Audio Research LS2B MKII - Tube / Solid State Hybrid Line Stage Preamplifier

**Please click here to check out our newly launched SkyFi Audio website with additional items for sale**

The Audio Research LS2 preamp came in multiple versions and variations beginning in 1991. Line stage in ARC terminology means that it does not include a phono preamplifier.

This version, the LS2B MKII released in 1992, is the last and best of them all. It features balanced inputs and outputs (hence the 'B"), and remote control capability.

It's a wonderful sounding hybrid tube/solid state design which allows the internal 6922/E88CC twin triode tube to induce just the right amount of warmth into the signal path.

In overall great condition and in rare black finish. We have ordered an official replacement remote from ARC which will be included with your purchase.

INTRODUCED
1991 (LS2) / 1992 (LS2B)

OPTIONS
Two versions:
LS2 and LS2B (Balanced).

ORIGINAL 1991/1992 MSRP
LS2: $2,495
LS2B: $2,995
LS2 MKII: $2,650
LS2B MKII: $2,995 = ($5,500 in 2020 today's dollars)

SPECIFICATIONS:

FREQUENCY RESPONSE
± .5dB, 1Hz to 100Hz, -3dB points below 0.1Hz and above 300kHz

DISTORTION (THD)
Less than .01% at 2V RMS output (typically less than .005% in midband)

NOISE & HUM
20µV RMS residual 1HF weighted noise at main unbalanced output with gain at minimum (100dB below 2V RMS output). xxx Balanced input noise 100dB below 1V input.

GAIN
LS2: Main Output: 18dB. Balanced output: 24dB. Tape output: 0dB (Optional 12dB gain reduction). LS2 MKII: Main Output: 18dB. Balanced output: 24dB. Tape output: 0dB (Optional 9dB gain reduction)

INPUT IMPEDANCE
LS2: 50K ohms. LS2: 50K ohms unbalanced, 3 megaohm balanced.

OUTPUT IMPEDANCE
LS2: 200 ohms main output. 500 ohms Balanced 1, Balanced 2 (10K ohms minimum load and 2000pF maximum capacitance). LS2 MKII: 200 ohms main output. 400 ohms Balanced 1, Balanced 2 (10K ohms minimum load and 2000pF maximum capacitance)

OUTPUT POLARITY
-

MAXIMUM INPUTS
LS2: 20V maximum. LS2 MKII: 20V maximum unbalanced, 8.5V maximum balanced.

RATED OUTPUTS
LS2: 2V RMS 1Hz to 100kHz into 60K ohm load (maximum output capability is 10V RMS (20V RMS balanced) output at 05% THD at 1kHz into a 10K ohm load). LS2 MKII: 2V RMS 1Hz to 100kHz into 60K ohm load (maximum output capability is 30V RMS (60V RMS balanced) output at 05% THD at 1kHz into a 10K ohm load)

POWER SUPPLIES
Electronically-regulated low and high voltage supplies. Two transformers (toroid for high voltage). Line regulation better than .01%

TUBE COMPLEMENT
LS2: (1) 6DJ8/ECC88. LS2 MKII: (1) 6922.

POWER REQUIREMENTS
100-135VAC 60Hz (200-270VAC 50/60Hz) 60 watts maximum

OTHER
Hybrid FET/Tube audio circuit, solid-state power supply

DIMENSIONS
19" (48 cm) W x 5 ¼" (13.4cm) H (standard rack panel) x 10 ¼" (26cm) D. Handles extend 1 ⅝" (4.1cm) forward of front panel. Rear chassis fittings extend ⅞" (2.3cm).

WEIGHT
LS2: 13 lbs. (5.9 kg) Net; 21lbs.(9.5 kg) Shipping. LS2B MKII: 14 lbs. (6.0 kg) Net; 22lbs.(10 kg) Shipping.

Audio Research LS2B MKII Owner's Manual

Our Testing Process for Preamplifiers at SkyFi:

We start with a visual inspection of all internal components to make sure there are no signs of stress or aging. Capacitors are checked for telltale sings of bulging or leaking, resistors are checked for signs of overheating or cracking, and transistors are checked for signs of stress or damage. Special attention is paid to the power supply which is the most common source of failure for preamps. We then power up the unit and run a simple 1k sine wave while monitoring the low voltage output on an oscilloscope for signs of distortion or noise to get a baseline.

At this point we will lubricate and clean all switches and potentiometers (that are not sealed) with a high quality contact cleaner, and then re-test all functions for any signs of noise or scratching.

Final testing involves putting actual music through the preamplifier We have learned over time that some issues are only noticeable to a trained ear while listening to a familiar source material. Our test bench has reference vintage KEF speakers that we are super familiar with which will quickly reveal any discrepancies. Some preamps will then move into the listening room where they will be tested with our in-house reference system.

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PURCHASING FROM SKYFI:

This item will be professionally packaged and insured for safe transit to your home unless you opt for local pickup from our shop. Please note that all local pickup items are only wrapped with industrial strength clear cling stretch wrap if the original manufacturer packaging is unavailable.

Local pickup is available in Glen Rock, NJ, just a half hour drive from Midtown Manhattan, with convenient parking near our building.

And if you’re looking to ship to Canada, simply follow this link to view and purchase this item. We ship to Canada via UPS Worldwide Expedited service and you’re responsible for any applicable import duties and taxes.

If we don’t have the original manufacture’s packaging, we use heavy duty double-ply corrugated boxes with custom made to your item Instapak expanding foam custom inserts. In many cases this has proven to be better than the original packaging! We also use high quality fiber reinforced tape to seal our packages. Lightweight items will be bubble wrapped and shipped in a high-quality box.

Click here for specifics on our specialized packing process that separates us from the rest.

NJ Residents or anyone picking up without a resale certificate will need to pay NJ Sales Tax.

Thanks for looking and be sure to call us at 201-879-0000 with any questions.

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WHO WE ARE:

SkyFi Audio is a small startup business specializing in the purchase, reconditioning, and reselling of select high-end audio equipment. We only buy equipment the we admire and are passionate about. No mid-fi, no gimmicks, no junk.

Each piece of equipment is cosmetically restored and fully tested in our well-equipped lab by an engineer with 30+ years of experience in the HiFi world. If it does not meet or exceed the original manufactures specifications, it will not be sold. We are very selective about the equipment we purchase, focusing on mostly analog, high-build quality, American, and European built units.

Through our sister company which is an authorized dealer for McIntosh, Audio Research, Sonus Faber, ClearAudio, Pro-Ject Audio Systems, and Sony ES, we have access to OEM parts, service, and support. If you’re local and looking for new equipment from the above-mentioned manufacturers, please drop us a line as we can arrange both sales and professional installation in the tri-state area.

PURCHASING GUIDELINES:

We do not accept or review any offers that do not go through the official Audiogon system. We have too many items for sale and it’s nearly impossible to keep track of offers outside of the official system. Please don’t message, email, or text any offers.

PAYMENTS:

We prefer working through PayPal which allows you to use a credit card, bank transfer, and their special financing to spread out payments over six months. We do not charge extra for any PayPal fees if you purchase the item at the asking price. You can also send us a personal check (which will need to clear before shipping), certified check, money order, or bank wire transfer. International clients without access to PayPal should use a bank wire transfer.

If you’re picking up an item, we do not accept PayPal. You must pay in person with a certified check, bank check, or wire transfer. If you make a PayPal payment and are picking up the item, your PayPal payment will be returned.

TRADE IN POLICY:

We accept trade-ins of equal or lesser value under certain conditions. Simply click here to submit your gear for full consideration. We will only consider high-end equipment from mainstream manufacturers such as McIntosh, Mark Levinson, Audio Research, Krell, etc. and will typically pass on displays, projectors, receivers, dated surround processors, and mid-fi equipment of any type. We will offer a fair value for your equipment, but keep in mind we’re running a business and will need to be able to resell the equipment at a profit after investing a great deal of time and resources in testing, certifying, repairing, cleaning, and packaging the incoming equipment. If you’re looking for top dollar, we suggest selling direct on your own.

SELL US YOUR GEAR (Working or Broken):

We’ll also purchase your used or broken gear and arrange pickup if you’re in our local market. Simply click here to submit your gear for full consideration.

SCHEDULING AN APPOINTMENT:

We are currently operating from our shop inside our dedicated building in Glen Rock, NJ. You’re welcome to make an appointment if there’s a piece of equipment you’d like to see in operation before or after purchase. We have several well-equipped and dedicated listening areas, plus a dedicated listening studio with tons of equipment of all makes and models. We’re not a store, so please don’t make an appointment if you’re just curious as to how a speaker or piece of equipment sounds. In essence - no tire kickers please.

You can call or text 201-879-0000 with any questions or to schedule an appointment. We can also arrange to install, calibrate, and tune your newly purchased gear in your listening room if you’re local to our area. This is super useful when purchasing large speakers or heavy amplifiers. It’s also great for ensuring your new turntable is setup correctly in its final resting place.

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