Sunday, 15 May 2016

Electro Harmonix Small Stone


08/02/2017 Layout Updated! Moved the 33K next to the trimmer. Had to change the layout because there was a mistake in the schematic and the Color switch wasn't working properly.
If you've used the previous one follow Panagiotis Tsiatsis' comments to correct it.

63 comments:

  1. Now way.. Get outta here!


    YES!!!!!!!!

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  2. May God bless your name!

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  3. amazing job alex. been waiting for this for a long time. looking at the layout and the schematic i wonder if the color switch could be replaced with a pot to allow for more variation in "color." could probably add depth pot. not to mention adding s witch for univibe

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    1. well it didn't take much digging, but......mods, mods, mods

      https://sites.google.com/site/flofxdiy/eh-small-stone-phase-shifter

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  4. i boxed four today another wigl vibe, proco rat,vox tonebendef , and a ross compressor with soft latch switching.i want to start this one ha ha.Whats a good sub for the LM324. i have tlo74 tlo64 tle074 and lf347 on hand

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  5. from what i can tell the tl064 would be my best sub on hand its low current but probably not as good as the lm324 but should be able to work

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  6. which schematic is this based off of?

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    1. I've used this:
      http://s853.photobucket.com/user/bernardduur/media/Schematics/SmallTone.jpg.html

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    2. Hey Alex,

      Are we sure this schematic is right? For one thing, it says "small TONE" in the upper left corner and for another it seems that there are differences with other schematics found online... and I couldn't find a schematic that used 3.3nF caps instead of 6.8n... any ideas? Thanks!

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    3. There are different versions of the Small Stone and Bernard d'Uur schematics are usually very reliable.
      His is based on this version of the pedal:
      http://freestompboxes.org/download/file.php?id=26559&mode=view

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    4. Ahoy Alex,

      With a quick look, there seem to be parts mmissing from the redrawn schematic around the bottom module of the lm324 (56k, 47nf and 10nf caps etc). I guess some resistor values have been changed in.order to keep ratios right (ie 11k Instead of 10k to match with the 33k instead of the original 30k) but there are also more changes in values. Some electrolytic values are different as well.

      Any ideas? Thanks!

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    5. The schematic is based on a pedal called Small Tone which is a clone of the Small Stone.
      Could no find any videos of it but I trust the guy that traced it.

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  7. Does anyone had a look at the first Sovtek Small Stone? This will definetly be on my build list. I had the opportunity to buy the Sovtek Small Stone when it was new, but at the time really needed more a distortion so bought the Green Russian Muff (One that got me really started on the whole stompbox "madness")

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  8. I have built this layout and I am getting some distortion but mostly ambulance siren style oscillation.

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    1. I swapped out the lm324 for other quad opamps and it stopped the siren but the effect became barely audible.

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    2. I've double checked again and it matches the schematic.
      The only thing missing between this version and the original is a 47R resistor between the transistor's Emitter and Collector.
      Can you try to add it?
      Can you measure your voltages?

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    3. This comment has been removed by the author.

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    4. Could you start a thread in the debugging forum with quality pictures? I would be happy to look at it maybe you missed something. I used a 47k at the input instead of the 100k for less volume drop. There are several mods for these on the tonepad site.If Alex double checked im sure you have a bad part or a bridge or a small mistake off by a hole or missed a cut. Alex is as sharp as a razor.I am going to make one but it will be several days before i can. Busy at the day job and have some troubleshooting to do on a couple of my mishaps ha ha.When I do make it ill post working voltages for sure if that will help

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    5. http://postimg.org/image/kxqmzwurl/
      http://postimg.org/image/6pwcxisox/
      http://postimg.org/image/460q3f54x/
      http://postimg.org/image/4hi6g6lkx/

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    6. What transistor did you use?
      Have you tried the 47R resistor?
      Can you measure your voltages?

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  9. few things beats a vero of a classic stomp, good job!
    gona build it ASAP and if it doesn't work... it's nobodys fault but mine :)

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  10. Is there any substitute for BC337?

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  11. I built a second one and it is good to go. I will say that it doesn't sound quite as deep as the small stone I own, but not bad.

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    1. Cool! Thanks for verifying it!
      Some Small Stones were built with different ICs and that could make the difference.
      Did you try to add the 47R resistor between Emitter and Collector to see if it makes any difference?

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    2. i see what looks like at least 3 solder bridges on the back top left row four or five and 6 or seven a few holes from the right. take a knife and cut between every row you have a lot of bridges or near bridges and or resin . i know resin isnt supposed to conduct but several times i cur resin and my pedal worked after. there maybe micro bridges hiding under it . . also found a leg that was poorly soldered bottom inch from the rright second last row on leg is mostly not soldered. canr reallt troubleshoot much more unless you mark the cuts with a red or blue marker. i know it takes a few minutes to mark the top and bottom for cuts but it saves way more time placing parts and troubleshooting. they are food reference points.I drill my holes its just as fast and cleaner cuts. after i drill i use a scotch bright pad and clean away any stuff sticking up . you have some stuff sticking up it looks like .you definitley have some solder bridges knife every row . hit that partially soldered leg with some solder. even if you have built 500 pedals on tagboard marking the top and bottom saves time trouble and headaches.

      wires are good electrolytics look good. i noticed you used 12k for 11k that shouldnt matter to much. might make it less small stoney but should work.

      you should post the voltages for the working and non working one if scoring in between rows doesnt fix it. i wish i could see the cuts better if knifing isnt the fix then recheck the cuts. also saw some solder that might be bridging across a cut longwise in the top left area. i should have written it all down but there were lots of things that looked shaky its hard to tell from a 2d pic. go over it again hit your cuts agiain and knife it. that top left has several bridges it looks like. i just knife the entire board now . it doesnt hurt anything sometimes you get some fray just resolder and it melts. good job on verifying a difficult build on the second attempt.


      does it have the volume drop? if so you can change the 100k inout to a 47k it helps lesson the drop.

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  12. I've noticed that the older small stones use 6.8nf caps in the phase stages, this one uses 3.3. Try the bigger ones.

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  13. wow lots of typos in previous post sorry burning the midnight candle

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  14. Very impressed with this Alex. I started this a few times but the way I do layouts always ended up with it becoming too big for a 1590BB ad so I stopped before the end. Nice job matey

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  16. Is there a way to have an LED status light change with the rate? I'd like to build this with a mix level mod, but I'm also in love with the rate LED idea having seen it on the chorus projects.

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    1. Not sure but try adding a CLR from 13700 pin 16 to LED+ and LED- to ground.

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  17. I posted this in the debugging forum and I'd be interested in some expertise:

    As I continue to troubleshoot this, I'm seeing something in the layout that doesn't make any sense as compared to the schematic. Reading left to right and top to bottom, there's a link in column 13 that links rows 17 to 21. Among other things, it links pin 2 of the LM324 to pin 6. However, these two pins are not linked in the schematic (OP1A- and OP1B-):

    http://s853.photobucket.com/user/bernardduur/media/Schematics/SmallTone.jpg.html

    It would seem to me that there is a missing cut in the layout - right above the one in the very bottom row. This would isolate pin 2 from pin 6. Pins 6&7 would be linked and connected to the 1k resistor which goes to the 3u3 cap and out. Pin 2 would then only be connected to the 15k and 18k resistors as in the schematic.

    Can someone take a look and verify? If I'm right, how would anyone have successfully built this?

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    1. Just to close the loop, that cut was added and I verified this layout. Sounds really great! Still not sure what the trimmer does.

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  18. Finished this pedal today and I also have an ambulance siren emitting from it's output when turned on.
    Glad I checked back on this page before starting to troubleshoot!
    Will add the missing cut tomorrow and report back.

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  19. By comparing this schematic

    http://freestompboxes.org/download/file.php?id=26559&mode=view

    to the Small Tone adaptation

    http://s853.photobucket.com/user/bernardduur/media/Schematics/SmallTone.jpg.html

    I can see that there is at least one mistake [R37 in SmallTone is 100R whereas in the first it is noted as 100K (luckily, the prototype uses Ω (omega) to denote Ohms so there is no chance that 100K could be mistook for 100R).

    Moreover, there is a 56K resistor in the negative input (pin 6) of the lm324, a 47nF cap between pins 5 and 7 and a 10nf between pins 6 and 7 of the same chip that are missing.

    There are some other important value changes ie the R40/R41 pair which is 4.7K / 1K in the hand-drawn version and 3.3K / 1.8K in SmallTone but I don't know how they are justified.

    Anybody has more info or explanation for the above? Thanks!

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  20. this layout is 31x22 and 22 cuts its not 33 long

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  21. Ahoy,

    Regarding my previous comments after I tested the values of the two schematics:

    1. The correct value is 100R and not 100K, so the value in the value in the vero is correct

    2. Same holds for the 56K of the original schematic that is replaced with a short here; again this vero is correct

    3. I tried the 47R between E and C of the transistor, it changes the shape of the lfo slightly but noticeably. I omitted it as per this vero since I liked it better.

    4. Strassercaster is right, the dimensions stated in the picture need to be corrected

    5. The first cut at the left of the 82K is not needed, there s nothing at its right (probably a remainder of a previous version)

    6. There is one important mistake though in this vero coming straight from the schematic used : The feedback path is never disconnected regardless of the color switch position. This path should be connected when the color switch is engaged and sent to ground when it's not. You can see this in the hard-written schematic that I posted above which uses a 2pdt switch for this reason. I was wondering why I did not notice such a big change in the sweep of the lfo between the two modes and I was assured when I tried to do the vibrato mod which did not work properly as the wet signal was always fed back in the normal color position. You essentially need to use a 2pdt switch for the colour that additionally controls the connection between the 68K res and the 6n8 cap at the bottom left corner of the vero: middle would be the 6n8 and the other two sides would be either ground when the colour switch is disengaged or the 68k when it is engaged.

    Have fun and again thanks a lot Alex!!!!!!

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  22. Forgot something:

    I ended up using a 47nF cap between pins 5 and 7 and a 10nf between pins 6 and 7 of the lm324, but I did not check if they help with ticking noise.

    I also added a 10nF cap between pins 1 and 2 of the lm324 that reduced the ticking without altering the lfo that match. You might want to experiment with other values for your case, and keep all cables as far as part from the board and between each other as possible to minimize the ticking and check whether a cap between pins 1 and 3 or 2 and 3 helps to this end :)

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    1. Thanks, mate!
      With the added switch part does it sound like the original?
      Has the trimmer any effect on the "Color"?

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    2. Thank YOU Alex :)

      Yes, it does sound like the way it should mostly (i have a nano xo) since there should be no feedback with the switch disengaged :)

      In lieu of a reverse log pot, I used a B500K - you lose the lowest speeds but you have more resolution in the upper speed range. Still, the slow speeds are slow enough, I d even try to go lower with a linear pot. [Of course using a log pot wired in reverse is NOT equivalent to a reverse log pot since this is a rheostat and you get exactly the same result]

      The trimmer definitely affects the intensity of the effect when the colour switch is engaged but most of the change happens in the first quarter if i recall correctly. I also used a lower stop resistance (the one used here is the 68K, I think I used a 39K) to increase the maximum intensity possible with the trimmer (the lower the resistance, the more intense the effect)

      I also did the univibe mod but used the default univibe values, i liked them better than the typically suggested ones :)

      Let me know how it works out for you :)

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    3. Ok.
      I'll add a new layout with the second part of the switch and a 39K resistor.
      Had to turn the trimmer and add the switch between the trimmer and the (now 39K) 68K resistor to keep the board of the same size.
      Thanks for the help!

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    4. Again, we are grateful for your work (and that includes of course Mark, Miro and the rest of the guys), we are just happy to be helpful from time to time in return :)

      The switching comes from this layout :

      http://freestompboxes.org/download/file.php?id=26559&mode=view

      maybe consider putting a note that 68K was lowered in order to give more range in the feedback strength :)

      Thanks again,
      Taki (",)

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  23. WOW I started three of old layout last weekend they are half done didnt save it . i have a request for version 2 is this till a version 2? i thought i would be ok and that this was verified. any chance of getting the old layout Alex? i will take the time to make the changes. is this a vwrsion 2? version 2 is the only one i know of that uses the lm13700 insted of the ca3080/3094 chips. if not anyine got a version 2 schematic to make the mods i need too. thanks ill restart tonight. i am 189 out of 190 for starts and finishes 189 out of 193 now ha ha oh well

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    1. I've sent it via email.
      This is the same version there was before with the switch's corrections.

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    2. You the man i got it. I went ahead and started two new ones. one for me and my customer. Im too busy to mess with the older layout at the moment ill come back to them eventually . is this new layout verified? I finished mine at 2 am last night ill test when i get home today . I am always a bit nervous on testing mega builds like this ha ha

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  24. How is the switch wired (from back)?

    1-2
    3-4
    5-6

    or

    1-4
    2-5
    3-6


    thanks!

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    1. This comment has been removed by the author.

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    2. Thank you.

      But anyway - i also get siren-like sound. Checked everything, cleaned all the traces. Just don't have any other IC's to test them.

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    3. There is a major issue i mad two have no mistakes i caN find.i did my triple check before firing up . It has a Low pulsing ufo sounding siren.i used audio probe its there on the 1st resistor the 100k. also 9v on bc337 all three legs. issue is at the beginning of the circuit.where is the schematic . my guess is last minute change or something . this cant be verified is it?

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    4. i assumed the switch is wired like a chip could this be the issue ?top left is 1 bot left is 3 bot right is 4 top right is 6 is this how its supposed to be ? I just saw the full drive it is 1-4 2-5 and 3-6 ill swap them out tonight and see if that does the trick I am sorry i steered you wrong Eugeene

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    5. I tried switch the other way same results pulsing synth sound . please check this Alex I have to finish it soon . I sold one ha ha i thought it was verified . audio probe issue at input first resistor has to be something simple

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    6. Found a mistake.
      The 33K resistor next to the trimmer is in the the wrong place. It needs to go between pins 1 & 5 of the LM324.
      Let me know if it works.

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    7. yes, that 33k resistor thingy was really the issue. Thanks a lot, all of you! :]

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  25. Bingo its a hit. it was the 33k resistor as you said. Thank you very much. This is considered the version 2 of the series run.I did the ca3080 version from tonepad a couple years ago one of my first. for those wondering i find the phase to have a different feel. it is a bit less prominent. the trimmer has way less affect than i remember.Now i will check out the suggested mods and tinker with them . i have unity volume currently much nicer than the tonepad phaser i spent weeks tinkering with it . i am happy right of the bat with this one.

    one other thing it seems a little noisier o when the color switch is engaged is this normal. I lent my other small stone to a friend in another state ha ha

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    1. No ticks either so far have boxed or cranked my 100w plexi yet though but so far so good

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  27. THe schematic shows lm13600 i believe . I tried both there seems to be a difference but not much. Ill do a shootout when they are Boxed. Your a life saver Alex Thank you !!!

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  28. Nice job, but if I look on other shematic on the web like http://freestompboxes.org/download/file.php?id=26559&mode=view
    and
    http://www.montagar.com/%7Epatj/smlstone.gif
    I see that the color switch shortcut the 470K resistor an the trimpot a th ON position. And connection between 470K and 39K is never broken.
    ON position --> Shortcut the 470K and the Trimpot
    OFF position --> use the 470K and the Trimpot connect the link between 470K and 39K to th ground.

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