Perreaux E160 - Manual (Page 18)

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Special Design Features
Rugged Build
Quality
Mechanical strength has been a hallmark of Perreaux products since the
company first started production back in 1974. The concept behind the physical
design and construction is that each structural member should contribute to both
rigidity and performance.
Stiff Power
Supply
The E160 incorporates a custom designed, toroidal power transformer,
employing 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 20,000μF 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 stages,
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, 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 E160 are run in Class A mode. This avoids
the crossover notch distortion and the resulting odd-order harmonics present, to
some degree, in all other classes of operation. The devices used in the E160
output stage are MOSFETs, which with high quiescent current circuitry, are run
in the equivalent of Class A to 10 watts. Beyond this point the output class 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 E160 output stage takes full advantage of the unique qualities of MOSFET
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
bandwidth 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 prevent 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 the internal amplifier
circuitry.
Earthing Perreaux engineers pay particular attention to designing the product to ensure
maximum separation between internal signal and power earths, only meeting at a
central starred point.