Avalon Design AD 2022 Overview
2 Channel Mic Pre
The newest member of Avalon Design's AD2000 Series, the AD2022 is a two-channel, fully discrete solid-state microphone preamplifier. The AD2022 shares lineage with Avalon's M5 mic pre, though the AD2022 employs a fully balanced signal path and its maximum output level is higher than that of the M5.
Perhaps most intriguing, each channel of the AD2022 features a five-position rotary switch for adjusting the input impedance. A balanced input transformer allows the load to be matched to the particular microphone in use. Though this concept has been largely overlooked in modern mic preamp design, it's interesting to note that manufacturers such as RCA produced mic preamps specifically matched to load their microphones correctly. As of this writing there's only one other preamp I know of providing this feature (GT Electronics' VIPRE).
The AD2022 incorporates the most advanced high-performance microphone transformer available. 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. The input signal selector, high pass filter, polarity-phase reverse, +48v power and the 20dB input attenuator all 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.
SYMMETRICAL PURE CLASS A DESIGN
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 the high level headroom capability, improves transient response and doubles the internal bandwidth of the ultra-high performance pure Class A signal amplifiers.
OUTPUT and METERING
High-current DC coupled, Class A discrete amplifiers are utilized for the output drive interface with +36dB capability into all known loads. Two large, high-quality analog VU meters indicate accurate signal readings while bi-color LED's offers peak indication at 0dB and +20dB.
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- Summary: Two-channel, discrete Class-A microphone preamplifier with DI
- Strengths: Variable mic input impedance. Quiet. Transparent signal path. Excellent headroom. Easy operation.
- Weaknesses: Remote power supply. Manual needs to furnish more information regarding variable impedance settings.
- Maximum input gain 64 dB
- Noise level -102 dB, unweighted at 20 kHz
- Frequency range 1 Hz to 120 kHz
- Input impedance 50, 150, 600, or 1.5k ohms
- Distortion 0.05% nominal
- Circuit Topology: Twin cascode FET and bipolar low level signal amplifiers,
- high-voltage, 100% discrete, symmetrical Pure Class A
- Input Type and Load: Transformer balanced low-ratio, 50, 150, 600 and 1k5 ohm input load selection
- Maximum Mic Level: +36dB balanced XLR pin 2 hot (with -20dB passive attenuator)
- Maximum Instrument Level +18dB at 100k ohms instrument input level, standard mono 1/4 inch jack
- Input Attenuator: -20dB resistive pre transformer primary, sealed silver relay
- Phantom Power: +48v regulated 50mA capability, sealed silver relay
- High Pass Filter: Passive, variable from 30Hz to 185Hz @ 6dB per octave, sealed silver relay.
- Polarity Reverse: Sealed silver relay on microphone input
- Gain Range Input: +20dB to +64dB in 4dB steps
- Gain Output Range: +/- 3dB variable conductive plastic potentiometer
- Maximum Output Level: +36dB balanced 600 ohms, DC coupled, discrete symmetrical Pure Class A
- Output Type: XLR connector, pin 2 hot
- Noise EIN Unweighted: -126dB 150 ohm
- Noise 20kHz Unweighted: -102dB
- Distortion THD, IMD: 0.05% nominal
- Frequency Response -3dB: 1Hz to 120kHz transformer limit
- System Bandwidth: DC to 1MHz
- Output Meter: High quality, illuminated analog VU meter 0dB = +4dB.
- Peak Meter: Bi-color LED's 0dB and +20dB peak detection circuit.
- AC power supply B2T: External toroidal 100V to 240V, 50-60Hz selectable,
- 150 watts maximum.
- Cables: 90V ac, 4 pin male power input connector, B2T required, internal DC regulation
- Dimensions: 19 x 12 x 3.5 in (482 x 305 x 89mm)
- Weight: 15lbs (6.8kg)
- Dimensions - Shipping Carton: 24 x 21.5 x 7.5 in (610 x 546 x 190mm)
- Weight - Packed: 25lbs (11.4kg)
