Instructables
Picture of ABY guitar box
This tutorial was also posted in my blog. Check it out for more DIY projects!

This is a A/B/Y box. It acts as a switch. You can plug in a guitar and have it's output go into two amplifiers.
You can choose between the amplifiers or use both at once.
This is a very simple build. As a beginner I had only moderate work.



 
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Step 1: Bill of Materials

Bill of materials:
2x 5mm LEDs
2x 4,7k Ohm Resistors
2x DPDT Switches (http://www.banzaieffects.com/files/images_detailed/d_4217.gif)
3x 1/4 jacks (P-10 jacks - http://www.effectsconnection.com/oscommerce/images/marshallstylemono.jpg)
Wires
Plastic container
9v battery clip (http://www.amqrp.org/kits/NCKeyer/elmer/P7190015a.jpg)

Tools needed:
Something that can drill, such as a Dremell
Soldering Iron & Solder

Step 2: Prepare the compartment

You'll need a plastic or metal compartment.

There should be four holes on top (2 for the LEDs and 2 for the DPDT switches), one hole in front (for the input and two holes on the back for the output.

You could also have an extra hole for a 9v input plug but I didn't use one in this project.

Step 3: Electronics

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Foto 0021.jpg
Foto 0017.jpg
Now for the fun part... connecting everything.

Follow the schematics available bellow. They are pretty simple.

The drawing was made with BEGINNERS in mind so it doesn't follow any conventions. I believe it is pretty self explanatory.

I tested everything out using a breadboard before soldering. This is a specially useful step for amateurs.

Testing the circuit.
Video
invalid movie: http://vimeo.com/5571157

Step 4: Testing

Now you should have your A/B/Y box.

You plug in your guitar in one end and the amplifiers on the output ends.

By pressing the A/B switch you can choose between any one of the amplifiers as the output.

By pressing the A/B or A+B switch you can choose between using only one of the outputs or using both at the same time (that's the difference between A/B and A/B/Y box).

Enjoy.

Testing the finished ABY box.
http://vimeo.com/5571171
alexanderm2 years ago
i find it odd that the author didn't respond to a single question about whether his pedal has issues with noise. Perhaps i can help:

This schematic works, but has a key limitation, which can create noise issues in many cases. If it works for you, great. But, if you have issues with noise, the cause may be because the circuit doesn't ground the bypassed line. The solution to this is simple: use a 3PDT switch, instead, and switch the grounds, as well. If you are willing to do without the LED's, you can use the DPDT switch, still. The schematics to do this are widely available via a quick Internet image search.

The "Y" capabilities of any passive pedal, in which two guitars are routed into one amp, are suspect, in terms of avoiding noise/issues. In a pedalboard configuration, it may work if you have buffered pedals before the "Y", or if you are using active pickups. But, in most cases, the loading will cause negative interaction between the two instruments. The solution to this is to create an isolation circuit, and/or buffer the inputs, but this turns the pedal into an active one, rather than having the passive simplicity. That said, the schematics are some of the easiest to build, but will require some electronics/soldering skills. Another solution might be to use pedals that buffer the input prior to the passive "y". That whole scenario is kinda' hokey, anyway, though. Just get another amp.

For the people asking about the kind of wire, it really isn't a big issue... obviously, if you use a high-quality wire, it will, technically, be better, but, i doubt you'd hear the difference between Canare GS-6 (what i use) or solid-silver-core Teflon-insulated wire, and an off-the-shelf hookup wire. The gauge should probably be between 22 and 18.
I want to build one of these to run two outputs from my guitar for recording - 1 to a mic'd amp / fx, and one clean line straight into a soundcard, so I am keen to reduce the possibility of noise when running 'Y'.
But I'm also a beginner.. any chance you could point me a wiring diagram for the 3pdt grounded version you're talking about?

Thanks!
shwing51502 years ago
cool!
andrecl2 years ago
Hi, I get a huming sound on the output that is not on. Is there a way to fix this, or did I do something wrong?
Great instructable BTW. My first DIY project :)
madsteex2 years ago
Sorry but the Grounding??
waka waka4 years ago
if u remove the LEDs would this work in reverse?
IF you preffer removing leds ( and i know this is a old post ) you can replace DPDT switches with SPDT switches simply leaving out the middle part. It'll function the same way, without the need for supply voltage nor the LEDs. Though I think you may have figured that one out by now :)
I prefer to build it without the leds but I don't understand very well..Does it function without battery?? and then...if I want to use 2 amplifier together I have to put the switch on "A+B" but the Out signal isn't the same then the Input signal...right??..cause the impedance are in parallel..I think.. (sorry for the english but I'm an italian student )
jphoton3 years ago
if you have a problem with "popping" sounds when you engage the switches, try putting a 1 meg resistor between the hot and ground of the jacks.
-Syrus-3 years ago
One question, sometimes with these boxes, you get a "pop" when switching, is this the case with yours too?
What gauge/kind of wires should I use? I've still not gotten around building this due to lack of time, and because I still need wires and the switches.
j-plan4 years ago
hiya gcmartinelli, ive tried making this project but it didnt work, i am an absolute beginner so it was probably something ive done wrong, so i used the 4.7k resistor on just the LED (without the rest of the circuit) and the LED wouldnt light up, i was wondering if the resistors you stated (4.7kohm) are to high a value? like i said i probably have done something wrong but wanted to ask anyway.
gcmartinelli (author)  j-plan4 years ago
Hi J-plan, maybe you soldered something wrong. I obviously built it and it works... :) The 4,7k resistors where alright because the voltage of the battery feeding them is high. I guess you could use a smaller battery and smaller resistors. Maybe you connected your LEDs inverted? I've received some LEDs with Anodes and Cathodes "reversed" (short legs on the wrong side). Hope you find the solution! Sorry I cant help much but I'm also a beginner!
thanks for the reply, i took it all apart and started again, works perfectly, very happy with it, great instructable!!!! would be nice to see some more like this for beginners like myself. im currently working on a passive di box, will upload a instructable on that once im done, though the transormers to be used arent cheap :)
gcmartinelli (author)  j-plan4 years ago
Good to hear it worked j-plan! :) Thank you for the compliment. I'll try to post some more projects. What exactly do you think this Instructable had that others don't have (for beginners)? Maybe I stumbled on a recipe here... :)
well its just that an AB switch is a very simple thing, perfect for a beginner like myself, i have since rewired the box slightly differently from yours:- i have wired the negative lead from the battery straight to pin 1 (sleve) on the female stereo jack, and then placed another lead going from pin 2 (ring) on the female stereo jack to the dpdt switch, this uses the jack plug as a switch so that the circuit is only complete when a guitar is plugged into it, by doing this you dont waste the battery by having the led's lit up permanently. obviously though, this will only work with a mono jack plugged in as the sleve of the mono jack makes the connection between pins 1 + 2 vand thus completing the circuit!!
noahcc j-plan3 years ago
Does having the power run through the stereo socket creat noise or pop when you change outputs.
gcmartinelli (author)  j-plan4 years ago
That's a great, simple mod... :)
This would be even awesome-er if it had volume knobs, one for A, one for B and and a master volume for both, which would control how much volume is fed to lines in specific, so that you could have, lets say, a low clean channel on A, and a louder distorted channel on B. ABY Guitar Box 2.0? Almost forgot to say, I LOVE THIS. I'm going to make one ASAP. That's kind of why I mentioned the volume knobs, 'cause I'm sure as hell you'd know how to do it better than me, all I do is read and do what instructables tell me, not understand them O_O
everblur4 years ago
Hi gcmartinelli, just wondering is this pedal noisy? do you get any hum or crack/pop sounds when you do the switching? thanks!
dave_hib4 years ago
ummm. i turned off my soldering iron, and the noise went away. silly me. i fitted the aby guts into a metal enclosure, but it was a tight squeeze and the wiring got a bit messy. but it works!! can't wait to test it at rehearsal with my new amp!!! thanks gcmartinelli!!
gcmartinelli (author)  dave_hib4 years ago
Glad it worked! :)
ya.calmate4 years ago
hi is there any way to reverse the switches, what i want is to connect two guitars and go out to one amplifier. i´d apreciatte your answer. great instructable! H
 I was wondering the same, because i have two guitars and one amp and when i play a show, i want to cut the signal from the one im not using. That way i can switch guitars silently :)
gcmartinelli (author)  ya.calmate4 years ago
Nope, I don't think that's possible ya.calmate... :( I think the voltage running from the amp would have to be split between the two guitars, one of them wouldn't receive enouth voltage and the sound wouldn't come out (or would come out very low). There may exists a ABY switch like that but I'm not sure... I can't even test it now because the ABY swtich from this instructables I made for a friend and it's not with me anymore. Thanks for commenting.
lfebrero4 years ago
If i wanna use 3mm LED's instead of 5mm should i change the resistors or what should i change??
 Could i put two guitars into one amp with this
gcmartinelli (author) 4 years ago
Hey guys, I'm glad you all enjoyed this Instructable! It was my first experience documenting a build and with any kind of open source. I think I'm hooked now. :)
dave_hib4 years ago
hI, GCMARTINELLI, thanks for this cool project! i've just finished making it and it works but i get a lot of buzz. have i done something wrong, or is this normal? cheers. dave.
iamtoats4 years ago
Very nice! I've been looking for one of these for a while... The commercial ones are way overpriced! I think I'm going to replace the battery with a 9v plug so i can use this on my pedalboard.... It may introduce buzz, but i have a noise gate anyway. (the 5150s really need it!)
justinadams4 years ago
can you switch the 1/4" stereo jack to a 1/8" stereos jack?
gcmartinelli (author)  justinadams4 years ago
Yeah, I guess you could do that. :)
awesome. thanx
stevie15 years ago
the switches are dpdt. but other than that awesome instructable!
gcmartinelli (author)  stevie15 years ago
Thanks Stevie! It was a typo, thank you for the heads-up! :)
no prob
Your Schematics are a little out of focus, Can you get a better shot for us?
I tried making a new schematic, I hope it helps.