Solid state stereo line stage.
Building on our thirty year tradition of designing electronics of the highest quality and value, Audio Research is pleased and very excited to introduce the LS12 stereo preamplifier, which bridges the usual gulf between solid-state and vacuum-tube sound, sonically outperforming the competition anywhere near its retail price.
The LS12 represents a major advance in solid-state circuit design in a non-stratospheric price range. Several circuit details and refinements have been implemented for the first time, with many others derived from more expensive siblings.
Physically and operationally the LS12 is identical to the LS16, with the same full-sized chassis and array of balanced and single-ended inputs and outputs. The LS12 uses the same microprocessor controls as the LS16 and LS25, including a 104 step volume control and bidirectional spring-loaded switches. There is also a single-ended, unity-gain processor pass-through, allowing the LS12 to be easily incorporated in a home theater system while preserving high quality two-channel music playback.
The fully-balanced, double-differential design is pure Class-A, utilizing all-FET circuits with unity-gain buffers between stages and a double-buffered output. Low-noise, critically matched high transconductance JFETs are used for all audio circuits, with local FET constant-current stabilization for each stage. The audio circuit is DC coupled throughout, with servo stabilization for low offset and subsonic control. Full muting protection is included for warmup stabilization and low-line voltage. Total gain is 18 dB balanced output, 12 dB via single-ended outputs.
The LS12's advanced-design power supplies use soft recovery rectifiers, highest grade "Muse" filter capacitors with our patented DEC (Decoupled Electrolytic Capacitor®) choke-decoupling, and a total of seven regulators. Mechanical vibration is carefully controlled with special Isodamp mounting for the power transformer and its own circuit board. Isodamp feet are used for the chassis. Like other Audio Research preamps, the LS12 has a removable IEC power cord, and it comes with the same remote control as the one supplied with the LS16.
All you really have to do is listen to the LS12 to appreciate what an outstanding value it provides. The LS12's sonics are remarkable from top to bottom, with startling transparency, resolution, dynamics and bass impact, speed, and control. The only blurring is the line between tube and solid-state sound: the LS12 presents soundstaging and "air" at which other solid-state preamps only hint.
MSRP (US new retail)
$2,495. Increased to $2,995 on Feb 5 2001.
|Frequency response||± 1dB, 0.1Hz to 40kHz at rated output. -3dB points below 0.06Hz and above 70kHz|
|Distortion (THD)||.01% at 2V RMS Balanced output|
|Noise & hum||40µV RMS residual IHF-A weighted Balanced noise output with gain control at minimum (94dB below 2V RMS output)|
|Gain||Main output: 18dB Balanced 12dB Single Ended output|
|Tape output: 0dB Balanced. (Processor output: 0dB Balanced)|
|Input impedance||150K ohms Balanced. 75K ohms SE. Inputs (7): AUX SE, PHONO, TUNER, CD BAL, AUX BAL, MONITOR (SE), and PROCESSOR (SE).|
|Output impedance||400 ohms Balanced, 200 ohms SE main, 10K ohms minimum load and 5000pF maximum capacitance. Outputs (4): 2 Main Bal, 1 Main SE, 1 Record SE.|
|Output polarity||Non inverting|
|Maximum inputs||14V RMS maximum Balanced, (7V RMS SE)|
|Rated outputs||2V RMS (1V RMS SE) into 200K ohm. Balanced load (maximum Balanced output capability is 12V RMS at 1% THD at 1kHz).|
|Power supplies||Electronically regulated low and high voltage supplies. Automatic 45 sec. warmup mute. Automatic brown-out mute.|
|Power requirements||100-135VAC 60Hz (200-270VAC 50/60Hz) 35 watts maximum.|
|Other||Controls: Volume (104 steps), Input Select. Toggle switches: Power On/Off, Operate/Mute, Monitor/Input, Processor/Input. All functions on Remote Control.|
|Dimensions||19" (48 cm) W x 5.25" (13.3 cm) H (standard rack panel) x 10.5" (26.7 cm) D. Handles extend 1.50" (3.8 cm) forward of the front panel.|
|Weight||11.5 lbs. (5.2 kg) Net; 21 lbs. (9.5 kg) Shipping.|