Lag on Pro Logic?

NathanE · 19 Jan 2006 at 14:22

Hi,

I recently reconnected all my old surround sound equipment which cost about £2000 about 8 years ago. Back then I didn't notice any "lag" on the sound (e.g. lip sync) however now I do?

Is it something to do with the plasma screen?

My AV receiver has a Delay setting which doesn't go any higher than 45ms when in Pro Logic mode. The lag gets worse if I reduce it down to 15ms so I am guessing if I could get the delay up to about 80 or 100ms it would sound perfect.

I am using the "Monitor Out" ports on the back of the plasma to pass the sound to the AV receiver. I also tried plugging directly into the back of the DVD player to make sure there wasn't some rogue circuitry in the plasma adding the lag and the problem remained.

I'm guessing this has something to do with the response time on plasma screens then?

Any ideas?

Ta!

pinkaardvark · 19 Jan 2006 at 15:53

Are you getting the lag from a DVD or telly? If DVD it could be your DVD player or the recording. The sound stream is seperate on DVDs so can get out of synch.

the delay setting is only of use if the delay is constant whereas on a DVD it usually grows.

darreny · 19 Jan 2006 at 17:55

does it happen using the plasmas internal speakers, im guessing the sound is ahead of whats happening on screen, if so i would say its more of a response delay with your screen rather than the sound.

NathanE · 19 Jan 2006 at 18:09

The lag is on everything, not just DVDs.

If I use the regular speakers attached to the plasma they are fine. And for example if I turn on both the plasma speakers and my AV receiver then it sounds like everything is echoing because the surround sound is just ever so slightly ahead

The sound is _ahead_ of what's happening on the screen.

Do you think the plasma's internal amplifier adds a certain amount of delay time to the sound? I think that is the only logical explanation?

Is there any way to fix it? It's a 42" Samsung.

Corasik · 21 Jan 2006 at 13:12

What brand of plasma screen is it? Plasma screens have high speed microprocessors controlling the generation of the image, and was quite common in the past for there to be delay getting the image on screen, which does cause lip sync problems on a home theatre setup.

I believe my Tag Mclaren processor allows up to 150ms to compensate for this.

I cant think of any way to fix it, except buying a new TV with a faster processor (Panasonic and Sony for instance are both supposed to be fast), or a more expensive Dolby Digital processor with longer delay settings.

Your correct in your observation that the TV's adding delay correction to the sound, but a big screen deserves a proper sound system, not just the telly speakers.

NathanE · 21 Jan 2006 at 14:38

It's a Yamaha AV amp (about 8 years old). It supports Dolby Pro Logic (the old analog one) not the new Digital one. The delay time setting will goto a maximum of 45ms but that's not quite enough to fix the problem.

Samsung 42 inch. I don't have the exact model number to hand but it was from their previous generation (e.g. the ones without HDMI), from a little over a year ago.

Buying a new plasma is out of the question. I'm not upgrading any of my AV stuff until all this "HD" stuff has calmed down and become properly standardised. It's all too confusing at the moment.

Is there some little box of tricks I could buy that adds a delay onto the signal running to the AV receiver? I estimate I'd only need an extra 30-40ms or so, on top of the 45ms the AV receiver is already adding. I reckon it'd sound perfect then.