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Topic: SA10 setup levels

Nic Margherio
Film Handler

Posts: 91
From: St. Louis MO, USA
Registered: Dec 1999

posted 09-19-2004 12:46 AM

I have a sound system consisting of a Dolby SA10, Sony DFP-2000, and a DTS 6D feeding a Dolby CP65. I am having difficulty matching the input levels to the SA10 between the DFP-2000 and the 6D/CP65. Obviously, these levels should be exactly the same when the respective processors' faders are at referece level so that the surround levels match between digital formats. (This has only really become a problem this weekend with the opening of Sky Captain, the only ES/EX feature ever that does not have an SDDS soundtrack as far as I can recall.)

The problem is that the Sony 1kHz (-20db) tone in the setup software and the DTS 1kHz tone from the setup disc do not appear to be recorded at the same level (as much as a 6dB differece in the pink noise SPL levels with identical 1kHz mV levels), thus making it impossible to accurately match the mV levels between formats. The best solution I have come up with so far is to match the DTS levels with an SPL meter to the already-established SDDS pink noise levels, yeilding the same SPL per channel. From this point I balanced the DTS levels using the 1kHz tone to withen 10mV of each other.

Two things I am not sure of:

1) The DFP-2000 has balanced outputs while the CP65 has unbalanced. The SA10 inputs are wired with the cold phases and the sheilds connected to audio common input and the SA10 chassis. The sheilds are not connected to the DFP-2000. As whith any other DFP-2000 setup (except Brad's maybe), the analog processor's outputs are routed through the Sony unit. Could this wiring scheme account for a level differece?

2) The cat. 441 card in the CP65 requires a higher B-chain level per channel (85dB) than other Dolby cinema processors (82dB). Could this also be causing a differce in the output (SA10 input) levels?

A tricky situation to be sure...maybe I'll ask Santa for a shiny new CP650, it sure would simplify things.

P.S. I am sure that there is no problem with the APR-6 board in the Sony unit. That was the first thing I checked when I started matching the levels.

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Michael Schaffer
"Where is the
Boardwalk Hotel?"

Posts: 4143
From: Boston, MA
Registered: Apr 2002

posted 09-19-2004 08:31 AM

Apparently you only have a level difference in the surrounds, did you also check that all channels levels are properly set in the SDDS setup? When you check the DTS levels in the same spot in the auditorium and adjust them accordingly, everything should be OK. Remember that the DTS channels go through the CP65 channel and EQ settings which all effect the output levels of the individual channels. If you set DTS levels correctly with the 1kHz tone and check the CP65 channel settings (do you have the Dolby pink noise generator?) you should find the problem spot, likely your 2).
If you don't have the generator card, I think setting all DTS channels using the 1kHz tone method at the DTS outputs and then adjusting the respective channel level settings in the CP65 (85 and 82dB pink noise in the room) using the SPL meter should also give you fairly accurate results which match the SDDS settings (provided those are OK).

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