Monday, 27 February 2012

Causality 4 Phaser MkII - Rick Holt (frequencycentral)

I usually opt for PCBs for larger circuits because I don't think vero lends itself particularly well to overly complicated schematics, but wanted to put a phaser layout together that was something other than a Phase 45 or Phase 90, and this one looked like a fantastic option as it is a great sounding and versatile phaser designed by Rick Holt (frequencycentral).  I went straight to the MkII version for the extra controls and this should fit in a 1590B if you can squeeze it in with 5 pots, but it may make more sense in a 1590BB or at least a 125B which has slightly larger dimensions than the 1590B (which would no doubt come in handy).  Get making links! :o)


Info from Rick:

Here's the latest design out of the frequencycentral fun factory. Designed to be an easy build, so no FET matching or hard to source parts - just build and phase! It's a four stage OTA based phaser with two fixed stages and two swept stages.

MKII Changes:
Width pot added, this defines how broad an LFO sweep the OTA's see
Shape pot added, waveform now continuously variable from upward sawtooth through triangle to downward sawtooth
The original Depth pot has been re-named as Range, and defines where in the audio spectrum the phasing happens

Here's a comprehensive demonstration video from keto:





Modification: Optional "wet only" switch detail added.


Modification: Optional "Speed" switch:


73 comments:

  1. Has anyone gotten this to work? So far it sounds like phasing but the speed doesnt work. If I turn the pot manually it phases. Any thoughts? Ive triple checked every component, replaced the IC's, checked for bad solder joints and bridges. Kind of frustrated at this point. Ive built the Causaity 6 with no issues but this one is a bummer.

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    1. I haven't built this yet, but I'll go over the layout later today to see if I can spot anything wrong on the layout.

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    2. Did you link Width 2 and 3, and are the Speed LEDs working?

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  2. Yea the width 2 and 3 are linked and the speed leds work when I switch through the different speeds. If the pedal functioned correctly, they would work with their respective speeds. Just cant figure it out.

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  3. I just finished this, and it doesnt do anything. The speed lights change while turning the speed knob, but theres no phasing at all. I didnt see any shorts, and it seems i've wired everything correctly. I think i may give up building pedals soon.

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    1. Don't give up Mike, you've just chosen two toughies in the two pedals. I'll try to go over this layout today to double check for errors, this one still isn't verified so it could be me.

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  4. yeah i was just exhausted yesterday. spent the entire day building that and refurbing the pedalboard it's going on. The speed LEDs seem to work ok, although they do seem a bit touchy in regards to the speed knob being moved. Theres no phase sound at all though.

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  5. I've built this pedal, but I had to use this layout:
    http://www.aronnelson.com/gallery/main.php/v/diyuser/Sundgist/Causality+4+MkII+Phaser+Stripboard.gif.html

    This is, without a doubt, one of the craziest and coolest sounding pedals I've ever messed with, and to know that I made it just sweetens the deal.

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  6. Verified. Finished this tonight and it works a treat, wet only switch only seems to add noise to the effect (will check that out tomorrow but i can easily live without it)other than that it works exactly as it should. Only variation i made was to sub a tl084 for the tl074 as i recall Rick Holt replying in a thread at circuit workshop that there had been reports of bad builds using subbed chips and his original spec was for a tl084. I will try a tl074 in the morning to see how it works, the way i have this set up on my bench it is face down and i aint gonna rip it out tonight, i`m gonna spend some time playing with this beauty. Thanks for another fantastic layout Mark, you are indeed THE MAN.;-)

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    1. Nooooooo, tonight YOU are indeed the man! I can't tell you how many times I've looked over the schematic and layout just looking for something I might have missed, so much so that I'm pretty sure my wife will hate Rick Holt just because of the number of times she's had to pick up pieces of paper with his name on it to tidy up after me! :o)

      Thanks for verifying!

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    2. One other thing, I used a 100k rev log pot for the speed pot, 470 seemed to have too much travel ccw with no affect on the speed. Will also try the speed switch tomorrow.

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    3. how did all this turn out dexxy? did the tl074 worked and did the speedswitch work? and you're saying that 100k rev log instead of 470 gives a better action to it?

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  7. Sorry forgot to update this, yeah, tl074 works fine, speed switch works well however i think Mark made a small faux pas with the orientation of the caps so you`ll need to reverse the wiring, wire marked ground to ic3 pin 5 and the other one to ground. I might rethink the c470 to accommodate the faster speeds. This is a truly remarkable pedal, there`s a myriad of sounds to be had from this, phaser to autowah to synth like delay, utterly fantastic. This layout works as is with the components specified, take your time building it and it is well worth it, no matter how long it takes you to build it you will be longer discovering all the sounds you can squeeze from it, the slightest touch from each pot alters the sound so much that the possibilities are enormous. I should also note that i managed to get the wet only switch to work, but it only worked with a battery not my power supply, so i guess that this circuit may be a bit voltage sensitive (a bit like the little angel v4) however i solved this by fitting a 500ohm sag pot, another pot added to the build but it also adds to the build by adding to it, turn it half way to add a bit of dirt, turn it right down and the pedal appears as if it only works intermittently, not my thing but somebody might like it.

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  8. Think the IC could be swapped for a NJM13700D or NJM13700M?

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  9. What do you exactly mean by link width 2 and 3? Am I supposed to take a wire and short between lugs 2 & 3 in the width pot?

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    1. Yes exactly. Both the 47K at the Width 3 wire, and IC3 pin 6 at the Width 2 wire need connecting to both Width 2 and 3. I did this because they were at opposite ends of the board, and rather than take the 47K resistor a ridiculous distance down to IC3 pin 6, I thought it made more sense to take each to one of the pot lugs and then make a link between them.

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    2. Thanks Mark......off the phaser, but pls check my voltages of deep blue delay, is it Ok?

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  10. Hello,
    I need to know if the leds is crucial part of the design, couse i haven't tried it with the doids. And the pedal only works with very limited settings.

    Any information is welcome. : )
    Thanks : )

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    Replies
    1. No you could use it fine with no LEDs at all. Check the usual suspects, bad solder joint or unwanted bridge is the most likely cause of the problem.

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  11. This comment has been removed by the author.

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  12. Finally done and working, there was an unwanted short due to which there was a constant motorboating, which is gone now. Great effect, very versatile; but mine didn't work with TL074, it worked with TL084 and LM324. Thanks again mark for a great layout.

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  13. Boxed it up. Its giving very heavy popping when switching. Put a 1m resistor between input and LED grnd and Output and LED grnd in the switch, still very heavy popping. Any ideas how to get rid of it?

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    Replies
    1. Disconnect the LED to see if that is causing the popping. Have a look here:

      http://www.muzique.com/lab/led.htm

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  14. Even after removing the LED, the pop is there...what to do now?

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    1. Which input did you connect the pulldown resistor to, the input to the board, or input socket?

      The only other thing to do is start swapping caps until you find the culprit.

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    2. I connected it from input terminal in 3pdt switch to LED negative terminal

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    3. After a long time I reworked on this one, all it needed was grounding of the input on the 3pdt, and its all quiet now, no popping. This has to be one of the best DIY circuits ever. Hats off to frequencycentral and thanks to you.

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  15. Noticed i never posted my version of this!
    Here it is: http://reaperpedals.com/phasing-medusa

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    Replies
    1. Yes I was looking at it on Facebook before mate. Very nice!

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  16. i just built this one today and it works great. what would the result be of 'adjusting the bias' be by putting a 100K trimpot in place of the 47K resistor on pin 6?

    personally, I wish it would have a smoother knee when the phasing peaks when the shape pot is centered instead of the 'hump' it has, but still, it's a nice sounding and very tweakable (tone-wise) phaser.

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    1. Can't remember mate :o) It was something from the big thread on DIY Stompboxes, I'd recommend having a read through that anyway because quite a lot of mods are mentioned by different people, some of which may cover your issue. Have a look here:

      http://www.diystompboxes.com/smfforum/index.php?topic=80456.0

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  17. I just replaced the 47K ohm resistor with a 100K trim pot and now I can adjust it's output closer to unity gain, since it had way too much output before.

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    1. Nice one John, thanks for letting us know. Have you got any pics yet?

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    2. I haven't mounted it into na enclosure yet but I will tonight.
      BTW, I tried a JRC13700 and an LM13700 and they work exactly the same. for IC2 i'm using a TL074 (Rick recommended and uses a TL084 but I didn't have any of those), but i also tried an LM324 and it works well with it too, although i'm sticking with the TL072. for IC3 (the LFO) I tried the recommended NE5532, a TL072 and a TL082 and I like the TL082 the best in that position, since it seems (or at least feels like it) to control the LFO a little better

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  18. got it boxed up. this baby sounds great!

    http://johnkvintageguitars.homestead.com/Effects/Causality/Causality-01-2.jpg

    gut shot:

    http://johnkvintageguitars.homestead.com/Effects/Causality/Causality-02-1000.jpg

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    1. That looks great John, thanks for the pics

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  19. So where exactly do the pins on the 100k trimmer go? I'm not an extreme noob,I've about 10 or 12 pedals mostly madbean. Little help woul dbe greatly appreciated,I can't wait to tackle this.

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    1. pins 1 and two connect where the resistor was.

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  20. Hi. I built this, and it sounds incredibly. Really throatey and robust. I do have one minor problem. On the very end of the sweep, it jumps back to the starting point, almost like it isn't making a full sweep. Could this be a bad TL074? Could it be that I used a TL072 instead of the NE5532? The LED's are very useful, as I can see it come back on almost to full brightness instead of swelling back up. Does anybody have any idea as to what it could be?

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    1. nope. in mine the TL072 and NE5532 sound nearly identical and operate the exact same way.

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    2. So what do you think it is?

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    3. Put a 22k resistor to pin3 and another 22k resistor to pin1 on shape pot, I did so and it removed the jump, you can put those resistor on the veroboard as well just on 24th and 25th raw 1st hole, then you'll solder the wires (shape1 and shape3) on resistors' free lugs. It worked for me.

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  21. I'm an amateur in the world of electronics, capital, solder and pcb I could make this FX,, sound is very-very crazy great incredible,, you know it sounds like a jet aircraft,, thank you Ivlark .. sorry i just use a standard pickup and plug into the tape

    http://www.youtube.com/watch?feature=player_detailpage&v=TVODoNd8Kz0

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    1. Ha ha, like the pic, although the LED really need to be red when it's illuminating him! :o)
      Thanks for the demo and glad you're liking the layouts.

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  22. Finished. It sounds incredible, lot of fun with all those knobs! Thank you Ivlark, great job. Here some pictures of my build:
    http://i242.photobucket.com/albums/ff176/pm7300/01_zps84785e37.jpg
    http://i242.photobucket.com/albums/ff176/pm7300/02_zps19b04405.jpg
    http://i242.photobucket.com/albums/ff176/pm7300/03_zpsd2a0e56f.jpg
    http://i242.photobucket.com/albums/ff176/pm7300/05_zpse114dc0b.jpg

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  23. I did some mods.....
    1) stacked two ICs in place of IC3, the lower is a NE5532 and the upper (piggybacked) is a TL072
    2) I'm running this baby @12volts
    really worth a try.

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  24. hi all.
    can anyone tell me how to replace the 47kR with a 100k trimmer. i.e. where to link each leg of the trimmer. merry everything.

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    1. You're using it as a simple variable resistor so just use the middle pin and any one of the other pins. I've got some trimmers that will span that sort of gap, but they're not very common. So because the connections required are spaced quite far apart it make be worth using a small daughterboard for the trimmer with flying leads to make the connections. Like the addon volume trimmer you can see at the bottom of the Offboard Wiring page (but of course with only 2 wires).

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  25. Hello everyone and merry christmas! is there an exact schematic of this baby somewhere? i'm trying to find one with the speed switch too and just can't... :D

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    Replies
    1. You'll find it on a big thread about it at diystompboxes:

      http://www.diystompboxes.com/smfforum/index.php?topic=80456.0

      If you've got any queries about it then Rick Holt (frequencycentral) is on that forum and you can ask him a question in the thread.

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  26. Happy new year to those who have it already! on the edge of the year i'm still trying to debug this baby, it's strange everything works even the leds, speed, range shape width regen, but when i turn the range above 50% i get a strange loud wobbling bass sound on every beat, and if i turn it up fully it becomes a siren (very loud) lower than 50% the phaser effect is almost not noticeable, i've triple checked the circuit even with the original schematics and everything is fine... read about tl074, switched to 084 but the same is happening... has anyone had a similar experience? thank you!

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  27. Hello everyone.

    First, thanks for great layouts.

    I made this phaser, had some trouble but I made it work, and have only one problem - it adds too much gain and volume so it is unusable. I already tried too add a trimer instead of one ressistor, as John Kallas told he done, but it didnt help.

    Does somebody have an idea how to fix that?

    Thanks.

    Mladen

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    1. Use a little volume daughterboard like at the bottom of the Offboard wiring page. Set it to the level you want and tuck it away somewhere in the box.

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  28. Thank you, I will try with this.

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  29. Not sure what happened to my last post, I guess my computer blew up or something. I'll try it again here...

    I'm running into two problems. The first one is that the two LEDs light up but don't alternate with the speed knob. Granted, I'm not using the correct values/tapers, I'm just using what I have that seems to get me into the ballpark. Are they supposed to hook up to the speed pot somewhere? And is there anything that connects to speed 1 that I'm missing, or is it just an empty lug?

    I got it all wired up and I'm not getting much guitar sound, which leads me to problem two...all I'm really getting is insane oscillation without much rhyme or reason. Is not having the correct pot values going to significantly change the effect of the circuit? I'm hoping having the correct values will fix the issues, but I'm still somewhat confused.

    I'm really stoked to get this circuit up and running, it seems like a pretty versatile phaser!

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  30. my last post dissappeared, too... weird!!

    thanks guys!!! i think i'm in love!!! <3

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  31. i am totally in love. i modded mine a bit, but it's basically the layout above with the dry kill switch, and an exp pedal jack for the speed.. here's a video

    https://www.youtube.com/watch?v=RfhjtW79O_U

    thanks brothers... hot damn!!

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    Replies
    1. You've done a great job there Jimi, I kept a note and think I'll have to build one with your mods.

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  32. I has built this pedal . but the speed LED doesn't work . any body has fixed the speed LED ? plelase help me . what must i do for fixing the speed LED . thank you . and sorry for my bad english .

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  33. Built and working great. This is a touchy Phasor due to the wave shape. The option is cool but if you are looking for smooth symmetry you will have to spend a bit of time dialing in the wave form. That was just an observation ,not a complaint. I did make one change on mine. I reduced the value of the range pot to a B10k. This seemed to be a better and more usable range. Before I was only getting control with roughly 7-10% of my sweep on that pot. That is my 2cents. It is a pretty cool build. I will be putting it in a 125B.

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  34. I made the causality phaser but It really don't work, I've inspected all the things but I don't find any bad solder on it. My problem:
    - The Speed LED 1 is always on
    - The Speed LED 2 lights after few seconds when I powering
    - I can turn the Speed LED 2 off/on at the begining (after put the DC jack) with the width pot.
    At start, I get no sound with the pedal, I finally find that I made the "wet only" vero, so I just put a wireon the two pads and now I've sound, just the dry sound, no phasing and pots do nothing on the sound.
    It's like all the phasing is bypassed (so before when I missed the wire between the two pads, the phaser was on wet only and so the phase don't changes).

    Have you a solution? I'm really desesperate...
    Thanks a lot

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    Replies
    1. IC pin voltages will always give the best clue

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  35. IC1:
    1:1,39V
    2:0/0,60V
    3:5,32V
    4:5,32V
    5:6,67V
    6:0V
    7:6,67V
    8:5,30V
    9: 5,27V
    10:6,57V
    11:10,94V
    12:6,54V
    13:5,24V
    14:5,22V
    15:0,60V
    16:1,38V

    IC2:
    1:5,20V
    2:5,20V
    3:5,20V
    4:10,80V
    5:5,20V
    6:5,20V
    7:5,20V
    8:5,20V
    9:5,20V
    10:4,88V
    11:0V
    12:5,2V
    13:5,2V
    14:10V

    IC3:
    1:9,95V
    2:4,92V
    3:5,11V
    4:0V
    5:5,02V
    6:5,02V
    7:4,99V
    8:10,58V

    Ouahou!

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    Replies
    1. These are the voltages Rick posted from his working build:

      NE5532

      1. 1.32v to 8.44v
      2. 3.56v to 5.81v
      3. 3.45v to 5.77v
      4. 0v
      5. 3.56v to 5.84v
      6. 3.55v to 5.85v
      7. 2.89v to 7.02v
      8. 9.10v


      TL084

      1. 3.89v to 5.34v
      2. 3.87v to 5.37v
      3. 3.85v to 5.30v
      4. 9.10v
      5. 3.63v to 5.02v
      6. 3.87v to 5.33v
      7. 3.87v to 5.33v
      8. 3.87v to 5.33v
      9. 3.87v to 5.35v
      10. 3.85v to 5.31v
      11. 0v
      12. 3.87v to 5.33v
      13. 3.88v to 5.33v
      14. 3.87v to 5.33v


      LM13700

      1. 1.304v to 1.373v
      2. 0v
      3. 3.87v to 5.33v
      4. 3.87v to 5.33v
      5. 5.05v to 6.51v
      6. 0v
      7. 5.03v to 6.53v
      8. 3.87v to 5.33v
      9. 3.87v to 5.33v
      10. 5.03v to 6.53v
      11. 9.10v
      12. 5.05v to 6.51v
      13. 3.87v to 5.33v
      14. 3.87v to 5.33v
      15. 0v
      16. 1.304v to 1.373v

      10.5V isn't unheard of if you're using an unregulated supply, but you need to check the following to see why the voltages are off:

      IC1 looks OK

      IC2 pin 14 shouldn't be 10V. Are you sure the link is going to the correct row?

      IC3 pin 1 shouldn't be as high as 9.95V. This pin is suspiciously next to the supply pin, are you sure the cut between them is complete and there are no burrs in the hole which may be making an unwanted bridge?

      You don't seem too far away but there is obviously something which isn't quite right.

      Delete
  36. How does one check the pin voltage? Do I just put the negative probe to common ground and probe out the pin with the positive?

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  37. Having an issue with this phaser. I have it hooked up to my test rig and have sound coming through, and the Led's light in time and depth with the pots, but no phasing. I checked all my voltages to the ones Rick posted and they are all in line. The only issue is pins 5&7 on the LM13700. I am getting voltages of .58-.73 on those pins. I tried tracing back but am not seeing why I am ~5volts short there.

    Any thoughts?

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  38. This comment has been removed by the author.

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    Replies
    1. LM13700N is fine to use.

      Be aware that this is a very difficult build, even for experienced builders (as are all of Rick Holt's pedals). Even if you build this with no errors at all, it may not work first time. De-bugging it would be very hard, unless you know exactly what you are doing.

      If you are a beginner, I would suggest building a few easier pedals to start with, and save this one until you are more confident.

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  39. Hi, just built this, worked well before boxing. now it's in the box there's a huge drop in volume. Can anyone give any pointers as to what would cause the volume drop please?

    ReplyDelete