The Power Supply. The S7900A/ S8900A uses an extremely well regulated power
supply. The heart of it is a massive power transformer employing very high
purity iron core material and heavy gauge copper wire for increased operating
efficiency and improved voltage regulation. Two large 7000 mfd electrolytic
capacitors insure the maximum in clean, well-regulated, low frequency audio
output.
Epoxy Printed Circuit Boards. Superior to conventional phenolic boards, these boards have improved moisture-resistance, higher "0", less internal losses.
Poly-Carbonate Capacitors. Fourteen of these new devices are used throughout the circuit. A "pure" capacitor, the poly-carbonate capacitor is superior to conventional mylar or paper capacitors-has less internal losses [higher "Cr], much less capacity variation due to temperature fluctuations, capacity tolerance of 5% instead of the usual 10 to 20%.
Exclusive Impedance-Sensing Overload Protection Circuit. [Patent applied for] New "ISOP" circuit senses the exact impedance condition of speaker load as well voltage to it; offers double protection to output devices and speakers.
Construction and Layout. Construction of the S8900A and S7900A can best be described as rugged. The thick steel chassis is strengthened by two side brackets to prevent warping or bending in shipment. Layout of the chassis is designed so that both sides of each printed circuit board are accessible for servicing.
Sherwood-Produced FM Coils. We manufacture our own coils. These coils-heart of any tuner section are part of the secret of Sherwood's consistently superior FM performance.
Darlington Fully Complementary Monolithic Output Transistors. These components actually houses two devices-the driver transistor well as the output transistor assuring optimum match, a simplified circuit design and better reliability. It's expensive, but the result is better power bandwidth and improved high frequency performance.
The beauty is more than skin deep.
In this era of ingenious cosmetic design, it's easy to be fooled by a pretty face. And misleading specifications.
Which is why we've decided to turn ourselves inside-out to show you we're something more.
Take the Sherwood S-8900A (FM) and S-7900A (AM /FM) as a case in point.
The measurements compete favorably against the top selling brands in the $400 to $500 price range.
The power output (IHF) is 280 watts total. RMS (both channels driven): 60 watts X 2 @ 8 ohms.
20-20,000 Hz. @ 0.3 T H D The FM sensitivity (IHF) is 1.7 uv (-30 dB noise, and dist ) The capture ratio: 1.9 dB alternate-channel selectivity: 65 dB. And stereo separation is 40 dB @ 1 KHz.
But the specifications don't tell the whole story.
The key to Sherwood success is the quality of the components.
The simplicity of design. And the uncompromising demand for performance.
This is the real beauty of Sherwood receivers.
To quote a review in High Fidelity Magazine (July 1973, issue):
How does it perform? Excellently. Sensitivity figures are superb: and though raw sensitivity numbers have little meaning in themselves, they are matched by excellent quieting curves.
Distortion is very low as are noise factors. The consistent excellence of these figures is a joy to behold-and the sound is a joy to hear even with signals that would provide only border line reception with most good receivers.
The word for the S-8900A is silky. The feel of the controls and the performance-on FM in particular-all contribute to this impression But there is a subtler elegance to the design: that of achieving significant purpose by simple means.
'In these days of almost baroque elaboration. often to very little purpose this is a welcome approach indeed. Or to quote Stereo Review's evaluation (February. 1973): The performance of the Sherwood S-8900A left nothing to be desired. Both its FM and audio sections delivered what we would consider 'state of the art' performance for a receiver.
The 60-watt power rating of the S-8900A was quite conservative: in our tests, signal-waveform clipping occurred at 75 watts per channel, with both channels driven into 8-ohm loads."At 60 watts per channel, and at 30 and 6 watts as well, the distortion stayed within the 0.06 to 0.07 percent range over the full 20- to 20.000-Hz band." This kind of quality standard is what you should expect from any Sherwood receiver.
The S-7100A has become perhaps the most popular stereo receiver in the $200-$250 price range.
The S-7200 moved Audio Magazine to say: 'This is one powerful set.'
But perhaps most significant is the fact that a leading independent consumer testing magazine gave all three receivers (the 5-7100A. S-7200 and S-8900A) BEST BUY ratings in their price categories.
If you'd like complete copies of the independent reviews on these receivers, write Sherwood Electronic Laboratories 4300 North California Avenue, Chicago. Illinois 60618 Or check us out at your local high-fidelity dealer.
Sherwood -- The word is getting around.
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