What is it?
A passive input and output selector with intergrated Bluetooth receiver and separate volume knobs for each output.

Why did I build it?
I wanted a way to connect the speaker sets in my kitchen and living-room. But I wanted the option to use different sources in different rooms, or one source for both rooms but with different volume. I wanted it to look good and be understandable to the less fortunate (electronically challenged) people.

Bare in mind that this is a passive build witch means it will just give me outputs to put into amplifiers, not speakers (unless they are active speakers).
You could use the same project and put 2 amplifier-boards inside and put speaker outputs instead of the RCA and 3.5 jack on the back.

Let's do it!

Step 1: Things Needed

It all depends on how many inputs/outputs you want, and what kind of connections you prefer. My setup needs:
1. 7x 3.5mm female jack (these will be the patch connections)
2. 4x RCA female jack (2 for input, 2 for output)
3. 1x 6 pin on/on flip switch (For connecting rooms)
4. 2x 1kohm stereo audio taper potentiometer (For output volume)
5. 2x 3.5mm jack - jack cables (I made short ones myself, for patching)
6. 1x Bluetooth receiver board
7. 1x Project box (Can be whatever you want)
8. 1x DC jack (For powering the bluetooth module)

Everything can be ordered from either eBay or your local electronics retailer. But i always incurrage salvaging stuff from other broken or useless stuff. Go recycling!

In addition to this you need:
- Wires, I went with green, red and black for left, right and ground.
- Soldering stuff
- Drills, pliers and general tools

Step 2: Make the Design

I started by sketching up a design. I put the input/outputs on the back, and the patches, volume knobs and flip switch on the top. Then i made a diagram for the wiring, and finally a design to put on the final product. Since the final design is in scale with the box i could also use it to mark up where the holes would be drilled.

Step 3: Wire It Up!

Time to get your gear, put on some random Seinfeld episodes in the background and pour yourself a beer cus this is the best part. Now everything is gonna be soldered together.

Start by drilling holes for your components and put them where they are gonna be, this way they are held up for you to solder them, and you can cut the wires to appropriate length.

Check the diagram above, but i will try and explain how it's all connected.

WAIT with all the ground wires.

Start with the inputs: I chose 1 RCA input and one stereo jack input.

Connect the left and right from your RCA to one of the jacks on top.

Connect the left and right from your jack input to the other jack on top.

Connect the left and right from your Bluetooth module to the last jack on top.

Then we do the outputs: I chose 1 RCA output and one stereo jack output.

Connect the left and right from the left bottom jack to the middle pins of your top Potentiometer.

Connect the left and right from the right bottom jack to the middle pins of your other Potentiometer.

Connect the left and right from both your bottom jacks together via the flip switch. (See image above) This is so you can choose to play one source on both outputs by flipping the switch and connecting them together.

Connect the left and right (the to pins to the right when the shaft is pointing to you) from the top potentiometer to the left and right on one of the outputs.

Do the same on the other potentiometer and the other ouput. Crash course on pots

NOW: You connect all the ground wires together on a metal ring or plate somewhere.

Then go ahead and wire the positive and negativ from the bluetooth module to the DC jack. Don't confuse that ground wire with the input/output grounds.

Step 4: Make the Patch Cables (Volontary)

I desided to make my own patch cables, becuse they are part of the design so i want them to look good. And it's not easy to get really short jack-jack cables, and we want to minimize cable length as much as possible to keep a strong signal.

For this you need:

Some shielded audio cable (stereo)

4x 3.5mm male connectors.

Make the cables so that theu are just long enough to reach without bending to much.

Connect the left and right (whatever the colors are on the cables, just do the same on both sides) to the pins on the jack connector.

Step 5: Paint It

When everything is wired up and you have checked that everything works (important) it's time to paint the box.

Check some guides to how you best prep your material for paint. This is hard plastic and aluminum so i cleaned it and sanded it down a bit to get a better surface for the paint to stick on. Then go ahead and spray it down.

Step 6: How Do I Use It?

Now you just go ahead and plug a patch cable from the source you want, to the room you want it in. You can have different sources in different rooms, or just link the rooms togheter using the flip switch.

I haven't figured out a way to get my design on the bow yet, i might try Aceton transfer, or maybe get a professional to do it, so for now i have to remember where i wired the inputs.

Extras:

Im probably gonna hack the bluetooth module by putting a bigger antenna and connecting it to the module

Good luck!