AB Box vs ABY Box vs Combiner

Discussion in 'Effects [BG]' started by minginitis, Mar 28, 2020.

  1. Hey guys, I was having trouble understanding the difference between AB boxes, ABY boxes, and Combiners. For example the Morley AB/ABY Box. The Morley has an A and B jack and an In/Out. Is it an AB box or an ABY? I’ve seen it marketed as both. Is it essentially the same thing? And as for Combiners, aren’t they the same as AB/ABY boxes? You can either combine or split the signal? Thanks!
  2. gh0st42

    gh0st42 Supporting Member

    Oct 25, 2019
    AB Pedal switches between one output or the other. It doesn’t do both outputs at once.

    ABY will do one or the other, as well as doing both outputs at once.

    A combiner is just a backwards version that switches between inputs instead of outputs.
    minginitis likes this.
  3. Couldn’t you just use an ABY to combine then? Or does using an AB/ABY to combine degrade the signal?
  4. gh0st42

    gh0st42 Supporting Member

    Oct 25, 2019
    Depends on the pedal, but many AB pedals can be used in reverse with no issues other than Jack labels being backwards.

    ABY backwards gets more complicated. If levels of the two signals being combined get too different, impedance gets altered, or phase issues get introduced, it’s difficult to keep the the two inputs balanced. Some ABY won’t do Y at all set up this way.

    A Summing mixer or combiner is usually a better fit if you need both inputs combing audio as you can set each channels level and often phase separately.

    Saturnworks makes a bunch of good options and configurations for decent prices.

    Depending on your goals, a Effect Loop Switcher, Loop Blender, or something like that might be easier.

    EarthQuaker Devices has a nice looking ABY switcher/loop switcher combo utility pedal called Swiss Things that could be a good option as well.
    minginitis likes this.
  5. jdh3000


    May 16, 2016
    A/B switches between one input to the other.

    Example, if you have 2 basses, you plug one into channel A, the other in B, then the other side runs into the amp, or effects pedal, or wherever.

    Pressing the switch changes which bass will be going through the amp.

    Now an ABY setup this way usually functions just like the AB with the option of switching to Y, which combines both channels, which in the above scenario would enable both bass signals into one amp.
    Now this isn't very useful in and of itself, however if you turn the pedal around, you can run one bass to two amps.
    In that scenario ABY you could switch between amps using A/B or use both amps at once.

    One could effectively use two of these pedals to run through 2 sets of effects then route them back into a single amp signal.
    Useful if you want two different setups but without having to hit several switches.

    I'm not 100% sure about the combiner pedal except if it's what I am thinking of, one type can do the above situation without using two ABY switches, and the other typ you can loop out to an effect or series of effects on one side and run an un affected signal on the other. These have a blend knob so you can mix as much or as little of your dry signal with the affected signal as you want. Someone please correct me if I'm wrong on this point, but I do know these pedals exist, just not sure if you would call them a combiner.
    minginitis likes this.
  6. Ok so I think I understand. I can use an ABY box to either switch between A or B into one output OR use it as a splitter from one input to two outputs A and B (like an upside down Y). However you cannot use an ABY to combine (A and B, or Y) because it can effect the signal. When combining you would want to use a Combiner/Mixer. Am I in the ballpark? Thanks again.
    gh0st42 likes this.
  7. gh0st42

    gh0st42 Supporting Member

    Oct 25, 2019
    You got it!
    minginitis likes this.
  8. Somanytoys


    Apr 29, 2019
    Also keep in mind that splitting signals into separate chains & amps can cause ground loops, and as mentioned above, phase issues.

    If that happens, you’ll need to get a splitter (ab-y) with an isolating transformer, which will usually also have a phase inverter switch. These are kind expensive, but much better if you plan on doing this seriously.

    2 examples are Radial Switchbone (among many other products from them, new and old) an the Fulltone Truetone AB/Y. Lehle also makes some good ones, as do some other companies.

    The EQD Swiss Things looks really cool. I haven’t tried it, but I do have a VFE Klein Bottle, which I think is more expensive but is a badass mixer.
    minginitis likes this.
  9. keyboardguy

    keyboardguy Supporting Member

    May 11, 2005
    Like to jump in here with a question:

    I want to run a bass guitar and a keyboard through my bass amp.

    Can I use an ABY switcher to play either the bass or keys, AND play them both at the same time?

    For example, I'm playing the keyboard and someone wants to also play the bass at the same time;
    will this work?
    If the keyboard has a volume pedal, will using it affect the bass guitar too?
    Or can I just use a Y cable splitter?
  10. keyboardguy

    keyboardguy Supporting Member

    May 11, 2005
    I tried a Y cable splitter and when both are plugged in, the bass volume is way low. The keyboard volume pedal does not affect the bass..
    Like the keyboard is at "8" and the bass at "3"...
    When I unplug the keys, the bass volume is back to the higher level..

    Will that happen with the ABY switchers?
    Last edited: May 28, 2020
  11. From my understanding, if you would like to combine two signals (keyboards and bass) you would need a Combiner/Mixer, not an ABY or Y cable splitter. If the volume pedal is before the Combiner/Mixer then it will only effect that channel, not both.
  12. keyboardguy

    keyboardguy Supporting Member

    May 11, 2005
    Thanks for the info.
    Would the combiner/mixer help with the disparity of the loud keyboard and soft bass volume?
    The bass volume was way down only when both the keys/bass were plugged into the Y-splitter cable..
  13. Yes. Thats the reason why you shouldn’t use ABY boxes and Y-splitters in this application. It will mess with the signal as stated. Only use ABYs/Y-splitters to split a signal, not combine two. Most Combiners/Mixers have individual volume knobs that allow you to set the level of each channel.
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