Denon & KEF - Funny noise on ProLogic2

[SimonJB]

Help please!
I've just invested in my first AV system. Got a Denon AVR 1804 receiver and KEF 2005.2 speakers. Films (in Dolby Digital) and music (in 5 channel stereo) sound great.
BUT I'm a bit confused by Dolby Pro Logic 2 - when I choose this option and watch TV programs through Sky Digital I'm getting a strange high pitched "chirruping" sound (best way I can describe it) accompanying dialog from the front left & right and the rear left and right speakers - centre is fine. Can anyone explain this? If I select 5 channel stereo the noise disappears.
Am I doing something wrong or does PL2 only work on cetain programs?
P.S. - terrestrial reception is very poor in our area (we're in a valley) so I watch virtually everything thru Sky.

 

[Malky1903]

I get that too but only on certain channels. Seems like some channels don't like the idea of you trying to listen to them in DPLII.

 

[balders]

Me too, with an identical setup. I found that this only happened on DPLII Cinema. I now tend to use DPLII Music for most of my TV viewing.

Balders.

 

[Crustyloafer]

I have never come across this problem on any Sky channels or with any surround mode on my receiver. It sounds like there is a problem with your receiver or your Sky box. The only chirping noise I have ever heard is when the Sky signal breaks up.

 

[Phil.LFC]

I have an ever present noise when watching Sky digital. It is only very faint but is noticeable. I made some enquiries about it on this forum a few months ago, and was told that it is a normal occurence with Sky digital broadcasts.
Can't remember what thread it was but if you do a search you may find it.

 

[Malky1903]

Just realised that the noise is there when played back through Neo 6 Cinema mode aswell.

 

[balders]

Do other 1804 users find the same? What about other Denon models? Do owners of different brands of amp find that this also occurs in cinema mode vs music?

Balders.

 

[Ettepet]

Dolby Pro Logic uses high frequencies and phase to add spatial effects, so this just means that those channels add a disturbance of that type to the signal. The centre speaker is an average between left en right speaker, with high frequencies filtered out, so you wouldn't hear it there.

As far as I know DPL 2 uses a similar approach, so I think people with other brands will experience this phenomenon too.

 

[engaged]

I have the same slight problem when listening to stereo sources (from Freeview) on PLIIC - I think that it's something to do with it converting a stereo signal to 5.1. It doesn't worry me as it's fine with DVD's.

 

[SimonJB]

Thanks everyone - its good (I think!) to know that I'm not the only one with the problem. Oh yes, mine makes the same noise with Neo 6 Cinema too.
I'll try PLII Music but if that doesn't do the trick I'll stick with 5-channel stereo.
Cheers.

 

[SimonJB]

Just thought I'd mention that my funny noise is still there with PLII Music as well.

 

[adc2000974]

little late but, try panorama which fiddles out high freq and quick not
pl2: cinema is only good with classical or very high quility sources i.e. most cd players

 

[SimonJB]

Sorry adc but I'm not with that at all! Please clarify.
What is panorama?
What does "fiddles out high freq and quick not" mean?
I was actually worrying about the "chirrupping" noise that accompanies peoples voices when I view TV progs thru Sky - I get the same noise on PLII Cinema and PLII Music and Neo6.
Listening to CD's is not a problem - why would I listen to CD's thru PLII cinema? - surely normal stereo or 5 channel stereo is much better.

 

[SimonO]

I first noticed this on the old Scoody Doo cartoons on Boomerang and put it down to PLII not liking a mono single, but I now notice it on other programs too, but it does seem to be worst on Boomerang... Could it be related to bitrates..?

 

[gIzzE]

I think it is the receiver not doing its job properly to be honest.
I had it with a 3802 and with my A1-se, changed to a Lexicon and then to a meridian and with them each channel is silent when there is not meant to be info there, even at -0db.

In the same way I could hear very very faint voices in the main speakers bleeding from the centre channel when you remove the centre speaker on both the Denons, not a thing on the lexicon or the meridian.

To be fair though when the levels are set correctly you shouldn't be able to hear this high pitched warble from your seating position.