Newsgroups: rec.audio.tech
Subject: Re: Connecting PC to stereo amplifier
References: 
"Sigurd"  writes:

> Honorable NG readers, 
> What is the optimal cable type and gauge to connect PC to stereo amp to
> replay MP3's?  

The optimal cable type for connecting PC to stereo ystem is shielded
audio cable as used for stereo interconnections. Or a high quality
microphone cable. Or any other good shielded twisted pair cable
suitable for audio use.

> I have been recommended four-strand "twisted,
> individually shielded 20 ga. computer" cable 

Your description does nto entirey specify the cable, but sounds
like usable cable type. I have used something in his line for some
audio interconnections.

> (is that the same as LAN cable.  

Some LANs long time ago used to use this kind of cable. Modern
LANs use almost always unshielded twisted pair wire (UTP) or
sometimes foild shielded twisted pair with one shield over all pairs
(FTP).

> And do I need to pre-amplify the signals?   Does anyone here
> have any experience on this subject?
> The distance between PC and amp is about 50 ft. 

You do not need to pre-amplify the signals. The line level output
of PC soundcard has typically a quite low impedance output
(tens of ohms typically) and high enough signal level (1-2V)
so that generally no extra amplification is needed. The signal
attenuation on those conditions is so low that no extra
amplification with typical PC soundcards is necessary
(althoguh there might be some exceptions, so if you hear
too much loss of high frequencies then consider amplification,
but usually it is not needed.)

I have run audio from various computer sources to on different
occasions. The runs of 10-15 meters from computer to amplifiers
have not been a problem. When I have needed to play really safe
and needed optimim sound quality (professional sound applications
with large venue size PA systems and TV broadcasting systems)
I have used a converter (passive DI-box) to convert PC output to
balanced signals whcih I have feed to an XLR input of the mixer.

When connecting to systems on other prts of house, check also
the situation for possible ground loop problems:
http://www.epanorama.net/documents/groundloop/index.html

> and the cable will be
> pulled in the crawlspace under my house.  My soundcard is traditional
> with one output plug driving both powered computer speakers.  What is
> the best way of flipping the signal between audio speakers and stereo
> amplifier?

You can use one signal output to drive both your stereo system
and local powered multimedia speakers. One line output is well
capable of driving them both.

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