what's better -- coaxial or optical digital?

[urameatball]

my old Hercules GTXP has both coaxial and optical digital out.

which one is better?

 

[JustAnAverageGuy]

optical i believe.

 

[Accord99]

Basically the same. Optical has no issues with ground loops and EM interference, but typically the cable costs more (you can use a typical video RCA cable as a digital coaxial cable for example), and are more fragile. Use whatever's more convenient.

 

[Matthias99]

For all intents and purposes they should be identical. Digital signals are nearly immune to noise, so don't run out and buy an optical cable for it if you already have coax lying around and can use that. It's usually more dependent on what you're hooking it up to -- some equipment will only deal with one or the other.

 

[buleyb]

Agreed, it really shouldn't matter all that much, but optical is sooo much cooler

 

[SpeedFreak03]

Yeah I dont see much difference either.

 

[mbackof]

This is a major pissing contest on the home theater boards. I don't see that it makes much difference. Use whatever link you want. If you are linking into a high end receiver, you might want to use a better quality cable, AR, Monster, New more expensive Radio Shack, because you will notice a slight sound improvement in a mid to high end system. I tend to notice a difference in my mid-range system using AR cables over the cheap ones that come with the equipment.

 

[Fencer128]

A lot of Hi-Fi mags suggest digital coaxial. The reason they claim (I've never tested this) is that because the signal need not undergo electrical-optical and then vice versa conversion, there is a small audible benefit. This would seem to make sense. I realise there may be issues with EM interference, but most co-axial cables are pretty well shielded anyway so I doubt this will ever be a problem.

Cheers,

Andy

 

[Matthias99]

Except that it's a *DIGITAL SIGNAL* being carried on the cable, and so it shouldn't matter how many times you convert it into other forms, or if there is a small amount of interference present. If there *is* an audible difference, there's something wrong with the E-O converter or the receiver.

 

[mbackof]

I agree that it is a digital signal and in theory the quality shouldn't be different between the two connections, but sometimes the hardware might use a better D/A converter or circuitry on the one connection than the other. I usually just try both and go with the best sounding one for that situation.

 

[thraxes]

In other words a 1 is a 1 and a 0 is a 0. No matter what cable you use.

 

[Gunbuster]

The real stuck up audio people will tell you how optical has jitter

You will find them saying things like "My own experience is that the coax typically sounds smoother and more detailed, hence more musical. I use coax whenever possible."

I dont have $100,000 equipment so yea just use what you want

 

[urameatball]

hehe...

I found a rusty RCA cable to use a my digital coaxial link.
Then borrowed my friend's optical to compare.

As much as I would like to believe that they're equal (1is1, 0is0), they do sound different. Optical sounded cleaner but bland, coaxial sounded more realistic... it's so wierd!

but wow, I like that optical cable though... you plug it in and you see is a flashy light coming out the other end... FUNKY! Oh well, I just upgraded to a $200 amp and $200 speakers... It's not audiophile quality so I'll stay with what's cheap... and what's cheap is a rusty RCA cable!

 

[RanDum72]

Theoretically, there shouldn't be any difference but based on my experience coax seems to sound better (crisper, better channel seperation on 5.1 sources). I don't know why but it might be dependent on the equipment used. Most British Audio/video mags prefer coax as well.

 

[Grizybaer]

for coax, can i use regular rca A/V cables or are their innards different

 

[Accord99]

Originally posted by: Grizybaer
for coax, can i use regular rca A/V cables or are their innards different

Video RCA cables are essentially identical to digital coaxial, so they will work. Audio RCA could and should work, but their generally not specced to 75Ohms like digital coaxial and video RCA cables.

 

[tallman45]

For such a short distance you may not see any difference. For longer runs digital signals over copper vs optical clearly favor the optical solution. The speed of light has some giddy up !!!

 

[Matthias99]

Electrons move at a pretty good fraction of the speed of light, last time I checked. Optical's great for long/noisy runs because electrical interference won't do anything to it, whereas it *will* eventually start to degrade a digital signal over coax.

I agree that it is a digital signal and in theory the quality shouldn't be different between the two connections, but sometimes the hardware might use a better D/A converter or circuitry on the one connection than the other. I usually just try both and go with the best sounding one for that situation.

This seems more likely -- it doesn't make any sense to me, but at least it's an explanation. I mean, after the digital signal is converted from optical back to analog (but still digital), shouldn't it go through the same exact decoding process? And digital-digital conversion (even between different physical formats) shouldn't have any effect on the data. I don't know much about digital amp design, and I'm not an HT expert, so please correct me if I'm wrong.

I wonder if the *encoding* process is different for the two signals? If I was designing it, I'd do the encoding from analog to digital on copper, then (if necessary) from digital on copper to digital on fiber and back (should be no change in signal), then from digital on copper in the receiver to analog for output. But if they used different encoding paths for the coax and optical connectors, that could affect it, I guess. But still, it's a digital signal being read from a digital source... these HT people just confuse me.

 

[FishTankX]

Originally posted by: thraxes
In other words a 1 is a 1 and a 0 is a 0. No matter what cable you use.

That is true. When data is being passed around.

However, jitter inside the clock signals may be responsible for changing the sound charachteristics at the DAC. While digital information may be unalterable, messing with the timings of the '1' and '0' pulses, (It's impossible to get them perfect) affects the output of the DAC which converts the digital signal to analog. After all, it's a circuit and also sensitive to timing discrepencies.

This is what the audiophile world calls 'Jitter'. I wouldn't worry about it unless you already have quite a rig already.

Optical cables are great, but the conversion process back and forth gives alot higher chance of introducing clock jitter into the digital signals, which is passed onto the DAC and can alter the sound if ever so slightly.

 

[LikeLinus]

I use optical from my DVD player to my receiver and from my HD DTV Receiver. I've never noticed any "jitters" and they sound crystal clear. I've been very happy with my optical. I picked up some AR Pro II?s for cheap!

 

[FishTankX]

Originally posted by: LikeLinus
I use optical from my DVD player to my receiver and from my HD DTV Receiver. I've never noticed any "jitters" and they sound crystal clear. I've been very happy with my optical. I picked up some AR Pro II?s for cheap!

Jitter isn't really noticeable unless you're paying careful attention to a very expensive system that's good enough to bring out the differences in optical/RCA.

Another source of contention is, as someone mentioned, the A/D and D/A stages. High quality equipment means higher quality stuff. So it depends almost as much on equipment (if not more so) than interface.

 

[mbackof]

Another reason a lot of the home theater buffs like the coaxial is because the connection to the devices is more secure than many of the optical cables. Cheap toslink cables have a tendency to fall out when moving equipment, and the plastic tubes can get crimped. The equivalent priced coaxial cable tends to be sturdier.

 

[buleyb]

Originally posted by: tallman45
For such a short distance you may not see any difference. For longer runs digital signals over copper vs optical clearly favor the optical solution. The speed of light has some giddy up !!!

Aside from the fact that the transmission is hardly the slowdown in the equipment (conversion and processing should be a bigger factor), that's a fairly vague statement, as the speed of light is different depending on the material its traveling through...

 

[RaiderJ]

Wouldn't D/A and A/D conversion loss be a moot point? As long as your conversion factor is equal to your source, DVD being 24 bits or so, wouldn't anything beyond that be wasted?

In any case, try both cables. Pick whichever you like. It's damn near impossible to quantify differences in optical vs coaxial.

 

[FishTankX]

Originally posted by: RaiderJ
Wouldn't D/A and A/D conversion loss be a moot point? As long as your conversion factor is equal to your source, DVD being 24 bits or so, wouldn't anything beyond that be wasted?

In any case, try both cables. Pick whichever you like. It's damn near impossible to quantify differences in optical vs coaxial.

The problem is jitter introduced on the A/D->DAC stage.

Optical has to go through another step, which can't be benefitial for sound quality.