Industries 750 Monoblock Power Amplifier Owners Manual

ManualsBrandsPerreaux ManualsAmplifierPERREAUX 750

Special Design

Features

Rugged Build

Quality

Mechanical strength has been a hallmark of Perreaux products since the

company first started producti

on back in 1974. The concept behind the physical

design and construction is that each structural member should contribute to both

rigidity and performance.

Ultra Stiff

Power Supply

The 750 incorporates a massive custom designed, toroidal power transforme

employing unusually heavy gauge wire that reduces copper losses to a

minimum. An electrostatic shield prevents AC line borne interference from

entering the signal path. The power supply filter capacitors, totaling 60,00

0µF,

have exceptionally low inductance and internal resistance. They charge and

discharge in response to load demand far more rapidly than conventional storage

capacitors and are capable of delivering the instantaneous current required by the

output stage

s, providing optimum dynamic range and transient response. The

wiring from the power supplies to the output boards is designed for unimpeded

transmission of the required current and voltage and utilizes heavy gauge, tinned

copper wire cables. Since power

supply leads radiate at signal frequencies, all

wiring is carefully loomed to minimise this effect.

Hybrid Class

A/AB

The bi-

polar transistors used in the 750 are run in Class A mode. This avoids the

crossover notch distortion and the resulting odd-orde

r harmonics present, to

some degree, in all other classes of operation. The devices used in the 750

output stage are M OSFETs, which with high quiescent current circuitry, are run

in the equivalent of Class A to 10 watts. Beyond this point the output clas

s is

technically Class AB (hence the hybrid nomenclature), but with a major

difference. The combination of MOSFET characteristics and their application in

this circuitry, result in crossover distortion so minimal that it is virtually non-

existent.

MOSFET

Output Stage

The 750 output stage takes full advantage of the unique qualities of M OSFET

devices and in many ways they are superior to bi-

polar transistors. A major

advantage is their tendency to draw less current over a large section of the power

bandwi

dth as their temperature rises (Negative Temperature Coefficient), hence

self stabilising thermally, whereas bi-

polar transistors draw more current as their

temperature rises (Positive Temperature Coefficient) and protection circuits

become mandatory to pr

event thermal runaway and eventual self destruction.

MOSFETs have the ability to swing fully across the amplifier’s internal DC

voltage and are therefore true "rail-to-

rail" devices. Using MOSFETs

encourages the highest performance from the balance of th

e internal amplifier

circuitry.

Multiple

Protection

Systems

The 750 is equipped with a number of protection systems, isolated from all

signal carrying circuits via opto-couplers, to protect both itself and ancillary

equipment.