By JULIAN D. HIRSCH
B y J U L I A N D. H I R S C H
J A M E S B . LANSING
SA-600
STEREO AMPLIFIER
•
A L T H O U G H it is now the rule rather than the excep-
tortion was under 0.15 per cent over the entire audiofrequency band. All distortion measurements, in accord
with the IHI standards, were made with 8-ohm loads,
both channels driven, and with a 120-volt line. At 1 6
ohms, power output is reduced to 32 watts per channel.
At 4 ohms, the SA-600 can put out 65 watts per channel
7
tion for modern transistor high-fidelity amplifiers to be
60TM
of good quality, we occasionally find one that is outstand-
T h e J B L SA-600 is a large, powerful, and attractive
unit, rated (with great conservatism) at 4 0 watts per
channel. Like a few other amplifiers, the SA-600 is claimed
QHIVEN
WITH 8 - O H M
LOADS.ONE CHANNEL
MEASURED
DISTORTION
of these to come to our attention, and it truly sets a new
standard o f performance for integrated amplifiers.
PERCENT
ing. T h e James B . Lansing SA-600 is the most recent
CHANNELS
1HH2 TOTAL HARM. DIST.
6 0 / 7 0 0 0 Mi
IMDIST.
JBL
SA-600
(o have immeasurably low distortion within its rated power.
Unlike most ol them, however, it lives up to this claim.
CONTINUOUS ANg EQUIVALENT SlNE-WAVE POWER OUTPUT PER CHANNEL IN WATTS
At or below its rated output, we were unable to measure
its harmonic distortion, which means that whatever dis-
for brief periods o f time. Prolonged operation with more
tortion was present was below our test-equipment residual
than 4 0 watts output per channel will cut in the automatic
o f about 0.1 per cent. T h e SA-600's frequency response
protective devices.
was flat within ± 0 . 2 5 db from 2 0 to 2 0 , 0 0 0 Hz. T h e
The S A - 6 0 0 had the lowest noise level we have ever
RIAA phono equalization was accurate within 1 db from
measured on an integrated amplifier. In spite of the
30 to 2 0 , 0 0 0 Hz, and N A B tape equalization was within
very high gain of its phono inputs (there are three switch-
1 db from 75 to 2 0 , 0 0 0 Hz, falling off to - 2 db at 5 0 H z .
selected sensitivities available; on the most sensitive posi-
T h e distortion characteristics o f the J B L SA-600 prove
tion only 0.2 millivolt o f signal was needed f o r 1 0 watts
that it is not necessary for a transistor amplifier to have
of output), the hum and noise were 6 6 to 7 5 db below
increasing distortion at low power levels. From 0.1 watt
1 0 watts. On the high-level inputs, hum and noise were
to over 4 0 watts, the harmonic distortion was somewhere
1 0 0 db below 1 0 watts. This is the only amplifier we have
under 0.1 per cent, and even at 5 0 watts it was only 0.25
ever used that could be operated at maximum gain on
per cent. Intermodulation distortion was under 0.15 per
the magnetic-phono input without a trace of audible hum
cent up to 30 watts, increasing to only 0.25 per cent at
or hiss.
about 50 watts.
Since the distortion at the manufacturer's rated power
Space does not permit a complete exposition o f the features and performance o f the J B L S A - 6 0 0 . Let us sim-
o f 4 0 waits per channel was too low f o r us to measure
ply say that it was superb in every detail. W c were espe-
reliably, we made measurements o f harmonic distortion
cially impressed by its tasteful design, simplicity, and free-
from 2 0 to 2 0 , 0 0 0 Hz at a 50-watt level. It was 0 . 2 5 per
dom from gadgetry. T h e input selector has only four posi-
cent from 50 to 1 0,000 Hz, increasing to about 0 . 4 per
tions: T A P E H E A D , P H O N O , T U N E R , and A U X . A switch
cent at 2 0 and 2 0 , 0 0 0 Hz. At half power or less, the dis-
underneath the amplifier converts the tape-head input for
P E R C E N T HARMONIC DISTORrtON
BOTH CHANNELS ORIVEN WITH 8 - O H M LOADS. ONE CHANNEL MEASURED
R E f - P O W E R OUTPUT (50*1
HALF-POWER OUTPUT (-3db)
LOW-POWER OUTPUT (-lOflbl
J8L
SA-600
FREQUENCY IN CYCLES PER SECOND ( H i l
of any electrical unbalance in the system, but cannot, o f
course, compensate for any differences in efficiency between two speakers.
From the standpoint o f operation, the J B L S A - 6 0 0 is
one of the simplest amplifiers imaginable. All controls
function with a silky smooth, yet positive action. T h e
lack o f the channel-reversing and other mode-switching
features found on some amplifiers is no drawback, since
there is really no need for them in a well-designed stereo
installation.
T h e circuits o f the S A - 6 0 0 are as sophisticated as its
operation is simple. In the preamplifier section, all equalization and tone-control action is accomplished by negativefeedback circuits for minimum distortion. T h e power-amplifier stages are direct-coupled throughout, with most
being o f the push-pull, complementary-symmetry type.
Overall negative feedback, extending down to 0 cycles per
second ( d . c ) , results in a rock-stable, low-distortion
amplifier. Balanced positive and negative power supplies
permit coupling direct to the speakers, thus preserving
the damping characteristics o f the amplifier from d.c. to
the highest audio frequencies.
The SA-600 is designed to be stable with any kind of
speaker load and to be immune to damage from any type
of improper load from open circuit to short circuit. Improper operation may blow a fuse, but the amplifier's
components will be undamaged. James B . Lansing backs
this up with a two-year guarantee covering both parts and
labor.
Using the J B L SA-600 is the quickest way to become
convinced of its merit. It is absolutely noise-free, has no
switching transients or crosstalk, and delivers more power
than most users will ever require. It would be difficult to
imagine a more satisfying amplifier for the most discriminating listener. I t is worth every cent of its $ 3 4 5 price.
As seen in the
NOVEMBER, 1966 ISSUE of
HiFi/Stereo Review
Copyrigfit 33 19S6 by Ziff-Davis Publishing Company. A l l rights reserved.
use with a second magnetic-phono source. The other knobs
are for setting volume, balance, bass, and treble. Toggle
switches control loudness compensation, tape monitor,
stereo/mono selection, and power. There is also a frontpanel stereo headphone jack that mutes the speakers when
phones are plugged in.
A special TEST switch provides a sensitive method o f
aurally balancing all inputs for equal channel gain. It
connects the two speakers in series across the outputs so
that they receive only the difference signal. With a mono
program input, a definite sonic null is heard when the
amplifier channels are balanced. This technique lakes care
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