# Does optical cable length matter?



## pennylane

I could use an optical cable and the ebay seller "uniqueproductsonline" is selling a ~6-foot for $19, but has a sale on the ~12-foot for $15. Are there any reasons, theoretical or otherwise, where the 12-foot may be worse? Thanks.


----------



## felixkrull6

I'm not sure if there is a difference but my general rule is not to get longer than you need. First, what's the point? Secondly, it always cost more. Last but not least, there is a chance that the sound could degrade.


----------



## B-side J

In my experiance (I instaled fibreoptics for highspeed internet) the length in not a factor , but the quality of the connections is key, but if you are talking about a home stereo application then 1m Vs 10m of the same quality glass will be exactly the same. At least to the best of my knowlage.


----------



## pennylane

felixkrull6,
 The longer one is actually cheaper (see original post). That's why I asked.


----------



## felixkrull6

Sorry about that pennylane.

 If the longer length is cheaper then the only real question is whether or not you mind having the extra length. For me, extra length is a pain because I have so many cords but if that isn't a problem then go with the longer one.


----------



## Sycraft

Unless optical S/PDIF is REALLY wierd, not it won't make a difference. With things like SONET and optical Ethernet any length cable works just as well until you go over the max and attenuation makes your signal not go through. I imagine TOSlink is the same.

 It's digital data so as long as it's above the required level, there's no problem. Also, since it's optical, there will be no EM or RF interference.

 If length doesn't matter for multi-gigabit SONET connections, I can't imagine it mattering for S/PDIF.


----------



## stevesurf

Hey everyone. Length IS a factor, even in optical signals. Please understand the source and transmission media. The source is an LED that pulses through the media (either glass or plastic) to its receiver. TOS link cables, like their big brother Gigabit Ethernet counterparts have length restrictions based on dB loss budget (signal degradation). You do not hear about these in Home Audio, because, unlike Ethernet, there are no standards!!!

 Solution: 

 Use a guideline of a high quality TOSlink cable made of glass and not plastic and, assuming your source has not inherent transmission limitation, you will be able to transmit around 10m (30ft). Please keep in mind that Home Audio Systems have shown transmission limitations (not due to media) of anywhere from 9 - 30 ft.

 FYI, your Gig-E fiber transmission system that (typically) powers your network at work uses pulsed lasers as their source through long-range 100 micron pure glass optical fiber.

 Good luck with your selection!


----------



## keiron99

I have a 20 metre optical cable (in fact 2 x 10 metre cables joined together) running under my floorboards. Works absolutely perfectly. Before installing it I tested it against a regular 0.5m cable. There was no audible difference whatsoever.

 I think for all practical domestic purposes, length, nor material, makes any difference in my experience. Others will obviously disagree though.


----------



## Tachikoma

Quote:


  Originally Posted by *keiron99* 
_I have a 20 metre optical cable (in fact 2 x 10 metre cables joined together) running under my floorboards. Works absolutely perfectly. Before installing it I tested it against a regular 0.5m cable. There was no audible difference whatsoever.

 I think for all practical domestic purposes, length, nor material, makes any difference in my experience. Others will obviously disagree though._

 

I hope you're right, to be honest


----------

