Dolby Laboratories CP500 Specifications download pdf (Page 40)

5-3

B-Chain Alignment

Before you set out to equalize the room, make sure you do the following:

Be sure to use the same Bypass crossover frequency setting header as the screen

channels use.

Carefully install the correct headers in the appropriate socket locations, making

sure to set the header correctly.

Set all power amplifier gain pots to the maximum. Carefully ensure that only HF

outputs are routed to the HF horns to avoid damage from excessive low

frequency excursion of HF horn diaphragms.

Place microphones in the auditorium and connect the mikes and multiplexer (if

available) to the CP500.

Set the fader level display to read “

”.

Enter the CP500 B-chain EQ screen and select Left channel.

Gradually turn the fader by moving the pointer to the fader slider on the EQ

screen. Verify by ear or spectrum analyzer or both that the low frequency driver

and HF horn are each producing only their appropriate halves of the spectrum.

Turn the fader up until a satisfactory level is achieved in the auditorium.

Set all EQ controls to flat.

10.

Using the Left trimpot on the edge of the CN683, adjust the relative HF horn

output level so that the low frequency driver and HF horn output levels match in

the octaves just above and just below the crossover frequency. For example, if

the crossover frequency is set to 500 Hz, then the level from 250-500 Hz should

match that from 500-1,000 Hz.

11.

Adjust the Right and Center channels, then proceed to room equalization as

described in

Section 5.3

5.2.3 Surround Channel Bass Drivers (Optional)

Both the Cat. No. 682 Output card and the Cat. No. 683 card have reversible filter

headers labeled 50/100 Hz for the surround channels. Ensure that the headers on

both cards are set to the same frequency (usually to suit the low frequency handling

capability of the surround speakers in use). If you have separate surround bass

drivers, it is probably best to set both headers to 100 Hz in order to improve the

low frequency power handling ability of the surround channel.

Enter the B-chain EQ screen and select Left Surround. Set the EQ to flat. Adjust

the Ls trimpot on the Cat. No. 683 so that the level in the room is reasonably equal

in the 40-100 Hz and 100-200 Hz regions on average. Now adjust the EQ controls

as usual.

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Dolby Laboratories CP500 Specifications Page 40