Proceed HPA3 Amplifier from Mark Levinson - Perfect for Home Theater or Stereo - 250W X 3

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Powerhouse three-channel theater / stereo amplifier from Proceed (Mark Levinson)

A few light scratches and scuffs but otherwise working perfectly. 

A perfect match to the Proceed AVP2 or PAV Processor/Preamp, along with the matching HPA2 two-channel amp, for a very capable 5 channel home theater setup. Simply click here to see all the available Proceed listings from our website.

Click here for a PDF copy of the Proceed HPA3 Owners Manual

Special Design Features (From the Owner's Manual):

Triple monaural design
Consistent with the finest amplifiers, each audio channel of your Proceed HPA 3 has its own, dedicated power supply — including a separate 663 VA toroidal trans- former for each channel. The resulting reduction in crosstalk between audio channels provides superior imaging and reproduction of acoustic space. Demands placed on one channel have virtually no effect on the performance of the other channel.

Low impedance power supply
A critical factor in the ultimate performance of an amplifier is its “power supply impedance,” which can be loosely thought of as the freedom with which the au- dio circuitry has access to the power it needs, when it needs it. The design of your Proceed amplifier has addressed this important characteristic in a comprehensive fashion. For example, the power supply capacitors (which act as “reservoirs” of power for the amplifier circuitry) are mounted directly to the printed circuit board rather than using point to point wiring. The layout of the circuitry uses short, thick traces for high current paths. This attention to detail yields an optimal environment in which the amplifier may operate to its maximum potential.

Balanced inputs
Each channel of your amplifier is individually configurable to receive either balanced or single-ended inputs. This approach allows you to take full advantage of the greater immunity from noise, RFI, and EMI which balanced transmission of audio signals offers on any preamp-to-amplifier connection where it is supported. At the same time, any or all channels of the amplifier may be configured for single-ended inputs to maintain compatibility with the majority of preamplifiers available today. The gain structure of the amplifier adjusts automatically when you select different inputs to facilitate this “mix and match” approach.

Robust output stage
Each channel of your Proceed amplifier uses twelve 150 watt power transistors. These transistors are all individually tested and sorted, and are used in matched sets to ensure that no one transistor bears a disproportionate part of the overall load. The combination of an “overbuilt” design specification and extraordinary attention to detail in manufacturing improves performance, reliability, and longevity.

Extensive protection
Your Proceed amplifier will shut itself down if it senses either the presence of either DC (direct current) or a short circuit at the output, or any unsafe operating temperature. In any case, a power relay will cause the amplifier to be disconnected from the AC mains. In addition, the AC input to each transformer is fused to protect against any possibility of component-level failure that could draw dangerous amounts of power. Finally, inrush limiting prevents premature aging of power supply components during power-up. Once the power supply has been charged, this in-rush limiting circuitry effectively defeats itself to allow unfettered power supply access to the AC mains.

Our Testing Process for Amplifiers (Solid State) at SkyFi:

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.

Please click here for detailed specifics regarding our specialized packing process that separates us from the rest.