21
7
77
7
Special Design
Features
Rugged Build
Quality
Mechanical strength has been a hallmark of Perreaux products since th
e
company first started production back in 1974. The concept behind the physica
l
design and construction is that each structural member should contribute to bot
h
rigidity and performance.
Ultra Stiff
Power Supply
The 6160 incorporates a massive custom designed, toroidal power transformer,
employing unusually heavy gauge wire that reduces copper losses to
a
minimum. An electrostatic shield prevents AC line borne interference fro
m
entering the signal path. The power supply filter capacitors, totaling 60,000μF,
have exceptionally low inductance and internal resistance. They charge an
d
discharge in response to load demand far more rapidly than conventional storag
e
capacitors and are capable of delivering the instantaneous current required by th
e
output stages, providing optimum dynamic range and transient response. Th
e
wiring from the power supplies to the output boards is designed for unimpede
d
transmission of the required current and voltage and utilizes heavy gauge, tinne
d
copper wire cables. Since power supply leads radiate at signal frequencies, al
l
signal wiring is carefully loomed to minimise this effect.
Hybrid Class
A/AB
The bi-polar transistors used in the 6160 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 6160
output stage are MOSFETs, which with high quiescent current circuitry, are ru
n
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 majo
r
difference. The combination of MOSFET characteristics and their application i
n
this circuitry, result in crossover distortion so minimal that it is virtually non-
existent.
MOSFET
Output Stage
The 6160 output stage takes full advantage of the unique qualities of MOSFE
T
devices and in many ways they are superior to bi-polar transistors. A majo
r
advantage is their tendency to draw less current over a large section of the powe
r
bandwidth as their temperature rises (Negative Temperature Coefficient), henc
e
self stabilising thermally, whereas bi-polar transistors draw more current as thei
r
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 amplifie
r
circuitry.