C H N I C a L R E F E R E N C E | Hafler P3000, P1500 instruction

T E C H N I C A L R E F E R E N C E

FIELD SERVICE CONSIDERATIONS

A primary focus during the design and development of the P1500 and P3000 was to ensure the dependability of the amplifiers. The use of lateral MOSFET output transistors and the low voltage trans•nova input stage combined with careful component selection for the circuit assembly made the reliability goals achievable. However, a parallel effort was also underaken to make sure any down time caused by an amplifier fault was minimized by making the amplifiers “technician friendly.” The modular construction allows for exchanging the entire operational portion of either channel quickly and easily. This section of the manual also contains circuit descriptions and block diagrams to assist technicians with component level repairs.

THEORY AND OPERATION OF trans•nova

The (TRANSconductance NOdal Voltage Amplifier) principle is based on our 1984 U.S. Patent 4,467,288. This patent describes the advantages of audio power amplifiers in which a MOSFET output stage is connected in a grounded source configuration. In this connection the output stage has its full voltage gain of typically 20dB (ten times), instead of the usual 1dB loss of voltage follower designs.

It is an inevitable result of electrical physics that this output with gain inherently increases the power gain (for the same bandwidth) of the output stage by typically ten times over the conventional follower connection, using exactly the same MOSFET devices.

The output stage is thus now ten times less wasteful of its incoming drive power. The driver stage can now be of a low voltage (± 18 volts) nature and be designed along the same principles always used in high quality preamplifiers: Class A operation, high linearity, and wide bandwidth. A topology utilizing an output stage with gain yields a much simpler, shorter total signal path than that of the usual high voltage driver designs. The number of serial stages is reduced from five or more, to only three.

But all of the above does not make an amplifier trans•nova. The output stage is further refined into a trans-impedance stage (current-to-voltage converter), to achieve extremely short loop (fast) negative feedback. The output stage is driven cooperatively by a transconductance stage (voltage-to-current converter).

The P1500 and P3000 are the most affordable amplifiers we have yet developed utilizing the basic trans•nova principle. And, although the measured specifications are very good, the numbers do not describe the realistic sound of the amplifiers.

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P3000, P1500 specifications

The Hafler P1500 and P3000 are notable power amplifiers that have earned recognition for their performance and reliability in various audio applications. Both models are designed to deliver high-quality sound reproduction while offering users an array of advanced features that enhance their usability in professional and home audio setups.

The Hafler P1500 is a two-channel power amplifier that boasts a robust output of 150 watts per channel at 8 ohms, making it suitable for driving a variety of speakers with ease. One of its standout features is the intelligent cooling system, which ensures the amplifier operates at optimal temperatures, minimizing the risk of thermal overload. Furthermore, the P1500 is equipped with a high-quality toroidal transformer, which helps to reduce distortion while providing stable power, contributing to the amplifier's overall clarity and dynamic range.

In addition to its power capabilities, the P1500 includes features such as a variable speed fan and comprehensive protection circuitry to safeguard the amplifier from overcurrent and overheating. The user-friendly design includes both XLR and RCA inputs, allowing for versatile connectivity options with professional audio equipment and consumer audio devices alike. The rugged construction of the chassis is designed to withstand the rigors of touring and studio environments, ensuring durability and reliability.

On the other hand, the Hafler P3000 elevates the performance level with a powerful output of 300 watts per channel at 8 ohms. This amplifier is particularly favored in larger audio setups where significant power is required. It utilizes similar advanced technology as the P1500, including sophisticated thermal management systems and high-performance circuitry aimed at keeping distortion levels to a minimum.

The P3000 is recognized for its exceptional headroom and dynamic capability, making it an ideal choice for driving large speaker systems in professional settings such as recording studios and live events. The amplifier features balanced XLR connectors for professional applications, and its dual-level LED indicators provide real-time feedback on performance, giving users essential information on levels and operation status.

Both the Hafler P1500 and P3000 are exemplary models that blend innovative design with high-quality sound performance. Their reputation in the audio community stems from their ability to deliver powerful performance, reliability, and flexibility, catering to a multitude of audio environments from home theater systems to professional sound reinforcement setups. Their enduring popularity reflects Hafler’s commitment to engineering excellence, allowing audio enthusiasts to experience superior sound without compromise.