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An easy to build, guitar A/B input box for switching between (2) 1/4 Jack outputs. Design incorporates (2) LED's, to let you know (which) input is active.

An Instructables article which helped me make this pretty easily ; was the wiring diagram found here:

https://www.instructables.com/id/How_to_make_a_AB_box/

Step 1: Tools & Parts List

To complete this project, you'll need:


-Soldering iron & rosin core solder
-Drill w/ bits
-Phillips Screwdriver
-Electrical tape

1x Project Box (plastic / wooden / metal)
1x DPDT switch (can be a sw like I used, or get a DPDT footswitch)
3x 1/4 Mono jacks
Wire
2x 5mm LED's
2x LED Holders
1x 4,700 ohm Resistor
9v Battery
9v Battery Holder / Terminals
Rubber Feet
22 Gauge Wire

Step 2: Wiring Your A/B Box & LED Wiring

Follow either of the wiring diagrams contained. One is an A/B/Y Switch ; with (2) DPDT's, and the other is what I did (a simple A/B switch with 1 DPDT switch)

*Connect the Tip on output A jack to the 1st and 6th prong on the DPDT switch.
*Next, connect the tip of the Input jack to the 3rd prong on the DPDT switch.
*Connect the tip on the Output B jack to the 5th and 2nd prongs on the DPDT switch.
*Finally, connect the sleeve of Output A to the sleeve of the Input Jack, And then connect the input sleeve to the sleeve of the Output B jack and finally connect that to the 4th prong on the DPDT switch.

I am using 22 Gauge Wire for this project between audio connections.

** Note: If adding LEDs, connect your 9v Battery's (+) to the (+) line of both LED's (that's the longer pin , or the smaller of the two internal filaments if you didn't know) with a 4.7k resistor in line before the LED . DO NOT FEED AN LED 9V, without a 4.7K ohm RESISTOR. Next connect the (-) of ea LED to the 'bridged' connectors on the switch found in this diagram. When switched into either on position, now the LED's will light up with the corresponding jack. **

Step 3: Finishing Up / Enclosure Installation

First, test your wiring by connecting a tuner on one of the outs ; and a guitar into the input and switch between both of your outputs (moving the output cable to the corresponding jack).

Once you are satisfied with how the A/B box is performing, now it's time to house the materials. I choose a carved wooden box to install my components ; but you can find project enclosures on the net or build your own from scrap metal. If using metal, be sure to insulate the metal before installing your components to avoid them grounding out on your enclosure.

The switch I used isn't right, but looks and works well, because it's flush mounted with the surface.

You can accomplish this by drilling the top with a larger bit on the outside then mount your switch after drilling out the center hole. This allows you to quickly kick the switch on/off/on ; but I highly recommend buying a DPDT Stomp switch if you are planning on kicking it around on the floor.

The DPDT Stomp switches :

http://store02.prostores.com/servlet/phonekingscom/the-396/Heavy-Duty-DPDT-Stomp/Detail

..... are much more effective if you plan on gigging with one of these.

When an A/B box is wired like this you fail to ground out the channel not being used, resulting in massive hum and hiss when distortion or fuzz pedals are left on. It is just an inherent problem with A/B Boxes ade with DPDTs. You need to use a design that incorporates a 3PDT switch in order to ground the channel that is not being used.
is there any way to ground out a dpdt switch? i built this and got horrible hum afdter spending all the money<br>
<a rel="nofollow" href="http://www.beavisaudio.com/Projects/ABSwitches/AB_DualLED.gif">http://www.beavisaudio.com/Projects/ABSwitches/AB_DualLED.gif</a><br/>
Thanks, that's some good input. While I haven't experienced any hum / hiss using this box ; I plan on using the 3PDT foot switch later instead of this DPDT one from Rat-Shack. ;)
how do you make one with 2 inputs and one output?<br><br>and, does it matter what kind of wire you use?
Thanks a lot for the attribution... <br /> https://www.instructables.com/id/SGK98WQFX23VMM6/<br />
Nice instructable. &nbsp;Love to see other people saving the $50 and building instead of buying one.&nbsp;
Can this also be used for 2 inputs to 1 output, as in 2 guitars to one amp?
This might be a stupid question, but why would you need to switch between amps?
Because Peavy's 5150 doesn't really have a clean channel...... =)<br/>(my reason..) (at stage volumes, it turns into a bad crunch channel...)<br/>
Sometimes you have a tuner connected so you can switch over to it without unplugging your guitar, which is why I have mine - other times you have another amp you want to play through... ; for example I can now play through my marshall stack for a huge sound, or switch to a subway blues amp ;)
Ahh. That makes sense. Thanks.

About This Instructable

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Bio: I am a musician, internet developer, and a hobbyist pedal builder.
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