Newsgroups: rec.audio.tech
Subject: Re: I want to wire my house for speakers but don't know what I'm doing :)
References: <[email protected]>
"The Choker"  writes:

> OK,  I know this is probably the most asked question but after getting
> a professional quote of $75/hour to do the wiring I figure I'd give it
> a shot myself...
> 
> Details:
> -I'd like to have my PC as the source of music (mp3's baby!)
> -I'd like wire speakers to 3 locations in the house (basement den,
> family room, outside deck)
> -I'd like individual volume controls for each location

Do you want the volume control to be for all speakers be 
at central location or at the location where speakers are ?

For central location control one option is to have separate 
amplifiers for all speakers at one place. Every one of them 
getting the same signal form sound cards, and each of them 
having separate volume controls. Then speaker wires from 
the central location to speakers. Volume control from 
amplifier fron panels or using suitable multi output sound mixer. 
Approach used in restaurants, arena PA etc..

Approaches with local sound level controls:

1. One amplifier on the central location distributing 70V or 100V  
   audio signals. At the listening location you have 70/100V line 
   speakers with local volume controls (usually rotatable switches 
   that switch the different settings on 70/100V to 8 ohm speaker
   adapting transformer inside speaker case)
   + can cover easily long ditances with thin wire
   + proven long time used technology on for example to play 
    background audio on shops and other places
   - this kind of systems are not usually "hifi" quality
   - expensive ? (price of amplifiers and speakers, electrical installation)

2. One or several amplifiers on one location supplying speaker level 
   signals to the cables. The speakers on the rooms are wired through 
   speaker level volume controls. (depending on amplifier and speakers 
   you could need from one to three amplifiers to drive three speaker sets)
   + can use normal hifi speakers, amplifiers and speaker wire
   - long distances need quite thick wire
   - suitable potentimeter can be expensive, limited on power handling 
     and can affect sound quality (adds easily considerable resistance
     to speaker wiring that can affect more or less sound quality depending 
     on speakers used)

3. Active speakers with local volume controls on all locations and 
   line level audio distribution to them using balanced signals
   + proven and well working technology 
   + audio need just this wires (preferably shielded twisted pair 
     microphone cable or similar, but CAT5 UTP will also usually 
     work acceptaly)
   + excellent sound quality possible when good speakers are selected
   + distance from central location to speakers can be long 
     (100-200 meters no problems)
   - cost of active speakers with balanced inputs are not cheap
   - you will need to invest to audio distribution amplifier with 
     several balanced outputs (also audio mixer with balanced out will work)

4. Active PC speakers with local volume controls on all locations and 
   sound distributing using "RCA cables" (unbalanced signals)
   + the speakers are very cheap
   + wiring can be made with normal ready made cables if wanted, 
     just use an "Y" splitters on soundcard out and feed cables from 
     it to all places
   - sound quality is limited with PC multimedia speakers
   - system can be sensitive to to noise pickup (hum, switching 
     noise from electrical network), at some locations things 
     work and at some other places not useable (can't know for sure 
     in advance before installation)

> Now what?  I'm about a week away from drywalling my house and would
> like to wire the walls ASAP.  

How about pulling installation electrical wire tubes from the central 
location to the places you will need now before the walls are ready. 
Intall thick enough tubes, and you can freely pull the needed cable 
type there later without touching the drywall construction.

> Besides my PC & stereo receiver what do I need?  

Depends on the system you choose. 

> My understanding right now is that I have to wire my PC's sound
> card to the stereo receiver.  With what kind of wire?  

Normal 3.5 mm stereo plug to RCA audio cable is the right cable type 
in most cases (when PC soundcard has 3.5 mm jack sound out and 
stereo receiver has line level input with RCA connectors). 

> What's the  minimum sound card requirements?

Depdens on your preferences on the sound quality. 
Any PC sound card that you are happy with the sound quality should do.

> What about from the receiver to the speakers?  Will my current receiver
> be able to wire 3 sets of speakers?  

In most cases normal average stereo hifi amplifier/receiver is not 
designed to drive three sets of speakers at the same time.

> What kind of wire should I use?

Depends on the system you selected to do this. 

> (all sets of speakers are under 50 feet away, I've been reading 16
> gauge, is this OK?).  What about volume control?
> 
> I know this is long winded...but my initial search of the internet gave
> me so many options!  What I'm looking for is a low cost solution that I
> can easily install with a friend or two over some beers.
> 
> Thanks in advance,
> The Choker
> 

-- 
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/