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Q: How long can I run a digital line?



 
 
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  #11 (permalink)  
Old February 6th 04, 06:53 PM posted to uk.rec.audio
Dave Plowman
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Default Q: How long can I run a digital line?

In article ,
Ian Molton wrote:
No problem. Use co-ax rather than optical - it's cheaper.


'scuse me? I picked up a 3m optical cable for 6ukp.


Right. I'd just make up one of the correct length. Haven't tried with
optical. Does it solder easily?

they were selling 12m ones for ~20 IIRC.


Oxygen free glass?

--
*Suicidal twin kills sister by mistake.

Dave Plowman London SW 12
RIP Acorn
  #12 (permalink)  
Old February 6th 04, 07:18 PM posted to uk.rec.audio
tony sayer
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Default Q: How long can I run a digital line?

In article , Nutter
writes


On Fri, 6 Feb 2004 14:53:42 +0000, Ian Molton wrote:

On Fri, 06 Feb 2004 14:13:23 +0000 (GMT)
Dave Plowman wrote:

I'd like to run a digital out from my DVD player to a DAC. How long can
this cable be? I can use a coaxial or an optical. I was hoping it could
run six metres.

Is this way out or is this possible?

No problem. Use co-ax rather than optical - it's cheaper.


'scuse me? I picked up a 3m optical cable for 6ukp.

they were selling 12m ones for ~20 IIRC.


MUG ALERT! Oh Dear Ian.

My Digital Coax cable cost me nothing, it was one of those 'free' ones
you get with every Hi-Fi box. Better still you get 2 of them, ones
colored Red and one White. Personally I think the Red one gives a
warmer sound.

Okay, I'll stop taking the **** now.... IT'S A DIGITAL SIGNAL, ANY OLD
PIECE OF ****E WILL DO (for coax)! Which is why on this group, Coax is
prefered, because it does the same thing and the cable costs virtually
nothing.

Ray.


Yep, we ran SPDIF down a couple of hundred metres of CT100 co-ax the
other month and it sounded fine!.....
--
Tony Sayer

  #13 (permalink)  
Old February 7th 04, 01:06 AM posted to uk.rec.audio
Ian Molton
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Posts: 1,243
Default Q: How long can I run a digital line?

On Fri, 06 Feb 2004 18:53:45 +0000 (GMT)
Dave Plowman wrote:

No problem. Use co-ax rather than optical - it's cheaper.


'scuse me? I picked up a 3m optical cable for 6ukp.


Right. I'd just make up one of the correct length. Haven't tried with
optical. Does it solder easily?


the SPDIF ones are plastic. a scalpel would probably suffice.

they were selling 12m ones for ~20 IIRC.


Oxygen free glass?


what, LESS than 50p/metre and you're complaining?

--
Spyros lair: http://www.mnementh.co.uk/ |||| Maintainer: arm26 linux

Do not meddle in the affairs of Dragons, for you are tasty and good with ketchup.
  #14 (permalink)  
Old February 7th 04, 01:12 PM posted to uk.rec.audio
Nutter
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Posts: 24
Default Q: How long can I run a digital line?

On Fri, 6 Feb 2004 16:55:09 +0000, Ian Molton wrote:

On Fri, 06 Feb 2004 16:08:42 +0000
Nutter wrote:

MUG ALERT! Oh Dear Ian.


WTF are you on about? 20ukp for 12 metres of optic fibre with 'plugs' on
is not bad at all.

Okay, I'll stop taking the **** now.... IT'S A DIGITAL SIGNAL, ANY OLD
PIECE OF ****E WILL DO (for coax)!


ILLITERACY ALERT! I said *optic fibre* not coax.

Which is why on this group, Coax is prefered


Is it? Cant say I've noticed a preference either way.

At least with the optic fibre I dont even have to CARE about wether
noise from my PC will ever reach my DAC (probably wouldnt on coax either
but I like that I dont need to care.

, because it does the same thing and the cable costs virtually nothing.


The Coax can *in theory* transmit more than just the wanted signal (no I
dont mean jitter). Wether it does or not is down to your individual
equipment. This is simply a non-issue with optic fibre.

I didnt buy a 12 m optic fibre anyhow - I bought a 3m one. that 6ukp was
including VAT+PnP IIRC too. Thats a good price for ANY interconnect,
even a coax one.


Ian, I think you have failed to understand how your original post was
interpreted.

You stated:
=============
No problem. Use co-ax rather than optical - it's cheaper.


'scuse me? I picked up a 3m optical cable for 6ukp.

they were selling 12m ones for ~20 IIRC.
=============

What I am saying is that, Coax is always cheaper, because you can you
a really crap standard piece of phono cable instead of a far more
expensive optical one.

Your comment interferance from the PC are incorrect. With Digital
coax, the signal either reaches the DAC intact or not. You will hear
if it does not reach the DAC properly. If the cable carries
interferance of any kind (unlikely) it is simply ignored by the DAC
due to the error correction built into the digital signal.


Ray.
  #15 (permalink)  
Old February 7th 04, 01:17 PM posted to uk.rec.audio
Nutter
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Posts: 24
Default Q: How long can I run a digital line?

On Fri, 6 Feb 2004 16:59:49 +0000, Ian Molton wrote:

On Fri, 06 Feb 2004 15:16:55 +0000
Nutter wrote:

First off, use Coax.


Or, better, use optic fibre which is just as cheap and eliminates any possibility of transmitting electrical noise between components.


Bull****! Tell be where you can get a 10m Optical cable for £1? Which
if you go to Maplins is all it would cost you in parts to make a
perfectly suitable coax digital.


Second, any old piece of crap phono leed will do.


For short lengths. and it really *ought* to be 75 ohm, too. That said, 6m probably counts as short.


No - For any length! In fact for long lengths your only option is
Coax.

As for length I'm
guessing 6m will not be a problem as the signal is digital.


Digital pulses can be *harder* to transmit due to being square waves. just because its digital doesnt make it easier. What it does mean is that if the signal is at all recoverable at the other end it will work *perfectly* (well, close to perfectly in the case of SP/DIF...).



If you can hear a sound with no skips or breaks, then the cable is working perfectly.


Not necessarily. a DAC could well conceal small errors in the signal.


Only it you've got a crap DAC, or the errors were so small as to make
no difference to the audible sound if the errors were not 'concealed'.
In any case, I challenge anyone to do a blind test and tell the
difference between Coax and Optical.

  #16 (permalink)  
Old February 7th 04, 01:35 PM posted to uk.rec.audio
Ian Molton
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Posts: 1,243
Default Q: How long can I run a digital line?

On Sat, 07 Feb 2004 13:12:01 +0000
Nutter wrote:

What I am saying is that, Coax is always cheaper, because you can you
a really crap standard piece of phono cable instead of a far more
expensive optical one.


And I would say to that 'no, not really'.

if you buy pre-made leads you will pay at LEAST a fiver for a 3 metre
phono and thats not even counting delivery. my 3m optic fibre was 6ukp
incl. shipping and VAT.

heres an example...
http://uk.special.reserve.co.uk/sear...c&sortorder=3a

Granted you could probably just jam some bell-wire in a coax port and it
would probably work for about 50p. Thats not the point though, is it?

Your comment interferance from the PC are incorrect. With Digital
coax, the signal either reaches the DAC intact or not.


Im not saying it wont. what I am saying is that the digital signal is
not ALL that can be brought across the coax - you could bring a sizeable
amount of high frequency switching hash (many digital devices use
SMPSUs) or LF hum or anything else across. As long as the peaks are
below the threshold the system considers 1s, it wont affect the digital
signal.

If the cable carries
interferance of any kind (unlikely) it is simply ignored by the DAC
due to the error correction built into the digital signal.


Ignored by the digital side of the DAC yes. but its not impossible the
noise could affect the analogue parts of the DAC.

Granted, any /good/ DAC will eb largely immune to noise of this type,
but its not impossible, and an optical link WILL remove it all.

--
Spyros lair: http://www.mnementh.co.uk/ |||| Maintainer: arm26 linux

Do not meddle in the affairs of Dragons, for you are tasty and good with
ketchup.
  #17 (permalink)  
Old February 7th 04, 01:56 PM posted to uk.rec.audio
Ian Molton
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Posts: 1,243
Default Q: How long can I run a digital line?

On Sat, 07 Feb 2004 13:17:37 +0000
Nutter wrote:

Or, better, use optic fibre which is just as cheap and eliminates any
possibility of transmitting electrical noise between components.


Bull****! Tell be where you can get a 10m Optical cable for £1? Which
if you go to Maplins is all it would cost you in parts to make a
perfectly suitable coax digital.


You show me the parts list...

I just went to maplins and the CHEAPEST phono *connectors* (no cable)
are 49 pence each.
cheap cable of a suitable type looks to be ~50p/metre so thats 1.50
worth of cable too.

so, you're talking 2.50 worth of material and thats BEFORE you add
shipping. Do you consider your time soldering worthless?

Shipping costs 2.50 btw.

so, your 3m coax lead will cost you 5ukp.
my 3m optical lead cost me 6ukp. (dont forget it wont propagate noise,
btw)

wow was I ripped off. **** maannn....

For short lengths. and it really *ought* to be 75 ohm, too. That
said, 6m probably counts as short.


No - For any length


Haha. yeah, ok whatever.

If you can hear a sound with no skips or breaks, then the cable is

working perfectly.

Not necessarily. a DAC could well conceal small errors in the signal.


Only it you've got a crap DAC,


No, nothing to do with crap. its a design choice - some DACs conceal 'clicks' or 'pops' (whilst not altering 'good' data) because they sound nasty. others choose to play it as is because some people like to hear the errors so they can seek ultimate perfection (or whatever).

In any case, I challenge anyone to do a blind test and tell the
difference between Coax and Optical.


With a GOOD DAC I very much doubt I would be able to tell.

Optical may not be 'better', or rather, coax may be no worse - but coax CANT do better than optical. As optical is not more expensive (1ukp isnt a significant difference, and thats comparing a commercial lead to a self-build), WHY NOT use it?

--
Spyros lair: http://www.mnementh.co.uk/ |||| Maintainer: arm26 linux

Do not meddle in the affairs of Dragons, for you are tasty and good with
ketchup.
  #18 (permalink)  
Old February 7th 04, 04:18 PM posted to uk.rec.audio
Laurence Payne
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Posts: 300
Default Q: How long can I run a digital line?

On Fri, 6 Feb 2004 14:53:42 +0000, Ian Molton wrote:

No problem. Use co-ax rather than optical - it's cheaper.


'scuse me? I picked up a 3m optical cable for 6ukp.

they were selling 12m ones for ~20 IIRC.


OK, use it because it's better then. Until amplifiers and players
have lightpipes instead of wire inside, there's going to be a
conversion from electrical signal to light and a conversion back at
the other end. This isn't going to INCREASE quality, is it.
  #19 (permalink)  
Old February 7th 04, 04:19 PM posted to uk.rec.audio
Wally
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Posts: 395
Default Q: How long can I run a digital line?

Nutter wrote:

Bull****! Tell be where you can get a 10m Optical cable for £1? Which
if you go to Maplins is all it would cost you in parts to make a
perfectly suitable coax digital.


Why is it that, when someone asks a newbie question about cables, some
arsehole thinks that the most suitable solution for them is to buy raw
materials and solder one up 'because it's cheaper'? How long would it take
for a newbie to source and acquire the parts - and the tools - and make up
the cable? How many goes would it take for them to get it right? All that
****ing around to save a fiver? I once watched (and occasionally helped) a
mate build a sports car in his garage. Next time somebody asks me about what
sort of sports car he should get, I'll tell him to make his own, right?

To view it from the other perspective, someone who can solder up their own
cables isn't going to come to an audio group and ask a newbie question about
cables - they're just going to go and get on with making one.


Second, any old piece of crap phono leed will do.


For short lengths. and it really *ought* to be 75 ohm, too. That
said, 6m probably counts as short.


No - For any length!


What a load of ****. Do you know what an "ohm" is?


--
Wally
www.artbywally.com
www.wally.myby.co.uk/music



  #20 (permalink)  
Old February 7th 04, 04:20 PM posted to uk.rec.audio
Laurence Payne
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Posts: 300
Default Q: How long can I run a digital line?

On Fri, 06 Feb 2004 16:08:42 +0000, Nutter wrote:

Okay, I'll stop taking the **** now.... IT'S A DIGITAL SIGNAL, ANY OLD
PIECE OF ****E WILL DO (for coax)! Which is why on this group, Coax is
prefered, because it does the same thing and the cable costs virtually
nothing.


Not so. Digital signals, and particularly their timing, can be
corrupted by unsuitable cables. But try the cheap cable. It will
probably be OK.
 




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