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Andy Yee
Guest
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 Posted:
Sun Nov 13, 2005 5:42 am Post subject:
Longest Length for RCA Cable? |
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I want to place my TV/DVD/VCR in the opposite corner of my room from where
the rest of my audio gear is...I would need 30 foot RCA cables...Is this bad?
What are alternatives, especially inexpensive ones?
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Andy Yee E-Mail: ayee AT mn dot rr dot com
President Home Page: http://home.mn.rr.com/andyyee
New Directions Engineering, Inc.
Godwin's Law: As a USENET thread grows, the probability of a reference
to Hitler or Nazis approaches 1.00.
Corollary: When such a reference is made, it is generally
recognized that the poster has LOST the argument.
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Michael R. Kesti
Guest
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| Posted:
Sun Nov 13, 2005 5:42 am Post subject:
Re: Longest Length for RCA Cable? |
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Andy Yee wrote:
| Quote: | I want to place my TV/DVD/VCR in the opposite corner of my room from where
the rest of my audio gear is...I would need 30 foot RCA cables...Is this bad?
What are alternatives, especially inexpensive ones?
|
There are several factors to consider when running "long" unbalanced lines,
including high frequency loss, ground loop hum, and induced noise.
High frequency loss occurs because the capacitance of the cable and the
output impedance of the device driving the line form a low-pass/high-cut
filter. The lower the source impedance and cable capacitance, the higher
the cutoff frequency. With most modern gear and decent cables, this is
not an issue for 30 feet of cable.
Ground loop hum occurs when the devices at each end of the cable are
grounded thru seperate paths and therefore are at different ground
potentials. When this happens, the common/shield/ground of the device
receiving the signal is driven with an AC voltage equal to the potential
difference of the two grounds. Because that device uses that part of
the line as its reference voltage (I.e., it assumes that the shield is
zero volts.), the receiving device sees the difference in grounds as
a 60 Hz signal, resulting in hum. Whether this will be a problem depends
on the grounding situation in the rooms of your home.
Induced noise occurs when an unbalanced line runs near a source of
magnetic or electrostatic interference such as a lamp dimmer, a
transformer (Such as those used in many wall warts.) or an electric
motor. You can reduce the effect of induced noise by routing the line
to avoid such devices.
The bottom line is that 30 feet is not all that long, but you may or
may not have problems depending on several factors. If you do have
problems, their solutions depend on their nature.
--
========================================================================
Michael Kesti | "And like, one and one don't make
| two, one and one make one."
mrkesti at comcast dot net | - The Who, Bargain |
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Peter Larsen
Guest
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| Posted:
Mon Nov 14, 2005 2:23 am Post subject:
Re: Longest Length for RCA Cable? |
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Andy Yee wrote:
| Quote: | I want to place my TV/DVD/VCR in the opposite corner of my room
from where the rest of my audio gear is...I would need 30 foot
RCA cables...Is this bad?
|
No. At a guess it is beyond 100 feet that you start to worry about what
you drive the cable with. The basic spec to look for is output impedance
of originating apparatus, it is generally less than 1000 Ohms nowadays,
and possibly 100 to 50 Ohms.
| Quote: | What are alternatives, especially inexpensive ones?
|
I would however prefer to use a quality mic cable. For long stretches,
ie. hundreds of feet, it can be better to use a headphone output since
it is designed to tolerate very low load impedances. You will know it if
you need to use balanced cabling, a low source impedance is generally
fairly uncritical.
| Quote: | Andy Yee E-Mail: ayee AT mn dot rr dot com
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Kind regards
Peter Larsen
--
*******************************************
* My site is at: http://www.muyiovatki.dk *
******************************************* |
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Mr.T
Guest
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| Posted:
Mon Nov 14, 2005 4:58 am Post subject:
Re: Longest Length for RCA Cable? |
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"Peter Larsen" <SPAMSHIELD_plarsen@mail.tele.dk> wrote in message
news:4377A0DC.6123E1CC@mail.tele.dk...
| Quote: | What are alternatives, especially inexpensive ones?
I would however prefer to use a quality mic cable.
|
Quality mic cables are balanced.
| Quote: | For long stretches,
ie. hundreds of feet, it can be better to use a headphone output since
it is designed to tolerate very low load impedances. You will know it if
you need to use balanced cabling, a low source impedance is generally
fairly uncritical.
|
If his output and input are unbalanced, then going to balanced and back is
NOT likely to be an "inexpensive" solution.
MrT. |
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Michael R. Kesti
Guest
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| Posted:
Mon Nov 14, 2005 5:41 am Post subject:
Re: Longest Length for RCA Cable? |
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"Mr.T" wrote:
<snip>
| Quote: | If his output and input are unbalanced, then going to balanced and back is
NOT likely to be an "inexpensive" solution.
|
I suppose that depends on one's threshold of expensive. Assuming stereo,
two each of Radio Shack's 274-016 and 274-017 come to $60, not counting
the cables.
BTW, these are two of the few Radio Shack items I have ever suggested are
worth purchasing. It's been about 15 years since I bought any, though, and
would not be at all surprised to learn that they are now using a cheaper
transformer and that I might now regret suggesting them. Others, such as
Shure Bros. and ProCo, make similar products that don't cost too much
more and are probably less of a gamble to purchase.
--
========================================================================
Michael Kesti | "And like, one and one don't make
| two, one and one make one."
mrkesti at comcast dot net | - The Who, Bargain |
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Joe Kesselman
Guest
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| Posted:
Mon Nov 14, 2005 5:41 am Post subject:
Re: Longest Length for RCA Cable? |
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Michael R. Kesti wrote:
| Quote: | two each of Radio Shack's 274-016 and 274-017 come to $60, not counting
the cables.
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I've done exactly this when I've had to run a line-level feed to a
remote amp and speakers. (Break-out room and similar.) Some of those
have been runs of several hundred feet out the door, across the hall,
into the stairwell, up two or three floors, down the coridor...) |
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