Surround Speaker System

Sound Track #4

With #1 signal, 1000 cycles, adjust the Perspecta Sound Integrator unit pre-amplifier gain control for a -3 dbm output at the integrator pre-amplifier test terminals. (Use bridging V. I. - 600 ohm calibration).

With #2 signal, 30 and 800 cycles, adjust the integrator 30 cycle gain control (R 11) for a 50 microampere indication on the integrator left hand meter. The 800 cycle signal should be heard on the left surround speakers and the level may be measured at the left power amplifier output. (Bridging V. I. - 12 ohm calibration). The level may be adjusted with the 3 gang fader and the power amplifier gain control for normal theatre operating level as the signal is 6 dB below 100% modulation. This will be the reference signal level for preliminary adjustments of the surround speaker system.

With #3 signal, 35 and 1000 cycles, adjust the integrator 35 cycle gain control (R 15) for a 50 microampere indication on the integrator center meter. The 1000 cycle signal should be heard in the center surround speakers and measured at the output of the center horn power amplifier. As a preliminary adjustment duplicate the left amplifier reference level by adjusting the center power amplifier gain control.

With #4 signal, 40 and 1200 cycles, adjust the integrator 40 cycle gain control (R 19) for a 50 microampere indication on the integrator right meter. The 1200 cycle signal should be heard in the right surround speakers and may be adjusted to the left amplifier reference level with the right amplifier gain control.

NOTE: Proper signal levels for the surround speakers must be determined by reproducing a special test reel through the integrator circuit (after the preceding frequency test reel alignment), and re-adjusting the surround speaker levels for best reproduction. A remeasurement of levels with the frequency test reel will then establish the levels to be maintained.