Optical cable running in ?

aznblue posted:

I've been using a glass Lifatec cable with excellent results, nicely constructed at a very reasonable price.  I prefer it over a Stereovox XV2 coax into nDAC. Would it be reasonable to suggest glass works better than plastic in toslink audio applications?

It might indeed be reasonable, especially for longer cable runs where greater transparency might result in fewer errors. The other factor is the quality of the connector, with "higher-end" cables presumably having a more durable and stable connection. Perhaps it is less likely to be compromised by bends in the cable pulling on the plug, for example. I don't know if it is a thing, and every Toslink I've ever had has been 100% reliable (and I've only had cheap ones). What I would put money on is that gold-plating a Toslink plug (yes it is done) will have an effect on the weight of your wallet only.

To continue Winky's thoughts, it seems reasonable that glass versus plastic would depend on the quality of the material. It also stands to reason that connections with tighter tolerances could provide more reliable transmission. Is there any reflection, signal loss, or introduction of noise at the connection points?

To continue Simon's input regarding microphony, it stands to reason that quality cable insulation and connectors are important. So the larger question remains, is there a SQ difference to be heard with more expensive optical cables or does price become fodder for one's perception of the results? Where is the monetary asymptote with optical cables?

Pure supposition on my part, but if I had a high-level audio system that required a toslink, I wouldn't be inclined to use a two-bit cable from Radio Shack or wherever.

When choosing glass or plastic fibre optic cable it is important to know what the system is designed for: glass is less good at shorter wavelengths and plastic less good at longer ones. If the wavelength is 850nm (near infrared - invisible)then the two are fairly similar, but if you use glass on a 650nm (visible red) system it will transmit less light than plastic, and vice versa at longer like 1300. For digital audio the standard is Toslink, which uses 650nm. The greater losses in glass at that wavelength are unlikely to be of any significance whatsoever in the short links commonly used as interconnects, but might be if you used optical from one end of the house to the other.

In digital optical transmission, the receiving end has a detector which requires a minimum level of light to record a '1'. The transmissiveness of an optical fibre (cable) and it's connections is only significant if it reduces the light level to the point where the pulses might not be detected reliably. The transmissiveness is directly related to cable construction, very much including the fibre composition (e.g. glass vs plastic). But transmissiveness alone is only likely to be a real consideration with long cables. Susceptibility to microphony effect as described by Simon will depend on cable construction, and here plastic being potentially more susceptible than glass because it is more compressible, but with any particular cable construction will be proportional to the length exposed to vibrational sources, so in any given environment the shorter the less the effect (possibly balanced by whether a longer cable allows less exposed routing). Key requirements the connections include tge quality of end finish of the fibre (e,g angle of cut and smoothness of cut surface, as they can affect transmissiveness and, potentially more significant in terms of quality of signal, the amount of reflection back along the cable), while the end fittings can affect the precision of location, and any susceptibility to vibration causing movement of the fibre end.

Aging of a cable as mentioned by others, e.g. in terms of reducing transmissiiveness, or changing mechanical resistance to external vibrations, will depend in part to the environment to which the cable is exposed, and resistance of the outer cover to that environment (that could include extremes of temperature, UV light, etc). However this is not burn-in, which would entail the light passing through the fibre to change the transmission characteristics in some manner that affects the received stream.
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I did try a qed glass cable 100£ ish and did think it was far better than a £15 opto cable, but still went back to cable

audio1946 posted:

I did try a qed glass cable 100£ ish and did think it was far better than a £15 opto cable, but still went back to cable

as mentioned the quality of fibre termination - the end finishing - can be significant, while the attenuation digpfference in a short cable is probably negligible.

Innocent Bystander posted:

audio1946 posted:

I did try a qed glass cable 100£ ish and did think it was far better than a £15 opto cable, but still went back to cable

as mentioned the quality of fibre termination - the end finishing - can be significant, while the attenuation digpfference in a short cable is probably negligible.

For glass fibre, yes, but I'm not sure that's a problem for plastic. DIY termination of POF, cutting it with a sharp knife is very simple.

ChrisSU posted:

Innocent Bystander posted:

audio1946 posted:

I did try a qed glass cable 100£ ish and did think it was far better than a £15 opto cable, but still went back to cable

as mentioned the quality of fibre termination - the end finishing - can be significant, while the attenuation digpfference in a short cable is probably negligible.

For glass fibre, yes, but I'm not sure that's a problem for plastic. DIY termination of POF, cutting it with a sharp knife is very simple.

If the cut is not precisely perpendicular and clean there could be increased chance of internal reflections from the end of the cable. Ditto glass finishing. Perfectly adequate for data transmission provided the cable length hasn't attenuated to close to the limit of reliable detection, but if people hear differences with digital audio, this is one of the few potential factors. I'm not saying that I believe it will have an adverse effect, but I can't say it won't...

Innocent Bystander posted:

ChrisSU posted:

Innocent Bystander posted:

audio1946 posted:

I did try a qed glass cable 100£ ish and did think it was far better than a £15 opto cable, but still went back to cable

as mentioned the quality of fibre termination - the end finishing - can be significant, while the attenuation digpfference in a short cable is probably negligible.

For glass fibre, yes, but I'm not sure that's a problem for plastic. DIY termination of POF, cutting it with a sharp knife is very simple.

If the cut is not precisely perpendicular and clean there could be increased chance of internal reflections from the end of the cable. Ditto glass finishing. Perfectly adequate for data transmission provided the cable length hasn't attenuated to close to the limit of reliable detection, but if people hear differences with digital audio, this is one of the few potential factors. I'm not saying that I believe it will have an adverse effect, but I can't say it won't...

I couldn’t say either. All I know is that having ‘wired my house with POF network cable, using the same Mitsubishi cable used in many Toslink cables, it has worked very well for the last couple of years, and all the terminations were done by me, just cutting the cable with a sharp knife.