HOWTO: Sky+HD Amstrad SPDIF Dolby Digital 5.1 over Cat5 to a second room


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I wanted a way to get Sky+HD Dolby Digital 5.1 to my second room over Cat5.

My wife bought me these Cat5 a/v baluns for Christmas:

£30 cat5 video and audio balun sender and receiver
Audio Video Over Cat5 Extender Balun Kit Only £26.50 at TVCables

My theory is to use the 75-ohm composite video "V" connectors on these unpowered baluns to pass the 75-ohm SPDIF coax signal over. I am planning to use them in addition to HDMI with remote control over Cat5 with something like this:
£73 cat5 hdmi and IR return balun sender and receiver pair
HDMI Over Ethernet with IR Extender Cat5e Cat6 Only £72.99 at TVCables

I just tried this over a £5 20 metre cat5e cable.
In short it works.

I tested for about 30 minutes, admittedly without lengthy A/B comparisons.
The surround processor is a Tag AV32R 192. I use Linn active bi-amped speakers and a kef 200c reference centre in an acoustically tuned room.

I tested with three sources:

1. Sky+HD Amstrad box. From the orange coax spdif dolby digital output.

Seemed to transfer the dolby digital audio fine. Material either showed as dolby digital 5.1 or dolby digital 2 with pro-logic2 engaged automatically, depending on the program material.

It sounded fine, although I have never heard Sky box digital audio over a relatively high-end system before. It was certainly discrete 5.1 including the sub at times.

2. HTPC m-audio 2496 soundcard.
Played Aladdin dolby digital 5.1 both directly in to the Tag and via coax cables, the balund and the cat5 cable.

It sounded fine. The THX intro glass explosion and deep thump intro sounded as big as expected.

Dialog remained clear and steering effects were working. It was definitely dolby 5.1

3. CD audio (not dolby digital) from my htpc via a Musical Fidelity V-Link SPDIF coax output.

This is my best cd audio source and sounds great playing my ripped CD's in 44.1KHz/24-bit. Certainly better than and CD, DVD or blu-ray source I have owned.

Over the 20m cable and baluns it sounded ok, perhaps somewhat thin compared to the V-Link directly. Probably irrelevant compared to a Sky box dolby digital output which is packet based and I think includes checksums for error correction) which I presume travels over a longer wire with less effects.

I suspect this is also why many reviewers report lower and AV kit being ok for dvd/blu-ray but poor for CD audio.

Two notes to add:

1. I have read that the HDMI output that I'm also planning to send over cat5 cable does not include dolby 5.1. Plus my tag surround processor does not take HDMI audio.

2. I think the older (Thomson) Sky HD boxes have optical SPDIF but not the orange coax digital audio out, so would also need a powered optical to coax converter to use this approach.


If you're referring to the HDMI output from a Sky PVR then it's generally known that it carries only stereo audio.
You're right that the Thomsons had only optical audio out but there aren't many of them around now.


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I ordered the hdmi and ir over cat5. Looking forward to them arriving and some fish tape to get the 5 cat5e cables thru the last bit to a socket next to the sky hd box.

I was surprised that all 9 cables i pulled before my plasterboard went up in the cinema room has survived and are all passing a cable test.


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Been using these for around a month of splendid sky hd viewing on a 1080p projector.

The ir receiver was always a little more directional than any of my oter kit in the rack at the back of the room, requiring the remote to be pointed p at the ceiling. Both using the original sky remote and a logitech 525 remote.

Last night i noted the infa-red didn't work at all from the second room.

I've tested the connections and ensured the ir emitter above the sky hd box hadn't moved, to i think i have a component failure here.

I'll contact tv cables tomorrow and post back what level of support i get.

The good thing the baluns are not in the wall, like wall plate based adapters.

I did also note during testing that the sky hdmi signal worked without the power supply connected. Perhaps its getting power over hdmi from the powered hdmi splitter connected to the sky box, or perhaps it only needs power for the ir feature or longer runs. I think mine is only about 20m.



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I had a week of slow exchange of emails with tvcables to arrange a return authorisation.

I must say i then had great friendly service, me sending the balun kit back tuesday lunchtime. The replacement set arrived yesterday.

They work well, with the infa-red receiver device being much stronger, allowing me to pint the remote at the screen whilst the IR receiver is at the rack in the back of the room.

I think the original kit had a marginal issue from the start that just became unusable.
I also noted the hdmi and ir works without the baluns power supply. I assume it's getting power from the powered hdmi splitter at the sky hd box end.

I would recommend tvcables and will use them again.

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