#Pcr 800 amp free#

The amplifier's exterior remained cool except at the air-exhaust slots. Before the required hour had passed, the PCR circuits had reduced the amp's supply voltage sufficiently to limit the output to perhaps 30 or 40 watts (which is still adequate for most home listening needs). When we drove the PCR800 at one-third rated power for the standard FTC preconditioning process, its fan switched to high speed within a minute or two. Continued high-level operation causes the supply gradually to reduce the voltage to the output stages, thereby limiting the maximum deliverable power and the corresponding heat generated to safe values without shutting the amplifier down.

In normal service, the PCR power supply delivers just enough current to the amplifier to meet the output-signal requirements, thus minimizing the generation of unnecessary heat in the unit. Thermal sensors on critical parts of the amplifier will increase the fan speed with rising temperature, however.

Normally the fan runs very quietly at a low speed. Air enters in the rear and exhausts through slots in the front panel. Since the MOSFET's will get hot under extreme high-signal conditions, the amplifier is fan-cooled. Bridged operation turns the PCR800 into a 600-watt mono amp. Low-impedance power ratings are 300 watts per channel into 4 ohms and 275 watts into 2 ohms. The PCR800 has no conventional current-limiting protection circuitry, but it is able to drive low load impedances (even a short circuit) indefinitely without damage or even a temporary interruption of service.

#Pcr 800 amp free#

These transistors are inherently free from 'thermal runaway' effects, which can easily destroy a typical bipolar-transistor output stage unless it is protected against excessive output current. The result, Soundcraftsmen's PCR800, can deliver 205 watts per channel, yet it weighs less than 21 pounds and measures only 8-1/2 x 12 x 4-7/8 inches.ДЄlso contributing to the amplifier's impressive overall performance is the use of power MOSFET's (metal-oxide semiconductor field-effect transistors) in the output stages. The technique is an efficient and space-saving means of controlling the average power supplied to the output stages of an amplifier without compromising the performance of those stages. One answer comes from Soundcraftsmen in the form of a power amplifier that uses a technique called phase-control regulation in its power supply. Designing an amplifier that is relatively compact, lightweight, and inexpensive but can deliver large amounts of 'clean' power is an engineering problem that calls for innovative solutions.