Coaxial audio lead.....any RCA cable will do?

[Ext User(Gyro)]

I just noticed that my TV has Coaxial-in and was wondering if i can use
some of the spare RCA leads i have (gold plated rca connections, 7mm
thick lead) or do i have to go buy a specialty Coaxial audio lead for
it? I didn't want to try it yet in case i do any damage.

thanks.

[Ext User(Trevor Wilson)]

"Gyro" <gyro@nospamplease.iinet.net.au> wrote in message
news:44d64f38$0$21266$5a62ac22@per-qv1-newsreader-01.iinet.net.au...
>I just noticed that my TV has Coaxial-in and was wondering if i can use
>some of the spare RCA leads i have (gold plated rca connections, 7mm thick
>lead) or do i have to go buy a specialty Coaxial audio lead for it? I
>didn't want to try it yet in case i do any damage.
>

**Ordinary RCA leads will work without damaging anything. For best
performance, however, you should use 75 Ohm cables. 75 Ohm cables need not
cost a fortune.


--
Trevor Wilson
www.rageaudio.com.au



--
Posted via a free Usenet account from http://www.teranews.com

[Ext User(Gyro)]

Trevor Wilson wrote:
>
> **Ordinary RCA leads will work without damaging anything. For best
> performance, however, you should use 75 Ohm cables. 75 Ohm cables need not
> cost a fortune.
>
>

Thanks Trevor.
I have a couple of spare gold plated RCA plugs as well, so i'll stop
into jaycar later and pickup some 75 ohm Coax cable.

[Ext User(Trevor Wilson)]

"Gyro" <gyro@nospamplease.iinet.net.au> wrote in message
news:44d6bac1$0$21311$5a62ac22@per-qv1-newsreader-01.iinet.net.au...
> Trevor Wilson wrote:
>>
>> **Ordinary RCA leads will work without damaging anything. For best
>> performance, however, you should use 75 Ohm cables. 75 Ohm cables need
>> not cost a fortune.
>>
>>
>
> Thanks Trevor.
> I have a couple of spare gold plated RCA plugs as well, so i'll stop into
> jaycar later and pickup some 75 ohm Coax cable.

**Why bother? They sell 75 Ohm cables for 6 Bucks and 7 Bucks for 1.5 Metres
and 3 Metres respectively. P# WV-7304 & WV-7306.


--
Trevor Wilson
www.rageaudio.com.au



--
Posted via a free Usenet account from http://www.teranews.com

[Ext User(Sean)]

Sorry about this possible stupid question.. but why would you get better
performance with a 75 ohm.. surely a digital signal means you either get the
signal or you don't.. so if you hear the sound then your cable should be
good enough or am I missing something on the digital front? ..

The reason I ask is because I have a soundblaster live linked in thru coax
to my denon amp.. using a stereo jack to 2 rca cable (standard cable)..
using the single RCA as input to digital (SB Live have a stupid connection
on the card) .. should I be using a different cable for this application?

--
Sean


"Trevor Wilson" <trevor@SPAMBLOCKrageaudio.com.au> wrote in message
news:44d67821$0$31481$88260bb3@free.teranews.com.. .
>
> "Gyro" <gyro@nospamplease.iinet.net.au> wrote in message
> news:44d64f38$0$21266$5a62ac22@per-qv1-newsreader-01.iinet.net.au...
>>I just noticed that my TV has Coaxial-in and was wondering if i can use
>>some of the spare RCA leads i have (gold plated rca connections, 7mm thick
>>lead) or do i have to go buy a specialty Coaxial audio lead for it? I
>>didn't want to try it yet in case i do any damage.
>>
>
> **Ordinary RCA leads will work without damaging anything. For best
> performance, however, you should use 75 Ohm cables. 75 Ohm cables need not
> cost a fortune.
>
>
> --
> Trevor Wilson
> www.rageaudio.com.au
>
>
>
> --
> Posted via a free Usenet account from http://www.teranews.com
>

[Ext User(Alan Rutlidge)]

"Sean" <sean@NOSPAMgrieve.com.au> wrote in message
news:44d85b1f$0$21264$5a62ac22@per-qv1-newsreader-01.iinet.net.au...
> Sorry about this possible stupid question.. but why would you get better
> performance with a 75 ohm.. surely a digital signal means you either get
> the signal or you don't.. so if you hear the sound then your cable should
> be good enough or am I missing something on the digital front? ..
>
> The reason I ask is because I have a soundblaster live linked in thru coax
> to my denon amp.. using a stereo jack to 2 rca cable (standard cable)..
> using the single RCA as input to digital (SB Live have a stupid connection
> on the card) .. should I be using a different cable for this application?
>
> --
> Sean

S/PDIF using a co-axail lead are designed with a 75 ohm impedance for the
source (transmitter) and receiver.
Maximum power transfer without reflection only occurs when the source
impedance matches the lead (transmision line) impedance and in turn the
receiver impedance. If an impedance mismatch occurs anywhere between the
transmitter and the receiver some of the transmitted signal will be
reflected back to the source from the point of the impedance mismatch. This
results in loss of signal strength reaching the receiver and the reflected
signal (if big enough) can contribute to errors in the data stream. IOW it
is much better to have transmisson line (aka the interconnect lead) of the
correct impedance to match the transmitter and the receiver.

Typical data streams used in digital audio, like those on an S/PDIF
connection have frequency components which are in the RF (radio frequency)
range. Unlike most audio circuits, RF circuits are more sensitive to
impedance mismatch. This impedance mismatch has the potential to corrupt
the data stream.

Pre-made 75 ohm leads intended for S/PDIF connections are not expensive.
Likewise you can buy 75 ohm co-axial cable and 75 ohm RCA connectors if you
want to DIY your own leads. There in no point in buying ultra expensive
"snake oil" leads for S/PDIF connections, just the correct ones.

As TW pointed out, standard audio leads will probably work (and they do over
short distances) without damaging your equipment, just not at anything
closely approaching optimum performance. If you don't buy a proper S/PDIF
lead, you could probably get away with a cheap 75 ohm video lead quite
nicely. :-)

Cheers,
Alan

>
>
> "Trevor Wilson" <trevor@SPAMBLOCKrageaudio.com.au> wrote in message
> news:44d67821$0$31481$88260bb3@free.teranews.com.. .
>>
>> "Gyro" <gyro@nospamplease.iinet.net.au> wrote in message
>> news:44d64f38$0$21266$5a62ac22@per-qv1-newsreader-01.iinet.net.au...
>>>I just noticed that my TV has Coaxial-in and was wondering if i can use
>>>some of the spare RCA leads i have (gold plated rca connections, 7mm
>>>thick lead) or do i have to go buy a specialty Coaxial audio lead for it?
>>>I didn't want to try it yet in case i do any damage.
>>>
>>
>> **Ordinary RCA leads will work without damaging anything. For best
>> performance, however, you should use 75 Ohm cables. 75 Ohm cables need
>> not cost a fortune.
>>
>>
>> --
>> Trevor Wilson
>> www.rageaudio.com.au
>>
>>
>>
>> --
>> Posted via a free Usenet account from http://www.teranews.com
>>
>
>

[Ext User(Trevor Wilson)]

"Sean" <sean@NOSPAMgrieve.com.au> wrote in message
news:44d85b1f$0$21264$5a62ac22@per-qv1-newsreader-01.iinet.net.au...
> Sorry about this possible stupid question.. but why would you get better
> performance with a 75 ohm.. surely a digital signal means you either get
> the signal or you don't.. so if you hear the sound then your cable should
> be good enough or am I missing something on the digital front? ..

**You are (missing something). The original poster asked about video
signals, not digital audio. The video signal is an analogue one and will be
affected by incorrect cables.

>
> The reason I ask is because I have a soundblaster live linked in thru coax
> to my denon amp.. using a stereo jack to 2 rca cable (standard cable)..
> using the single RCA as input to digital (SB Live have a stupid connection
> on the card) .. should I be using a different cable for this application?

**Alan's answer is bang on. Read it.


--
Trevor Wilson
www.rageaudio.com.au



--
Posted via a free Usenet account from http://www.teranews.com

[Ext User(John Saunders)]

"Trevor Wilson" <trevor@SPAMBLOCKrageaudio.com.au> wrote:
> "Sean" <sean@NOSPAMgrieve.com.au> wrote:
>> Sorry about this possible stupid question.. but why would you get better
>> performance with a 75 ohm.. surely a digital signal means you either get
>> the signal or you don't.. so if you hear the sound then your cable should
>> be good enough or am I missing something on the digital front? ..
>
> **You are (missing something). The original poster asked about video
> signals, not digital audio. The video signal is an analogue one and will
> be affected by incorrect cables.

Actually the word audio was in the subject title and in the
message body, however video did not appear at all. Like Sean,
I also understood the question to refer to an RCA audio
(presumably S/PDIF) socket on the posters TV. Presumably it
is an audio output allowing audio from a HDMI input to be
passed to an amp (at least that is the only S/PDIF audio
connector I have seen on TVs).

However if he is talking about a video cable, then the same
impeadance issue is involved.

>> The reason I ask is because I have a soundblaster live linked in thru
>> coax to my denon amp.. using a stereo jack to 2 rca cable (standard
>> cable).. using the single RCA as input to digital (SB Live have a stupid
>> connection on the card) .. should I be using a different cable for this
>> application?
>
> **Alan's answer is bang on. Read it.

As an electrical engineer I can also confirm Alan's answer
is 100% correct. The biggest problem with impeadance mismatch
is the signal reflections, and the longer the cable the
larger the time delay of the reflection.

With a video cable it makes the image look fuzzy due to
ghosting. For S/PDIF it can cause bit errors in the
digital signal that if bad enough can cause clicks and
pops.

Having said that, if the audio sounds fine chances are
the cable is working. If you are happy saving money by
using a cable you already have then good. If you plan
to spend money then get the correct cable, or if you
need along cable then get the correct one.

[Ext User(Trevor Wilson)]

"John Saunders" <news1@saunders.id.au> wrote in message
news:44d9ab25$0$5108$afc38c87@news.optusnet.com.au ...
> "Trevor Wilson" <trevor@SPAMBLOCKrageaudio.com.au> wrote:
>> "Sean" <sean@NOSPAMgrieve.com.au> wrote:
>>> Sorry about this possible stupid question.. but why would you get better
>>> performance with a 75 ohm.. surely a digital signal means you either get
>>> the signal or you don't.. so if you hear the sound then your cable
>>> should be good enough or am I missing something on the digital front? ..
>>
>> **You are (missing something). The original poster asked about video
>> signals, not digital audio. The video signal is an analogue one and will
>> be affected by incorrect cables.
>
> Actually the word audio was in the subject title and in the
> message body, however video did not appear at all.

**Mea culpa. I saw the word 'TV' and focussed only on the video side of
things. You are correct. However, for digital audio, 75 Ohm cables are still
desirable.


--
Trevor Wilson
www.rageaudio.com.au



--
Posted via a free Usenet account from http://www.teranews.com

[Ext User(Sean)]

Thanks for the reply Alan.. and to the other replies too.. cleared up some
misconceptions of mine! :) might actually invest in a proper lead .. damn
I'm glad I read these forums!

--
Sean

[Ext User(Gyro)]

Trevor Wilson wrote:
>
> **Why bother? They sell 75 Ohm cables for 6 Bucks and 7 Bucks for 1.5 Metres
> and 3 Metres respectively. P# WV-7304 & WV-7306.
>
>

I ended up buying this.
http://www.altronics.com.au/index.asp?area=item&id=P6328

The audio seems to have a bit more bass and fidelity now.
Would that be because of the TV's surround sound processor or the
quality of the audio?

[Ext User(Trevor Wilson)]

"Gyro" <gyro@nospamplease.iinet.net.au> wrote in message
news:44dbc3af$0$15993$5a62ac22@per-qv1-newsreader-01.iinet.net.au...
> Trevor Wilson wrote:
>>
>> **Why bother? They sell 75 Ohm cables for 6 Bucks and 7 Bucks for 1.5
>> Metres and 3 Metres respectively. P# WV-7304 & WV-7306.
>>
>>
>
> I ended up buying this.
> http://www.altronics.com.au/index.asp?area=item&id=P6328

**That's the tickets.

>
> The audio seems to have a bit more bass and fidelity now.
> Would that be because of the TV's surround sound processor or the quality
> of the audio?

**I couldn't say.


--
Trevor Wilson
www.rageaudio.com.au



--
Posted via a free Usenet account from http://www.teranews.com

[The Guru]

Cables...ah yes, the magical relm.

Over such a short distance, you could use a coathanger and get the proper transfer of signal. use the crummy leads you have or lash out and get a 75 ohm cable...it will make absolutely no difference.

really, when it comes to choosing leads for your gear, you just want to cover the frequency range of the signal your using. The crummy leads will have a decent enough range to carry the transfer speeds your using for SPDIF. A good 75 ohm lead will absolutely garuntee you can carry the transfer speeds. They aren't expensive, just buy one.....no need for Monster cable or anything, it's all a load of wank and the theories they apply to their cables relate to runs over 100m !