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Author Topic: L/R & Centre sound mix Matthew Taylor Expert Film Handler Posts: 186 From: Essex, UK Registered: Mar 2004 posted 10-30-2005 02:57 PM                     I've been setting up my CP-50 and have noticed that there's almost no dialogue crosstalk in the surround channel but considerably more in the L/R channel, although the bias is toward the centre. Do sound mixes generally put a reasonable amount of dialogue in the L/R as well as the centre or should I be getting minimal dialogue in the L/R speakers?  |  IP: Logged Rick Long Jr Expert Film Handler Posts: 211 From: Toronto, Canada Registered: Jul 2000 posted 10-30-2005 03:36 PM                     What model cat 150 do you have? Dolby level been set?  |  IP: Logged Matthew Taylor Expert Film Handler Posts: 186 From: Essex, UK Registered: Mar 2004 posted 10-30-2005 05:12 PM                     I have the cat 150b. The dolby level has been set - as I say, the surrounds are working very well with no crosstalk now.  |  IP: Logged Stephen Furley Film God Posts: 3059 From: Coulsdon, Croydon, England Registered: May 2002 posted 10-30-2005 05:32 PM                     I have no way of knowing how the film you are listening to was mixed, but the matrix encoding/decoding process only gives a partial separation between the centre channel and the left/right channels. If set up correctly, it should give almost total separation between the centre and surround channels. The dialogue you are hearing in the L amd R channels may be there because: a) the track was mixed that way. b) the decoder is faulty. c) you are just hearing the normal crosstalk between the C and the L/R channels which is inherrent in this system. Or some combination of the above.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 10-30-2005 06:25 PM                     If memory serves the 150b was about 25-30db seperation between channels  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 10-30-2005 09:00 PM                        Gordon is correct. The later 150 cards had much improved steering. "Discrete" center only is on the later cards: d,e,f or maybe just e & f; the 150b was actually not very good in this regard. Remember the center channel actually doesn't exist in analogue; it is the sum of what is on left and right. The later cards supress the latent center on L/R. Louis  |  IP: Logged Marin Zorica Jedi Master Film Handler Posts: 671 From: Biograd na Moru, Croatia Registered: May 2003 posted 11-01-2005 12:07 AM                     Ok, if film have good sound mix, do we hear dialogue from left and right channels, or just from center? We are talking about CP-50.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 11-01-2005 06:14 AM                     A Cat 150 (any generation) should have enough steering that the Left and Right channels do not have any pronounced center channel information in them. While you might be able to hear it with a monitor just selected to Left and/or Right, when all three are playing, the Center should be so predominate that one shouldn't perceive the other two channels playing. There was one (silly, in my opinion) thing called "draped dialogue" where dialogue was indeed placed in all three channels with the center being predominate. I don't recall it being used with SVA prints since I don't think the decoder could pull it off...however it was done on 70mm mixes. Early Dolby Stereo decoders as used in the CP100 and early CP50s prior to the Cat 150 would indeed have all three channels playing at all times. These systems used a Cat. 110 for the CP50 (my memory escapes me on the CP100 but I think it was the Cat 82...I do recall you could use the cards interchangably though the CP100 card was metal clad). This card merely boosted the center channel for summed information and reduced the center channel for non-summed to form a primative steering that was not at all convincing. As an option, the Cat 116 could be added to the CP50 to decode the surrounds. The Cat 116 was also used in the SA1 through the SA3 for the CP100...though the suffix of the card changed with the card cages as the delay was moved onto the card itself. With the Cat150, all of this changed. There was true steering of the sound and the surround decoder was now attached to the card for a composite card that did it all. The Cat 146 portion of the Cat 150 performed the L, C, R decoding. The later cards, Cat150E and Cat150F are certainly better decoders and provide better steering to the sound.  |  IP: Logged Matthew Taylor Expert Film Handler Posts: 186 From: Essex, UK Registered: Mar 2004 posted 11-01-2005 05:58 PM                     So could it be a bad cat 150 that's causing noticable sound on the L/R then (as my surround doesn't have any bleed-through)?  |  IP: Logged Richard Hamilton Phenomenal Film Handler Posts: 1341 From: Evansville, Indiana Registered: Jan 2000 posted 11-01-2005 06:17 PM                     Matthew, Is the dialogue in the monitor, or is it very noticable in the theater. Are you being too picky and standing an inch from the Left and Right speaker, or can you actually tell from anywhere in the auditorium? Rick  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 11-02-2005 01:13 AM                     steve said "There was one (silly, in my opinion) thing called "draped dialogue" where dialogue was indeed placed in all three channels with the center being predominate. I don't recall it being used with SVA prints since I don't think the decoder could pull it off...however it was done on 70mm mixes." actually what they did was encode the dialogue with a 45 phase shift and the older decoders would smear it between the 3 stage channels you are coorect the cp 100 was the pentoptical module cat 82 which was the same as a 110  |  IP: Logged Matthew Taylor Expert Film Handler Posts: 186 From: Essex, UK Registered: Mar 2004 posted 11-02-2005 02:14 PM                     Hi Richard, It is hard not to be picky because it's in my small home theater. Although the focus is on the centre speaker, it's really noticable on the L/R - you don't have to be close to notice it.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 11-02-2005 03:26 PM                        See if you can borrow a later model 150 card; pref an e or f or later model. As I said before, the B was not very good. Louis  |  IP: Logged

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