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Conrad-Johnson ACT2
SOLD $12,000.00
JAN
2010
Stereophile Review
SoundStage Review
Manufacturer's Website
The ACT2 preamplifier embodies
conrad-johnson's latest advances in line-stage preamplifier technology.
It is the successor to the legendary ART preamplifier that has been
widely recognized as the reference standard for line-stage preamplifiers
since its introduction in 1996. The ACT2 incorporates the breakthrough
concept of the composite triode circuit (which has garnered more than a
dozen international awards for conrad-johnson preamplifiers). The ACT2
refines this approach by implementing circuit upgrades and by taking
advantage of recent advances in materials technologies. The end result
is a line-stage preamplifier that we believe will quickly be recognized
as the new industry-wide reference standard
The ACT2 Preamplifier is a vacuum-tube, line-stage preamplifier that
looks as good as it sounds. It is also notable for convenience and ease
of use. The unit features input selection and level adjustment by
microprocessor-controlled relays. Level and balance can be adjusted in
100 steps of approximately .7 dB per step. All functions can be
controlled by the hand-held wireless remote control.
The circuitry of the ACT2 Preamplifier is elegant in its simplicity. The
audio circuit consists entirely of a single amplifier stage
incorporating one composite triode comprised of four paralleled sections
of ultra-high transconductance miniature dual triodes. This arrangement
achieves a low output impedance while reducing the number of active
stages to the absolute minimum of one, resulting in unparalleled sonic
purity. DC voltage is supplied to this stage by cascaded discrete
voltage regulators that absolutely isolate the audio circuit from the
power line by maintaining virtually zero impedance across the audio
frequency band. Infrasonic noise is minimized by operating the tube
filaments (heaters) on a dc voltage supplied by another discrete
regulated power supply.
Considerable care and attention have been paid to the physical aspects
of the design as well. Microprocessor controlled relays, used for
selecting sources and level setting, are located right at the input
connectors, keeping signal paths short to minimize crosstalk between
channels and inputs. Critical audio circuitry is mounted on a subchassis
that is isolated by a suspension system designed to minimize
microphonics. The dramatic casework features an attractive clear Lucite
tube guard outside the chassis, allowing for easy access for tube
replacement.
At conrad-johnson we have long appreciated that the full potential of
any circuit can only be realized by using the finest available parts.
Each part for the ACT2 has been selected on the basis of both sonic
performance and durability. The audio circuit (including the level
control) is executed entirely with precision metal foil resistors and
Teflon and polystyrene capacitors. Tubes have been carefully hand
selected for minimum noise and microphonics. The dc regulated power
supplies use the same quality resistors as the audio circuits.
Capacitors for the power supplies are exclusively polypropylene,
polystyrene, and Teflon - there are no electrolytic capacitors in the
audio circuits or their related power supplies. Switching relays are
sealed and have gold plated silver contacts. Input and output connectors
are machined from oxygen free copper, and are gold plated. The ACT2 is
built without compromise to achieve a new standard in musical
performance, and it is built to last.
Specifications:
ACT2
Gain: 21.5 db
Maximum output: 10 vrms
Output impedance: under 500 ohms
Distortion: less than .1% THD
Frequency response: at unity gain: 2 Hz to more than 10OKhz
Hum and noise: 100 db below 1.0 v
Tube complement: 4 x 6N30P
Dimensions: 15.75D x 19W x 5.375H inches
Total weight: 30 lbs.
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