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webby
09-06-2009, 16:54
Hi,

Is there a limit to the length of USB cable used? I need a run of roughly 16ft.

Where can I get this length to connect from iMac to DAC?

Or is it best to use optical for this purpose?

Thanks

sponge
10-06-2009, 11:22
Hi,

Is there a limit to the length of USB cable used? I need a run of roughly 16ft.

Where can I get this length to connect from iMac to DAC?

Or is it best to use optical for this purpose?

Thanks

Rapid do a 5m A to B USB 2.0 (code 19-8664) for 3.36. Of course the inevitable Ebay list numerous 5m cables - Various combination of ends. The choice is yours...

Ken

Clive
10-06-2009, 16:19
For lengths greater than 5m you need an active repeater, you can buy cables with these attached, they are not expensive. However active repeaters may not be good for the sound. Also some say lengths over 3m (others say 1m) cause sonic degradation. Try to get a thick shielded cable. What length sounds best in you situation will depend on the RFI you have near your system.

webby
10-06-2009, 16:32
What length sounds best in you situation will depend on the RFI you have near your system.

The what?

Clive
10-06-2009, 16:39
Radio Frequency Interference, electrical noise and grunge emitted by power supplies, TVs, CD players, computers etc. Cables act as aerials picking this up. Don't worry about this too much, if you need 16ft / 5m then try it. If you can find a way to use a shorter cable then try that too.

webby
10-06-2009, 17:03
Ok, cheers Clive

trailer
12-06-2009, 11:36
I run a 5m USB to an external HDD with no problems.

The Vinyl Adventure
12-06-2009, 11:40
my 5m usb from pc - printer or scanner is intermitant at best but that might be because it was cheapo

trailer
12-06-2009, 11:42
http://www.lindy.co.uk/usb-firewire/usb-cables/type-a-to-b/

That's the one I'm running.

(Not the premium one)

webby
12-06-2009, 11:44
So it may be better to connect via the Toslink optical then? I've seen these up to 10m in length.

Edit: It's difficult to keep topics together when I have questions regarding different gear, so I decided to update my Hello thread in the welcome area.

Basically, I found (and was shocked) that my cable run from iMac to Hifi rack was more like 6-7m, so now I'm thinking about optical. Or is coax better? Argh! So many options! :)

Thanks for helping me guys

NRG
12-06-2009, 13:06
So what's the actual cable length now?

Max USB hop is 5m up to a total of 30m so you may need a repeater. USB differs to toslink/SPDIF in that it's a packet based differential signal bus not a realtime transmission line with no recovery mechanism. USB utilises CRC protection and error recovery and has a number of transmission modes, however, for audio Isochronous mode is used which means packets are still transmitted with CRC protection but packet delivery is not guaranteed. So what Clive was saying about possible interference and thus dropped packets could be an issue over a long distance or with poor cable positioning.

Toslink will not be without its problems either over that distance, the quality of the optics will be very important as the LED signal progressively degrades due to absorption and dispersion over distance...in fact it may be more of an issue.

I'd be inclined to use USB with a repeater if possible....just my 2c worth.

webby
12-06-2009, 13:48
No cable at the moment. I'm trying to gain info before I indulge.

The Vinyl Adventure
12-06-2009, 18:00
my vote goes coax, its better than tos

trailer
12-06-2009, 18:30
Airport Express?

webby
12-06-2009, 18:38
Airport Express?

Well, that puts the budget up somewhat.

I'm confused now. If I go coax, does that go in the ethernet output of the mac?

I've got loads of coax cable at work but I don't know anything about spec. What would I need?

Cheers

trailer
12-06-2009, 18:51
There's no coax out on a Mac is there? It's either USB, optical or wireless.

webby
13-06-2009, 10:11
There seems to be no conclusive answer to this issue. For me USB is unheard of in lengths over 5m, but of course they can be added together.

Toslink is available in 10m lengths which makes me think that that's an acceptable length for it's use.

Looks like it might be a case of suck it and see!

Clive
13-06-2009, 10:29
There seems to be no conclusive answer to this issue. For me USB is unheard of in lengths over 5m, but of course they can be added together.

Toslink is available in 10m lengths which makes me think that that's an acceptable length for it's use.

Looks like it might be a case of suck it and see!
5m is the max length according to the USD standard, active repeaters are needed when adding them together.

Yes this is all very much suck it & see. Likely there will be few problems in real life situations.

webby
13-06-2009, 18:34
Airport Express?

This is something I'm now considering. More reading to be done methinks!

trailer
14-06-2009, 15:42
For the price the AE is a really useful bit of kit.

80 for one plus a 7510/7520 really does take some beating for quality music streaming.

webby
14-06-2009, 18:53
Thanks Trailer!

webby
14-06-2009, 21:14
One more thing; can I connect standard RCA cables to the Express using an adaptor to tied me over until I get the DAC?

trailer
15-06-2009, 07:32
One more thing; can I connect standard RCA cables to the Express using an adaptor to tied me over until I get the DAC?

The AE has a analogue out socket that doubles as the mini TOS.

You'll need a 3.5mm headphone male to 2 phonos cable.