JBL SG520 - Page 4

1.3.3
OUTPUT LEVEL TO AMPLIFIER.—Separate output. level controls allow adjustment of the strength
of the signal which is fed to a JBL Solid State Energizer or other stereo power amplifier. These
controls are set to accomplish two functions: first, to adjust the gain of each channel individ-
ually so that with the main BALANCE control in its ‘O’ position, the listener hears properly bal-
anced stereo on particular speakers. Secondly, the output level controls limit the loudness at
which you can run the system. To prevent accidental overdriving of the power amplifier or
loudspeakers, and to give the proper range of operation for the volume control, the output level
controls should be set so that normal program material is reproduced just a little louder than
one would ever want to hear it when the VOLUME control is set at ‘8’.
1.4 BACK PANEL CONNECTIONS
1.4.1
1.4.2
1.4.3
1.4.4
1.4.5
1.4.6
1.4.7
1.4.8
1.4.9
All jacks on the back panel receive standard phono pin-plug connectors. TO PREVENT POS-
SIBLE DAMAGE TO THE POWER AMPLIFIER (OR ENERGIZER) OR SPEAKERS, PLUG OR
UNPLUG CABLES ONLY WHEN SYSTEM IS TURNED OFF.
All connections in top row are Channel A. (Left-hand source of sound when fating loud-speak-
ers.) All connections in bottom row are Channel B. (Right-hand source of sound when facing
loud-speakers.) For connecting monophonic sources, use either one plug in Channel A (which
requires the use of the A+-B button) or use a ‘Y’ connector.
CHASSIS GROUND.—At the extreme left of the panel is a spring-loaded terminal provided for
connecting to any equipment which requires a separate ground wire. It also can be used for
connecting the entire system to a cold water pipe as a ground.
PHONO 1.—Input from any low-level pickup which requires standard RIAA equalization (any
high-quality cartridge having a minimum of one millivolt rated output).
PHONO 2.—Input from a second low-level pickup cartridge or from a tape head. The tape head
connection is required for a tape playback deck which has no electronics built in.
To change the equalization from Magnetic Phono pickup to Tape Head, remove the chassis
bottom plate and adjust the equalization switch to the desired. position. The switch is located
on a bracket immediately behind the front panel output level controls. The positions of the slide
switch are marked MAG PHONO and TAPE HEAD. Refer to Fig. 4-2.
MICROPHONE.—lInputs from any high-impedence microphone or pair of microphones can be con-
nected to these inputs. Generally speaking, no more than 25’ of shielded cable should be used.
If making a long run of wire to a microphone in a remote location, this should be a low-im-
pedance microphone and connected through a_ matching transformer to the Graphic Controller.
Separate microphone jacks for Channel A and Channel B are found on the back panel. The
Channel A microphone input also appears on the front of the Graphic Controller.
TAPE PLAY.—Inputs to these jacks may be from any tape machine which has its own electronics
built in. These jacks are the only input jacks which are not shorted when unused. ALL OTH-
ER INPUTS REMAIN SHORTED UNLESS THE APPROPRIATE SOURCE BUTTON IS DEPRESSED.
AUX REAR.—This is an all-purpose input which can be connected to any program source which
puts out 0.3 volts of signal or more.
TUN 1.—The most often used tuner should be connected to this input.
TUN 2.—Used for connection of a second tuner.
OUT TO RECORDER.—Outputs from these jacks connect to the ‘‘line’’ or high-level inputs on a
tape recorder. The jacks are duplicated on the front panel for connection to a portable machine.
Note that the Graphic Controller TONE BALANCE and VOLUME controls have no ‘effect on the
signals which appear at these jacks.
1.4.10 OUTPUT TO POWER AMPLIFIER.—Outputs from these jacks connect to the stereo power ampli-
fier or JBL Energizer. The SG520 can drive an impedance as low as 10,000 ohms. The Graphic’
Controller can drive more than one amplifier or JBL Energizer. Two sets of jacks are provided
for such-a purpose.
1.4.11 REMOTE RELAY ACCESSORY FUSE.—This fuse has no affect on the normal operation of the
$G520. It protects against an*accidental short circuit which could result from improper use of