View Full Version : Optical vs coaxial
nbaptista
28-06-2023, 09:05
Which is the better connection for audio, optical or coaxial?
walpurgis
28-06-2023, 09:17
Coaxial
After a lot of experimentation I came to the same conclusion. Some prefer optical though.
nbaptista
28-06-2023, 09:21
And how much do you need to spend on a coaxial cable to get better resulta?
Lawrence001
28-06-2023, 09:55
Better than what, optical? I've found you can chuck in a single good quality screened analogue RCA and get good results if you've got a spare one.
Some will say it's the wrong impedance and you'll get reflections or something but apparently RCA itself is the wrong impedance and you need a BNC socket I've no idea why that is.
If you've got BNC rather than RCA on your dac ignore the above and get a MarK Grant G1000HD I think it is, the copper coloured one, very good value.
RCA phono connectors were chosen by Sony and Philips for the digital interface, not because they have a 75 Ohm impedance (they don't; in fact they cannot have an impedance greater than ~ 57 Ohm, and usually the impedance will be 30 - 40 Ohm), but because they are electrically short, which means that any impednce mismatches which would give rise to reflections, tend to be self cancelling.
if its well made, connection wise you'll be fine imo... same goes with optical. the ends are more important, especially with optical
Optical has limited bandwidth.
Coaxial has greater bandwidth so supports high resolution 24bit if that's your thing.
Optical has limited bandwidth.
Coaxial has greater bandwidth so supports high resolution 24bit if that's your thing.
think optical can now do 24/192 max.. depends on the dac tbh too.. coax can go higher but it is grounded and hence if you have hum issues you might be better with optical. usb again is different and can be better as its timing is not done til it hits dac; again its all about implementation... best choice is dependent on your needs and system. generally unless your golden eared or need a particular rate, or your system requires a type your likely not to notice
think optical can now do 24/192 max.. depends on the dac tbh too.. coax can go higher but it is grounded and hence if you have hum issues you might be better with optical. usb again is different and can be better as its timing is not done til it hits dac; again its all about implementation... best choice is dependent on your needs and system. generally unless your golden eared or need a particular rate, or your system requires a type your likely not to notice
One thing I did notice recently was choice of cable quality certainly does make a difference. I have had USB and Coax and optical cables that caused issues in my system with drop outs and poor connection so a decent quality cable is certainly a good investment.
As to cables actually sounding different in digital systems I am not so sure? From my experience there are marginal gains here.
One thing I did notice recently was choice of cable quality certainly does make a difference. I have had USB and Coax and optical cables that caused issues in my system with drop outs and poor connection so a decent quality cable is certainly a good investment.
As to cables actually sounding different in digital systems I am not so sure? From my experience there are marginal gains here.
yeah, the fitments are crucial as is workmanship. its nice to see a decent cable on board too.. gives confidence etc
Optical may have the limited advantage of galvanic isolation, but the price you pay is the need for two electro-optic converters.
Also, IMO, the quality of the fibre optical cable used is far more important than that of the corresponding 75 ohm coaxial cable.
prestonchipfryer
28-06-2023, 14:17
Your ears will let you decide.
my optical cable cost a tenner, the coax cost £25 which was a bit excessive but I've had issues with cables failing or falling apart in the past. Professional cable so it's made to last.
I can't tell between them at all in my present set up although in previous set ups I thought optical was maybe very slightly softer sounding.
Optical has the advantage that it can't transfer hum or noise so maybe useful in solving a grounding issue or if your source has a lot of power supply noise.
nbaptista
28-06-2023, 20:07
I have here a spare optical cable.I will try it.
narabdela
29-06-2023, 19:40
Optical has limited bandwidth.
Coaxial has greater bandwidth so supports high resolution 24bit if that's your thing.
Sorry, but in real world audio applications, this is "received wisdom" nonsense.
Sorry, but in real world audio applications, this is "received wisdom" nonsense.
Must have been reading a load of bollox then.
Shouldn't trust anything I read on the internet including what is written on forums!:)
Lawrence001
29-06-2023, 23:20
Sorry, but in real world audio applications, this is "received wisdom" nonsense.Is it the Toslink receivers that have historically limited the resolution over optical to 24/96? I read recently that you can get up to 24/192, which I assume means someone makes a better receiver now rather than the cables have got better [emoji23]
Is it the Toslink receivers that have historically limited the resolution over optical to 24/96? I read recently that you can get up to 24/192, which I assume means someone makes a better receiver now rather than the cables have got better [emoji23]
yes it's nothing to do with the cable.
Yes both correct. I did not say it was the cable just that you can obtain greater bandwidth using coaxial. It is indeed the equipment at each end of the cable that determines how much bandwidth each can carry and until recently optical was limited by the receivers.
I've connected both at once and flipped between them with the remote control until I've lost track of which is the feed.
With decent equipment there should be no discernible difference and that's what I found.
nbaptista
30-06-2023, 08:56
I'm keeping the Toslink.It is noiseless...
I would like to typify, That My coax will do 360 mb/s. A 24bit 192 khz. is 9 mb/s. So high quality coax way exceeds the bandwidth needed for audio.
I also have a Bluetooth 5.3 streamer that dose very high resolution for Bluetooth , 24 bit at 48 khz. I do use an all glass fiber Toslink cable for it.
But investing in an all glass cable is important, as the cheaper plastic cables age they turn yellow and the signal is degraded ,mostly the speed.
It's why real glass fiber it used for communications networks.
Also stay away from any 1 meter or shorter SPDIF cables. 1.5 meters is the sweet spot. To short of coax causes a high standing wave ratio, ( reflections = jitter).
A well made cable will have a 1.1 at 1.5 meters and longer, this is Ideal.
High standing wave ratio is a bit of a 'red herring'. Any modern CDP or DAC will have, respectively, output and input impedances close to 75 Ohm.
A standing wave ratio of 1.1:1 implies a cable impedance of 68 Ohm or 82.5 Ohm. The tolerance for a typical 75 Ohm impedance cable is +/-3 Ohm, that is the measured impedance can lay anywhere between 72 to 78 Ohms, which implies a SWR of 1.042:1 at worse. Better cables will have an impedance of 75 +/-2 Ohm.
Lawrence001
03-07-2023, 06:52
I had wondered about cable length on the basis that resistance doubles as you double the length and presumably impedance does the same. But cables were described as "75 ohm" regardless of length.
So it appears the causes of impedance are not the same as resistance and therefore this rule doesn't apply.
narabdela
03-07-2023, 06:56
Also stay away from any 1 meter or shorter SPDIF cables. 1.5 meters is the sweet spot. To short of coax causes a high standing wave ratio, ( reflections = jitter).
A well made cable will have a 1.1 at 1.5 meters and longer, this is Ideal.
This is out of date advice that has pretty much been debunked nowadays. Theoretical stuff that has no real world effect.
Hey chaps this is all a load of nonsense.
Doesn't matter what any one says on a forum or in a technical review the only way to know if you should use coaxial or optical is to try both in your system and then choose which one you think sounds best. Surely?
And to decide whether you prefer glass or plastic fibre optic cable.
Stryder5
03-07-2023, 10:14
Just to add... AES cable?
Gary
Just to add... AES cable?
Gary
Does that use XLR connectors? XLRs are not constant impedance designs.
Firebottle
03-07-2023, 14:23
Yes it does Barry, 110 ohms balanced impedance.
Aes wasnt a great way to do digital if i remember right. Bnc and coax was the usual way, then i think cat5 cable was used a lot.
Stratmangler
03-07-2023, 19:08
Just to add... AES cable?
Gary
AES was created for the pro users, because they weren't going to spend big money on new wanky wires.
Every pro studio has a box of XLR cables
Stryder5
03-07-2023, 19:31
Aes wasnt a great way to do digital if i remember right. Bnc and coax was the usual way, then i think cat5 cable was used a lot.
Why wouldn’t it be a great way to do digital?
Are there other considerations that made BNC and RCA the “usual” way, rather than the “better” way?
Why would Ethernet cable be used given it’s impedance?
Gary
Stryder5
03-07-2023, 19:40
AES was created for the pro users, because they weren't going to spend big money on new wanky wires.
Every pro studio has a box of XLR cables
Aren’t cables used for AES and XLR different, although using similar connectors?
Gary
Lawrence001
03-07-2023, 21:13
This has some interesting info on pp4-6
https://www.dbaudio.com/assets/products/downloads/ti/dbaudio-technical-information-ti315-1.0-en.pdf
Stryder5
04-07-2023, 08:54
This has some interesting info on pp4-6
https://www.dbaudio.com/assets/products/downloads/ti/dbaudio-technical-information-ti315-1.0-en.pdf
D&B has an interesting product philosophy and whilst the above is relative to a certain product it does contain information.
The document is almost 20 years old, has technology advanced?
Gary
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