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.