A/B/Y BOX

[GuyaGuy]

does anybody have a diagram for an A/B/Y box that they can share with me OR know of one already posted online somewhere?

i've heard you can make a good 'un w/ radio shack parts for $15, which is exactly what i'd like to do if someone can help a guy out!

[wolf]

Hello GuyaGuy
I drew up an A/B box using MS Paint:



I have a feeling you'll have questions so feel free to ask them.

[jdtogo]

hey wolf ..... thanks I was just thinking about doing that . your the man !

[GuyaGuy]

wolf, i swear you can whip out a diagram at the drop of a hat. and you've done it plenty of times for others, and now for me--so many thanks for all yr efforts!

i think everything in the diagram is self-explanatory. looks like an easy job. the only thing i'm wondering about is the switch. the switch in yr drawing seems to be a single on/on, which would make it an AB box but not an ABY, which allows a combination of A and B. (for example splitting the signal to 2 amps.) so, i'm assuming i just need to attach the A and B jacks to individual on/off switches which then meet at the input jack?

[JohnH]

the switch in yr drawing seems to be a single on/on, which would make it an AB box but not an ABY, which allows a combination of A and B. (for example splitting the signal to 2 amps.) so, i'm assuming i just need to attach the A and B jacks to individual on/off switches which then meet at the input jack?

Wolf's diagram is also good for a three position on-on-on switch, if you can find one

[wolf]

If you want an option for both A and B then the switch should be a SPDT Center ON switch. Radio Shack should have one.

[GuyaGuy]

thanks a lot!
after doing my last post i remembered i actually have an old DOD AB box, so i can just modify that to be a ABY. i'll just need a new switch! easy peesy lemon squeazy!

so, if that's all there is to an AB or ABY box, how is it that people complain about certain brands of AB(Y) boxes robbing tone and what not?
obviously, there will be volume loss if splitting a signal, but it seems like there's nothing there capable of altering tone.

[lethargytartare]

First things first -- I'd say give it a shot and see what you get. Best way to discover new quirks and tricks is to dive in and start soldering :-)

As for the ABY thing...I think the problem with a simple passive ABY idea is that, as you mentioned, you're splitting the signal and trying to drive two effect chains, and then you want to recombine those two signals. I'm not sure you can get consistent or acceptable results like that. The better plans out there buffer the signal at input, give both chains their own clean signals, and then the circuitry processes both signals at the end. And when you have that circuitry involved, there are just many places for the original tone to get altered or impaired (hence complaints about different models). But there are other things that a better design will give you -- like pop-free switching between the channels, lower levels of noise, etc.

GEOFex has the reigning king of A/B/Y plans, so if you get ambitious, that's the way to go.

If you do try the passive route, write back with your results!

Cheers!

ltt

[wolf]

lethargytartare
Well, there you go discussing the problems of a passive A/B/Y Box and how a buffered system is better and that GEOFEX has the best schematics.
Heck, I drew that diagram based on the fact that someone wanted to spend $15 for such a box.
Well it seems, not only do I have to draw a diagram but I have to post a link too?
Okay here is the circuit you mentioned:
www.geofex.com/FX_images/splitter.gif
I don't know about you, but I'm willing to take a wild guess and state
1) this might cost more than $15 and
2) all of the parts are probably not available at Radio Shack.

[GuyaGuy]

well, i liked your schematic just fine, wolf! ;D

i didn't know about GEOFEX and discovered it shortly after you posted yr diagram.

lethargytartare, thanks for yr tips. i guess it gets more complicated when you're splitting the signal to 2 amps, dealing w/ vol + tone loss, etc. but i think a simple box is just fine for me. i took a look at the guts of my DOD AB box and it's pretty much exactly to wolf's specs. and it works just fine for my needs. there is the sound of the switch, but i just need something to bypass or include certain pedals in my chain. i won't be switching mid-song, so the switching sound's no problem. i just need to add a new switch.

[wolf]

GuyaGuy
Thanks for your comments about the diagram I drew.

I believe that putting a capacitor across the switch terminals will eliminate that loud "pop" you sometimes hear when switching circuits. I'll have to look that up to see where it goes and what value(s) you'd need.

And to all the Board Members, I'm sorry if I sounded a little angry about lethargytartare's posting but I felt at least he should have posted a link.

[erikh]

The common practice to prevent popping is to put a 1 Meg resistor from the input and out jack to ground. You don't want a cap there, that will make it pop louder because the caps will he holding some sort of charge. The pop is caused by that charge. The resistor will take that charge and shunt it to ground. The same thing can probably be done with the switch in the A/B/Y box.