Axiom Home Page Forums General Discussion Stereo Couple of dumb questions...

First, what's the maximum length that an A/V cable can be used? Say if I had one system in one room of my house and another in some other room, can a rca cable be used? I may be wrong, but wouldn't it be the same as say electrical wire or speaker wire regarding length?

Second, why is the cubic feet of the listening area used so much to determine thespeakers? Is it due to the capability of the speaker in terms of loudness?

Just curious.

Length limits vary with the kind of signal -- digital things like HDMI are apparently more distance sensitive than others. One of Alan's articles talks about this a bit.

Biggest worry with a normal RCA coax connection is ground loops -- a long wire will normally be enough to take you from one circuit to another and so ground loops become more of a possibility.

The reason for cubic footage mattering is exactly as you suspect... the further you are away from the speakers the more "space the signal has to cover" so the old inverse-square law starts to kick in.

At high frequencies things like ceiling heights don't matter so much because you're mostly dealing with line-of-sight, but "bass goes everywhere" so cubic footage matters the most when you are choosing a subwoofer or full-range mains.

This is kinda OT, but it's one of my more favorite sayings, feel free to use it if you like:

"The only Dumb Question, is the one that's Not asked"

Ok, so it's totally off topic.
Sorry,
Rich.

In reply to:

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This is kinda OT, but it's one of my more favorite sayings, feel free to use it if you like:

"The only Dumb Question, is the one that's Not asked"

Ok, so it's totally off topic.
Sorry,
Rich.

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Yea I know, but as I was telling Rick (wid) the other evening my Dad used to tell me the same thing as a youngster but yet sometimes he'd turn around and ask me...'Where in the hell did you ever come up with such a dumb question?'

I'm not kidding.

Oh believe me, as a newbie in the audio/video world and being a grown man, I'll never be too ashamed to ask a dumb question...I have lots of them!

Thanks!

Bob, no, connecting cables have a different set of rules for distance than do speaker wires. Also, strictly speaking, "RCA" refers to the plug on each end, not the entire cable. Often a cable that isn't of 75 ohms impedance is called RCA, while a 75 ohm cable might be called digital, etc. If you're talking about an analog connection for CD any of the standard cables would be fine even for hundreds of feet, so far as signal strength is concerned. If it's a digital connection(or for TV), for the length that you probably need you should be sure that the cable has a 75 ohm impedance, then it would be okay for a hundred feet or more.

The size of the listening room is one factor in determining how loudly the speaker should be able to play with low distortion(or how much amplifier power is needed); at least as important is the distance of the listeners, since in a given size room the loudness falls off with increasing listener distance. The speakers don't necessarily have to "fill" the room; they have to be loud enough where the listeners are. As an extreme example, if you were in the middle of an empty big auditorium with a portable radio a couple of feet away, it could play loudly enough for you although it certainly wouldn't "fill" the auditorium.