Conrad Johnson Premier 350SA Solid State Amplifier, 350 Watts!

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One of the most powerful amplifiers Conrad Johnson ever made, presented to you here in pristine condition with its original box and owner's manual.

Fully tested in our lab where it performed flawlessly.

In the listening room it was able to drive our most difficult speakers without breaking a sweat.

The matching CJ preamp is available by clicking here

Conrad Johnson Premier 350SA Stereo Amplifier - Manual

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Premier 350 Solid State Amplifier
— Introduced October 2003
The Premier series of conrad-johnson products are precision music reproduction instruments designed to meet the needs of audio industry professionals and other audiophiles who require near perfection from their reference systems. The Premier 350 is a high-power amplifier with plenty of muscle to control any loudspeaker system, yet capable of capturing the delicate textures and subtle nuances of live music performances.

Hybrid Solid-State Circuit
The Premier 350 benefits from an interesting hybrid of solid-state technologies. The distortion characteristics of an amplifier are dominated by it’s voltage gain stage. We have selected FETs for this application, because, like tubes, and unlike bi-polar transistors, they produce almost no strident odd-order harmonic distortion. The output stage of an amplifier must efficiently couple the high amplitude signal produced by the voltage gain stage to the loudspeaker system to assure the power and control needed to produce a musically accurate response. Bi-polar devices have been specified for the output stages of these amplifiers because they offer about 1/4th the output impedance of a MOSFET, resulting in much better control of the loudspeaker. This is most noticeable in faster, more solid bass response.

Zero Feedback
Negative feedback is an engineering technique used to reduce measured distortion. While feedback does achieve this goal, it also introduces aberrations in the tran-sient response characteristics of the circuit. The Premier 350 uses conrad-johnson’s unique auto-linear gain block for the voltage gain stage, which achieves low distortion with zero loop feedback by exploiting the symmetrical distortion properties of n and p channel FETs.

Solid Power Supplies
Power supply circuits present a parallel signal path to the audio circuits. Ideally this signal path provides ac signals with a zero impedance path to ground. Any deviation from this ideal is reflected in the reproduced audio signal. Thus the power supplies are as important to audio performance as the audio circuits and must be accorded equal attention in design. The Premier 350 features a discrete dc regulators to power the critical voltage gain stage.

Quality Parts
As with all Premier components, the Premier 350 is constructed from the highest quality, carefully selected parts for unrivaled sonic performance and reliability. The circuits employ polypropylene and polystyrene capacitors extensively, except in the main power supply storage, where special high-speed electrolytics are used because of the extremely high capacitance required. The audio circuit and related power supplies utilize precision low inductance laser-trimmed metal foil resistors. The obsession for parts quality extends to the high quality, gold plated input jacks and output connectors – even the internal wiring is chosen on the basis of its sound quality in its specific application.

Thoughtful engineering, specification of the finest available component parts, and painstaking care taken in production make this an audio amplifier without peer in music reproduction.

Specifications:
• Output Power:
350 watts per channel from 20 Hz to 20 KHz at no more than 1.0 % THD or IMD, both channels driven into 8 ohms.

• Frequency response:
(at 10 watts): 20 Hz to 20 kHz, +/- .1 dB

• Hum and noise:
104 dB below rated power

• Sensitivity:
1.1 volt rms to rated power

• Input Impedance:
100 KOhms

Mechanical:
• Dimensions:
19 W | 8 H | 16.375 D inches

• Weight:
84 lbs.

The SkyFi Testing Process for Solid State Amplifiers:
We start with a visual inspection of all internal components to make sure there are no signs of stress or aging. Capacitors are checked for telltale sings of bulging or leaking, resistors are checked for signs of overheating or cracking, and transistors are checked for signs of stress or damage.

We then power up the unit carefully and run a simple 1k sine wave while monitoring the output on an oscilloscope for signs of distortion or noise. Finally, we run the amplifier to its full rated power into the appropriate resistive load provided by our Sencore amplifier tester. If there is an issue, it will usually be noticeable at this point. If everything reads clean, we will often test for THD (Total Harmonic Distortion) measured by our Keithley distortion meter, and compare it against the original manufacturers specifications. The amplifier then remains powered on to "burn in" on our test bench for a few hours to make sure there are no heat related issues. If there are balanced inputs available they will be also be tested.

Final testing involves pushing actual music thorough the amplifier. We've learned over time that some issues are only noticeable to a trained ear while listening to familiar source material. Our test bench has reference vintage KEF speakers that we're very familiar with which quickly reveal any discrepancies. Some amplifiers will then move into our listening room where they are tested with our in-house reference speakers of choice.

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