Pioneer spec 4 owners manual

Page 2

r CONTENTS \

Features ............................ 2 Using the Input Level Controls ........... 7
Stereo System Set-up .................. 3 Additional SPEC-4 Applications .......... 8
Installation Precautions ................. 3 Installing in Rock ...................... 9
Connection Diagram ................... 4 Specifications ........................ 10
Connections ......... . ............... 5 Characteristic Charts . . . . . ............. 11
Front Panel Facilities .................. 6 Setting the Line Voltage Selector

Switch ............................ 12
Operating Procedure ...................

L J

FEATURES

Dynamic 150+150Watts Power Output, Generous
High-power Design

The SPEC-4 employs DC construction which excludes
capacitors from the NFB circuits and uses a dual transistor
differentia amplifier with a current mirror circwt in the lst
stage. This provides a stable operation and also high gain
over a wide frequency range. The pre-driver stage is a class
A amplifier circuit with a regulated current circuit for
the load. This makes for high-gain amplification with
superior linearity. Furthermore, there is an overdrive limiter
and power limiter circuit which is designed to protect the
power transistors and make for added reliability.

The power stage employs a 3-stage Darlington pure comple-
mentary parallel SEPP circuit. The SPEC-4 delivers

Cnntim farm" Output oi 150 watts'per
:hannu. no. at 8 ohms from 20 Hertz to
20. 000 Hertz with no more than 0.01 96 total
harmonic distortion.

Completely Independent and Perfectly Stable
Lefthight Power Supplies

The mighty power supplies are completely separated for the
left and right channels. Also, each channel is prowded with
two 22,000uF large-capacity electrolytic capacitors and
large transistors with a superior regulation. They achieve
outstanding channel separation and a clear. powerful
reproduced sound, in addition to the wide frequency
response. There is a built-in surge killer circuit to suppress

inrush currents from the power transformers and high
currents which charge the electrolytic capacitors. This

circuit ensures that none of the parts are affected by these
adverse currents.

Protective Circuits Composed of Fast-response
Relays and Electronic Circuits

Each channel is protected by a DC and overcurrent
detection relay circuit. in the event of the speaker terminal
shorting due to poor connections or when DC current
is generated in the output, the output circuit is
immediately disengaged and the speakers and transistors
are safeguarded against any possible damage. The protective
circuits also function as muting circuits when the power
switch is turned on and off.

Peak Level Meters with Outstanding Waveform
Response

This power amplifier incorporates togarithmic compression
peak meters with a wide scale (~40 7 +3dB). With B-ohrn
speakers. they allow the output to be read our from
0.01W to 300W. Moreover, the meters feature a fast
response for peak signal indication. In addition to the peak
output reading, it is easy to interpret the dynamic margin
with respect to the SPEC-4's clipping level.

Input Level Controls with d8 Calibration

The SPEC-4 is equipped with input level controls with
direct readout attenuation values (-dBl. These can be
used to continuously adjust the input levels for each
channel in accordance with the rated output voltage of the
preamplifier. In this way, the SPEC-4 can perform the
proper gain control according to the preamplificr's output
level. The preamplifier will thus be used in the condition
possible for the best S-N ratio and distortion
characteristics.

Stylishly Professional Front Panel Design

lust as you would expect from a sophisticated system. the
SPtC~4's front panel is professionally designed with the
large level meters in the center. Also, the front panel's
dimensions allow the model to be mounted in an EIA
standard rack, last like real professional~use amplifiers.

B Measured pursuant to Federal Trade Commission 's Trude Regulation rule on Power Output Claims for Amplifiers