Film-Tech Forum ARCHIVE: SR card on an Ultra Stereo JS-5/95

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Topic: SR card on an Ultra Stereo JS-5/95

Christopher Wehrman
Film Handler

Posts: 15
From: St. Louis, Missouri
Registered: Apr 2001

posted 06-05-2001 08:19 PM

Hi,

We have an Ultra Stereo JS-5/95 processor set up for front/back with sub. It currently has the Dolby A N.R. card in it. My question is: could the new SR noise reduction card work in the JS-5/95's NR slot?

Also, I noticed that when listening to the suround channel only, there seems to be a general leek of audo from the center cannel. Could this be a bad card or is it just the way the old JS-5/95 systems work when configured to work with out a matrix card? Would having a matrix card or upgrading to the SR noise reduction card help?

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Aaron Sisemore
Flaming Ribs beat Reeses Peanut Butter Cups any day!

Posts: 3061
From: Rockwall TX USA
Registered: Sep 1999

posted 06-05-2001 10:37 PM

Yes and no. Yes the SR card will function and fit in the slot for the Type A card, but since the SR card does not provide the meters for setting the Dolby tone, you have no way to make this adjustment. And since the circuitry differs, i cannot recommend setting Dolby Tone with the A-Type card (which has the meters) then replacing it with the SR and get satisfactory results.

And since there is only one NR slot provision on the 5/95, you obvously cannot use both NR cards.

As for the surround leakage, is it very loud, as to be easily heard during normal operation? if so, its likely that something in the A-chain is way out of alignment. Otherwise i am sure that there would be a very tiny amount of dialogue leakage (that cannot be plainly heard under normal listening conditions) because the matrix cards arent perfect...

Aaron

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Christopher Wehrman
Film Handler

Posts: 15
From: St. Louis, Missouri
Registered: Apr 2001

posted 06-05-2001 11:04 PM

Araon,

It sounds like using the SR card is out of the question. But what am I going to do when we have to upgrade the the red LED "JaxLite", I herd that using the SR card will help the distortion.

The leakage is not verry loud. From what I can tell from the block diagram, the processing for the surround is done in the NR card becouse the matrix card is not used when set up for front/back.
So what I was thinking, if I used the matrix card, I should get more precise processing.
Does this sound right to you?

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Darryl Spicer
Film God

Posts: 3250
From: Lexington, KY, USA
Registered: Dec 2000

posted 06-06-2001 12:46 AM

No do not use a matrix card in a front surround system. You would have to switch the switches on the back of the unit for it to work properly and you would loose certain information like dialouge that could be paned to the right or left. The front surround system works by summing all mono signales to the center and mixing the left and right signals in with the surround information. the slit lens may be out of adjustment needing to be checked with an RTA and a scope to be sure that you maintain the high frequencies. This will help prevent some crosstalk but with the way the unit processes front surround you can not eliminate it all like normal four channel systems.

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 06-06-2001 10:21 AM

Yes you can use the sr card in the regular A type slot. I have several theatre that do that regularly. Just remmeber to swap it as required.
The leakage is there because many Front/surround units use a simple matrix that sums Lt and Rt and feed the centre with it and takes the difference and sends it to the surrounds
Alignment of the cell and slit are very criticle to keep crosstalk to a minimum.
level matching between the left and right cell outputs and the azimuth is the most criticle

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