmm.
      IC1: JRC4558

      IC2: MN3007

      IC3: CD4047BE

      IC4: MC1458L



      L78L15 (gets warm)

      JRC4558 Stereo DB

    6. 28V on the input of the regulator? That is far too high, are you sure about that?

    7. ...An the 7660 is getting 14,58V on its input. Which means the chip has been dead for quite some time.

  22. sorry about that Mark (as an aside, I thought your handle was IVIARK pronounced like Ivy Lark...) **18.45 @ input of L78L15 regulator. I cant read or write. After searching for working voltages for the Clone Theory, i've seen a lot of "HELP ME" threads (no verified working voltages though) and everyone seems to be getting variable voltages on the 4047 pins 1-3 and 13. Twisting my depth pot does vary those pins. Miro, I am going to order another 7660 and Regulator as these were my last, but thanks for your help!! I dont know what im doing with my audio probe either. Im Sorry if i sound like a complete ass, Only 4 months ago i learned how to install a humbucker... since then ive spent all my free nights reading, prototyping, learning, building, and burning myself trying to better understand the whys behind the whats... but i feel Ive shot for the moon with my bb gun of a brain and am now flapping my arms in desperation

    1. You should start by checking your power supply. If it's supposed to put out 9V, it's most likely broken with ~15V at the output. Just measure the plug...

    2. Hey Miro- My power supply is actually just 2 9V batteries, i had (barely) read Pinkster's post above and in my anxiousness to get the thing working i doubled 9v to 18v, maybe why my 7660 is fried? ... i checked for faults on the power DB and couldnt find any so ive built another and am still awaiting the new chips. Thanks for the helpful feedback dude. its always nice to get a nudge in the right direction from the people you look up to

    3. ICL7660 is rated for 12V absolute maximum for the input. So if you want to use 2 batteries, you'll need to feed the 18V coming from the battery straight to the regulator. The 7660 is there to pump your 9V supply to 18V. Giving the pins 1&8 more than 12V will burn the chip in instant.

    4. shouldve looked over the datasheet, i cant decipher much on them yet but i will be checking them from here on out. Gonna build a 3rd power daughterboard and feed everything from the 78l15 can i use a MAX1044 here in place of 7660? Tayda has no 7660 and they take forever to restock some things...

    5. Just thought I'd let you guys know I got it fixed now and it sounds great! I had to step back for a few days and come back with a fresh set of eyes to see my simple mistake. The whole issue stemmed from me orienting the 12k resistor coming from pin 4 of IC 4 instead of just below it. I must have gotten it confused with the nearby 1Meg. I guess thats what i get for populating at 3AM. Miro, I got my power sup. fixed as well, No IC at all and 18v straight into the regulator. I think i responded to you earlier before I even read what you said, and just now realized my previous response sounds like i didnt hear you at all... but it works now so Thanks for that one!

    6. Excellent glad you got it going ok. Having a rest from it so you're fresh always helps with these things

  23. hi there.
    i've build it and it works great...but...i get a tiny tick tack going with the rate in the back when i don't play anything. it's annoying so i thought i could post to get some help.
    i had a bad 4558 in there at first, that gave me voltages at 0,2 everywhere but pins4&8 witch where ok.
    i've changed that with an other one and now it works
    here are my voltages, crazy i could say at some pins

    ic1 4558

    ic2 mn3007

    ic3 cd4047
    1- ~5,8
    2- ~8
    13- ~5

    ic4 5532 in place of 1458
    1-?? from5 to 9 volts
    5-?? 6 to 8 volts
    7-???? from 2 to 13volts!!!!

    g 2,5
    s ~8
    d 6,98

    any help would be great

    1. problem with ticking solved.
      this was from bad supply filtering, cause i was using a 18v supply to a 15v regulator on a bad...with no filtering caps! when i used some everything worked fine.
      i have a question though...i've ordered some 7660s ics months ago and never came.i can't wait so long for those to box this up. could i use the NE555 Voltage Doubler posted here?

  24. Built this last week but couldn't get it working. All voltages correct etc. but still no luck. At first thought it was the footswitch as i was getting no bypass signal. Eventually discovered i had a dodgy input jack which was the last thing i was expecting. Anyway problem solved.

    This is an awesome chorus/vibrato pedal just what i was looking for. Thanks for the layout Mark.

  25. This comment has been removed by the author.

  26. Weird stuff here, nothing whatsoever coming out and not even the LED lights up.
    The transistor on the daughterboard was getting quite hot and still so after trying different ones, so I decided to cut that daughterboard off.
    Haven't got a 15V supply handy, but I tried with 9V and nothing came out (except a verrrry faint oscillation only slightly sensitive to turning the pots) though that may be normal. I daren't try 18V in.
    Any specific ideas apart from a simple build problem?

  27. Can anyone recommend an appropriate 15v power supply I could buy to power this circuit with? Thanks in advance!

  28. 18volt dc center negative positive supplies will work with a clone theory. it will not fire at 9v without using a charge pump. on the originals i have (some of which were used by scruffie to work this up) the power supply is a bipolar 36v power supply... in effect 18-0-18volt.
    the original clone theory's "stereo out" is literally nothing more than a jumper from the input jack. hope this helps a little.
    as for chips, other than the BBD nothing is critical and any dual opamps should work fine (must admit i am responding to someone from FSB and haven't looked at the posted layout). low noise chips work better. watch your lead dress too as these have enough gain to pick up noise easily. a smallish cap across the output can help with hiss. you gotta play with values to find what works best.
    the stereo version of the clone theory sounds horrible and nothing like the originals. the modern eh is more of a tweaked small clone than an actual clone theory.
    glad to see you guys vero'd this. if i ever get time to build again, maybe i'll take a crack at it for shits n giggles.
    if using a charge pump, all you need is a 9 volt adapter. if not, that's where you need the proper power supply. if NOT using a charge pump, then a standard dunlop style 18v is fine. you can either add voltage regulators to run it at 15v or you can run it right at 18, it won't hurt it.
    hope this helps.
    peace out

  29. quick question regarding the gain trimmer on the stereo daughterboard. It this controlling the gain of the stereo signal? i.e. adjust to balance the output volume of the mod board and the main board?

  30. This comment has been removed by the author.

  31. Just finished my build of this (LED replacement pending), and I'm pretty proud if it! The picture's all yours if you want to add it to the community gallery.
    Underneath it is a Catalinbread SFT's temporary home...
    When you care about the look of your build vs. when you don't! Both are as good IMO!