1978 CONCEPT 16.5 MONSTER RECEIVER
Featuring 165 wRMS/ch "Twin Transformer" Amplifier
The 1978 Concept 16.5 Receiver, retailed for $950.00 and has the distinction of being the most powerful receiver ever fielded by a "house brand", in this case, "Pacific Stereo", a subsidiary of CBS. In fact, many vintage receiver collectors regard the 16.5 as one of the best ever made by anyone. The circuitry was allegedly designed by Dick Schram, who went on to greater glory with Parasound. Rumor has it that Dick still collects 16.5s. According to my Tech, Tom Ishimoto, former Manager of Product Development for Marantz, the Concept Receivers were built in Japan by NEC.
The 16.5 featured a "dual mono" design with huge twin power transformers. And, it has a damping factor of 450, much higher than any other contemporary receiver. This was a "spec" you can really feel. The bass output on the 16.5 is simply stunning.
I recently found a great new application for this old Monster. I plugged the output from my computer's Audigy LS audio card into the Tape 1 input on the 16.5 and now stream audio from the Internet into the 16.5 which powers it to some DCM Time Windows Speakers. The 16.5 gives the streamed music an AWESOME punch and clarity that it simply did not have being played over my "high-end computer speakers". If you're interested in this, try www.listen.com's Rhapsody service which has over 100,000 albums and 850,000 recordings.
I'm showing the Concept 16.5 with a trusty companion, an extremely rare Concept 2QD Quartz Direct Drive Turntable.
Double click the thumbnails for the "big picture":
Left Front
Right Front
Twin Transformers
Side View
TECHNICAL INFORMATION (INCLUDING SPEC SHEET):
The following technical information is quoted directly from the Concept 16.5 Owner's Manual:
FM SECTION:
"A dual-gate MOSFET and 5-gang tuning capacitor provides Concept with excellent sensitivity and immunity to overloading from very strong local signals. Concept also has an extremely steep quieting curve to achieve an outstanding signal-to-noise ratio on very weak signals.
The IF section utilizes three hand-picked, linear-phase ceramic filters to maximize selectivity while still keeping distortion extremely low.
Precise impedance matching of the limiter to the IF filters is also important in keeping distortion low. Concept accomplishes this by using three high-gain symmetrical limiters, which have over 90dB of gain. The detector package is also high-gain, with a wide-band, low distortion full quadrature detector. Overall gain for the IF system is better than 130dB, assuring you of noise-free, low-distortion reception even on the weakest signals.
A Phase-Locked Loop IC chip in the multiplex decoder keeps the tuner perfectly synchronized to the transmitter to achieve maximum stereo separation and the lowest possible distortion. Steep 19 and 38 kHz filters are built in; these eliminate spurious output signals without rolling off desired audio frequencies. This is especially important when making a Dolby-ized tape recording off the air, as such spurious signals can interfere with the Dolby process."
POWER AMPLIFIER SECTION:
"The Concept 16.5's power amplifier uses direct-coupled, fully complimentary driver and output stages, with four output transistors per channel to increase reliability. The transistors are mounted on extruded aluminum heatsinks for maximum heat dissipation, another measure promoting long transistor live. Two differential gain stages provide the lowest possible distortion at any power level.
A slew rate of approximately 38V/�S assures excellent square wave response, even at 10KHz. The slew rate exceeds the minimum required by over a 5 to 1 margin, indicating frequency response extended far beyond specification, and insures the clarity and transparency inherent only in a wide-bandwidth design, with no sacrifice in ruggedness.
An active protection circuit senses excessive current in the output stages and then disconnects the speakers until the fault has been removed. This circuit protects the output transistors, and also prevents DC from reaching the speakers and damaging them.
The Concept 16.5 is the only high powered receiver that features entirely independent dual power supplies. This ensures that each channel can deliver it full output power at all frequencies under all conceivable drive conditions. The benefits of independent power supplies extend beyond that: they insure musical clarity. In a conventional amplifier, heavy power demands in one channel induce cross-modulation into the other, and this crosstalk obscures fine inner musical detail. Independent dual power supplies insure that each channel will reproduce all the detail, with no crosstalk, no matter what the demands on the other channel. This enhances clarity and improves stereo imaging.
Each channel of the Concept 16.5 has its own oversized power transformer, heavy-duty bridge rectifier, and a pair of 10,000� high-voltage electrolytic capacitors. Low-level power supplies are obtained from separate transformer windings and are fully regulated for complete isolation from the power supply.
A separate relay is used to switch each pair of speakers, assuring that all the power is available to them."
CONCEPT 16.5 RECEIVER OWNER'S MANUAL:
For the technically oriented, below are thumbnails of the complete Owner's Manual and schematic diagrams for the Concept 16.5. Double click each image to view.
Written by Chris Opfell
