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Need schematic for ABY+Looper

Discussion in 'Effects [BG]' started by Vic Winters, Mar 8, 2008.


  1. Vic Winters

    Vic Winters Supporting Member

    Apr 20, 2006
    Rochester, NY
    I want to make an ABY box with a switchable loop in one of the channels. I have a Morley ABY and a home made true bypass looper, but I'd like the convenience of both in a single enclosure.

    I want the ability to do the following:

    A w/ loop
    A w/o loop
    A w/ loop + B
    A w/o loop + B
    B

    I have the majority of parts I need, and I'm handy with a soldering gun, so all I need is a schematic. I found a schematic for the Morley, but the Morley has a PCB and I have no idea how to trace that, nor do I really wish to try and recreate it.
     
  2. I doubt you're going to find a schematic out there that does exactly what you want. You're just gonna have to Frankenstein a few ideas together.

    What's the issue with the Morley? You have a schematic, there's no need to trace the PCB.
     
  3. Vic Winters

    Vic Winters Supporting Member

    Apr 20, 2006
    Rochester, NY
    [​IMG]

    Questions I have.

    1. What are the V+, V-? Battery leads?
    2. What are the boxed A's?
    3. Anyway around having to use those jacks? If not, I assume Small Bear would be a source for them?
    4. What is the purpose of the 100K ohm resistors?
     
  4. ABY schematic straight from the horses mouth!

    V+ is positive voltage, V- is negative voltage, but you shouldn't need a dual rail supply to do this (ie; V= and V- in one device.) In fact, if you are prepared to go without LED's you won't need ANY supply voltage whatsoever.

    You can use whatever jacks you want to use provided they suit the purpose. Something this simple doesn't require a circuit board - you will be able to wire all this up point-to-point style once the switches and jacks are mounted into the enclosure.

    So, if you have made a bypass looper before, this is just an extension of that. My advice would be to copy what you did with your bypass looper, then just Frankenstein in the ABY switches. Ignore the LED's for now just to keep it simple, then once you've got the important bits working, think about adding a battery and some LED's.
     
  5. This page has a really good diy bypass article. It contains this picture. If you install that picture in between the A/B jumper (input side of TB switch) and R4 (output side of TB switch) on the Morley diagram that should bypass your B loop. I would like to have made a better drawing, but my pdf editing capabilities are slim.
     
  6. Vic Winters

    Vic Winters Supporting Member

    Apr 20, 2006
    Rochester, NY
    It shows TRS jacks in nifty's schematic, but I have no idea which leads to run to each tip, ring and sleeve since my schematic is awful in that respect.
     
  7. In nifty's diagram, the only jack requiring a TRS is the B output jack as it is closing the -9V lead. On that one the -9V goes to the ring and when you plug a 1/4" mono in it shorts the ring to the sleeve and -KAPOW!!- completed circuit. (Hopefully not kapow as that would be a poor design, but you get the idea) The box should still work without the battery, but there will be no indication of what is on or off and that will all be guesswork.

    All the rest should have the input/output soldered to the tip and the sleeves should all be connected as the ground via the casing (or some other means if your casing isn't conductive). You can use TRS, but you don't need to and it doesn't matter as long as you wire to the correct positions, the rest will take care of itself.

    Hope that was clearer than mud.
     
  8. Tip is ALWAYS signal. Sleeve is ALWAYS ground. Ring is only ever needed to 'switch' the power, and it is usually always wired to the negative lead of the battery. When you plug in a mono jack plug, the plug shorts the battery negative to ground and wang, current flows.

    But like I said, I suggest you just ignore the battery and LEDs for now - but do still install a TRS jack socket so you can add the electronics later. It's more important to get it working right without having to worry about melting something!
     
  9. Vic Winters

    Vic Winters Supporting Member

    Apr 20, 2006
    Rochester, NY
    I'm working on it right now. It's gonna be a little different than usual.

    (2) DPDT switches (toggle) for the ABY. Because I don't switch loops mid-song and I can still tell setting without LEDS. A 3PDT switch (stomp) with LED to switch on effects mid-song, and the ability to see the loop status.


    What is the purpose of the 100K ohm resistors? Obviously the 12K are for the LEDs. I have a pack of them, but if I don't need them, I have the receipt to return them.
     
  10. Don't know exactly why Morley put them in, but they do set the input impedance of the two inputs, they can be left out if you want. Return resistors? Aren't they worth like, 2 cents.
     
  11. Vic Winters

    Vic Winters Supporting Member

    Apr 20, 2006
    Rochester, NY
    It was a pack of 5 for $1.00, but I have some other stuff I can return as well. LEDs, 10K resistors, momentary switch. About $6 total.
     
  12. Vic Winters

    Vic Winters Supporting Member

    Apr 20, 2006
    Rochester, NY
    If anyone wants it, here is a simplified, color version of the regular ABY schematic without the LEDs and resistors.

    Left is Input, Top Right is A, Bottom Right is B.

    abynoLED.
     
  13. Vic Winters

    Vic Winters Supporting Member

    Apr 20, 2006
    Rochester, NY
    Well I finally finished and tested it. The results I wanted, sadly I did not get.

    What I wanted:

    A w/ loop
    A w/o loop
    A w/ loop + B
    A w/o loop + B
    B

    Here is what I got:

    Switch 1 (A), Switch 2 (A+B), Loop Off - Both Clean
    Switch 1 (A), Switch 2 (A+B), Loop On - Both Effected
    Switch 1 (B), Switch 2 (A+B), Loop Off - Both Clean
    Switch 1 (B), Switch 2 (A+B), Loop On - No Sound
    Switch 1 (A), Switch 2 (A/B), Loop Off - A Clean
    Switch 1 (A), Switch 2 (A/B), Loop On - A Effected
    Switch 1 (B), Switch 2 (A/B), Loop Off - B Clean
    Switch 1 (B), Switch 2 (A/B), Loop On - No Effects

    It looks like I'll have to go with Plan B, which I should have went with in the first place. Just make a Loop pedal as is, with a second output wired straight from the Input, but with a kill switch right in front of the second clean output.
     
  14. I was under the impression that you were planning on using 3 switches, which in my mind is the minimum that you would be able to use to create what you are asking for. Two for the ABY (as nifty's diagram shows) and then a third for the true bypass loop. I can't see how two would get it done. Maybe if I gave it all kinds of time, but even then I think the operation of such a device would be much trickier than 3 switches.
     
  15. Bryan R. Tyler

    Bryan R. Tyler TalkBass: Usurping My Practice Time Since 2002 Staff Member Administrator Gold Supporting Member

    May 3, 2002
    Connecticut
    I actually had Brian at Loop-Master build me a pedal like this- it's an ABY with a tuner mute, and a loop for the A output and another loop for the B output. It's a very useful loop box- maybe you could ask him for advice. I imagine you'd definitely need three switches for it.
     
  16. All right, I broke down and drew one.

    This is W/O leds so you will have to add another pole to each switch to add an led and do the TRS thing to one of the jacks to switch the battery if you want to do that. Any questions let me know.

    [​IMG]
     

    Attached Files:

  17. Vic Winters

    Vic Winters Supporting Member

    Apr 20, 2006
    Rochester, NY
    I am using 3 switches.

    Switch 1 toggles between A and B.
    Switch 2 toggles between A/B and A+B.
    Switch 3 is for the loop.
     
  18. Vic Winters

    Vic Winters Supporting Member

    Apr 20, 2006
    Rochester, NY
    As it stands right now, I can't switch between A and B. I get both signals no matter what position Switch 2 is in. On the plus side, I get 1 clean and 1 effected signal when I engage the Loop now. Cheapbasslovin, I'm not sure how to transpose your diagram to what I currently have. If it's not too much trouble, could you show me what I'm doing wrong with my diagram below?



    SOAB2.
     
  19. The yellowish and brownish wires that run between the two switches seem to serve no purpose. Same goes for the black wire joining two terminals of the 3PDT.

    Otherwise it looks kinda right to me. Perhaps you've got the 3PDT rotated 90 degrees?
     
  20. Vic Winters

    Vic Winters Supporting Member

    Apr 20, 2006
    Rochester, NY
    The black wire on the 3PDT is for the ground following this diagram which is connected to a ground point on the case. http://www.singlecoil.com/tb-strip/images/dia1.gif. I have

    You're right. Neither were necessary. I disconnected both and I still have the same results. Pic updated.
     

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