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Poor Man's Whole House Audio?
robtheauditor asks: "I would love to have my music in all the various rooms of our house. I can't afford the thousands for a turnkey system. What are the possibilities for a poor man's whole house audio system? For example, would it be possible to take my PC external audio connector and feed it to a bunch of powered speakers in different rooms? Could I just bring a bunch of 3.5mm plugs wired together in parallel, or would that not work? I was thinking that even if the signal is weak because it is split to 6 different speaker pairs, because the speakers are powered it wouldn't matter. Or will I risk burning out my sound card?"
That approach has worked great for me, driving a set of three powered speaker pairs. Radio Shack even sells a one-in/three-out adapter plug; I use that to split the signal three ways, coming right off the soundcard speaker jack. Then I run 30-50 feet of shielded audio cable (bought in bulk and then connectorized; an easy soldering job) to each of the three powered speaker sets. Sound quality is fine.
I'm guessing that a six-way split would work just as well as my three-way split does.
Alright, the WAY TO GO for whole house audio is 25V systems. You just need a 25V audio amplifier (figure like 2W per speaker) and these special speakers which have transformers built into them. You could also go with 70V audio but its more expensive (although easier to find). Don't try to get this stuff new though; you'll pay way to much. Instead, go to business auctions (restaurant auctions are a good place for this) and going out of business sales. You'll get much better deals. Strangely, this stuff is somewhat hard to find on the internet.
Just so you know, the benefit of 25V (and 70V) audio over standard direct to speaker connections or 3.3V/5V/8V audio signals is less attenuation. 25V and 70V systems can transmit audio signals without degradation over very long distances, like what you would need to wire a whole house or building. The more usual types of audio transmission can only go a few feet.
The other benefit (perhaps more important) is that you can have as many speakers as you want on the same wires in parallel (as long as your amplifier can handle it). Under ordinary wiring schemes, you can only have one device per output channel. If you split it, either the signal will degrade or the amplifier will overload.
The only problem with this scheme is that you need completely separate amplifiers and wires for each channel (left and right) if you want stereo output instead of mono. This precludes the usual combining of grounds that most people use.
If you want to be able to control the volume of each speaker independently just toss a potentiometer between one wire and the transformer on the speaker. Like a 50 Ohm ought to be fine.
Now, just so every knows, this scheme is only cheap if you find the equipment used. Brand new, this stuff is quite expensive. BUT, this stuff is pretty easy to find used if you look for it.
If you have no patience, you could try any number of other schemes. I think one of my favorites (I have a friend how actually did this) is to buy a bunch of very crappy computers (think Pentium 200), take them out of the cases and embed them in the walls (he had fans to push the heat into his airducts). Then he attached them via ethernet and multicasted his audio signal to all his crappy machines. All ten of them (he has a HUGE house). The computers are hooked up to vintage stereos which he uses as amplifiers for each room. He controls all this with his laptop and SSH. He usually leaves the stereos on and turned up and turns the sound to each room on and off by sshing into the approriate machine. He recently told me that he's thinking of changing his setup to using one of those network audio protocols, (nas, I think) so that he can have different stuff playing in each room. He also said he was thinking of adding IrDA transcievers to his crap machines so that he can control them with his Palm.
It doesn't have to be difficult.
The sound card is almost always designed to drive headphones with its "line-level" output. It is, therefore, low-impedance - typically in the several-hundred Ohm range.
Powered speakers are high-impedance. 47K ohms is common.
This all conspires to mean that you can drive lots of pairs of cheap self-amplified computer speakers with a single cheap computer sound card, and that it such a topology is even within the design parameters of the gear in question.
But don't just take my word for it: We'll make some assumptions and pound out a silly example!
Let's assume we want to drive 16 (!) amplified speaker pairs of 47K ohms each.
This gives us a load of about 2.8K, which is nowhere near as demanding as the set of headphones that the sound card device is intended to drive. It is also substantially higher than the output impedance of the sound card, and is therefore Just Fine(tm) by the defacto standard methods of interfacing consumer line-level audio devices.
Sure, it'll be attenuated somewhat compared to driving one set of speakers. It will be measurable. It will be predictable. Is it such a big deal to turn up the volume in compensation? The frequency response will be fine, so what's the big deal?
This is just line-level audio, folks. It's supposed to be easy, and in this case, it is particularly so.
Kid-proof tablet..
I'm out of my league when slashdotters start suggesting $200 pieces of gear, but I am an enthusiastic cheap hardware hacker and have some suggestions based on stuff I've tried. Please don't comment saying these approaches are ghetto. I know they are ghetto. That doesn't mean they won't have great results for cheap.
:)
:) Rat Shack and others sell 50 foot cables with headphone jacks on both ends. These are nice if you are terminating in an old set of computer-style self powered speakers. I've run three of them in series with no noticeable noise. If you are really hard up, the dollar store sells 100 foot phone cables. Don't bother trying to solder the fabric woven wires in them, use old phone sockets for breakout boxes. For line level signals this works well enough up to a few hundred feet.
It sounds like you want a system originating from just one source- since you were willing to spit the headphone hack signal so many times. For starters, maybe poke around for a device called a 'video distribution amplifier'. You can buy one for something like $20-$50 bucks in the US that will split one set of signals five or six ways. If you just want to split audio right now, ignore the video. Later, you can use the video to send an (admittedly low quality) image of the computer screen to TVs and video monitors around the house if your video card supports this or if your scrounge up a VGA to composite adapter.
Watch thrift stores for old receivers from the 70s. I've had great luck with old Panasonic and Technics receivers- they're surprisingly high quality. You can use these receivers two ways- to distribute and/or to receive audio in each room. To distribute, wire the audio signal from your computer into the AUX or TAPE PLAY inputs. The outputs labeled TAPE REC (there might be two sets of these hopefully) can go to another room to input into gear there. My experience has been that you can safely split each of these TAPE PLAY outputs once without noticeable degradation- so you can go to as many as four sets of amplified speakers, or four more amplifiers, or four car stereos from here.
Since you're hacking, you can also use the headphone jack on your receiver as another output- preferably to amplified speakers which are designed for this sort of signal. Although, be warned, on some equipment the presence of a headphone plug automatically turns off the local speakers if you were planning to use them. By the way, some (maybe 5% of what I've seen) 70's gear prefers 16 ohm speakers- 8 ohm speakers on them will sound a little funny, especially after you blow them out.
The receiver will also have some other inputs too, for your CD player, etc which then can be easily distributed to the whole house. Keep in mind that the old PHONO inputs prefer a different kind of signal from what your computer and CD player puts out.
As for cabling.. the best cable I've snagged while dumpster diving was some Ma Bell cabled with 16 or so sets of twisted pair, maybe 16 gauge or so. This works beautifully. For very long runs, poke around for the cable ordinarly used for composite video. There are some semi-cheap options on ebay like this, but for stereo you'll need two. People say not to use coax, but I've used it for audio when I've had some excess laying around, and it worked great for me. You can solder standard RCA plugs on the ends and seal. I like to use a bit of clay epoxy because it not only insulates but also protects.
Ok, now let's talk about how to actually play the audio you've very professionally sent to each room. I think the best bet in this kind of setup is the computer-style self powered speakers. They have volume and power switches on them, which is all the control you're going to have in that room anyway (unless you use VNC or some such like I do to control the media server). You can find old computer speakers in thrift stores pretty easily, but they always seem to be missing their power cables. This is where your lifetime spent not throwing away AC-DC power adapters
I'm a big fan of the Apple AirPort Express at $129. It'll stream audio over 802.11g or ethernet, will do standard 3.5 or optical minijack out. Granted, you have to use iTunes to stream to it and it may or may not be what you're looking for in terms of having to stream to a specific unit, but it's an option. As an added bonus, it's can act as a wireless router or print server. I don't know how it's feature set compared to the SqueezeBox everybody keeps mentioning, but it's really a top-notch piece of off-the-shelf hardware for about half the price. May or may not work for you, but I like it. Andrew Beard
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I see that answers are all over the map. You may want to be more specific in terms of budget, and what you will accept for audio.
In my case, I wanted a system that didn't require large cash outlay (i.e. no large multichannel amps). I wanted one that I could grow piecemeal and buy things a bit at a time on a shoestring budget, yet they would work as an integrated whole. But I wanted true stereo in each room, from real in-ceiling speakers (FM radios don't cut it).
The solution I settled on is A-Bus. A-Bus is a music-over-Cat5 technology with You wire a single Cat5 (much easier to fish through walls than speaker cables) from a hub near your music source to each room. The hub is less than $100. In each room, you put an amplified volume control (less than $50 - see e.g. http://www.basshome.com/product_8464_detailed.htm - you can also get one that can pass IR to your audio source) and wire from that to your speakers, which is usually a fairly short run.
Works well, sounds great, looks like a high-end system, and not too much cash outlay at any given time.
bp