audio research

Tube stereo line stage.

From the ARC website

The LS8 is ideal for those who demand true musicality and essential control functions in a vacuum-tube stereo preamplifier with no compromise in mechanical integrity or parts quality. While the LS8 is the most affordable preamp in the Audio Research line, its remarkable sonic performance cuts no corners when measured against the competition.

The LS8 is beautifully simple: single-ended inputs and outputs, rotary volume control and input selector, and power-on and muting-function toggle switches. The volume control is a 64-step microprocessor-controlled device with impressive sonic transparency and smooth, continuous rotary action. 40 steps in this control are .5 dB increments, offering precise control and tracking.

Inside, the LS8 features an all-tube gain circuit providing 12 dB overall gain from four 6922 twin triodes. Electronically regulated low- and high-voltage power supplies insure consistently excellent musical dynamics under the most dynamic conditions, while costly Inficap coupling capacitors at the output preserve maximum sonic transparency. Input impedance is 50 K ohms. RCA-type inputs and outputs are rugged, gold-plated connectors selected for best sonics.

Five inputs (Tape, Tuner, CD, Video, Aux) and two main outputs are provided. A.C. power is supplied via an IEC three-pin socket and heavy 14-gauge detachable cord. Remote control is not available with the LS8. Three front-panel finishes are available at no extra cost: anodized natural, black or dark gray.

Sonically, the LS8 offers system resolution never before available at anywhere near its price. Source material is reproduced with remarkable fullness, transparency and vivid soundstage focus. Musical dynamics, bass extension and definition are clearly superior to any previous Audio Research model in this price category.



LS8 MKII (1999)

From the ARC website

Introduced in 1997 as an affordable, yet reference-caliber single-ended tube preamplifier, the original LS8 model has been reengineered to Mark II status. This change takes advantage of some of the same advancements introduced in our more recent and costly preamplifiers, including the LS16, LS25 and Reference 2.

The new LS8 MKII is a pure Class-A circuit design with a large, fully-regulated power supply and is hand-assembled to the same critical standards as other Audio Research products. MKII component improvements include new regulator FET devices, higher-quality resistors, new Infinicap(r) coupling capacitors and our latest selected 6922 twin triode vacuum tubes. Mechanically, the MKII incorporates new chassis isolation feet, extensive internal chassis damping, and the proprietary clear tube damping rings also used in the LS16, LS25 and Reference 2 models. The cumulative sonic gains are exciting: less smearing with tighter focus of individual instruments, more lucid and natural-sounding upper frequencies, better sorting out of complex orchestral programs, improved dynamics and better bass control and impact. The overall sonic presentation is smoother, more extended in range and more convincingly authoritative.

External appearance and operational controls -- Gain, Input Select, Power On / Off, and Mute / Operate -- are unchanged except for the identifying MKII designation on the rear panel (which sports a removable IEC-type power cord). A factory update to MKII status is available to owners of original LS8 units. Suggested retail for the update is U.S. $495, plus shipping to and from our factory. Updates must be prescheduled through your authorized dealer or through the Audio Research Customer Service Department.

We believe the new LS8 MKII actually outperforms the recently discontinued LS15 when driving a power amplifier with single-ended inputs. There is simply no other preamp in this price range which is better able to provide such refined resolution, musicality and naturalness in a simple-to-operate, easy-to-own package.


MSRP (US new retail)
$1,995. Increased to $2,495 on Feb 5 2001. (LS8 MKII)


Frequency response ±.5dB, 0.5Hz to 100kHz -3dB points 0.1Hz and 250kHz
Distortion (THD) Less then .01% at 2V RMS output (typically .007% in midband)
Noise & hum 20µV RMS IHF weighted noise at main output with gain control at -60dB (100dB below 2V RMS output)
Gain Main Output - 12.2dB unbalanced
Tape output - 0dB
Input impedance 50K ohms
Output impedance 200 ohms main output. Recommended load 60K ohms and 100pF (20K ohms minimum and 1000pF maximum)
Output polarity Non-inverting
Maximum inputs 3.5V maximum
Rated outputs  
Power supplies Electronically-regulated low and high voltage supplies. Line regulation better than .01%
Tube complement LS8: (4) 6922
  LS8 MKII: (4) 6922/E88CC dual triode
Power requirements 100-135VAC 60Hz (200-270VAC 50/60Hz) 30 watts maximum
Other Controls: Gain (64 step, 0.5dB per step for 40 steps), Input selector. Toggle switches: Power On/Off, Mute/Operate.
Dimensions 19" (48 cm) W x 5 1/4" (13.4 cm) H (standard rack panel) x 10 1/4" (26 cm) D Handles extend 1 1/2 " (3.8 cm)forward of front panel. Rear chassis fitting extend 1/2" (1.3 cm).
Weight 10 lbs. (4.5 kg) Net; 19 lbs. (8.6 kg) Shipping.


Vol. 22 No. 3 (LS8)