Film-Tech Forum ARCHIVE: External 6 channel usage in a cinema

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Posted by Monte L Fullmer (Member # 2797) on 01-05-2010, 01:52 AM:

Okey, coming back for another question that was presented to me and need help again with this one:

I did a service call to a local twin cinema. The owner asked if there was a possibity to utilize his six channel system to receive the same amount of channels from DVD playback.

Here is his setup:

Simplex X-90 setup

CP55 - not upgraded for 6 channel. still has the 241 cards..
SONY SDDS - (prob was stuck with this system for 6 channel since he was told by the installer that this was the only ext digital source to work with his CP55, 4 ch setup)

ASHLY 2000 amps.

Powered BGW subwoofer.

He has a receiver that will do 6 channel output, thus wonder on how if he can connect this up directly to the amps so he can have his 6 channel sound playback with his DVD presentations..

..any possibilites on this and what kind of steps would be taked to make this work?

thx-Monte

Posted by Richard May (Member # 2627) on 01-05-2010, 06:30 AM:

I guess a quick way is to go right into the inputs of the Sony. You would have to adjust the volume with the amps or the reciever's controls. Also, you would have to use the reciever's controls for the sub if the sub has no volume control. I've done it this way before.

Posted by Scott Norwood (Member # 30) on 01-05-2010, 07:02 AM:

If he is doing this regularly, he could install a patch panel between the CP55 and the SDDS unit, normalled for the CP55 output. That would make it fairly easy to patch in the DVD sound, assuming that there is a gain control somewhere in there.

Posted by Richard May (Member # 2627) on 01-05-2010, 07:09 AM:

That would be a good permanent way to do it.

Posted by Mark Gulbrandsen (Member # 72) on 01-05-2010, 08:26 AM:

Or just get an Oppo Blue Ray player that has the 6 channels as line outs on it!

Posted by Frank Angel (Member # 248) on 01-05-2010, 11:37 AM:

For awhile we were using a simple computer printer switch like this: a manual printer switch for cheap. add breakout cables and insert it AFTER the processor and before the amps -- (A) position would be the output from the processor -- (B) position selects the DVD player. This assumes the DVD player has regular six analog outs AND an internal volume control. BUT this method will play havoc with your gain structure since the DVD player will only be consumer level -10dbv output and the processor will be +4dbv. The only way to avoid this discrepancy will be to either pad down the processor output (doesn't the CP55 have a 2 position gain switch on the backplane that selects output levels -- not sure if this will compensate enough). This is not recommended as it slices your headroom although it will work if your amps have enough gain to still reach Dolby without clipping).

OR, you can put THIS box in between the DVD player and the switch; Level matching line amp this will bring the DVD output up to equal level of the processor at about $50 (each -- you will need three which makes it no longer a dirt cheap way to do it.

This does rely on the internal volume control on the DVD player to set levels -- you can no longer manually use the CP55's fader. So you have to manually set the level by listening in the theatre and when it's right, leave it there. Since I was the only one operating this setup, there was no problem; I am not sure I would want to hand that over to commercial theatre where The Unknowns will be operating the booth. I guess for the occasional DVD video projection, the levels could be set by ear each time and it wouldn't a big deal to do it. Someone would have to do an audio test before the engagement, set the volume and then hide the remote -- our player didn't have the redundant volume controls on the face of the unit. [thumbsup]