Pioneer Spec 4 Brochure

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Stereo Power Amplifier in DC Configuration with Independent Left/Right
Dual Power Supplies & Circuitry

Think of the Pioneer SPEC-4 Power
Amplifier as two Independent mono
amps in one chassis. Our stay-
ahead reputation in hl-fi technology
is upped another big step here by
achieving real independence for the
essential circuits In both the left and
right channels. Physically separated
signal paths and dual power trans-
formers. four big capacitors (two

per channelho prevent power dry-up,
separate left-right relays-every-
thing to prevent crosstalk and distor-
tion that erode stereo clarity and
tonal quality. Because the SPEC-4
is of Pioneers new generation of
"DC" configuration power amps, its
performance is never compromised
by capacitors in the negative feed-
back Ioop. The results: a comm-

uous poweroutput at 150 watts*
per channel,min.RMS,at8ohms
from 20 to 20,000Hz with no
more than 0.01 % total harmonic
distortion. Check out the details
of the SPEC-4 in the following
pages, and see how Pioneer earns
its stay-ahead reputation in quality
high fidelity.

'Meaaured purulent lo the Federal Trade Commission's Trade Regulation Rule on Power Output Claims for Amplifiers.

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DVNAMIC POWER WITH ULTRA-LOW
DISTOHTION

Why go for a separate component for
power amplification? Pioneers SPEC-4
clears up that question, and your music,
with indisputable proof that separate
power amplification is really worth it. It
delivers a continuous power output
of 150 watts per channel, min. HMS,
at 8 ohms from 20 to 20,000Hz with
no more than 0.01% total harmonic
distortion. Massive power reserve is
available throughout the spectrum, in-
cluding the super-low and ultra-high
ends. Pulsive signals-Le. musical sig-
nalsiarereproducedwithtransparency
and clarity at all levels, at all times. This
high quality is achieved with Pioneers
stay-ahead technology, as explained
below.

STAY-AHEAD AUDIO CIRCUITRY

The Pioneer SPEC-4 uses the latest
circuitry for power amplification, as
follows: The input is formed by a dual-
PNP transistor differential ampilfier,
loaded by a current mirror circuit. This
is followed by a constant-current~loaded
predriver and a 3-stage Darlington con-
nected driver. The final output is in the
parallel SEPP (Single Ended Push Pull)
configuration. Here are the advantages,
one by one:

(1) Dual-PNP Differential - Zero DC volt»
age is constantly maintained at the input.
(2) Current-Mirror Loading-Reduces
the load to the differential input to achi-
eve a high gain which, in turn, permits
the application of sufficient negative
feedback for the effective reduction of
distortion. DC stability is also improved.
(3) 3-Stage Driver-Again loads are re-
duced so that the transistors in the cir-
cuit are called on to operate only at their
most linear operating curve. Distortion
is reduced and gain is high.

(4) Parallel SEPP-This output configu-
ration reduces by half the amount of
current flowing through the output
(power) transistors. again allowing the
utilization of only the most linear parts
of their operational curves, reducing
distortion without sacrificing output.

DUAL POWER SUPPLIES FOFI LEFT
AND RIGHT CHANNELS
Better 2-channel performance all

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around. That's the result of physically
separating the left»channel and right~
channel power supplies and Signal
paths. Paired power transformers are
employed. one for each channel. The
advantages show up in steady-state as
well as dynamic conditions. Weve even
separated the power relays for the two
channels. No matter how complex the
signal handled by one channe|,the other
is always ready to perform indepen-
dently for more musical clarity. Think of
the SPEC-4 as two independent mono
amplifiers housed in one stereo unit.
both as perfect as we can make them.

MASSIVE POWER RESERVE

Power dry-up? It takes an acute
ear to detect it from most amps
when they are playing ordinary music.
But it shows up easily during dynamic
stereo passages in rock, classics and
other music unless definite measures
are taken to prevent it. The Pioneer
SPEC-4 takes those measures. Because

Measured pursuant to the Federal Trade Commission's Trade Regulation Rule on Power Output Claims lor Amplifiers.