need noise-free A/B box to switch between pedal chains -

Discussion in 'Effects, Pedals, Strings & Things' started by samhambone, Feb 12, 2008.


  1. samhambone

    samhambone Member

    Messages:
    652
    Joined:
    Nov 22, 2007
    is there such a thing? i need to switch between my basic effects chain - a few light dirt boxes, tremolo and delay - and a full throttle big muff. this set-up is the most convenient for me because i can leave the big muff on all the time and not trap dance to shut off pedals and turn on the fuzz.
    i've built a couple of A/B boxes from various layouts - including the one on the fulltone website - and they all hum like freakin' crazy. is there such a thing as a dead-quiet A/B box or am i dreaming? is it likely that the noise i hear is due to things other than the A/B box - ground loops, etc.? any help would be great. thanks
     
  2. Zero

    Zero Member

    Messages:
    2,784
    Joined:
    Dec 18, 2002
    Location:
    United States
    What's your set-up? Are you going to two amps or do you want two loops going to one amp?

    I built the Fulltone A/B and it thought it worked great. I think there might be a small bit of hum going to two amps with it but nothing like, say the Morley ABY which hummed insanely bad.
     
  3. vorvick

    vorvick Member

    Messages:
    964
    Joined:
    Mar 28, 2005
    Location:
    Oregon
  4. sh333

    sh333 Member

    Messages:
    404
    Joined:
    Dec 13, 2005
    Location:
    Canada
    Indeed, the Lehle stuff is killer.

    I have a few of last year's D.Loops left in stock that I would sell for the same price as a Little Lehle ($159). the D. Loop is likely the one that you want.
     
  5. plygtar

    plygtar Member

    Messages:
    119
    Joined:
    Mar 12, 2007
    Location:
    West of Phila, PA
    Just got a Radial Engineering Big Shot ABY. I added it to my chain of pedals feeding two amps and encountered no ground loop hum. No tone coloration or tone suck either. It is passive so no battery to fuss with. Has true bypass with a built-in transformer and three other switch if needed towards eliminating any hum. After trying a couple of basic switchboxes I found this one works best for its price. Only minor downside is it doesn't have an LED indicator for the A, B or Y position. I have another brand new one for sale.
     
  6. samhambone

    samhambone Member

    Messages:
    652
    Joined:
    Nov 22, 2007
    i use the AB to split the signal into two small pedal chains - "A" has a few light dirt boxes, tremolo, pitch shift, analog delay and "B" has the full on big muff (and the AB box is the on/off switch between the two lines). I take A and B and feed them into a general guitar gadgets 4 line mixer (it's buffered and has an op amp powering it) - into lines 1 and 2 (with 3 and 4 turned off) turned up all the way - and then out to my amp.
    basically, i need to take my guitar signal - split it in two for the two pedal chains (use the AB to toggle between them) - then bring the two back together to go into my one amp (i don't have a stereo amp setup).
     
  7. stinkfoot

    stinkfoot Member

    Messages:
    6,020
    Joined:
    Jun 20, 2004
    Location:
    Uppsala, Sweden
    With that setup, you shouldn't need anything fancy - a regular passive A/B switch wired right (with the unused output shorted to ground, to shut that chain up) should do just fine. The Fulltone layout is a-ok in that regard, so it really shouldn't give you any extra hum. The Radial or Lehle (Little Dual should do the trick) will isolate the two chains from each other, which may or may not help. After all, you're re-connecting their grounds at the mixer, so I doubt having isolation would make any difference.

    Again, a regular properly wired A/B box should work fine. Does the Muff hum as much when you plug the guitar straight into it (keeping the rest of the chain intact, mixer and all)?

    /Andreas
     
  8. samhambone

    samhambone Member

    Messages:
    652
    Joined:
    Nov 22, 2007
    the muff it doesn't seem to hum nearly as much plugged in directly. could this be the cause of my problem - in an effort to keep the wiring in the AB box as short as possible, i have some cross over between the A and B sides - could it be that contributing to the added hum? also, i used standard 24 gauge pre-tinned stranded wire - should i get and use shielded wire?
     
  9. SkipTracer

    SkipTracer Member

    Messages:
    416
    Joined:
    Apr 6, 2007
    Location:
    Vancouver, BC
    I think the easiest and probably least expensive way to do this would be a Boss LS-2. It will switch between two different loops. If I understand your post correctly, that's what you want, right?
     
  10. fly135

    fly135 Member

    Messages:
    800
    Joined:
    Nov 27, 2007
    Location:
    Orlando
    I just made an A/B box and it doesn't hum at all. I only ground the send jack and not the recv so there in no ground loop in the FX chain. I also keep the LED power ground separate from signal ground.
     
  11. stinkfoot

    stinkfoot Member

    Messages:
    6,020
    Joined:
    Jun 20, 2004
    Location:
    Uppsala, Sweden
    Well, the signal and ground wires are supposed to go across the switch, like so:

    [​IMG]

    But I'm not exactly sure what you mean by having some wires "cross over between the A and B sides".

    24awg wire should be just fine, and as long as the box is conductive (made of metal), you shouldn't need shielded wires.

    /Andreas
     

Share This Page