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LG TV & home cinema optical problem

by Swell6foot / February 5, 2011 9:37 PM PST

I have an LG 32LE5300 LED tv - great picture, sound lacks depth.

So I've also bought an LG HT321DH 2.1 home cinema amplifier. The TV only has headphone out or optical out, so I'm using the optical. It does work but intermittently only the left channel being picked up by the amp. It can be corrected by switching amp input using the remote and then going back to optical. It always just outputs left channel when the amp is already on and the TV is switched on. If the TV is already on and the amp is switched on, then no problem. I've tested the amp with another optical source and the same problem isn't there, so it seems to be the TV that's causing the problem - or it's only apparent with the TV.

I'd have thought really that with optical it's all or nothing as the signal is multiplexed into one stream. As I say, the amp is fine on all other input channels and other sources.

So, does anyone know what's causing this? Is this a common problem? Is the TV faulty? It is under warranty. Could it be the cable? It's only a cheap one.

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Built-in audio on HDTVs is an afterthought
by Pepe7 / February 6, 2011 1:18 AM PST

The subject line says it all, unfortunately. In addition to the native speakers/sound being lack luster, sometimes the digital optical output on many of the HDTVs is not ideal for what you need to accomplish.

In your case I need to know a little more info just to verify what's happening and the equipment involved. Is the HDTV tuning in a signal and passing it along to the amp(?) Or is there a separate cable or satellite box involved too you could use? That is the ideal scenario for good audio quality- avoiding passing it back from a TV.

I see on p.15 of the LG amplifier/receiver user manual that there appear to be some digital optical audio settings accessible via the remote. Is yours currently set to 'AUX OPT'? Here's the link to the user manual so you can check that as well-

Also, in the manual for your HDTV, I read that you have to set it so the HDTV's built-in speakers are off. [TV Speakers option -off in the Audio menu] See p.44 & p.110 of the manual here-

Let me know if that works. There was also a reference to 'Audio Copy Protection' on that HDTV for certain types of content. Perhaps that's what's going on here. Sorry I am not familiar enough yet with what you guys have across the pond from your cable & satellite providers ;).


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Further clarification of the optical issue
by Swell6foot / February 6, 2011 4:40 AM PST

I'm just using the TV for terrestrial freeview digital TV using the decoder built into the TV, so the sound is basically good but just not through the built in speakers. So I'm using the TV's optical out to send the sound to the amplifier. I tried it with the built in speakers switched off and the issue is still there. I am using 'AUX OPT' on the amp and have followed the manual for setup.

As I say, it's strange that just one channel is playing when the TV is switched on. The issue can be corrected in 3 ways:

1. pulling the optical cable out and re-inserting
2. switching channels on the amp and going back to 'AUX OPT'
3. switching the amp off and back on.

Turning the TV off and back on the issue is nearly always there. With optical it either works or it doesn't. So my guess is that either the sound is not being processed correctly by the TV and the TV is literally just sending the left channel to the optical port, or there's a problem with the amp. I think I've eliminated the amp being the culprit by testing it with another optical source and that being fine, though I suppose it may not be processing the particular digital signal from the TV correctly.

I suppose the cable may be at fault, but again with optical I imagine it's either working 100% or not at all so I can't really see why it could be the cable - unless there's a break somewhere in the cable and the signal ends up too weak - just thinking out loud.

I'm out of ideas. I've ordered a new cable anyway. The cable I have is also a bit short so there are a couple of tight bends, but I've tried repositioning the amp closer, and the issue is still there.

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regarding the cable.
by R. Proffitt Forum moderator / February 6, 2011 1:23 AM PST

My experience on optical is it's all or nothing. I'd not replace that but there will always be a first time it will be the cable!

Ok the next annoying thing about today's HDTV and "home cinema theater" boxes is they all have FIRMWARE. For some I have to write software, apps or code. Be sure to see if they offer updates for that.

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Interested in firmware updates
by Swell6foot / February 6, 2011 4:42 AM PST
In reply to: regarding the cable.

How are firmware updates applied? Both TV and amp have USB ports.

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by Swell6foot / February 6, 2011 5:27 AM PST

do you know where firmware updates can be downloaded?

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Those items are found
by R. Proffitt Forum moderator / February 6, 2011 7:33 AM PST
In reply to: Also..

At the product maker's web site. And they will have instructions about how to install.

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by Pepe7 / February 7, 2011 1:01 AM PST

...firmware updates are intended to be installed by trained technicians, and sometimes not via USB ports. I'd suggest perusing AVS forum, as well as the online support site for LG to see if anything specific applies to your HDTV which would be end user serviceable. You don't want to update firmware w/o first knowing what is intended to fix ;).

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New optical cable fitted - issue still there!!
by Swell6foot / February 8, 2011 2:04 AM PST
In reply to: Sometimes...

I bought a 2m Profigold cable. Tested it and at first all seemed well, then the same issue appeared again. Only the left channel being picked up. It doesn't correct itself but can be corrected by either:

1. pulling the optical cable out and re-inserting - either end
2. switching channels on the amp and going back to 'AUX OPT'
3. switching the amp off and back on.

So it's still a mystery.

The optical out port on the TV is a bit wobbly. It's a terrible design really - small plastic housing mounted on the PCB of the TV. I'm not sure if it was always wobbly of if the cable has been pulled and that caused it. I've examined it closely though and for the life of me it does seem that wobbly or not the optical cable mates with a narrow tube inside the housing within which is the laser, and it's clear that the optical signal will be picked up either way so I really don't think that's causing the issue.

I'm convinced that it's something to do with the encoding or decoding of the signal - making sense of which channel's which. Why that's corrected in the ways I've listed above is a mystery.

Anyone able to shed any light on what's going on here?

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See my comment about audio copy protection
by Pepe7 / February 8, 2011 2:50 AM PST

For reasons proprietary to the system and licensing used in your area, perhaps your audio is being throttled. YMMV.

I would also suggest you find a UK based discussion forum with more specifics on what you can expect in your area with the OTA broadcasts/features.

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