What would I need to make my in-wall speakers work?
July 9, 2015 1:32 AM   Subscribe

The house we have just moved into has in-wall speakers (Jensen EHT-8) and outdoor speakers all wired to a bunch of jacks in the wall where, as I understand it, they would have had an AV receiver connected. I don't own a TV or video, but I wouldn't mind using them for music if there's a relatively cheap way to do so. Is there? What manner of thing would I have to buy to make the music that is currently on my computer play through these and how would I hook it up?

My current music playing system is a Raspberry Pi full of mp3s running squeezebox server and streaming to all my other gadgets around the house (PC, laptop, iPad with usb speakers, and a Squeezebox boom). I am quite happy with this, so I'm unwilling to pump lots of money into a different thing, especially since I can't even know if the in-wall system even works. But I would spend, say, up to $100. It seems a pity to have these speakers and not use them, especially the outdoor ones.

Please explain your answer as though I was five years old. I only found out what an AR receiver is today, and I'm not sure I know what a subwoofer is even now.
posted by lollusc to Technology (14 answers total)
And you can tell my inexperience from the way I just referred to an AV receiver as an AR receiver.
posted by lollusc at 1:34 AM on July 9, 2015

You have hit on an important point:

> can't even know if the in-wall system even works

We have had a similar system in the walls, but when we tried it the sound was atrocious due, no doubt, to deterioration of the wiring over the years.

What was probably intended to be plugged in was a stereo receiver and amplifier. The 1960s to -90s technology called for an input source, such as a turntable or a cassette player, to be plugged into the amplifier. It was called a "receiver" because it also included a radio receiver. The amplifier would boost the power so that it could be sent to the speakers.

You could find an old small amplifier at a Goodwill store or a yard sale and buy it for a couple of bucks, and try plugging that into the inputs to see how good the sound is.
posted by yclipse at 4:33 AM on July 9, 2015

Yes, you want an amplifier. Second-hand is a good option, as there's not too much that goes wrong with them (at least not since they stopped using valves). They exist to turn a relatively weak signal (the line out from your device) to a more powerful signal capable of driving a set of speakers.

Your PC speakers have their own built-in amp (because even small speakers need amplification).
posted by pipeski at 5:54 AM on July 9, 2015 [1 favorite]

I think the speakers were installed only a few years ago as the online photos from when the house was previously sold in 2008 don't have them. So hopefully not dealing with 60s-90s tech. But okay, an amplifier should do it? And then I can plug e.g. a laptop into the amplifier and the amplifier into the speaker wall jacks and something might happen? Any type of amplifier at all?
posted by lollusc at 6:09 AM on July 9, 2015

i have a similar system to you. i stream from a computer over wifi (i actually used audioengine wifi bridges, which are nice, but expensive) to various places. one of which is connected to wires that feed various speakers.

i didn't reply earlier because i thought someone would give a more professional solution. i have this idea that living in america (i assume) you could pick up some used professional equipment and do it "right". but since no-one has described how to do that, here's what i do at the part where the wires come out of the wall:

i have a wifi receiver that is connected to a power amplifier. and the output from the power amplifier goes to a speaker switch, where each output is connected to a separate circuit (a separate pair of connectors going into the wall). i control the volume digitally at the source. in theory that increases noise, so you and some audiophiles might frown at that. in which case you need an integrated amplifier (with a volume control) instead of a power amplifier.

anyway, that's what i do. if you want to do something similar, at as low a price as possible, i would do the following:

* you don't seem to have any kind of standalone amplifier. so you need one. i'd suggest something from the first two price bands here.

* you need some kind of receiver for the music streaming. like a squeezebox duet. those are pretty expensive. i don't know what will work with your system that's cheaper. just for testing, i think the boom (is your display ok? - mine faded) has a line out you can use around the back.

* with those, you can connect things up by hand (with some wire) to each channel in turn and test them out.

* if things sound ok, you can then buy a switch like i linked to so that you can select where to send the sound. there are various kinds of switches. many have protection circuits that - i think - sto pyou from damaging your amp by connecting too many speakers at once. the one i have doesn't, so you need to be careful not to select more than one speaker pair at a time. you could even make some kind of automated switch with relays, arduino, and a wifi shield!

so i think, if i've understood right, you can test things out with just a $50 amp and some wire. if they work ok then you can get a dedicated receiver (instead of the boom) and a switch box.

and, as i said at the beginning, there is also "professional" equipment that does all this...

[posting, i saw your latest comment: yes.]
posted by andrewcooke at 6:16 AM on July 9, 2015

And then I can plug e.g. a laptop into the amplifier and the amplifier into the speaker wall jacks and something might happen? Any type of amplifier at all?

That is precisely what you should do. As long as you keep the power off on the amp and the volume down while plugging everything in (and then increasing the volume gradually for testing), you're unlikely to break anything.

A class D amplifier is a cheap way of finding out what works. It's a simple device - an input for your laptop, an output for the speakers, a power cord, a volume knob. It may not end up driving your whole system, but it should either work well enough to be a cheap interim solution or let you know what's wrong.
posted by eschatfische at 7:48 AM on July 9, 2015 [1 favorite]

Low tech answer: We are old school and play music from our iPod through our receiver/amplifier, which is connected to our in-wall speakers. When you are looking at the amplifiers, look to see if there is a jack that accepts a mini plug (headphone size plug). You can plug your laptop/gadget into the amplifier with that mini to mini cable. We've plugged our iPod into numerous amplifiers, car strereos, boat radios, etc, with just that cable, but not all amplifiers have the correct port.
posted by sarajane at 10:45 AM on July 9, 2015

So this would work, I guess? What about this cheaper option?

I took a look at second hand amplifiers on eBay and can't find anything cheaper that claims to be in working condition.

(I'm not in the USA, by the way, but Australia.)
posted by lollusc at 6:19 PM on July 9, 2015

Oh my and I just realised the speakers we use with our desktop computer have a subwoofer with integrated amp that in turn powers two passive speakers. So now I suspect I could use this subwoofer with the in wall speakers to test them instead of buying an amp. Yes? No? I can't just try it and see as I don't have the right connector cords/jacks to plug the l/r outputs from the subwoofer into the l/r wall speaker inputs, but I assume these are connectors I can buy very cheaply if I work out how to convey what I need to the person at an audio shop.
posted by lollusc at 7:39 PM on July 9, 2015

Well, it depends. If the impedance of the wall speakers is significantly less than that of the speakers the subwoofer is meant to drive, you could ruin the amp in the subwoofer.

However, that is pretty unlikely if you keep the volume low and just use it to test whether the speakers and wiring work. Just get the appropriate cable to connect the two and give it a shot if you like, just don't run it that way permanently.

If the subwoofer has the typical 3.5mm headphone style connector and the wall has two RCA jacks (red and white, typically), you can get a cable from Monoprice for a couple of bucks. It's the same thing you'd use to plug a computer in to an amplifier, so you'll need it regardless.
posted by wierdo at 8:06 PM on July 9, 2015

Here's a link to the page with the cables you probably need.
posted by wierdo at 8:10 PM on July 9, 2015

The specs for the in-wall speakers say "nom impedance 6 Ohms" and the specs for the Gigaworks system says "input impedance 8 Ohms". Is 6 "significantly less" than 8?

The subwoofer has two RCA jacks for the speakers, and the wall has something I don't recognise. An RCA jack sits in it but feels a bit loose. I've put a photo here.
posted by lollusc at 8:30 PM on July 9, 2015

So this would work, I guess?

I think so, yes, although that amp likely doesn't have enough power for your speakers, depending somewhat on how many speakers you have. But it should be enough for a basic test.

What about this cheaper option?

Nope. That is a headphone amplifier, not designed to power actual speakers.

(Note on both - I, personally, would be really leery of products whose basic instructions & specifications are so poorly translated as to be virtually incomprehensible. I read specification sheets for audio equipment all the time, and both of those products' info on the website was so far from actual comprehensible English that I'm a little stunned. IOW, all those words about the amplifiers don't read like gibberish to you because you don't know anything about audio - they're actually borderline gibberish. Maybe this is more common in Australia than the U.S., but still . . . . . .)

Is 6 "significantly less" than 8?

No, close enough for testing, BUT . . . . the actual total impedance (and power requirements) of a system changes depending on how many speakers you have hooked up and in what configuration. So you're probably fine for basic testing at low volume, but by "basic" I mean, "Does this speaker work? yes/no." You might not get useful enough results to tell whether the whole thing sounds good enough to invest more money into it.

the wall has something I don't recognise. An RCA jack sits in it but feels a bit loose. I've put a photo here.

Those are commonly called "binding posts." Image here. The bit with the cross-hatching is an outer sleeve that unscrews, there's a hole in the post, you stick a piece of wire with a little bit of the insulation stripped off the end into the hole and screw the outer part back down. Depending on the diameter of the hole at the end of the post (the hole you can see in your picture) and the spacing of the posts, you could use a "banana plug" (Single banana plugs Dual banana plug), where you put the bare wire end into the banana plug and then plug into the jacks in your wall.

I doubt you're going to get a good connection with an RCA plug.

Is there any way for you to contact the previous owner for info about the system? 'Cause, I mean, you've got a custom installation here, whether installed by professionals or DIY'd by the previous owner, and the problem with custom anything is it can be really difficult to figure out what's going on or what was done unless you've got a pretty thorough knowledge of the core concepts of whatever-it-is that was customized. Also being able to lay hands on the thing can help a lot. Maybe you've got a home-stereo-enthusiast friend who could take a look at the thing in exchange for dinner & beers?
posted by soundguy99 at 9:10 PM on July 9, 2015

soundguy99 said everything I was going to say and more. The only thing I have to add is that you can get an appropriate cable for your test on eBay. It's totally nonstandard, though. When using an actual amplifier, you'd probably just want to use short lengths of speaker wire rather than the banana plugs.

I'd suggest a used Onkyo (something like this TX-SR604 would be fine, but so would a 5xx) once you've determined the speakers and wiring are actually functional. Most of them support two audio zones, so you can drive 3-5 speakers in the main zone and two in zone two. (The exact number depends on whether it is a 5.1 or 7.1 home theater receiver)

You'll definitely want something of that nature, since connecting multiple speakers in parallel to a single channel halves the impedance (approximately), which will put you pretty far out of spec for most cheap amplifiers.

If you just want to see that the wiring is good, you can use a multimeter to check continuity by bridging the two wires for a given speaker and using the test leads on the binding posts.
posted by wierdo at 9:27 PM on July 9, 2015

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