a-b-y switchbox design

[Philippe]

when building/designing one of these things, is there more to it than simply soldering/connecting the appropriate jacks, LEDs, battery clip & 3PDT switch? while assembling an a-b switchbox is pretty basic, is there something more involved (or to consider) when creating a switchbox designed to run two amps at once?

[stallik]

Yes there is. Sometimes. Hum can be a problem when connecting 2 amps. RG's hum free aby helps in such cases by isolating the outputs but if you don't need it, the passive solution you are talking about is simpler and usually better.

[rumbletone]

Also, if you are plugging a passive guitar into it with no buffer, the passive split may adversely affect the tone (I say 'may', because you may not mind the affect on tone of doing the passive split). This is why many splitters use active circuitry.

[canman]

Not to hijack the thread, but do active ABY boxes cut back on hum issues?  I know the RG one does, but is an active ABY box a happy medium between the isolated output version and the passive ones?

I've been exploring various splitter circuits and it seems like they would make a decent addition to an ABY box.

[Mike Burgundy]

Depends on the design...

[Philippe]

the necessity of buffer circuitry for the 'Y' is what I was most curious about as the incoming guitar signal is now being 'split' into two outputs. I imagine that variations in amp input stages also impact this factor/consideration especially if using two different ones. the purpose of this conceptual build is so that an acquaintance can run two dumble combos in stereo and/or two different amps (an old tweed deluxe & a blackface model) simultaneously for tonal variation.

[deadastronaut]

checkout morley pedals...i was looking at their AB/Y mix/combiner the other day...

http://www.morleypedals.com/downloads.html

[canman]

Depends on the design...

Anything in particular one should look for in the design to eliminate hum?  Besides isolated outputs?

[trixdropd]

Good wire routing, trace routing and isolation. With those 2 things it will defeat (most) hum

[PRR]

Start SIMPLE. Try a Y-cord.

If the load of two amps and two cables causes tone-suck, you want a buffer. (However if you are coming from any effects pedal, two amps should not be a problem. Beware of hearing problems which are not really there.)

If that works good, you can go on to add switching as you like it.

What often happens is two amps with inputs wired together will hum from stray current on the wall-plug loop. You certainly should have both amps on the same outlet. A power-strip may be convenient to encourage this in strange places. Both amps MUST have working 3-pin safety grounds. (Don't die for stereo.)

If the amps won't play nice together, and other amps are not an answer, you need to explore isolated outputs. R.G.'s plan is basic and should be effective.