Hi there. I am not an electrical engineer.

I received an Echo Dot for Christmas, which does not come with a very power speaker. I have hooked it up to our stereo, but I do not want to have to switch inputs every time I want to hear the audio output. I also do not want to plug it into a dedicated speaker, I want to use the ones already there in the room. I knew that plugging it directly into the speakers themselves would require some power amplification, and after doing some research I managed to build one myself with a potentiometer and some basic wires. Essentially I now have a box that plugs into a power source, connects to the Dot, and then outputs audio to stereo wires that I have plugged into my speakers.

Lo and behold, it works. Except for when the stereo itself is also putting out a signal to the speakers. I did some more research and realized I need to now build a mixer.

This is my ideal end-result:

1. A device that takes audio from two sources and mixes them into one output.
2. This device might as well also take over the duties of the amplifier I built, so as to limit the clutter of boxes behind my TV.
3. CRITICAL: the Stereo input signal is automatically attenuated whenever a signal is detected coming from the Echo Dot input. I feel like this shouldn't be incredibly difficult, but my research thus far hasn't yielded any workable results. There just doesn't seem to be a demand for what I am doing.

Based on what I've found so far, I think I could make a basic mixer, although I'm still not 100% confident on what that requires (more potentiometers, resistors, capacitors...). What I am really interested in is a simple solution for the auto-attenuation. It would be nice if it did this on a gradient, easing the volume up and down, but I feel like we're getting into more complicated territory with that, so I'll take what I can get.

My setup: Media devices connected via HDMI to my smart TV. TV outputs an optical signal to the stereo system. Stereo outputs via speaker wires to a subwoofer, which then also outputs to the Left and Right speakers via speaker wire. As of right now I have to switch the input wires to the subwoofer whenever I want to use the stereo or Dot, which entirely defeats the purpose of my original project.

I'm not afraid to learn stuff for this project (in fact that is ideal), and have even been considering looking into Arduino for a solution. However, I want this to work as soon as possible, and I would be starting on the ground floor if I went that way (although I do have some programming experience).

Please let me know if this is not going to be as simple as I'm thinking, or if I should just buy some pre-existing product (that I haven't found yet). Hopefully, though, someone out there will have a great solution.

Thanks!

 

Welcome to AAC.
Perhaps you could adapt this voice-over circuit, using the Dot instead of the mic for input.

 

Based on the description, yes, that sounds like it'll do the trick. I'll have to research a number of the symbols/markings on the schematic, but this might just work. Does this replace the functionality of a mixer? I would assume so, but I should ask these kinds of questions before I start building...

I don't have a soldering kit, is this something I could put together easily enough on a breadboard?

 

Does this replace the functionality of a mixer?

No. A mixer allows signals from two or more sources to be superimposed. A voice-over circuit (automatically) suppresses a first signal when a second signal occurs.
A breadboard is intended for temporary cicuit assembly for design/testing of relatively simple circuits. For a more permanent job use veroboard (strip-board) or perf board. Veroboard has the advantage that the strips provide connections between components.

 

Ok, just to make sure I understand exactly what you're saying: while this doesn't replace a mixer's functionality, it does at least eliminate the need for it. Correct? That's what I meant, but should have worded it differently.

Veroboard, check. Thank you!

 

it does at least eliminate the need for it. Correct?

Yes.