Coaxial or Optical ?? (1 Viewer)

[Ted Lee]

i posted a thread specific to the bandwidth issue over in a/v sources. feel free to chime in if you'd like.

btw - sorry to threadjack this one.

 

[ChrisMcL]

Ted:

You mistake my incredulity for hostility. But let us not muddy the issue, and that is that coax sounds better than TosLink. No amount of debate, no changing threads, no surprise at finding out for the first time the bandwidth limitation, will change that. All of these are reasons, not results. The result of listening is an acknowledgement that coax sounds better. The reasons do not very much matter.

It is the hubris of engineers that reasons matter. Let the engineers that design the equipment quibble over the "why's." Let those who enjoy high-end audio hear and be pleased.

 

[Ted Lee]

ahh...my apolgies chris!

The result of listening is an acknowledgement that coax sounds better.

....to some people.

okay, i just had to sneak that in.

 

[JohnAJR]

Isn't it interesting that the only way to quantify and spec what sets a Stradivarius apart is to use the most sensitive equipment available - our ears.

 

[ChrisMcL]

John:

You understand. Now if only Ted would quit naysaying and join us. There is a reason that ultra-high-performance transports and D/A converters don't include TosLink connectors; coax is better, AT&T is better, AES/EBU is better, everything is better than TosLink.

 

[Justin Ward]

I don't see how a toslink could be a bottleneck on a 448kb/s DD stream.....

 

[John Royster]

Posted in other thread. Here's the latest specs on toslink transmitters/receivers.

Most are limited to 6 Mhz and 5 or 10 meters.

http://www.toshiba.com/taec/cgi-bin/...ategoryID=7071

 

[Jonathan_E]

My point about the MRI comment is as Ted said, Fiber optic has the capacity to be better than coaxial, it just hasn't been taken advantage of yet.

The problem with any traditional cable is that it can be effected heavily by cables running close to it that are not properly shielded. Now, very heavy amounts of shielding within the cable can fix this problem, but that jacks up the price of the cable. Fiber optic requires no shielding, so if the home audio manufactures would start making higher quiality fiber optic components, the price in the long run could be cheaper for the consumer than having to worry about heavily shielded cables.

I'm not trying to change the topic of the thread here, but I just have a small question for anybody: Has anyone ever seen shielded speaker cable? Speaker cables are quite often carrying up to 100 watts of an AC current, which can create E-M fields around the cables, so if you have two speaker cables running next to each other, this could potentially cause small amounts of distortion in the sound when it is reproduced at the speaker, just a thought.

-Jonathan

 

[ChrisMcL]

John:

You seem like the kinda' guy who believes that the rest of the world is not as smart as him. I think it was Plato, maybe Socrates, who is first known to have said, "The more I learn, the less I know." Believe it or not, there are a lot of very bright people who design and manufacture A/V equipment--even the stuff that sounds bad.

I recommend that you take some time out, and research high-end audio. You may find that there are very good reasons for the things that now confuse you. You may also find that a background in working with medical equipment will be of limited value. At the very least, I hope that you will learn enough to not make puerile suggestions on unrelated threads.

Here are some places to start:

Get yourself a primer on A/V gear at Amazon.com called The Complete Guide to High-End Audio

Visit your local independent A/V store, where you can sit and ask questions, and kvetch about equipment.

Visit your local book store, and pick-up copies of the most recent issues of The Absolute Sound, The Perfect Vision, and Stereophile.

By doing just those three things, you may find that after several weeks, you'll end up knowing more about A/V gear than most of the people in this forum--including me. Let us know how it works out.

 

[Steve>Smoker]

Just to add my 0.02 ...

I work in the oil industry where we use alot of cables of all varieties to carry both sensetive and extremely safety-critical signals.

First off, we use alot of fiber-optics.
It's primarily used for two reasons - signal purity and effective transmission length.
The main 'ring' of the data highway (sometimes miles) is of fiber-optic, so the comments on bandwidth and short distances are not strictly true of all optic cables.
I think the main reason the Toslink could be less than satisfactory is down to price.
Fiber-optic splicers on average in our industry get around $500 a splice.
They use extremely expensive machines and have to guarantee the work they do.
Add on top the cost of the optical modems and to get a top-quality signal transmission your into the hundreds if not thousands of $.
So toslink substitute plastic (not ideal) and use cheap connectors.
I am assuming folks here know how fiber-optic actually works, and to use plastic over glass is asking for trouble.
The weak points in the chain are the terminations, they should be mechanically sound and hooded to prevent the ingress of ambient light.

Now - onto coax.

All coax cables are not born equal!
I've worked on analogue signals down into the pica-amps.
As long as the cable was of high purity and the ends correctly terminated, it worked quite happily, virtually noise-free.

Shielding and terminations were the main considerations.
Digital signals by their nature are more resistant to noise.
This doesnt mean we should scrimp on the quality of cable we use, but I'm pretty sure I could make up a digital cable of as good if not higher quality than alot of the commercially available (and damn expensive) ones.

Maybe I should borrow the specialist crimpers from work and givde it a go!

As a last note - how many folks actually know the difference between resistance and impedance ?

I would also love an explanation of why 75ohms is required.
Just to satisfy my curiosity more than anything.

In my experience a cables core resistance should be as low as possible (prevents voltage drops) and the resistance between the inner and outer conductors should be infinite unless you like blowing stuff up.

I may well be wrong as regards Audio equipment, feel free to correct me.

Answers on a postcard, usual address.

 

[HienD]

Just to clearify, a optimized fiber optics cable/network will blow away any coax cable/network in terms of: length, signal purity and bandwidth. There's a reason why fiber optics is used for all the backbone application. Telcos, cable companies...etc.

Now, when were talking about a 6" digital cable, could anyone really justify the astronomical price it would cost for the optimized fiber connection's components ?

 

[ChrisMcL]

Steve and HeinD:

I think I know what you guys are trying to get at; that in ideal circumstances, optical should beat coaxial in terms of the quality of sound one hears through each system, all other things being equal. We could argue theory all day long; hell, that's what we're doing! But, I prefer to limit my attention to the here-and-now. An upgraded optical system that does not yet exist for A/V gear could sound very good-- it might even write poetry and blow-dry my hair. But we, you and I, are stuck with only four more-or-less universal ways to transmit digital information in digital form from one A/V component to another. The oil drilling and the telephony industries chose their particular methods for... who cares what reason! Their equipment is incompatible! I've never heard Beethoven through an oil rig, and maybe there are other factors influencing my opinion of music-on-hold, but it stinks!

I don't remember who said it first, but all analogies are untrue. This forum is about home theater equipment, and this thread is about coaxial vs. optical. Please weigh-in with your stories and experiences with digital AUDIO.

 

[Stephen_J_H]

Basing my judgment on ears alone (my DVD player is hooked up coax, and my CD player is Toslink), both sound great, but I would give Toslink the edge on the bottom end. I haven't tried comparing bandwidth or anything like that, because I lack the equipment, but I have always found that if you spend a reasonable amount on your cables, you will get good sound regardless of the connection type.

 

[Steve>Smoker]

Steve and HeinD:

I think I know what you guys are trying to get at; that in ideal circumstances, optical should beat coaxial in terms of the quality of sound one hears through each system, all other things being equal. We could argue theory all day long; hell, that's what we're doing! But, I prefer to limit my attention to the here-and-now. An upgraded optical system that does not yet exist for A/V gear could sound very good-- it might even write poetry and blow-dry my hair. But we, you and I, are stuck with only four more-or-less universal ways to transmit digital information in digital form from one A/V component to another. The oil drilling and the telephony industries chose their particular methods for... who cares what reason! Their equipment is incompatible! I've never heard Beethoven through an oil rig, and maybe there are other factors influencing my opinion of music-on-hold, but it stinks!

I don't remember who said it first, but all analogies are untrue. This forum is about home theater equipment, and this thread is about coaxial vs. optical. Please weigh-in with your stories and experiences with digital AUDIO.

I think thats a pretty ignorant attitude to take to be honest.
I'm sure the designers of high end telecoms equipment couldnt give a toss about some overly-anal music buffs ignorance of the technology behind the systems they employ.
I was hoping by shedding some light on the theory behind the applications folks here could make a more informed decision on which cable to choose.

Maybe the way I put it was a little complex, so heres the simple version just for you:

Cheap & Nasty Optical = BAD
Cheap (quality, not price) co-axial = Better

With coax is alot cheaper and easier to manufacture a good performing cable tho there isnt any 'black magic involved'.
Fiber-Optic requires much more expensive equipment and the glass core is much more fragile.
I guess the 'exotic' deal of using an 'optical cable' is what sells the Toslink.

I hope this time its clear, and I promise, you dont need to buy an oil rig or a telephone exchange to get good sound.

 

[John Royster]

Take a look at the toslink core. See how big it is?

big core = bad optical transmission. There's a reason it is so bandwidth limited and that reason is the humongous diameter of the fiber.

Real world - fiber bandwidth only limited by transmitter and receiver.

-ps- I've paid 100,000 dollars for a fiber transmitter. But that is professional stuff.

Audio world - limited to a pathetic 6-15 Mhz.

So yes, by all means fiber is a superior medium to coax in digital transmissions. But for some inane reason (cost) in consumer audio that is not the case.

 

[Cees Alons]

I'm extremely sorry, but in my life I never read so much nonense together as I did at some places in this thread.

Here's a quotation of something I recently wrote in another thread:

The difference between coax and optical for the sound can only be minimal, because it's digital bits that are transferred, not any analogue signal. And bits are either right or wrong - but they carry error-correction/detection data. You cannot standardly lose "some part" of the data (you can, of course, but it would constitute a communication error). Put it another way: assume you had both connections in operation and a circuit on the receiving end compared the two byte-streams: it would find no differences if the connections were correct.

Same for the "quality" of the cables involved: either they are poor (and many transport errors may occur), or they are "good enough" (meaning: no errors).

Try to envisage the thought-experiment I suggested there: both digital streams are compared by a circuit. They deliver the same bytes (they have to, and they certainly can). Now which one would you send to further to the audio-decoders? And what difference would it make?

Optical connections are at the very least as good as wire connections. I'm not going to fight the personal experiences of those who hear a clear difference. I believe you do. Really. But I think it stems from quite something different than the cables we're discussing.

Cees

 

[Frank Zimkas]

IMHO...I prefer the sound that I hear via Coax! Your results may vary! The only way to know which will sound good to you is to listen to both in your home, with your music/movies. It's easy to get bogged down with technical mumbo jumbo when the only thing that really matters is which cable your ears prefer.

 

[Don Black]

Any recommendations on where to buy a coax cable from please? Thanks.

 

[Chu Gai]

I had a lot of fun reading this thread. As far as a digital coax, you can get away with just about any 75 ohm cable that's got a copper center conductor. Why even a coathanger works for short lengths!
BTW, one day play a test tone and measure the voltage at your speakers with Toslink and then with Coax. Think the different voltages just might translate to 'perceived' differences? What do you think happens once the voltages are adjusted to be equal?
A recommendation from Harley is like a recommendation from John Edwards. Well at least to me it is