Wireless Speakers

November 12, 2004 12:53 PM

Following an earlier question I uncovered and had an old parquet floor refinished. Its beautiful, and I thank everyone that advised me.

Now I want to reinstall my surround sound speakers, and I cannot think of a neat (non-destructive) way to get the rear speakers installed. Rugs are out of the question - and I really don't want to run cables all the way round the room.

Are there any wireless speaker solutions that don't suck?
posted by mattr to home & garden (16 answers total)

I'm assuming it's your house ? Run speaker wires into the wall, through the floor, along the basement ceiling, and back up thru the wall.
posted by troutfishing at 1:00 PM on November 12, 2004

we have wires and it's not as bad as you might think. i'd always heard you needed balanced lines to avoid crosstalk and radio reception, but we have simple multistrand cables going throughout the house and it sounds fine (no pickup or noise, haven't noticed any crosstalk, but haven't really tried either).
in some places the wires are inside the wall (ie embedded in the plaster/concrete). in others they run along a little indentation that goes round the top of our walls (difficult to describe!). painted over, you don't see them. another option would be behind the bit of wood you have between floor and wall at the edges of the room (whatever that is called).
sorry - i know it's not what you asked i exactly, but i was surprised how well wires worked for us.
posted by andrew cooke at 1:03 PM on November 12, 2004

another option would be behind the bit of wood you have between floor and wall at the edges of the room (whatever that is called).

Wainscoting.
posted by PinkStainlessTail at 1:07 PM on November 12, 2004

Do cat-5 cables work well as speaker wires, or does it mess with the expected impendence?

A fun microcontroller project would be to create your own wireless bridge. I would look for the following:

16 bit 44.1 KHz ADC (Analog to Digital Converter)
16 bit 44.1 KHz DAC (Digital to Analog Converter)
Cheap, easy to program and interface microcontroller that can sustain 1Mbit/sec of I/O. Ideally with a built-in WiFi or Ethernet interface.

Connect the ADC to the microcontroller, and the DAC to the other microcontroller. Program the DAC unit to configure itself as 10.19.0.1, tell the ADC unit to choose another 10.* and look for the DAC unit. Transmit raw audio over UDP. Plug the stereo into the ADC unit and the speakers into the DAC unit.
posted by b1tr0t at 1:19 PM on November 12, 2004

Wainscoting.

Baseboard. I think of wainscoting as something that goes up the wall and stops at a chair-rail.
posted by stopgap at 1:33 PM on November 12, 2004

cat 5 wires would probably work, if they were thick enough - i don't know what current they'll take. impedance of the wire (asusming it will take the current) isn't a problem at audio frequencies, afaik. you probably want to use a single twisted pair for one channel.
posted by andrew cooke at 2:03 PM on November 12, 2004

oh, and we called them skirting boards.
posted by andrew cooke at 2:12 PM on November 12, 2004

All the wireless speakers I've ever seen suck pretty bad.

Our house had a professional job done before we moved in. They had wires going in at baseboard level and going up through the walls, exiting at speaker height. Only problem I ran into was when I changed from carpet to wood floors -- they had the wires running under the carpet. I cut and spliced, to make the wires longer, and milled a recess into my baseboards. Another similar method involves crown molding.

I would not call it difficult work but it's exacting and often calls for techiques your average homeowner doesn't have. I don't think I could have done as good of a job as the installer did. They also installed some all-weather speakers out back that I have on our B channel. This is really nice.
posted by RustyBrooks at 2:26 PM on November 12, 2004

I know you're looking for 'neat' solutions, but it'll cost you much, much less to get someone in to professionally run wire through your walls than it will to get wireless speakers that don't suck.
posted by Jairus at 2:45 PM on November 12, 2004

I wouldn't use CAT5. That's like 24 gage. Way too light for any power. I put wall-plate speaker connectors behind the TV and on the other side of the room and I ran 12 gage speaker wire in the basement between the wall plates. Shorter lengths of speaker wire connect the amp to one plate, and the surround speakers to the other.
posted by AstroGuy at 4:56 PM on November 12, 2004

You won't have any problems with the gauge of the wires.

You can use two sets of pairs (one positive, one negative) per speaker, because you get four in a cat 5 cable. Using two pairs should effectively bring you down from 24 to 20 AWG, IIRC. That would be two cables, of course.

Here's a resistance chart. Note that at 24 AWG your resistance is 0.0273 ohms per foot, and at 20 AWG your resistance is 0.0105 ohms per foot.

If you run a long amount of wire, say 25 feet, that's 1.365 and 0.0.525 ohms, respectively (you must double the resistance -- you're using both directions!).

Ohms law (remember, LAW -- don't toy with this one, audiophiles):

V = I * R, P = I^2 * R, I = (sqrt) (P / R)

Let's say your amp can output 100 watts RMS (that'd be a good $3k $5k Amp) and you use the 20 AWG wire, with 8 ohm speakers:

Iamp = (sqrt) (100 / 8)
Iamp = 3.54 A

Vamp = 3.54 * 8 = 28.32 V

Itotal = (sqrt) (100 / 9.365)
Itotal = 3.27 A

Vdrop = 3.27 * 1.365 = 4.46 V
Vspeakers = 28.32 - 4.46 = 23.86 V

Pspeakers = 3.27 * 23.86 = 78 watts
Ploss = 100 - 78 = 22 watts

It's much less with the 20 AWG. Because I'm lazy, I'll use this calculator from this page for the 20 AWG calculation: Total loss -- 11 watts.

And, at 16 AWG (cheap wire): 4.81 watts.
12 AWG (expensive wire): 1.95 watts.
8 AWG (yup, I've seen this): 0.88 watts.

Quite simply, don't waste your money on expensive wire when you can buy a better receiver to compensate, instead.
posted by shepd at 6:26 PM on November 12, 2004

If your baseboards are painted you might try a flat tape wire. The advantage of the tape style is that it tapes flat against the baseboard and after it is painted it is very hard to see. It is only 18 gauge equivalent, but it will be plenty for surround speakers. Even the twisted pair from CAT5 cables would likely be enough for surround speakers. Narrow gauge wires tend to actually sound better in the higher frequencies than fat wires, but can have some roll-off in the lower frequencies. Since most surround speakers don't actually go very low anyway a fat wire is wasted on them. As for wireless speakers, I have not heard of any that "do not suck."
posted by caddis at 6:40 PM on November 12, 2004

caddis, unless your hearing extends to the MHz range (it doesn't) there's no way the diameter of wire will affect the tone of the audio. Skin effect doesn't appear until VERY far out of the audio frequency range, and that's the only thing that will affect EQ of the audio.

The resistance of the wire at all audio frequencies is virtually perfectly flat, and it is truly impossible for anyone, in a proper ABX test, to tell the difference between any gauge of wire, except by flat volume output alone. Anybody who says differently is either lying about the results, or wasn't tested properly.

BTW: I ran, without even warming up the wire, 18 AWG zip cord to the bass bins (which handled, as far as I could tell, about 500 - 1000 watts RMS, and were hooked up to a similarly powered amp) at my old college's parties. Nobody ever complained about a lack of bass or any other problems.

18 AWG wire is plenty for *any* home audio application. Any application requiring a thicker wire, I dare say, isn't a home application, it's more inteded to be used in a stadium, instead.

To put it simply: If you are buying speaker wire that is thicker than the wire in your receiver's power cable, you're throwing your money away. Your receiver won't magically generate more power than what it can use! (yes, I'm oversimplifying, the speakers are a low impedance, whereas the receiver is a high impedance, but hey, it proves a point).
posted by shepd at 2:34 PM on November 13, 2004

Here is not the place to debate speaker wire physics theories. Sufficient napalm has been spewed over this topic on audioasylum and other forums to heat every home in the USA into the next century. Nevertheless, I think it is agreed that narrow gauge wires will work just as well for mattr in this application as firehose sized wires (and perhaps better).
posted by caddis at 10:26 PM on November 13, 2004

You're right, caddis.

Sorry, but from my experience, about 99% of the people out there believe that they need car battery jumper cables for speaker wire. Just trying to help edumacate!
posted by shepd at 3:56 PM on November 14, 2004

I had a roll of thin solid copper line, 4 X insulated line with an exterior sheath ( officially for a fire alarm system ) that I used. They worked great.
posted by troutfishing at 4:16 PM on November 14, 2004