Krell Phantom II Manual - Manual (Page 6)

6
SECTION
ONE
Phantom II Features and Technology
This section describes the innovative features and technology of the Phantom II
preamplifier, and defines CAST and other key terms used in this reference.
Circuity highlights
Sharing the same audio circuitry as its bigger brother, the Phantom II preamplifier
is a dual monaural circuit design with the left and right channels afforded their own
power supply regulation and individual full chassis sized boards. All signals gain is
realized in surface mount topology using proprietary multiple-output current mir-
rors with nearly 500 times the open loop linearity of other designs. Approaching 1
MHz of open loop bandwidth in a zero feedback, balanced, Krell Current Mode,
the Phantom output stage terminates in Krell CAST. A Complete Krell system
(source, preamp, and amplifier), connected using CAST interconnects reduces the
number of voltage gain stages to the minimum, one. The resulting noise floor
approaches the theoretical limit of technology. Negative feedback is not used any-
where in the preamp, nor is it necessary. Open-loop distortion is typically less than
0.003%. The volume control is realized with a balanced resistor ladder bandwidth
and transient response of the circuitry are virtually unaffected by the volume set-
ting.
Power Supply Highlights
The Phantom II audio circuits receive power from a Krell Current Mode analog
power supply. The power supply avoids the common integrated circuit topology
used in many preamplifiers and instead mimics the deign topology of Krell
Evolution e Series amplifiers. The circuitry is completely discrete giving it the ability
to respond quickly to current demands and also be unaffected by AC voltage
power fluctuations. Oversized for a preamplifier, the power supply features a 140
VA transformer and 35,000uF of capacitance.