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View Full Version : RCA Cables - how good is good enough?



patrija
2005-05-25, 20:13
I hook my SB2 to a receiver that uses its "Zone 2" outputs to connect to a 6 zone (12 channel) amp that sends music throughout the house. The connection from the receiver to the amp is a simple L/R RCA connection. I'm currently using the basic black RCA cable that came in the box with the amp. Is it worth upgrading this cable - if so, where's the price break of diminishing returns? Cable suggestions? Thanks!

pfarrell
2005-05-25, 20:26
On Wed, 2005-05-25 at 20:13 -0700, patrija wrote:
> Is it worth upgrading this cable - if so, where's the price
> break of diminishing returns? Cable suggestions? Thanks!

IMHO, no, it is not worth upgrading.
But that is without listening to your cable.
I would be willing to spend something like
$10 on a "better than junk" cable. Or $5 to
a friend (or to buy a beer for the friend)
to borrow a decent cable to be sure. But I'd start
out with any cable in my box of old cables collected
over the past 30 years.

I doubt if you seriously listen to the sounds in
a multi-zone system like you describe. And in that
case, as long as there is no obvious breakup,
any cable will do.

I don't even seriously listen to my second room's
SqueezeBox, altho I occasionally sync it with my
main stereo.

--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

Mike Hanson
2005-05-26, 05:38
I've quite happy with this for a number of applications: http://www.svideo.com/stereocables.html.

-=> Mike Hanson <=-

patrija
2005-05-26, 06:54
Thanks guys

John Stimson
2005-05-26, 23:47
Kevin at SlimDevices clued me in to the existence of a company called Blue Jeans Cable (http://www.bluejeanscable.com/store/audio/index.htm). The custom-fab cables using very high quality crimp-on 75-Ohm RCA connectors and a variety of coaxial cables. Their recommendation is Belden 1505F; I use Belden 89259 at home.

Skoff, Robert P.
2005-05-27, 13:16
I second John's recommendation of bluejeanscable.com. I've purchased
audio cables and dvi cables from them. Very well-made stuff and great
customer service. I have no idea if cables make a difference, but at
least these guys seem to be taking a scientific approach and their
prices are reasonable.

Rob

Andrew L. Weekes
2005-05-27, 15:28
...using very high quality crimp-on 75-Ohm RCA connectors...

There's no such thing that exists, since by definition to make an RCA 75 Ohm, would require totally different physical dimensions, making the connectors incompatible with standard RCA sockets!

Andy.

pfarrell
2005-05-27, 15:53
On Fri, 2005-05-27 at 15:28 -0700, Andrew L.Weekes wrote:
> -...using very high quality crimp-on 75-Ohm RCA connectors...-
>
> There's no such thing that exists, since by definition to make an RCA
> 75 Ohm, would require totally different physical dimensions, making the
> connectors incompatible with standard RCA sockets!

Tons of video cables are 75 ohm and terminated with RCA connections.

Perhaps all of them are mislabeled? or there is something else
going on?

--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

Mike Hanson
2005-05-27, 21:00
Tons of video cables are 75 ohm and terminated with RCA connections.

Perhaps all of them are mislabeled? or there is something else
going on?
The wire may be 75ohm, but the connectors are not. For the entire cable to be 75ohm, it must be maintiain the standard throughout. Here's a bit of light reading: http://www.bluejeanscable.com/articles/75ohmrca.htm. If you want more, then Google "rca 75 ohm connector".

-=> Mike Hanson <=-

Aylwin
2005-05-27, 22:41
Hi patrija,

For what it's worth, I agree with Pat's original post. For your particular application, I don't think it's worth upgrading your RCA cables. Of course, there's no harm in trying but I doubt there'll be any significant improvement in sound quality.

Aylwin

pfarrell
2005-05-28, 07:26
On Fri, 2005-05-27 at 21:00 -0700, Mike Hanson wrote:
> pfarrell Wrote:
> > Tons of video cables are 75 ohm and terminated with RCA connections.
> The wire may be 75ohm, but the connectors are not. For the entire
> cable to be 75ohm, it must be maintiain the standard throughout.
> Here's a bit of light reading:
> http://www.bluejeanscable.com/articles/75ohmrca.htm. If you want more,
> then Google "rca 75 ohm connector".

Interesting reading.

The original poster was talking about audio interconnects, which
while they must have some characteristic impedance, don't seem
to have any standard. At audio frequencies it isn't much of an issue.
Nor at the lengths most folks use for interconnects.

My memory has that RCA connectors were not designed even for
audio, they had some military use for gear during WW2, and
there were lots of surplus parts available when all
the veterans were getting into "hi fi" with their
GI bill training.

The general use of RCA for 75 ohm video cables is interesting.
Several citations say it was not engineered, and not considered
important when early VCRs went from RF re-modulators to direct video
connections. Clearly RCA connectors are cheaper than BNC, but
probably not that much cheaper in volume.

My guess is that the video quality of early VCRs (and even
late VHS VCRs) was to marginal that the short impedance mismatch
didn't matter. Just like all the SPDIF connections over
coax that specify 75ohm cable with RCA.

The Benchmark DAC1 has a BNC connector for its SPDIF
(they ship an adaptor to RCA) and lots of recording
studio gear uses BNC for clock timing and other
digital signals over coax.

Many of the higher end TV connections use BNC for
component video, but I bet that the DVI and HDMI
connections that are becoming popular have
the same impedance issues at least at their
connectors

--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

Andrew L. Weekes
2005-05-28, 07:53
The reason RCA's are often used for SPDIF is the consumer specification for the interface specs RCA's. A classic case of an engineering compromise for low cost solutions.

Professional AES/EBU sepcs 110 ohm balanced with XLR's IIRC.

For -SPDIF a 75 ohm BNC is a far better solution, and depending upon the DAC and it's sensitivity to jitter, will be audibly worse than a properly matched 75 ohm interface (or any properly matched interface for that matter!).

For audio, there's a big mismatch at each end anyway (we are not trying to maximise power transfer, just keep signal amplitude), so cable / connector impedance matching isn't a big issue, things like cable capacitance and dielectic are more important, sonically.

Andy.

pfarrell
2005-05-28, 07:55
On Sat, 2005-05-28 at 07:53 -0700, Andrew L.Weekes wrote:
> Professional AES/EBU specs 110 ohm balanced with XLR's IIRC.

That is correct, but XLR connectors have an inherent impedance
mismatch because of their shape. Plus XLRs usually have
wiring options (pin 2 hot, etc.) which adds more uncertainty
and mismatch potential.

XLRs are great for solid connections at reasonable prices.


--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html