Hi Guys,

Can anyone please tell me if it is better to use the digital coax or the optical fibre connection for audio out of my LG 5100p HD box. Do not have a surround system yet but working on it.

I think the price for the cables also varies greatly between coax and optical. If this is the case, surely one connection must be better that another.

Cheers

Tom

Hi Tom,

It won't make any difference on the audio quality (both carry a digital audio stream, hence the improved noise immunity that fiber offers is not really of any benefit), it is purely a 'physical' choice (note however that coax is more physically rugged than fiber but is thicker).

Regards,

InTune

Some folks have previosly argued in this forum that the conversion from digital to optical and back has the potential to introduce errors.

It is like everything else, if quality components and chips are used then there should not be a problem. To illustrate, fiber optic interfaces on FDDI data networks and other data networks operating over fiber backbones operate at much, much higher frequencies very reliably. I use both coax and fiber multi-channel audio connections with my HT gear and have not had any glitches with either.

InTune

Where is the cable going to Tom?

They're both digital. By definition, if the signal gets through without error, there cannot be any difference.

Generally, errors may start to occur with longer cables.

Cheers Dudes,

Good to know there is virtually no difference.

The connection would be going to an amplifier (home theatre or dedicated 2 channel) not sure yet. Need to work out what to get as I also like to listen to normal CDs. I hear home theatre amps are not that good for listening to normal stereo music as they do not provide enough punch for good floor standing screamers.

Tom

Tom,

There are all sorts of AV (Home Theatre) amps out there, some excellent ones costing thousands and performing just as well as specialised stereo amps and some not so good ones. You will find a few AV amps that will output close to a kilowatt (RMS) in stereo mode (is that enough for your 'screamers!'). Many even allow you to completely isolate the sound processing DSP circuitry (function often called 'DSP Bypass') to get a 'purer' sound (on Denon gear, the bypass switch also bypasses pre-amp equalisation/tone adjustments if you wish). I listen to CDs (and HDCDs) through my Denon with as much pleasure (and more) than through my old very expensive stereo amp. So do not underestimate the power and musicality of AV amps, some are very, very good.

Note that you do not need to have a separate subwoofer to get the bass out of the AV amp (as many people believe). All AV amps can be configured to have their LFE (Low Frequency Effects channel) and bass output through the front speakers. Some high end AV amps have a 'pure stereo' option that combines the power of the other amps to the front stereo channels (in 'bridge' configuration) to get very high power output to your front speakers only (with the addition of bypassing the sound processing digital circuitry for purer stereo sound as mentioned earlier). These amps also have their digital circuitry isolated from the analog circuitry to eliminate 'digital contaminations', including separate 'digital' and 'analog' power supplies for these.

Note that you may find it a tad difficult to find a stereo amp with digital input(s) - it is generally a feature found on AV amps only (simply because multi-channel audio requirements on AV amps are not applicable to stereo amps - eg: 6 channels Dolby Digital and DTS decoding etc ...), although they may exist.

InTune

As has been mentioned, there should be no difference what-so-ever.

However, some have reported that in their particular setup optical sounds better, others have reported that in their setup co-ax does it for them.

IMHO, I'd prefer co-ax, but only because it has a more positive connection. Depending on your configuration, I'd use as many of my co-ax's as possible, and then when I ran out of co-ax, I'd put the remaining on the digital connections. Once again, only because I prefer them physically.............

Austen.

They are both digital conections.

D'Oh ............

...................and then when I ran out of co-ax, I'd put the remaining on the optical connections.

Thanks Peter, you spotted the deliberate error !!!

Austen.

i've also heard a slightly warmer sound through my klipsch, when going through coax as opposed to optical, so therefore whenever i can i stick with coax..

The 0's and 1's must have rounder curves.

Many other people have the same experience.



No. Among others, co-ax has wider bandwidth and produces less “jitter” (timing inaccuracies) than fiber optic cables.

Thanks a lot InTune for your educated response.

Good to hear AV amps are good for stereo music listening as I do not want to buy two separate components - obviously one processor for both TV watching (surround) and for CD playback.

How much should I budget - to get a decent box - 1-2K? What are good models in that price range.
Do not need 1kW output - this is insane and that distortion at that output would be too much.
Quality, features and usability is rather what I am after instead of max power.
Oh dear - another remote to the collection coming up!!!
Any replies appreciated.

Tom

I understand what jitter is, but do you know what effect it has on the resulting sound?

Distortion.

Hi Tom,

I would not like to bias you one way or another with your choice of AV components. I know of probably around 20 manufacturers of decent AV gear and they all have something good to offer. Personnaly, I've stuck to Denon for a lot of my gear as they produce good quality stuff (some very very good) at a reasonable price and they've been around in the stereo business for a long time before the 'digital revolution' came-in (Oh no, what did I just say ... expect to see a thousand comments coming back here ... so may I stress that this is only my personal taste based on my own technical knowledge and musical inclinations ... and yes there is probably better gear out there, but I've been happy with my choices so far).

I do not know your technical/musical expectations and requirements Tom to tell you what you should buy, it often comes down to personal choice (especially if you have a 'good musical ear', a bit like choosing speakers). With regards to useability, there is not much difference between brands these days, they all pretty much offer similar functionality (do not get tricked by those units that provide a 1000 DSP modes, I use 2 or 3 at the most and bypass them altogether when I listen to good stereo material and I bet most people do to!). For my money a sub $2k AV amp is sufficient for my setup. Spend more only if you have exceptionally good speakers, surrounds (and a listening/viewing room with good neutral audio characteristics that go with them!).

With regards to remotes, you can purchase a 'universal programmable' remote that controls all your devices and let you program macros so you can switch and control multiple devices at once at the press of a button (I use the Sony RM-AV3000 - it also controls my A/C and projector).

The fun just begins for you Tom, there is lots out there for you to get your teeth into!

InTune

I've got a Denon Amp too and and am very happy with it.

IMHO, As you seem prepared to spend up to $2K on your AV amp (bracing for impact) it probably won't make too much difference what you buy............

It seems that this is the price range that is well clear of the HTIB solutions, and yet not quite at the dedicated pre/pro 2-channel amp solution.

I'd be thinking about what features you're going to want such as number of inputs (I've filled my Denon 3805 inputs up already), what sort of zoned outputs you're going to want (I use all three zones) physical size if space is limited, but finally do have a listen, just in case you find you don't like it after all !!!

I'd (bracing for impact......... yet again) would be putting the prospectives amps rated power output quite low down on the list of priorities, unless you do have special requirements.

BTW, Like InTune says, You're going to need a programmable remote, Personally I like my Harmony 880, features to consider are batteries (life and disposable vs rechargeable), colour screen, number of components / activities and ease of programming.

Austen.

I would have to question that statement, unless the fibreoptics are basically fishing line. Fibre is the preferred medium for carriers for a good reason.

Rob.

If these are both digital connections, then it should be possible to do an electronic comparison of 2 bitstreams and detect any variations.

Has anyone done this or knows where it has been done?

I don't think it's like speaker cable where characteristics of the cable can introduce qualitative variations into the coloration of the sound.

I'm with you 100% on this one...........

Having said that, I don't question for a second people who have said they can tell the difference, I put it down to the "smarts" in their particular setup decoding / processing / amplifying / massaging the digital signals differently as they pass on their way to the rest of the system.

So, NO difference between optical and co-ax transmission, but I'd accept that the 0's and 1's appearing at the optical port may not be identical to the 0's and 1's at the co-ax port. And that's a whole new story.................

That's my $0.02

Austen.

Agreed - but someone should be able to measure this. This is not a value judgement. Either they are identical, or they are not.

Another way to measure it would be to compare the input bitstream with the output bitstream for each type of connection and determine any variations.

To me it's like saying that microsoft word has a different "feel" depending on whether you use NEC disk drives or Maxtor drives. It just doesn't make sense.

Gentlemen,

You will be hard pushed finding differences in the bit-stream of optical versus coax audio transmissions (in a 'reasonable' setup) as we are talking very low bit rates - it's around 3Mb/s, for a total bandwidth of about 6MHz (taking into account the clock rate at twice the audio frame's bit rate for a standard 48KHz audio sample). Both the humble 75-Ohm coax and the TOSLINK fiber cable can carry these very comfortably (over reasonable distances of course - in a typical HT environment I would consider it to be < 10m). So let's not scare Tom away with technicalities guys! Be mercifull! I maintain that he will hear no difference between the two (if he or anyone else were to hear a difference then it would have to be down to a technical fault somewhere, be it a faulty cable, bad connectors or connections/soldering on the coax, dirt/dust in the optical pick-up of the fiber, etc ...).

InTune

I think you will find that although there may be some differences in the digital waveform at the end of the cables the signal is then buffered and "AND" gated with the amp's master clock. This will eliminate any shortcomings (jitter, rise time, amplitude, etc) of the incoming signal whether due to cable or the source. If people seriously believe that they can hear a difference then its most likely to be due subsequent signal processing and not the cable.

hornblower

PS I cannot tell the difference but then my hearing is down to only 9.6 kHz.

That's excatly what I was trying to say.......


I thought it was just me ............

Austen.

I would agree, particularly as most setups have only a short length of fibre or co-ax say <10m. In theory, fibre has a much wider bandwidth, hence its widespread use in networks such as Telstra and Optus where they can drive the signal up to 50km without regeneration. However, this is probably not the same fibre as your typical TOSLINK cable. Having said that, TOSLINK is probably only bandwidth limited at HT distances (say <10m) by the electronics at each end.

Rob.

Correct Crossy. The TOSLINK cable is in fact a low grade fiber, but as you said, for distances of <10m it does not matter. There is a simple test anyone can try: go home tonight and try for yourself with your own gear (many devices offer both coax and optical audio connections) - sure it is a 'low tech' approach as you are relying on your earing - but at the end of the day if you cannot tell the difference with your own built-in sonic transducers (your own ears!) then how relevant are the results from complex and convoluted measuring tools!!!

InTune

If you believe there is any real difference in sound quality between coax and optical, or 'digital cable' quality, then it's wroth having a read of the good old Coathanger Test

I cannot believe that this thread is going on & on & on over a $20 Coax cable or Toslink connector

Keep that up and we'll start talking about the costs (and benefits) of Monster cables !!!

Fee Fi Fo Fum....I smell a cable war !!!

Austen.

OH YEH - we're coming to get you :ph34r:

Like your attitude Austen ... and you are absolutely right!!! I'd like to know what possesses people to spend mega bucks on cables (especially audio speaker cables) that promise Heaven on Earth when a sub $1/m (and much less) will do EXACTLY the same job. There have been hundreds of tests perfomed by the most serious labs all around the bl*#dy world and have published their results for all to see on the Web but there are still people out there who insist on spending their monthly salary on a 20m run of figure-8!!! I have even heard of 'water cooled' speaker cables - got to get my hand on 1m of this just for curiosity and to remind myself from time to time that there are two kinds on people on Earth, those who have a sense of humour (and large bank accounts by now) and make these things and those who just don't have a clue (and are afraid to know the truth).

... just trying to launch your war Austen! I can already hear a counter attack just around the corner, got to admire them! Anyway, this is my last post on this thread - the initial query from Tom has been clarified (and thanks for Trainspotter and his 'coat-hanger' article that sealed it!).

InTune

Thanks InTune for ending this thread - could not believe that a simple question could turn into such a long thread.
Was happy with answers by the end of first page but things just kept going.
Obviously if manufacturers provide two different digital audio connections, I just wanted to know if there is any difference and what the different applications are.