Предусилители — Audio Research LS-3

The LS-3 is a solid-state line preamplifier from Audio Research, whose design takes its cue from the original LS3 line stage the company introduced in 1992. Instead of valves, the new model combines a fully balanced differential JFET input stage, a voltage amplifier built on bipolar transistors and output stages running in Class A. Its anodised aluminium case, finished in black or silver, is the same one used for the LS-2.

Key specs that matter

At the back there are six line inputs, two on balanced XLR sockets and four on single-ended RCA. Input impedance is 25 kohm for both types, and output impedance is 10 ohm balanced or 25 ohm single-ended. Audio Research gives a flat response from 10 Hz to 40 kHz within plus or minus 0 dB, measured on the balanced output into a 100 kohm load. THD plus noise is under 0.007% at 2 V RMS balanced output, noise is -75 dBV with the volume at its maximum setting of 99, and channel crosstalk reaches -82 dB. The front is 48.3 cm wide, the chassis stands 17.8 cm tall and 44.5 cm deep, and the unit weighs 15 kg net or 21.8 kg packed. Maximum consumption is 35 W on a 120 V AC, 60 Hz supply, falling to 4.2 W in standby. The balanced output keeps absolute polarity, while the single-ended output inverts it.

Engineering and use context

Audio Research lays out the signal path as dual mono, with a separate power transformer for each channel. Linear power supplies feed the circuit, and the voltage reference is designed without gain cascading, both choices aimed at keeping noise down. The aluminium chassis is engineered for stability and vibration isolation. A touchscreen on the front panel handles input naming and lets the owner change display intensity and colour, along with further operating functions.

Pairing

The preamplifier is sold in four configurations - on its own, with the DAC card, with the phono card, or with both cards installed. The DAC card is built around an AKM Velvet Sound converter and takes digital signals from USB, optical, coaxial and Bluetooth inputs, all of which are upsampled before conversion. The phono card works with MM and MC cartridges, with moving coil loading adjustable from 50 to 1,000 ohm by remote control. Power amplifiers can be driven over XLR or RCA, so models without balanced inputs remain an option.

Alternatives

The Audio Research LS-2 has the same input count but builds its line stage around two 6H30 dual triode valves.