The AD2022 Dual Mono Symmetrical Pure Class A Preamplifier from Avalon Design includes the original sonic capabilities and transparency of M2, M22, and M5 Preamplifiers and several additional features including selectable microphone source loading for optimized cable/mic matching, improved, high-voltage Class A-regulated power supplies, two high Z instrument inputs, variable-passive high pass filter, polytetrafluoroethylene / silver wiring, and double-plated circuit boards for superior low level signal transfer.
The AD2022 Preamplifier incorporates an advanced, high-performance microphone transformer. Split low-ratio primary windings are carefully combined within a custom mu-metal core for extended smooth frequency response and very low distortion.
Sealer silver relays are used for minimal signal invasion. Input signal selector, high pass filter, polarity-phase reverse, 48V power, and the 20 dB input attenuator utilize local, sealed relay operation. A variable passive high pass filter provides a minimum phase shift design while eliminating low frequency rumble, wind noise, and mechanical vibration at sub sonic frequencies.
Two 100% discrete, high-voltage, symmetrical Pure Class A signal amplifiers are utilized per channel. The first operates in a cascaded-cascode FET configuration, while the second stage amplifier is fully bipolar. The twin amplifiers share the total available gain requirement. This shared architecture increases high level headroom capability, improves transient response, and doubles the internal bandwidth of the high performance pure Class A signal amplifiers.
The high-current, DC-coupled, discrete Class A amplifiers are utilized for the output drive interface with 36 dB capability into all known loads. Two large, high-quality analog VU meters indicate accurate signal readings, while bi-color LEDs offer peak indication at 0 and 20 dB.