Saturday, 21 June 2014

Durham Crazy Horse

I noticed we didn't have this one in the library yet. The circuit is rather interesting mash of different bits and pieces. TS-styled clipping amp with serious sag called "Volts", followed by two fuzz face style (with some features from the bazzfuss) circuits in series, which is followed by Big Muff-styled tone control. Not your standard Overdrive/Distortion/Fuzz, but i do find this interesting.



57 comments:

  1. Very cool. D5 is a series polarity protection diode, just remove the cut to the right of it. I'm sure Miro will remove it from the layout when he sees this.

    ReplyDelete
    Replies
    1. Nope. It's not for polarity protection. D1 is. D5 is per schematic - anode unconnected.
      http://1.bp.blogspot.com/-Y_v7W2o-ULg/TxxWWCZgHkI/AAAAAAAAAqI/dTzIiVHfUHU/s1600/durham_crazy_horse.jpg

      I believe that's the magical ingredient for the Crazy Horse sound.
      +m

      Delete
    2. This time i also left the parallel protection intact, since the series method could possibly mess with the "Volts". This control comes through a LED, so placing a series protection before it could affect it in undesirable manner.
      +m

      Delete
    3. Oh wow, God knows what that is supposed to do then, because it certainly isn't doing anything to the circuit.

      Delete
    4. It's that old magical "cathode to the BazzFuzz" trick :P
      +m

      Delete
  2. ok i built this thing and all it does is whistle like crazy.it says something about a green defussed green LED.is that my problem.i just have regular cheap LED?

    ReplyDelete
    Replies
    1. I don't think the LED type matters that much. Diffused just means it's not super-bright, nor "clear water green".

      Symptoms do sound like there's a short, which makes it oscillate.

      Check the usual suspects, bad cuts, bad joints and solder bridges. I'll double check the layout.
      +m

      Delete
    2. I did spot a small error right away. The 100n cap is connected to vref and not to ground as it's supposed to. There's a 22k resistor coming from IC1 pin 6. Other end of that resistor goes to a strip with 100n cap on it. The other end of that cap needs to go to ground. take it one row lower or to the empty hole next to Q1 emitter.

      I keep checking.
      +m

      Delete
    3. Layout fixed and updated. Let us know if that did the trick. In my understanding, that *should* fix it. The vref on this design cannot be used as a virtual ground as its voltage is controlled by "volts" and it's not constant.

      I also moved one of the "fuzz" wires around, but that doesn't affect anything but aesthetics... So you don't have to worry about that.

      Other than that, i can't find anything else wrong with it...
      +m

      Delete
  3. the drive pot does absolutely nothing,it hasnt worked yet,makes a loud hum everytime i touch the shaft of the drive pot and still squealing whistle with my guitar knob up half way.i double triple checked for shorts and bridges.i know for sure i dont have any bridged or short solder joints.my multimeter wont read my MPSA13.they all show OL,maybe i can use a substitute for these?

    ReplyDelete
    Replies
    1. I'm still thinking the issue is with the opamp, so let's worry about the transistors later. It's a long shot, but your pot could be bad if touching the shaft or casing affects the sound. When you have volts control maxed, what voltages are you getting on IC pins?
      +m

      Delete
  4. 1) 3.70 8) 7.47
    2) 3.72 7) 3.72
    3) 3.72 6) 3.77
    4) 0 5) 3.388

    ReplyDelete
  5. I also tried multiple pots and different values,still has the same hum when i touch the shaft.i just removed the 8 pin socket and solder the ic direct to the board.still know change.drive pot still didn't work.

    ReplyDelete
    Replies
    1. Those voltages seem healthy to me. And you fixed the cap to ground that was wrong earlier? Does the oscillation seize when you turn down the volts?

      Cay you probe it to confirm that the oscillation comes from the IC? If the signal is overdriven at IC pin and there's no oscillation, then the problem must be somewhere else...

      I'll try the board myself, but i'm 300km away from my desk and i won't be back home before next weekend.
      +m

      Delete
  6. Want a perfect build every time? Read on.
    After making all the cuts. (I start by marking the copper side of the tagboard from RIGHT TO LEFT with a line from top to bottom every 5th hole. Again count RIGHT TO LEFT. If your board is 21x16 then the 1st hole is upper right and the 21st is upper left. You end up with a grid 5x5 to get accurate 'cut' placement. Here is the part to get perfect builds every time. Some of you may know so go on to your build.
    You will need EXCEL or something similar.
    Start by making a series of vertical lines evenly spaced. Then overlap them with horizontal lines evenly spaced. On a sheet of 8x11 paper make the grid about 4"x4". Print it.
    Set a piece of tagboard on your paper and compare spacing of lines and columns. Adjust the spacing until the rows & columns on your printed sheet match those on your tagboard. I put a line every 5th hole vertically and horizontally.
    When they match SAVE your 'sizing grid'. Save it several time as gris 1, grid2 etc..just in case.
    Now click on a tagboard project picture and select 'copy image' and do it. Go to your 'sizing grid' and 'paste' the picture over the grid.
    Make sure the picture is selected and right click on it and select 'order' and then 'send to back'. This will put your grid OVER the tagboard pix.
    'Grab' the bottom right corner of the picture and make it smaller so it somewhat fits the grid.
    Use the corner to size the pix until your 5x5 grid is close. After it gets close use the top middle and side middle sizing points and get the 5th, 10 15th... rows to match up and down. When they match start using the top and bottom middle sizing points to match your horizontal lines. Right click on the pix and select 'order' , 'bring to front' then print it. Cut it out, spray glue it to the NON copper side matching cut, upper left or whatever. Start with poking holes at the ends of the jumpers and put them on. Get the picture? Don't use a bunch of glue and if it fails dfo a little re-sizing or a re-print. It gets easier the more you do. I've done 6 builds with not one error! I know that's no big deal to some of you but geeze!!! After 30 mistake free builds we'll talk. Have fun.
    Jeff

    ReplyDelete
    Replies
    1. Nice one Jeff thanks for the tutorial. It always makes me smile when I see a build made using this method, it just looks cool! :o)

      Delete
    2. Or you could just flip (reverse) the image on the horizontal axis in a photo editor and print it... use that to cut the traces. Then, like you, I number every 5, but on the non-copper side, and left to right... put the same numbers on the (non-flipped) layout... and add the jumpers and stuff the components.

      Delete
  7. Yes when I turn the volts almost all the way down the oscillation stops.I did put the 100nf cap in the correct place but still have the oscillation and turning the drive pot up and down makes no difference in sound.I tried the drive with the fuzz all the way ccw and at different points.still drive pot doesn't work.I will probe it tonight and get back to you.thank you for your help.i hate to be a bother but I'm really stumped and just got have this pedal.

    ReplyDelete
  8. pk i probed the ic.im getting oscillation on pins 1,2,3 and 7 not sure what this means?

    ReplyDelete
    Replies
    1. It means that the problem is within the IC, as expected. The rest of the circuit may be fine. I'll have a look if i can find anything to sort it.
      +m

      Delete
  9. When i have the fuzz turned all the way down it still sounds like it has alot of fuzz unlike the in he video.when i probed the transistors they also have oscillation in them too

    ReplyDelete
  10. The signal path goes from input to right hand side of the opamp (clipping amp) to the left side of the opamp (sort of recovery) to the Q1-Q2 pair (fuzz face with bazzfuss features) to Q3-Q4 (another fuzz-like stage) to tone stack to output. So if we have oscillation in the second part of the opamp, it's bound to be present at the rest of the circuit too. Which means that the signal isn't correct after the opamp - which means it won't sound right at the fuzz stages either.

    There's no actual room for it, but you might try to press a small cap, something like 470pF between opamp pins one and two - just to see of that tames the oscillation. It sure doesn't explain the drive knob behavior though.
    +m

    ReplyDelete
  11. Hi all. I suppose this has been asked many times. Maybe by me. Is a PN222A the same as 2N2222A?
    jeff

    ReplyDelete
  12. Replies
    1. Yes just a different manufacturer

      Delete
    2. Thanks. Last question....maybe.
      I looked at the data sheets and see that MPSA13 has a lesser voltage rating than the MPSA18, and the legs are flipped 180. Can I use the MPSA18 in this build?

      Delete
    3. MPSA13 is a Darlington transistor, while MPSA18 is "general purpose transistor". So it should work with MPSA18 as well, i doubt it will sound the same.
      +m

      Delete
    4. I'm moving to Australia next door to Tayda!!!

      Delete
  13. I mentioned this on the facebook page, but I am pretty sure D5/D6 should be antiparallel if they aren't! The original schematic appears to be wrong.

    ReplyDelete
  14. have you got an original crazy horse to confirm that? the one that was traced to provide the schematic had one end of D5 connected to nowhere, which is why miro did the layout that way.

    ReplyDelete
    Replies
    1. If either of you have checked the guts shots, it can't be confirmed just by looking at the original board. So John, if you have degooped unit, i'd like to see it too.

      And. If you look at Sabro's layout of the circuit, he has only one diode in his. So this and Sabro's layout are from same origin - i just left the diode per original. Sabro's layout is verified, which makes me wonder why this layout isn't working for Chris...
      +m

      Delete
  15. Goddamn it! Idiot me! Why didn't i see it!

    Just spotted it. Obvious really. And explains everything.

    Chis! Solder a jumper over the cut next to Drive 1. Currently that lug connects to nothing - and that'll explain all the symptoms you had.

    Updated. Now this should work.
    +m

    ReplyDelete
  16. Are you referring to the cut between D3 and D4? This would connect pin 8 of the IC to volts 3. This is the only cut I see in the vicinity of drive 1?

    ReplyDelete
    Replies
    1. There was a cut under D4. That cut should not be there. If your board still has it, just solder a piece of resistor leg over the cut. I've fixed the layout already.
      +m

      Delete
  17. The 1M linking to 22k connected to pin5 on the IC is connecting to pin 8 I think may be wrong.according to sabrotones layout of goes to ground instead pin 5 to 1M to 22k to ground.im just comparing between the two layouts I don't mean to offend in any way.

    ReplyDelete
    Replies
    1. No that is not wrong. On Sabro's layout, that 1M is is R2, and the two 22K resistors creating vref network are R3 and R4. As you can see, the R3 is connected to IC pin 8.
      +m

      Delete
    2. I see (IC)..lol My bad i missed the R3 to pin8 was concentrating on the volts to ground and didnt look farther to the right.i was useing my cell phone at work to comper the two veros and didnt have a wide enough screen to see it at the time.I do have the cut under D4 im going to jumper it and get back to ya.

      Delete
  18. It works great now.thank you very very much for your help and posting this.

    ReplyDelete
    Replies
    1. Yay! Good to hear it! And thanks for verifying!
      +m

      Delete
  19. Is this verified or do I dive in?

    ReplyDelete
    Replies
    1. Well the tag says verified and if you look above your comment, Chris has his board working.
      +m

      Delete
    2. I tried different op amps in this and the OPA2604 sounded a bit stronger than the 4558. I also used a 5mm red led. I might have imagined it but it sounded a bit ...bolder than others. I forgot to try a UV but will do it when I finish the art work.

      Delete
  20. My LED keeps burning out and I don't know why :( any ideas?

    ReplyDelete
    Replies
    1. You have a path to ground after the LEDs cathode? There shouldn't be one. A short or tiny solder bridge maybe?
      +m

      Delete
    2. Hm, checked it out again. I ensured there were no bridges or anything. I think I should just start again - unless there are any other component issues that would cause the LED to burn out? It's obviously receiving too much voltage right? Gaahh.

      Delete
    3. Not about voltage, it's about passing too much current. My next guess would be that your Volts pot is shorting one of its pins (or insides) to ground. That would explain it too.
      +m

      Delete
    4. Uhh yeah I meant current ;) Haha ok, thanks I'll have a look when I get home from work. Kinda weird. I have checked all the traces over multiple times and have nothing :(

      Delete
  21. So I got this working a while ago thankfully. With magic. Though when I turn the fuzz knob up really high, past 3oclock, I get really loud fizzy hissing. Sounds kinda badass, but is this normal?

    ReplyDelete
    Replies
    1. Hmm, just noticed it has the same exact behaviour on the youtube demo here - https://www.youtube.com/watch?v=F2oC3_POYJY ahh!

      Delete
  22. This comment has been removed by the author.

    ReplyDelete
  23. Just built this and it is a bit crazy as the name suggests but a like the harmonics it creates. Bit hissy when you turn the fuzz pot as previously mentioned but hey overall its quite a good fuzz pedal. May mess about with different diodes, transistors and opamps to see what effect they have as i just used those noted in the layout.

    ReplyDelete
    Replies
    1. Yeah the hiss is just it's natural behaviour. It's good fun I reckon. :) GOES PRETTY HARD.

      Delete
  24. Tone pot is backwards compared to original.

    ReplyDelete
  25. Just finished that but i think it has way too much gain even on the lowest settings of drive and fuzz, sounds no where like on that pro guitar shop demo, however i suspect that he has the guitar volume turned down on the very beginning the only way mine would sound close to that. Also there are a few demos of the pedal on youtube that sound more like mine, well much more gain, fuzzy, fizzy - not so happy with that. Dont really think that i have made an error though. Tried two ICs, will try to swap tranistors but dont have high hopes. Any Ideas ?

    ReplyDelete
  26. well after fiddling around for some time i think the build is ok. What it does great are those completely wild compressed noise Neil Young Sounds, using the Voltage starve, but that dynamic low gain crunch like at the beginning of the PGS video not so great, at the knob settings they have at that video i get an extremely bright, harsh high gain fuzz that sounds bad. Nice build but not essential for me. thanks for posting anyway.

    ReplyDelete