AVALON AD2022 DUAL MONO PURE CLASSA PREAMPLIFIER

The AD2022 is Avalon's fourth generation of fully discrete, symmetrical Pure
Class A microphone preamplifiers. The dual mono AD2022 includes the original
sonic capabilities and transparency of the M2, M22 and M5 preamplifiers plus
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, teflon/
silver wiring and doubled plated circuit boards for superior low level signal transfer.
 
AD2022 FEATURES
Symmetrical Pure Class A design, two channels
Microphone and hi-Z instrument inputs
Gain switched 4dB steps plus +/- 3dB fine output trim 
Selectable microphone input impedance matching 
Low noise -126dB EIN
Ultra high quality, low-ratio, balanced input transformer
Balanced, high-current Class A output to +36dB
Large illuminated analog VU meters and twin peak LED's
Regulated phantom power supply +48v 
Input polarity phase reverse 
High headroom +36dB input before overload
Input -20dB pad for high level signals
Sealed silver relays for all signal routing
External AC 150w toroidal power chassis
Fully discrete Class A regulated audio power supplies
Deep, musical sound-stage, transparent amplification

MICROPHONE INPUT
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.

AD2022 PREAMPLIFIER SPECIFICATIONS
 
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) 

Having had great success with the PRE-73 preamp, we have received many requests for a version for the 500 eries rack format. We are therefore happy to present the PRE-573, expected to start shipping in late September.
 
The PRE-573 is a one width module that has the sound and the features that made the PRE-73 so successful and a few additional ones.
The circuit still uses the preamp and output section from the classic 1073-module, adapted to work in the api rack format. It has a total  gain range from -15 to +80 dB. The 10 - 70 dB range is handled by a turn switch  and there is a separate toggle switch to select an additional 5 or 10 dB gain. The input can be configured to accept line level signals by another switch, the gain is then lowered by about 25 dB and the input impedance increased to about 15 kohm.
 
The input impedance of the mic input mode can be switched between 1200 and 300 ohm. Phantom power and phase reverse is also selectable by front panel switches.
 
An added feature, using the same circuit as in the PRE-73 DLX, is the active DI-input with a high input impedance of about 1,5 Mohm. The output signal from the active DI circuit passes through the input transformer for some extra character.
The DI-input is very flexible since it can be changed to a purely passive one by a front panel switch. The DI input is then exactly the same as in the PRE-73 Mk2 where the signal is feed directly into the second gain stage, bypassing the transformer and with an input impedance of about 100 kohm.

These two DI-options makes it possible to get different tones from electric instruments and the passive DI input mode is more suited for injecting active units like sound modules. 
 
A new feature is the switchable AIR mode that  adds a small boost above 10 kHz that peaks at 2 dB at about 35 kHz.

A simple but effective signal and overload indicator is offered by a single LED that starts glowing red at about +4 dBu and then increases its intensity up to the maximum output level.
 
The PRE-573 has a dedicated insert connector at the back allowing it to interface with other GAP 500 modules. The insert can be activated by removing a jumper connector at the back of the module.
The second Golden Age Project module for the api 500 rack will be the EQ-573, expected to ship in November 2012. The EQ-573 consists of the inductor based high pass filter section  and the 3-band eq section from the classic 1073 module with some added frequencies. These two modules together will offer a fully fledged 1073-module in a compact format at a very low cost.
 
There is a second jumper at the back of the module that selects 600 ohm termination on the output. The standard mode is termination on, since it gives the flattest response when the PRE-573 is used with modern line inputs that typically has an input impedance of 10 kohm or more. The user can chose to remove the jumper and deactivate the termination resistor, this will increase the level above 10 kHz and create a peak in the response for an even more pronounced  "Air" effect.
The output is transformer balanced and fully floating and can drive a 600 ohm load up to level of about 28 dBu.

 The OctaMic II provides 8-Channel 192 kHz / 24 bit AD conversion with eight hi-class microphone and line pre-amplification channels, featuring a combination of sophisticated components and approved RME technology.

Lowest distortion, excellent signal to noise ratio and perfectly linear frequency response transmit and amplify the microphone signals truly unchanged.

The OctaMic II includes some significant enhancements compared to the OctaMic:

The balanced TRS inputs of the Neutrik Combo XLR jacks are phantom power-free and can be operated as real line inputs too. The improved design of the input circuits allows for a maximum input level of +21 dBu with a convenient gain range from 6 dB up to 60 dB.
Improved signal to noise ratio (SNR) ADC 107.5 dB
Improved THD, especially at higher gains
Optimised heat dissipation by a new and larger housing with improved convection
Internal wide range power supply with line filter, insensitive to voltage fluctuations
Super-stable, short circuit proof 48 V phantom power


Features

OctaMic II offers 8 balanced XLR mic / line inputs via Neutrik XLR/TRS combo jacks. Each channel contains switches for 48V phantom power, a low cut filter and phase reversal. Amplification can be set between 6 and 60 dB. LEDs for signal, clip, and activated phantom power give a complete overview on the unit's status. When the special Clip Hold mode is activated, any detected clip-state will cause the corresponding LED to flash once per second. With this, the user gets a long-term peak detection, and no longer needs to constantly watch the LEDs. At the same time momentary overloads are still displayed correctly.

Frontside switches include power on/off and output level, for a choice of -10 dBV, +4 dBu or Hi Gain (+19 dBu) as reference level. This unusual feature offers two advantages. First, the reference level can be easily switched to match any of RME's current interface devices, from HDSP 9632 through Multiface up to the renowned ADI-8 series converters. Second, the Signal to Noise ratio is optimized, and the Clip-LED will exactly match the ones of the ADI-8 (2 dB below 0 dBFS).

The balanced line level output signal is available at the back of the unit via 8 stereo TRS jacks. The specially developed, internal hi-performance switch mode power supply lets the OctaMic II operate in the range of 100V to 240V AC. It is short-circuit-proof, has an integrated line-filter, is fully regulated against voltage fluctuations, and suppresses mains interference.

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AD-Conversion

The 8-Channel AD-conversion of the OctaMic II operates at up to 192 kHz. The digitized signal is available simultaneously at the double ADAT output (S/MUX, up to 96 kHz), and at a DB-25 connector (4 AES/EBU outputs, up to 192 kHz). The digital part can be clocked internally (master) and externally via word clock, AES/EBU and SPDIF.

RME's outstanding SteadyClock(TM) ensures perfect AD-conversion, as jitter on the external sync-sources is nearly completely removed. All settings are done via DIP-switches on the back of the OctaMic II. Analog outputs and both digital outputs operate fully simultaneously. The choice of reference level affects the analog outputs only, the signal/clip indication and the AD-conversion will react only to the Gain-pots.


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Tech Specs

8 balanced XLR/TRS mic/line inputs

54 dB gain range

Input impedance: XLR 2 kOhm, TRS 5 kOhm

Analog input level: from -40 dBu up to +21 dBu

Maximum output level: +21 dBu

Output impedance: 75 Ohm

Output level switchable Hi Gain / +4 dBu / -10 dBV

Signal to noise ratio (SNR): 129 dB EIN @ 150 Ohm

THD:
Large frequency range (200 kHz) with special EMI input filtering

Frequency response -0.5 dB: 5 Hz - 200 kHz

Hi-pass filter: 80 Hz, 18 dB/oct.

Line Out: 1/4" TRS (6.3 mm stereo jack), servo-balanced

Phantom power: +48 Volt switchable per channel

Internal wide range switching power supply 100-240 Volt AC

Unbeatable price/performance ratio!

AD conversion

SNR: >110 dB(A)

Supported sample rates: 28 kHz - 200 kHz

THD:
Sync Sources: AES/EBU (also SPDIF coaxial), wordclock, internal

SteadyClock(TM) ensures best sound quality even with jittery external clocks


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Accessories

Digital breakout cable Pro, AES/EBU, D-sub25 to 4x XLR-3 female + 4x XLR-3 male, 1m/3m/6m (ALVA Audio)
Digital D-sub cable, AES/EBU, D-sub25 male to D-Sub25 male, 1m/3m/6m (ALVA Audio)
Optical ADAT Toslink cable 1m/2m/3m/5m/10m (ALVA Audio)
Word Clock cable, 1 x BNC male to 1 x BNC male, 1m/5m/10m (ALVA Audio)

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Add-On

BOB-32    Universal Breakout Box with 2 x 8 XLR to 2 D-sub connectors (supports TASCAM and YAMAHA format), flip-frame case

The PRE-73 Mk2 is the first one-channel low-cost preamp on the market that is using a fully discrete signal path with three separate transformers for the balanced mic input, the line input and the output.

The circuit is very similar to the classical preamp section of the Neve 1073 pre/eq module with a corresponding sound character that is warm, punchy, sweet and musical.
This classical sound has been heard on countless recordings through the years and it is a versatile sound that works very well on most sound sources and in most genres.

The PRE-73 Mk2 has a maximum gain of 80 dB on the mic input and the gain range on the Line input is -20 to + 10 dB. There is also a high-impedance instrument input.

The PRE-73 Mk2 is perfect for almost any signal source, no matter if it's a microphone with a high or low sensitivity (like a passive ribbon mic), a syntheziser or sound module or an electric guitar or bass.

The input impedance of the microphone input can be switched between 300 and 1200 ohms, which makes it possible to affect the tone of most microphones. There is also phase switch and an simple 4-step LED signal level meter.

The output level control makes it possible to make fine gain adjustments and also to overload the main gain stage for more character and then lower the signal to a suitable level before the output stage.

The Mk2 update consists of:
- An unbalanced insert jack (nominal level about 18 dBu) added on the back panel for inserting units like the coming GAP EQ-73, a three band eq.
-  LED meter levels adjusted.
- 600 Ohm termination resistor and jumper added to power supply board (accessible from the inside of the unit).
- Revised Gain switch, turning the know clockwise now increase the gain.
- Reduced noise at high gains by a change to the power supply grounding scheme.

The PRE-73 MKIII is a one-channel vintage style microphone-, line- and instrument preamplifier. The signal path uses only discrete components like resistors, capacitors and transistors. The in- and output is transformer balanced, using two different transformers, each one optimized for its purpose. This is the way audio components were built before integrated circuits became available.

The circuit used in the PRE-73 MKIII is similar to the preamp section in the classical 1073 module with a corresponding sound character that is warm, punchy, sweet and musical. These classic characteristics have been heard on countless recordings through the years and it is a versatile sound that works very well on most sound sources and in most genres.
The essence of this sound is now available at a surprisingly low cost, making it available to nearly everyone.

Features  :

• Vintage Style electronics. No intergrated circuits in the signal path.

• Maximum gain in MIC mode is 80 dB, enough to handle passive ribbon mics with quiet sound sources.

• GAIN switch range 20 - 80 dB. GAIN/LINE mode switch, gain is reduced by 30 dB in LINE mode.

• Selectable two position high frequency AIR boost eq, 3 or 6 dB @ 30 kHz.

• Selectable 6 dB/octave two frequency high pass filter at around 40 (HP1) and 170 Hz (HP2).

• Tantalum capacitors in the signal path.

• Switchable impedance in MIC mode, 1200 or 300 Ohms, will change the tone of most mics. The input impedance in LINE mode is 10 kohm.

• Switchable phantom power and absolute phase.

• A high-impedance instrument input for any sound module, electric guitar or bass.

• A simple but effective 4-step LED output level meter.

• The output level control makes it possible to make fine gain adjustments and also to overload the main gain stage(s) for more character and then lower the signal to a suitable level before the output stage.

• Combo XLR/TRS input jack and separate output XLR and TRS jacks for flexible connections.

• Insert jack for inserting EQ´s and other units.

• Selectable 600 ohm output termination.

• The pcb is prepared for the Carnhill input transformer.

• External power supply to avoid interaction with the audio circuits and transformers.

• A solid build quality that will last many years of normal use.

The MKIII has the following new features compared to the MKII:

• Tantalum capacitors in the signal path.

• Selectable two position high frequency AIR boost eq, 3 or 6 dB @ 30 kHz.

• Selectable two frequency high pass filter, 6 dB/octave at 40 or 170Hz.

• The pcb is prepared for the Carnhill input transformer.

• Revised and less complicated GAIN switch with a separate switch for MIC/LINE selection.

• All GAIN settings can also be used in LINE mode .