Audio delay from Sky to amp.

ixtlan

Hi all,

I've just bought a Philips lx3900sa DVD/home cinema system, and am now experiencing post-purchase depression, over whether it's good enough/too expensive etc etc

Anyhow, I have a Sky+, so I intend to connect the optical digital out to the 3900, but first I need to get an optical->coax converter and some cables.

Anyhow, right now the audio signal for Sky is coming through the scart cable connected to the TV, so that the 3900 is processing the TV audio. This should be a Dolby surround/pro-logic signal. Anyhow it works fine except that there is a slight audio delay, which I can sometimes (but not always) perceive as a lip-sync issue. It is very subtle. Probably too subtle for me to send the system back. I know it's real because if I activate the TV speakers there is a slight echo apparent between them and the amp speakers.

Anyone experienced anything like this?

When I connect the Sky+ digital out, might this get better? Or even worse? Would the optical-coax converter possibly add some kind of delay also?

What do people think of the DD 5.1 signal from Sky+? Is it worth me spending the €50 or so that the converter and cables will cost?

Ix

slegs

i have a technics DD amp hooked via optical to Sky+..DD 5.1 is broadcast on Sky Mov 1,2,3 and Disney...i presume they will expand this to sky one soon.

The quality is excellent...with the RGB picture and DD5.1 sound watching a movie on Sky Movies is actually better than my DVD player.

The lip sync problem sounds like a setup thing with either Sky+ or the amp..try out different settings.

How come you have to get optical -> coax...i thought all amps came with at least one optical input and usually 2-3.

legend99

I have the exact same issue with the LIDL combined VCR/DVD/Home Cinema system sold before Xmas. In fairness though, i only have standard Sky Box nto Sky+.
However, I noticed a huge difference in the speed of the sound depending on what sound processing mode the amp is in. For example, if its in basic Prologic 2 mode, the sound is more or less in line. if i switch to 3-D, its a good .5 secs behind. I guess the extra processing the amp has to do to create a full 3-D effect slows the sound down...like any computing system, the more procesing the slower it is...I'd say play around with the sound format on the amp.

ixtlan

I guess while an AMP would come with multiple inputs, many home cinema packages don't come with any digital inputs at all, ie the low end Sony I think it's the SB-100. The assumption is that you only get DD from a DVD.

So the Philips lx3900sa is a tiny bit higher up the food chain. Just one co-ax digital input. I thought about this a lot before I bought it. I knew I would need a converter, but at €258 with a DVD/divx player it was just the right price for me. Anything I could see with an optical input was a lot more expensive.

I figure I can just use a co-ax splitter if I need more than one device connected, and even with the optical-coax converter (seen one for €28) it was still cheap... I am kind of worried that it doesn't have component outputs for progressive scan, but since I don't yet have a PS TV...

Tonight I must hook the TV output into a powered speaker and see if the delay is there. Should have thought of trying this.

Ix.

Tony

I've just watched apollo 13 and there was lip sync error which i'm almost sure is at the broadcast end, if it was at my end it would ne apparent on all DD programming

pH

Most audio processing is fairly instantaneous. Some amps actually let you delay the audio (as some projectors/lcd tvs delay the picture a bit due to video processing). Check if your amp has this feature and if so check it hasn't been turned on.

Check the Amp hasn't been set to any sound processing mode (like stadium,disco) as these 'effects' will also produce an echo.

Do you have a DVD player with a coax digital out to check if the amp has an inherent delay problem?

ixtlan

Hi,

Last night I connected a powered speaker to the TV output to make sure the delay was not being introduced in the TV. There was no delay, speaker and TV speakers perfectly in sync.

The amp has a speaker delay setting. It is set to zero. The delay exists whether the sound setting is plain stereo or prologic.

I don't have another DVD player as I gave away my old one.

It could be that I am too fussy. The sound processing is indeed fairly instantaneous, just not completely. Most of the time you cannot tell that there is a delay, just occasionally my perception suggests that something isn't completely in sync, and because I can turn up the TV speakers I can verify what my perception is telling me.

I can't tell what the delay is, but it must be very small, because if I introduce a 2ms delay into the centre speaker, I can definitely perceive that the echo is worse. So I'm guessing that the delay is in the order of a few ms. According to my web research, I shouldn't normally be able to perceive lipsync delays until close to 20ms... so maybe I'm just very sensitive.

I mailed Philips and got a very annoying reply, that they had not heard of this before, and please take it to my nearest service agent. Doesn't any company want to engage in discussion? All I'm looking for is a little re-assurance. I'd be happy enough if someone told me that there might be a few ms delay and that this was normal in such systems, and normally you won't perceive it. As I said most of the time it isn't noticeable, and I'm wary about bringing the box to a repair centre when I'm not sure they will even think there is anything wrong.

Has anyone ever tried having the TV speakers activated with amp speakers to see if there is an echo?

On a tangential issue... do most people always use the amp with the TV or only for movies? and leave it turned on all the time? Do you reset your Sky remote to control the amp volume, and disable the Tv speakers?

Ix.

clarkbelt

I have come across this before , I think the delay is caused by your audio and video being delivered from two different sources ,

ie. an av amp , and your tv , pictures arrive at your tv but there is a slight delay with audio delivered from amp .

Solution , get an av amp with audio AND video inputs and run both audio and video through av amp , worked for me .


"Anyhow it works fine except that there is a slight audio delay, which I can sometimes (but not always) perceive as a lip-sync issue."

pH

When you switch to the digital cable the amp will be getting a PCM 48 feed. Depending on how the amp works this may improve or not you really got to try.

My amp (Yamaha RX750) works great with Sky+, no audio delay problems. This amp has both separate speaker distances( a delay) and an overall audio delay in milliseconds. If your amp has both settings then make sure they're all set correctly.

ShaneOC

ixtlan wrote:

On a tangential issue... do most people always use the amp with the TV or only for movies? and leave it turned on all the time? Do you reset your Sky remote to control the amp volume, and disable the Tv speakers?

I always use the amp when when watching TV. The sound is so much better. I have changed the Sky+ remote to operate the amps volume.

slegs

I always use the amp also...its easier than fiddling back and forth all he time and the quality is much better

I have the Vol+- buttons on the Sky+ remote setup for the amp....would be nifty if the Sky+remote could send on/off signals to both the amp and the tv when on/off pressed...but being able to use the < button for the amp is the next best thing.

Zapho

Does your amp have an optical input? It really should have both an optical and a coaxial digital input. Anyway using the digital connections should get rid of the problem, seen as all the sound decoder has to do is seperate the 6 tracks and send them to the right speakers. Pro-logic needs to use digital signal processing to decide which frequencies go to which speakers which maybe why you're getting a delay. This is why it usually works best with music listening, seen as you wouldn't notice the delay.
On saying that, I haven't noticed a delay when I use prologic on my tv.

ixtlan

Thanks for all the replies guys.

I found a discussion on avforums where this was discussed and several people commented that they did get an echo between the TV speakers and the amp speakers, which makes me feel a bit better.

It'll be a week or two before I have the optical/coax converter in place (really, just one coax in, that's all I have), and I'll post back then on whether it makes a difference.

Best regards,
Ix.