JBL SG520 - Performance Specifications; Measurement Techniques

a
a
a
Ne
TE
ES
LE
Ee
TTI
CE
GET
the REMOTE RELAY switch. If the fuse should blow, the operation of any remote cuntrol devices
will be affected and hum may possibly be introduced into Channel A.
1.4.12 REMOTE RELAY SWITCH AND SWITCH LOCK.—Unless the JBL F22 remote relay accessory is
connected to the Graphic Controller, this switch should remain in the OFF position. Should it
accidentally be turned ON, the fuse described in the preceding paragraph will blow.
1.4.13 AC OUTLETS (SWITCHED).—The five AC outlets at the extreme right are for plugging in any de-
vice which must be turned on or off along with the Graphic Controller. These would include such
components as tuners, tape recorders, power amplifiers, etc. If the system uses the JBL Solid
State Energizer and does not have the F22 Remote Relay control, an extension cord can be run
from one of these switched outlets to the energizer so that-it will be switched off when the
system is not in use.
1.4.14 UNSWITCHED AC OUTLET.—The single outlet to the left of the power cord is live at all times.
1.4.15 110-120/220-240 VOLT ADJUSTMENT (EXPORT MODEL ONLY).—On the export model Graphic
Controller, there are two holes in the upper portion of the name plate on the rear panel. The
hole on the left is marked 220 VOLTS and the other 110 VOLTS. The Graphic Controller is
shipped with a slotted nylon screw in the 220 VOLT position. If the unit is to be operated from
a 110-120 volt line, change the screw to the opposite hole.
Note that the fuse on the concealed front panel should also be changed whenever the AC line
voltage is changed. For 110-120 volt operation a 0.3 amp Slo-Blo Fuse is required. For 220-240
volt operation the fuse should be changed to a 15/100 amp Slo-Blo unit.
Section 2
PERFORMANCE SPECIFICATIONS AND TESTING
2.1 SPECIFICATIONS
2.1.1 RATED OUTPUT.—3 volts.
2.1.2 HARMONIC DISTORTION AT RATED OUTPUT.—Less than 0.15%, from 20 to 20,000 CPS.
2.1.3 NOISE.—Less than any other preamplifier —- only 1 microvolt referred to low-level phono input.
From high-level inputs, 90 db below rated output.
2.1.4 GAIN.—Low-level inputs, 54 db; high-level inputs, 21 db.
2.1.5 FREQUENCY RESPONSE.—Typical response within +14 db, 20-20,000 CPS (with ail filters out
of the circuit).
2.1.6 POWER CONSUMPTION.—20 watts.
2.1.7 TONE CONTROLS — MIN.—+18 db at 20 CPS; +16 db at 20,000 CPS. See curves in figure
3-4.
2.1.8 TRANSISTORS AND DIODES.—The unit contains two signal diodes, eight rectifier diodes, a zener
diode, one power transistor and 22 low-level transistors.
2.2 MEASUREMENT TECHNIQUES
Most of the commonly available instruments used in testing audio amplifiers have higher dis-
tortion and/or noise than the SG520 generation by itself relative to the signal. In order of pref-
erence we recommend for the audio oscillator a Radford Low Distortion Oscillator or a Hewlett-
Packard Model H20-200CD. For making IM Distortion measurements we recommend the THD
measurements should be made with a Hewlett-Packard Model 333 or the Audio Instrument Com-
pany Model 168 Analyzer. Because the residual distortion, hum and noise of the SG520 is so
low, the measuring techniques recommended below should be used to be sure that you are
measuring the amplifier and not the test instruments.
2.2.1 TESTING HIGH LEVEL INPUTS
2.2.1.1 Total Harmonic Distortion
Step 1. Connect the oscillator to either the A or B TUNER 1 input jack witha standard shield-
ed cable.