Chris Alexander

On Engineering

Alexa: Play through my speakers

Giving Alexa a voice in your lounge

22nd January, 2017

We have recently welcomed Alexa into our home with an Echo Dot in the lounge:

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The main difference between the Dot and the larger main Echo device, other than £100, is the speakers - the Dot is very small and thus has just basic speakers. Good for listening to Alexa talking, but not so great for listening to music or the radio.

But that’s ok! We have 5.1 surround in our lounge, already hooked up to an EQ and the TV, so Alexa should be good to go through that as the Dot has a headphone socket.

It took a bit of time to figure out the various audio terms and bits of kit to get this working (could be an expensive mistake!) so I thought I would share how I got it going.

So you need a mixer…

As we already have the TV hooked up to the speakers, you need either a TV with a line through (even when it is off) so you can hear Alexa at any time, or you need some more hardware. So far as I am aware most TVs don’t have this line through (and ours certainly doesn’t), so extra hardware it is.

The piece of kit you need is called, in the industry, a mixer. These are what you see in recording studios with millions of twisty buttons on them - fortunately we don’t need something bigger than the TV to accomplish what we need.

The one that I went for in the end is this Behringer Xenyx 502:

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Now this mixer is listed as 5 inputs, which is slightly misleading, because depending on how you count it, it has 6 or 4. This is because audio kit is typically mono - this is a very important point to remember.

So on this mixer, input 1 is designed specifically for a microphone; it has a mic pre-amp (nice bit of kit actually) and has either a jack connection (more commonly known as 1/4”) or an XLR input. This input we won’t be using, as we need stereo for the TV and Alexa.

Inputs 2 and 3 are mono jack connections - that means they only deal with one channel of audio, not the left/right of stereo. But that’s ok, because they can be paired together - note that on the control dials, you have a left/right balance dial plus an overall level dial for inputs 2 and 3 together. So if you had two guitars, and put one in 2 and one in 3, you could control how loud both of them are using the overall gain, and how loud they are relative to each other using the balance dial. Bit fiddly but could be done. However in our scenario we are going to use 2 and 3 for left and right channels of the same input, so the overall gain controls the volume of the input (left and right), and the balance we leave dead centre as no need to change that.

This principle also applies to inputs 4 and 5, so you have two mono inputs or a single stereo input.

The final input is the 2-track, which is for mixing in another stereo audio source - we don’t need that now (nor do we need the output) so that can be ignored.

The output to be used will be the main mix, which is again left and right mono channels paired together.

… and you need adapters

All of the inputs we will be using (essentially the bank of 6 silver 1/4” ones in the middle at the top of the device) are all jack sockets, but both the Alexa and the TV in our setup only have headphone outputs.

Fortunately I have a couple of headphone to phono cables laying around - this one will do perfectly fine. This means you now have phono cables which we need one final adapter to get into the mixer.

I just got this pack of adapters off Amazon; they are cheap but at least you get 10, so 4 can go wrong before you’re short!!

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Stick one of these in each of the 4 input channels and 2 output channels, then you can wire up Alexa and the TV to the two inputs, then the output can go to your speakers (or in the case below, it actually goes through the EQ to the speakers).

You can then use the various gain controls to make Alexa louder or quieter relative to the TV, adjust overall volume etc. By using this approach it also means you can get updates from Alexa while the TV is on (and hear both). It also cost me only £40 compared to the extra £100 for the full Echo, which seems unnecesary at this point.

You mentioned an EQ…

Yep, we have an EQ (or equaliser) in our lounge to tone down the bass from the speakers. The speakers were originally designed for PC so are very heavy in the bass end. When we lived in a flat in London we had to get the EQ to stop movies rattling the furniture (and irritating the neighbours).

The one that we have is this Behringer FBQ800, which works just great for sorting out the bass and making the treble a bit happier as well. It also uses phono inputs and outputs so is in between the output from the mixer above and the speakers.

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