DTS center channel question

[Rudy]

I own only two DTS discs, and both of them have a weird "phasey" sound when I play them in my 4.0/4.1 system. (Can't use a center channel speaker because it's right in the middle of the fireplace we use almost daily.)

I'm using a Pioneer DV45A, and I do have it set up in the Audio Setup menu so there is no center channel. It works great for DVD-A and SACD, as they play back fine. But in DTS, the music that should come from the center sounds a bit quieter (the mix sounds like something is slightly missing), and there is a phasey sound from the fronts that makes me wonder if I'm missing something.

My electronics past the player are all analog, so I'm using whatever comes out of the back of the DV45A. (IOW, the gear downstream is incapable of decoding anything.)

Is DTS smart enough to play back through a 4.0/4.1 system? The two discs I have sound OK, but not as good as on my much cheaper 5.1 system in the den (which is a 578A and a recent garden-variety Pioneer surround receiver that also decodes DTS).

 

[phydo]

Rudy:

Since you said you disabled the center channel the only thing I can think to check is to ensure your speaker wires are properly connected and your speakers are in phase.

Justin

 

[Rudy]

Rudy:

Since you said you disabled the center channel the only thing I can think to check is to ensure your speaker wires are properly connected and your speakers are in phase.

Justin

Speakers are fine. It's sort of a phasey sound that comes only from these two DTS discs...

 

[spenceo]

Speakers are fine. It's sort of a phasey sound that comes only from these two DTS discs...

What two discs are they? Are they old quad 4.0 mixes converted to DTS, or a 5.1 mix? It's been a while since I had my system configured to 4.0 but if I have the same discs that you have, I would be happy to give them a spin. I don't recall any phasing sounds when I was set up for 4.0.

BTW, I'm using a Pio 578A and a LG DVB418, both with 6 analog outs.

Spence

 

[Rudy]

Spence: they are DTS-specific mixes. Herb Alpert, "Passion Dance" and David Benoit: "American Landscape".

I'm wondering if maybe the downmixing (IF it takes place) for DTS is less than optimal for sending the center channel out to the L/R front speakers.

 

[JonUrban]

Hmmm. Those were created especially for DTS CD, so you would think that the center channel would be legit - not fabricated.

"Quadtrade" would know if the centers are "real". Maybe he'll check in.

 

[Rudy]

Hmmm. Those were created especially for DTS CD, so you would think that the center channel would be legit - not fabricated.

"Quadtrade" would know if the centers are "real". Maybe he'll check in.

Jon--I'm wondering that if I choose to use only four of my five surround speakers, if the DV-45A sends the center channel of the DTS program out to the left and right speakers. It almost seems like it's not. Short of moving some cables around, I don't have a way to find out if the center channel output is muting when I set up the 45A to use only L/R front speakers (and no center).

Wish someone could hear this same effect. It's puzzling at best.

 

[Quadzilla]

Jon--I'm wondering that if I choose to use only four of my five surround speakers, if the DV-45A sends the center channel of the DTS program out to the left and right speakers. It almost seems like it's not. Short of moving some cables around, I don't have a way to find out if the center channel output is muting when I set up the 45A to use only L/R front speakers (and no center).

Wish someone could hear this same effect. It's puzzling at best.

That was going to be my suggestion. Just move one of the front output cables from the player to the center channel output. If anything is there, you will hear it from that front speaker. I don't have either of those discs, otherwise I would try it on my DV-45A for you. Good luck. Mike.

 

[Rudy]

Those are the only two DTS titles I own, but I have a feeling any other DTS might sound like this also. I may have to try your idea and see if I get any center info while playing DTS. OR at worst, the player could just be muting the center...

I'm wondering if the 578A is similar enough to the 45A, where I could disable the center channel in the player and then try playing these discs in my other system via the analog inputs. I could see if any center information comes through that way.

The "phasey" sound actually sounds similar to a tape head that is not quite aligned...like a cassette player. (Now I have memories of shoving a matchbook under the tape in my car cassette player to adjust the azimuth until I could pull it out for its bi-monthly head alignment... *sigh* )

 

[Dolby CP-200]

Rudy

Well if what he has described as a wired phasing sound that sound like the left and right fronts, where some films like Apollo 13 dts 5.1 Dolby 5.1, Cocoon Dolby 4.1, Close Encounters of the Third Kind dts and Dolby 5.1, Star Trek II the Wrath of Kahn Dolby 5.1, Alien Dolby 5.1, Ransom Dolby 5.1 Aliens Dolby 5.1.

That’s just a few that I can think of, this is either to do with the re-recoding mix on the dubbing stage and it would not appear to be a fault, as you can see there are many films above with various dates going back from 1995 to 1977.

Most of the time the dialogue can be heard on the left and right channels in monaural form, while it is still playing in the centre channel, with Apollo 13 most of the launch scenes have dialogue on the left and right, along with the sound effects and music, while the centre channel will be playing a small portion of the music mix at a lower level, sound effects and dialogue cut though with grace, although there are a few parts of the dialogue that are not mixed into the centre channel rather it is sent to the left and right.

Centre phantom, “Jim, you’ll all set” this plays over the left and right only, now I can easily send this signal to what I call an upper centre channel, where the use of a Dolby Pro-Logic matrix decoder is connected to the left and right pre-outputs where it is assigned to other amplifier EQ and loudspeaker and via using the Dolby Pro-Logic switch with no loss or degrading of the signal it just gives the film a wow!

This also helps to clear up the rest of the stray sounding dialogue that is on the left and right and reduces the amount of confusion and will send it to the upper centre, but you will hardly notice it, due to the strong level in the discrete centre channels output level and the balancing of the outputs with wideband pink noise testing.

 

[neil wilkes]

Centred dialogue with effects on it - reverb for making an artificial room, for example (As you would need to do if using ADR or dubbing to replace poor location sound & preventing too bad a mismatch in tone) will naturally have "ghosting" in the L & R channels, unless the reverb used was routed to centre channel only, and that would result in an un-natural sounding dialogue that would stand out like a sore thumb.
Cinematic mixing is so different from music mixing, and should not really be confused as the two are utterly incompatible.

Not sure about the routing through DPL II decoders - that is matrix technology, and the downside is a collapse of the soundfield into the centre only when 2 sounds pan in opposite directions or different directions. This collapse of the soundfield is what is possibly giving this effect described above, and if this is indeed the case it is an artifact.

Other problems with centre channel in 5.1 movies are caused by incorrect use of Dialnorm & Dynrng settings in the Dolby Digital Encoders, and in DTS from incorrect dialnorm. Remember dialnorm will attenuate L,R,Ls,Rs by the value set subtracted from a "norm" of -31dB which isequal to no attenuation at all. So a dialnorm of -27 is actually attenuating L,R,Ls,Rs by -4dB to compensate for the reduced levels in the centre channel, to make the dialogue more audible & clearer. With 5.1 music mixes, dialnorm should always be set to -31, or no attenuation.

 

[Dolby CP-200]

neil

I think the dialnorm is a waste of time, don’t get me wrong here mate, all I’m saying is, I have plenty of films that have this encoding on the films soundtrack. Starman 1984, WOW what a complex Dolby film mix it has complex.

There are some sounds in the film on the left and right that require good home cinema setting up to hear the complex sounds, and more importantly the centre channel as well! Street sounds on the highway with a truck placed in the centre channel and person speaking loudly on the right channel, totally isolated, “All right lets move it along now move it!” check out Starman the six-track Dolby Stereo mix is a classic on DVD!

But this film doesn’t have the phasing sound of, dialogue sloshing around in the left and right, and even if it is, the signal is monaural, while all the sound effects and music are in stereo! :banana: