Audio Research LS28SE Linestage Preamplifier

The LS28SE line stage is a flexible and intuitive preamplifier. Four balanced and four single-ended inputs, and two sets of both balanced and single-ended outputs, allow maximum connectivity. The straightforward menu allows control of numerous parameters, including input naming, tube hours, auto shutdown, and home theater passthrough. Phase invert and mono are also standard functions.

At the heart of the LS28SE are four 6H30 vacuum tubes in the analog circuit. While the LS28SE is the perfect match for any Audio Research amplifier, it has been designed to work with nearly any amplifier on the market today.

The improvements in the LS28SE stem from what was learned during the creation of Audio Research’s Reference 160-series amplifiers. Very similar to the wire and parts changes incorporated in the REF6SE and REF PH3SE, the LS28SE also includes upgrading to the same proprietary gold coupling caps used in the REF6SE. These numerous and costly component upgrades elevate the LS28SE’s performance to an entirely new level.

The improved clarity, resolution, transient snap, sense of space, and a relaxed purity are instantly noticeable and will inspire extended listening sessions.

Audio Research is pleased to introduce the Foundation Series. From the same engineering and design team responsible for the award-winning Reference Series, the Foundation family of vacuum tube components has been created to provide incredible musical experiences. Spatial definition, dynamics and detail abound while providing the most natural musical experience.

Since 1970, High Definition has been more than ARC’s trademark; it has been their guiding principle for all products. The Foundation Series continues this passion and philosophy, offering the listener stunning playback, great value, and unparalleled long-term support.

All products at Audio Research follow the exact same path from concept to production, regardless of the series or model. The Foundation Series shares the same lineage, build quality, and many design characteristics found in the more costly Reference Series. The result is a consistency in the Audio Research sound, and the ability to create a range of components which offer exceptional performance and value.

• FREQUENCY RESPONSE: +0-3dB, 0.4Hz to 200kHz at rated output (Balanced, 200k ohms load)
• THD+NOISE: Less than .007% at 2V RMS BAL output.
• NOISE: Less than -100dBv at max volume (103).
• DYNAMIC RANGE: 122dB (AES17).
• CROSSTALK: -105dB
• GAIN: Main output: 18.5dB balanced output. (12.5dB SE output.) Record output: 0dB (Processor input: 0dB balanced out).
• INPUT IMPEDANCE: 100K ohms Balanced, 50K ohms SE. 8 Inputs – 4 balanced, 4 single-ended.
• OUTPUT IMPEDANCE: 600 ohms Balanced, 300 ohms SE Main (2), 20K ohms minimum load and 2000pF maximum capacitance. Outputs (3): 2 Main, 1 Record (XLR and RCA connectors).
• OUTPUT POLARITY: Non-inverting.
• MAXIMUM INPUT: 16V RMS BAL, 8V RMS SE.
• RATED OUTPUTS: 2V RMS (1V RMS SE) into 200K ohm balanced load (maximum balanced output capability is 17V RMS at less than 0.5% THD at 1kHz).
• CONTROLS: Rotary volume selector (103 steps) and rotary input selector. Push buttons: Power, Menu, Enter, Mono, Invert, Mute
• POWER SUPPLIES: Electronically regulated low and high voltage supplies. Automatic 45 sec. warm-up/brown-out mute. Line regulation better than .01%.
• TUBE COMPLEMENT: (4) 6H30P dual triode.
• POWER REQUIREMENTS: 105-125VAC 60Hz (200-250VAC 50/60Hz) 130 watts maximum.
• STANDBY: 2W
• FREQUENCY RESPONSE: ±.2 dB of RIAA, 5 Hz to 20kHz; 1 dB points below 0.3Hz and above 80 kHz.
• DISTORTION: Less than .015% at 3V RMS 1kHz output.
• GAIN: 55 dB at 1 kHz
• INPUT IMPEDANCE: Selectable loads: 47k, 1000, 500, 200, 100 Ohms.
• OUTPUT IMPEDANCE: 200 ohms. Recommended load 50k-100k Ohms and 100 pF. (10k Ohms minimum and 2000 pF maximum).
• OUTPUT POLARITY: Non-inverting.
• MAXIMUM INPUT: 80 mV RMS at 1kHz.
• RATED OUTPUTS: 0.5V RMS 10 Hz to 60 kHz, into 100K ohm load (maximum balanced output capability is 0.46V RMS at less than 0.5% THD at 1kHz).
• CONTROLS: 6 Push Buttons: Power, Menu, Option, Enter, Input, Mute.
• POWER SUPPLIES: Electronically regulated low and high voltage supplies. Automatic 2 minute warm-up/brown-out mute. Line regulation better than .01%.
• NOISE: >77 dB, shorted inputs.
• TUBE COMPLEMENT: (3)-6H30P dual triodes, plus (1 each) 6550WE and 6H30P in power supply.
• POWER REQUIREMENTS: 100-125VAC 60Hz (200-250VAC 50/60Hz) 120 watts maximum.
• Standby: 2 watts.
• DIMENSIONS (WHD): 19” x 6.5” x 13.7” Handles extend 1.6” forward of the front panel.