What is stereo?

There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.

H.H. Scott '59

JBL SA 600

 Solid State Amplifier / Preamplifier
Recognized by all leading test organizations and audio publictions as the finest complete amplifier available. Absolutely lowest noise. Intrinsic distortion lower than the residual distortion of the finest test instruments. This award-winning design features professional quality controls, and the JBL T-Circuit for a sonically transparent, conservatively rated 40 watts per channel. Built-in Aural Null system permits perfect stereo balancing. 

 The SA-600 Amplifier consist of three major functional sections.
These are: The two-channel preamplifier contained on a single, large circuit board, the two separate power amplifiers on identical circuit boards, and the power supply.
Each preamplifier has five inputs any one of four are selected by the Sellector Switch. The main output of each preamplifier is coupled to a power amplifier. An auxiliary preamplifier output is available at the :Out to Recorder Jack". A separate "Tape Play" input is provided, bypassing the slector switch and "Out to Recorder" jack.
The two power amplifier circuit boards ahare a cast heat sink with common power supply. The channel A power amplifier is on the top and the channel B is underneath.
The power supply uses silicon diodes and provides +23 volts DC regulated for the preamplifier and six balanced plus and minus supply levels to the power amplifiers. The power supply common return is chassis ground.
 Special Features:
Built-in JBL Aural Null stereo balancing system for simple, exact balancing of stereo installation.
Three-position phono switch for best possible signal-to-noise ratio.
Tape monitor switch for direct comparison of program source with recorded signal while recording.
Front panel stereo headphone jack.
(All specifications are measured with both channels operating simultaneously into 8 Ω loads. AC line voltage is held to 117 volts, 60 cycles. During normal use, the performance of the SA-600 is not appreciably affected by line voltage fluctuations between 110 and 127 volts.)

Power Output:
80 watts continuous RMS power;
40 watts per channel, at any frequency from 10 cps to 30,000 cps
Frequency Response:
From high level inputs : ±0,75 dB (20 - 20,000 cps);  ±1,5 dB (10 - 130,000 cps)
Power amplifier only (measured at test point provided) :  ±0,25 dB (20 - 20,000 cps);  ±1,5 dB (3 - 200,000 cps)
Harmonic Distortion:
From High level Inputs :  less than 0,2% (20 - 20,000 cps at 80 watts or any level less than 80 watts);  less than 0,1% (20 - 20,000 cps at one watt)
Power Amplifier Only :  less than 0,15% (20 - 20,000 cps at 80 watts or any level less than 80 watts)
Intermodulation Distortion:
From High level Inputs :  less than 0,2% (at 80 watts or any level less than 80 watts); 
less than 0,07% (at one watt)
Power Amplifier Only :  less than 0,15% (at 80 watts or any level less than 80 watts)
Sensitivity (Signal required for rated output):
Phono Input (at 1,000 cps reference) :  4, 8 or 16 mV into 47 k Ω, switch selected
Tape Head Input (at 500 cps reference) :  2 mV into 47 k Ω
High Level Input :  0,25 V into 30 k Ω
Maximum Phono Signal:  250 mV at 1,000 cps with less than 0,1% harmonic distortion. The highest output magnetic cartridges available will not overload the input stages of the SA-600
Hum and Noise:
Through both preamplifier and power amplifier : 
Low level inputs (1 k Ω termination) :  72 dB below rated output, equivalent to 1 mV at input terminals or 80 dB below 10 mV.
(These specifications are measured with the phono switch set a t Low, giving rated output with 4 mV signal. With switch set at Med. Or High noise is further reduced to 75 dB or 78 dB below rated output, respectively. )
High level inputs :  85 dB below rated output.
Transient Response:  rise time measured at high level inputs is 2,5 ms from 10% to 90% of square wave signal at 160 watts peak power or any lower power level.
Power amplifier only 2,0 ms at 160 watts peak power or any lower power level.
Response to such square wave signals is free from detectable overshoot or ringing, as observed on an oscilloscope.
Overload Recovery:   less than 1/10 of one cycle to recover from 100% single cycle overload at any frequency from 20 to 20,000 cps.
Output Impedance:  8 Ω rated impedance, 4 to 16 Ω nominal impedance.
(when driving a 16 Ω load, the SA-600 meets all published specifications except that power output is reduced to 64 watts. Wen driving a 4 Ω load the SA-600 produces 130 watts of undistorted power for brief periodes of time.  Prolonged operation at more than 40 watts per channel however will trigger the built-in automatic overload devices.
Stability:  The SA-600 is completely stable when connected to any loudspeaker system or even to a capactive load, AC line surges do not affect the stability of the circuit.
Short Circuit Protection:  Absolute, The SA-600 cannot be damaged by accidental or intentional short or open circuit at the output terminals, or by any degree of impedance mismatch.
Transistors:  36 silicon transistors plus 19 silicon diodes.

Dimensions (W x H x D):  16-3/16" x 5-1/16" x 13-3/4"

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