Dolby Laboratories CP65 - Manual (Page 11)

2-5
STEP 9 Next, check the jumpers in the following locations:
Cat. No. 441 Surround Equalization, Subwoofer and SR•D Interface Card (if fitted).
J3
J2
High
Cat. No. 441
J1
Low
Subwoofer
Level Range
High
Low
Output Level
Range
J4
Optical Subwoofer
Crossover Frequency
Surround
Stereo Mono
100 Hz 50 Hz
auto
subwoofer
off
The Cat. No. 441 has four jumpers that are used to configure the card to suit the installation in
which it is used.
J1 Right Surround output level sets the output gain range for the right surround channel.
J1 is set at the factory for a power amplifier input sensitivity of between 90 mV and 1.23
V. If the power amplifiers used in the installation are very sensitive (10 mV to 100 mV
input sensitivity), it may be necessary to move this jumper to the low output position.
J2 Subwoofer output level control sets the output gain range for the subwoofer channels.
J2 is set at the factory for a power amplifier input sensitivity of between 90 mV and 1.23
V. If the power amplifiers used in the installation are very sensitive (10 mV to 100 mV
input sensitivity), it may be necessary to move this jumper to the low output position.
J3 Surround Mono / Stereo selects stereo or mono surround operation. Set J3 to the
Stereo position if your cinema is equipped with separate power amplifiers and speaker
wiring for left and right surrounds. Note that stereo surround signals are only available
in format 10 Dolby Stereo digital. Install this jumper in the stereo or mono position
according to your installation.
J4 Subwoofer upper frequency limit sets upper frequency limit of the subwoofer channel
in optical or non-sync to either 50 or 100 Hz. The recommended setting of this jumper
depends on the type of screen speakers in your cinema.
If you have the older horn-loaded type of speaker (such as Altec A-4), the jumper should
be set for 100 Hz and the equalization for the screen speakers rolled off below this
frequency. These settings will remove frequencies from the screen speakers that they
cannot gracefully reproduce at full power and send them to the subwoofer which is
better able to handle them.
If you have the newer direct radiator type of screen speakers, set J4 to the 50 Hz position
and adjust the equalization of the screen speakers to roll off below that frequency.