Xref: utzoo rec.audio:8823 sci.electronics:4188
Path: utzoo!attcan!uunet!seismo!sundc!rlgvax!smadi
From: smadi@rlgvax.UUCP (Smadi Paradise)
Newsgroups: rec.audio,sci.electronics
Subject: Re: Extracting "Center Channel" from Stereo Image
Summary: Nothing new under the sun
Keywords: Fisher center speaker
Message-ID: <1016@rlgvax.UUCP>
Date: 1 Nov 88 07:21:13 GMT
References: <355@ivucsb.UUCP>
Reply-To: smadi@rlgvax.UUCP (On Paradise)
Organization: Computer Consoles Inc, Reston VA 22091
Lines: 31

In article <355@ivucsb.UUCP> todd@ivucsb.UUCP (Todd Day) writes:
>What I propose is that we remove Johny from the "center channel",
>if you will, and put his voice in a speaker that sits on top
>of the TV.  In this manner, you will remove the dependence of
>having to sit in the exact center to hear the center channel
>properly.  You will be able to sit right next to the left
>speaker, and Johny will still sound like he's talking from
>the center (during his monologue, he is the only person
>on camera).

Very old (tube) Fisher amps used to have terminals for _three_
speakers, labled ``L'', ``R'' and ``Center''.  The last was connected
(via two power resistors? transformer tap?) to the left and right.
I have never hooked the third speaker up, but it might be doing just
what you had in mind. 

Leaving phase aside for a moment, the ceneter speaker adds k * (l + r)
to both channels. This reduces the stereo separation, and creates
a _better_ stereo image when the speakers are placed too far from each
other. (The inverse is also true: adding -k * (l + r) to both channels
widens the stereo image, and this is done in many boom-boxes.)

I'm afraid that the next lines are not going to be of much help,
but it seems as if your question can be unasked by ``correct'' placement
of the speakers. In general, people tend to place them too far from
each other: the speaker-listener distance should always be larger
than the speaker-speaker. This does not ruin the stereo image:
reasonable speakers tend to create an image which is much wider
than the distance between them!

On