Signature Preamplifier Mk IIa

Deluxe, fully balanced hand-wired preamplifier with manual signal switching
Though its principal outputs, the Signature Preamplifier contains “no coupling capacitors” from input to output. No coupling capacitor hinders the purity and detail developed by the “hand-wired direct-coupled Class A1 triode” tubes. Additionally, “no loop negative feedback” is used; the output interface is completely stable and free from dynamic interactions with the load. In addition to five standard line inputs (four when phono is fitted), a “fully balanced input” is provided. “Fully balanced outputs” are present, as are dual standard RCA outputs. Balancing is achieved by differential triodes driving a special output transformer. This design ensures a true balanced signal, ”capable of driving even the most cruel professional studio equipment,” something impossible with cathode followers and totem circuits. In addition, the transformer output may be used with unbalanced loads. In this manner, galvanic loops and interaction between source & power amp feedback loops are eliminated, allowing for the most liquid, dimensional sound. The laquered aluminum remote control is standard. The VAC logos are backlit with an elegant blue in normal operation, but display red when the mute is activated. These are set in the heirloom-quality sculpted 3/8" fascia. The liberal use of sound deadening material compliments the “1/4" thick CNC-machined aluminum chassis,” creating a solid mechanical foundation. Internal parts are specified from the finest and most exotic materials, as extreme measures and the most careful "voicing" are required to reach this unequaled pinnacle of perfection. (black or silver)

Basic specifications:

• Inputs: 3 sets RCA line input, 2 sets balanced/RCA selectable inputs; optional 1 MM and 1 MC (or additional line input if phono is not fitted); 1 set RCA tape monitor input; 1 set RCA cinema bypass input
• Outputs: 2 sets RCA, 2 set balanced XLR (EIA "pin 2 hot" studio standard); 1 set RCA tape output
• Optional MM/MC phono stage with user adjustable loading
• Absolute phase is correct from all inputs to all outputs
• Dimensions: audio chassis 18" wide x 5.5" high x 14.5 deep (plus knobs & connectors); power supply 18" x 3.9" x 14.5" plus connectors
• Shipping weight: 80 pounds total (with phono) or 65 pounds (without phono)
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• Line stage:
• Two 12AU7 twin triodes and two 8416, 7308, 6922, E88CC, ECC88, 6DJ8, or 12DJ8 twin triodes
• Gain: 12 dB
• Frequency response: flat over audio band; -3 dB bandwidth 5 Hz - 210 kHz
• THD: <0.009% @ 1 kHz, 1 V RMS
• Maximum output: > 8 V RMS
• Output impedance: < 150 ohms, 20 Hz - 20 kHz, static (i.e., not dependent upon feedback)
• Recommended output load: >300 ohms
• Channel separation: >80 db
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• Phono stage:
• Six 12AX7 twin triodes
• Gain: 44 dB MM / 64 dB MC selectable
• MC load impedance selectable, 470, 300, 250, 200, 150, and 100 ohms
• MM load impedance selectable, 47k, 30k, 25k, 15k, and 10k ohms
• Frequency response: RIAA standard +/- 0.2 dB (20 Hz - 20 kHz); -3 dB bandwidth 10 Hz - 80 kHz
• Maximum input: > 130 mv @ 1 kHz, MM; > 13 mv, MC
• Channel separation: > 80 db @ 1 kHz