Project · Boosters & Volume
A/B Switch Box
This is a simple A/B switch box. There are some examples of how to use this box below. The circuit is passive except for the LED indicators to indicate which "channel" is active. The two channels are interchangeable as input or output channels as illustrated in the examples below.
Although there are limitations to the use of passive A/B switch boxes, we've found them to be useful in many applications. You may experience problems with hum and noise especially if you use the A/B outputs into to separate amplifiers, but many times they work well even into amplifiers.
Project files
Everything you need to build it
Parts layout
Parts Layout / Wiring Diagram
What you will need
Bill of Materials
Version 2015February16 · Copyright 2008, 2015 JD Sleep · Permission refused for posting/serving this file from any site other than www.generalguitargadgets.com · Trademarks are property of their owners
Resistors
| Resistor ID | Value | 3-band Marking | 4-band Marking |
|---|---|---|---|
| R1 | 1k | brown-black-red | brown-black-black-brown |
| R2 (optional) | 100k | brown-black-yellow | brown-black-black-orange |
| R3 (optional) | 100k | brown-black-yellow | brown-black-black-orange |
Other
| Part ID | Part Name |
|---|---|
| D1 & D2 | A/B Status indicator LEDs |
| J1 | Stereo quarter-inch jack (Input) |
| J2 | Mono quarter-inch jack (Output A) |
| J3 | Mono quarter-inch jack (Output B) |
| J4 | DC Jack |
| B1 | 9 volt battery (not included in the Kit) |
| Sw1 | Heavy Duty 3PDT foot switch 9v battery snap, 24 gauge stranded wire, Enclosure |
How to build it
Instructions
Version 2015February16 · Copyright 2008, 2015 JD Sleep · Permission refused for posting/serving this file from any site other than www.generalguitargadgets.com · Trademarks are property of their owners
This is the A/B Switch Box kit. Simply a switch box to switch one input to two outputs or two inputs to one output. Some of the typical uses of this switch box are shown on the project page. It is called passive, since the signal paths do not have any active circuits (no boost or buffering, etc). The 9 volt power going into the box is only to control the LED indicator. You can build it without the LEDs and power jack if you prefer to have it simple with no power needed. You can add the optional 100k resistors to the two A/B Jacks (J2 & J3) jacks. This should prevent any switch popping you may experience if you don't have them. Use the project documents provided, starting with the General Build Instructions. Just wire the jacks, switch, resistor and LEDs according to the wiring diagram.
Here's an inside view of the unit we built to give you a real view of the construction.
More about this project
Notes, sounds and related links
Here are some diagram examples of some of the most common uses of a passive A/B switch.
The first example is a set up to enable silent tuning in a live gig environment. Your guitar is input with one output channel to your amp, the other to the input of your electronic tuner. This is a very popular use for passive A/B Switches.
Example 2 is to split your signal into two amps. With this box, you would be choosing the signal to go to either amp A or amp B.
Example 3 is used if you have two guitars into one rig, live or in the studio. Here the 2 channels are input channels, one for each guitar, with the output going to your pedal board or amp.
Example 4 is a very useful function for studio rig set up or testing different effects pedals. Here the A/B switch is used as a "Kill" switch. Locate the A/B switch box at the end of your effects chain and use it to switch off the input while you unplug/plugin different pedals to try out in your rig.
Ready to build? We have the kit.
Buy an A/B Switch Box Complete Kit. Includes all the parts and materials you need to build one, all for about the price you would pay for the parts.