1. Join Now

    AVForums.com uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Finding extra channels Todd-AO and SDDS 8

Discussion in 'AV Pre-Amp/Processors & Power Amps' started by JBL 4645, Apr 23, 2005.

Thread Status:
Not open for further replies.
  1. JBL 4645

    JBL 4645
    Banned

    Joined:
    Apr 20, 2005
    Messages:
    127
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    16
    Ratings:
    +0
    Finding extra channels within left centre right and center…it’s all in the mix? Some cinemas have SDDS 8 channel which has 5 screen channel speakers placed behind the screen for a whole wider sound stage while this is not new…when back in the 1960’s when Todd-AO developed the 70mm six-tack magnetic format to but more bums on seats!

    This used process used five tracks for screen channel placement, films like the sound of Music Oklahoma The king and I…and hearing the performers voices moving from centre as positioned on the screen and the next performer stand about half way to the right and hearing there voice in that position of space…and so while the age of the digital domain made it possible for resurrecting the old five-screen channel and with stereo surrounds and LFE sub bass this is just two channels more over the Todd-AO format of that day…

    So mixed within the front you can find extra information that is retrievable by simple re-plugging of the left centre and right and using a two Dolby pro-logic processor…

    Left and left center decoder.
    First unplug the pre-outputs left centre and right take an rca phone lead from left pre-output plug it into Dolby pro-logic Left-total input this will be for Left front speaker… then take a Y lead and plug that into the centre pre-output of the AVR connect two rca phone leads to the female output and take one of the leads plug it into the Right-total input this will be for the Left centre speaker…

    Right and right centre decoder.
    Now the second Dolby pro-logic decoder plug the rca phone lead from pre-output right channel into the Right-total input this will be for the Right front speaker and the center rca phone lead plug it into the Left-total input this will be for the Left centre…

    Now send these five channels to the three stereo amplifiers set the volume to maximum or less…keep the volume level on all amps at the same settings…

    Once all in place the matching volume levels for the five-screen channel array…start calibration and alignment by playing pink noise from a DVD set-up disc with wideband pink noise or the dts demo disc which as wideband pink noise on the testing tracks…

    Set all speakers to 75dBc slow weighting for the left centre and right centre channels adjust the main volume just a little bit and the centre volume control on the Dolby pro-logic decoders…

    Matching speakers must is used for this to work properly as for the voicing of the speakers is paramount…

    Now it’s all up and running look for extra-hidden channels on films like U-571 The perfect storm Indiana Jones and the temple of doom and the Last crusade…plus a whole lot more enjoy... :thumbsup: :thumbsup: :smashin:

    Ashley…
     
  2. alexs2

    alexs2
    Well-known Member

    Joined:
    Nov 13, 2002
    Messages:
    13,896
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Ratings:
    +1,674
    JBL....having offered your advice in the Subs area,I feel I have to say something regarding this "advice" also.

    Apart from the extra,and in many cases unwanted extra expense and setting up generated by your suggestions,all that you are in fact doing here is using a Prologic decoder to generate a synthesised set of signals,as it will do under its usual circumstances of use with a stereo signal from e.g. a TV.

    I'm not sure where you get the impression that there are extra channels buried in the 5.1 channel digital feeds,that only a Dolby Prologic system can reveal....as explained in the technical summaries in the Dolby Labs website,the decoder at it's simplest delivers a surround signal from the difference between the input signals,with additional delay processing and vectoring added after.

    Obviously others here can decide for themselves,but I'm not sure that many of us require or would want to add 2 more speakers to our front speaker arrays,with all the attendant amps,wiring and ancillaries.,for the benefit of a more diffuse front sound field,in a home environment.

    In the case of a moderate to large cinema,having extra speakers to fill in gaps at the front may be of some use,but even in some of the largest home settings,this sort of thing seems to be unneccessary to most of us.
     
  3. JBL 4645

    JBL 4645
    Banned

    Joined:
    Apr 20, 2005
    Messages:
    127
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    16
    Ratings:
    +0
    Your home cinema must really rock then?

    But I’ll see if some like to take this approach for there home cinema…it’s clear to me that you are cynical…me too I can be really negative but seeing that Sony said they will never realise the SDDS 8 channel format into the consumer market…pity though I would welcome it’s arrival with a positive frame of mind…

    So this does work using to Dolby pro-logic decoders…just depends on how you what to show off your home cinema…like the chief projectionist said to me many years ago…in this filed you have to think like a projectionist…

    So that’s what I want to but on the page see how it goes…also why on earth do most people spend a whole lot on new AVR every two years…I know why and for simple reason I don’t what to talk about that most of what I’m running is years old…it’s not like SQ the old Quid sound system with it’s early demise…if I can find ways around getting the sound to be positioned differently then I’m not scared to experiment…

    It’s a question of science?

    Any lets not fight lets work together we all have the same interest Hi-Fi or home cinema…and for me and we I like to go many steps further and begin we are all individuals… some are new to the home cinema arena some would like to know what more can you get out of it…

    You have to remember why back in 1992 when Dolby digital first come out a lot of us wanted it and just then was not doable for at lest two more years with it’s arrival on NTSC laserdisc clear and present danger then around 1993 when dts came out we wanted it not tell around mid 1990’s SDDS came out the same year as dts 1993 so I might not be proud to say using Dolby pro-logic to give a five-screen channel effect, but if I see something that’s an ancient technique then why not use it if it works…

    "ANY SUFFICIENTLY ADVANCED TECHNOLOGY IS INDISTINGUISHABLE FROM MAGIC"
    ARTHUR C CLARK
    Ashley… :thumbsup:
     
  4. alexs2

    alexs2
    Well-known Member

    Joined:
    Nov 13, 2002
    Messages:
    13,896
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Ratings:
    +1,674
    I see that you've now revised this to a 5 screen channel "effect",rather than finding extra channels within the 5.1 channel mix.

    I am neither cynical nor negative,but have a reasonably healthy disdain for techniques which at best add little if anything to the sound within an average UK living room....your advice,as i said earlier,may work in a moderate sized or lager cinema,but I think that my comments regarding the technical specs laid down by Dolby make it clear that this is simply a technique for synthesizing a difference signal,not too far removed from another ancient technique(Hafler Surround)which you are no doubt conversant with as well.
     
  5. JBL 4645

    JBL 4645
    Banned

    Joined:
    Apr 20, 2005
    Messages:
    127
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    16
    Ratings:
    +0
    Sorry alexs 2

    Sorry mate for implying that word…it seems there is a lot of clashes going and in the cinema filed there is a lot of politics with which is the best cinema sound system Dolby SR-D dts or SDDS 6 or 8 channel it’s all possible to do this in a room even the size of my home cinema which is 14 feet length 10 feet wide and 9 feet in height and very doable as I have tried this and it fits…and there is one word that I do not want to hear…that’s word impossible…

    I’ve got a very good background I look at the problem with the tools on hand and I’ll go over it time and time again to find the position and the sound balance with audio limiters active electronic crossovers and EQing as well…

    I don’t give in to it…sound is my pet love and there are always ways

    Also I’ve got a newer idea written down and I call it crossover side surround…no it does not involve an active crossover…till I get enough items to make it work it’s just waiting for no…

    I’m convinced that the idea is sound!

    And it involves really listening hard to Saving Private Ryan in Dolby digital or dts and has the ability to turn off any channel like mine and monitor the film mixes soundtrack…I cant give to much about this project that I’m working and though I have listened to another film that had a similar sound to it Goldeneye dts THX laserdisc the sounds are still going though my head as I’m writing this out…and the medium is if you don’t have the tools then your not going to get the message across… :)

    You have to understand it took an army to do the sound for Fantasia back in 1940… :)

    And I said it before and I’ll say it again…if I see an ancient technique that works then why not use it… :thumbsup:

    Ashley…
     
  6. alexs2

    alexs2
    Well-known Member

    Joined:
    Nov 13, 2002
    Messages:
    13,896
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Ratings:
    +1,674
    I think that this one has just about run it's course.

    I'm sure no-one would say that what you've suggested is impossible,especially since you've done it with your own gear,but quite likely would say it's not required.

    Anyway,since this now veers into ideas about which you can't say too much,we'll consider the thread closed.
     
Thread Status:
Not open for further replies.

Share This Page

Loading...