Audio Research LS27 User Manual
Preamplifiers are strange creatures. If your gear doesn’t suffer from impedance
mismatches and you don’t use a turntable, you don’t really need one. Do you
need a separate box for volume attenuation? Many of today’s D/A converters and
CD players have volume controls. Of course, a simple potentiometer will also do
the trick. Do you need source selection? Just add a simple switch. Indeed, some
audiophiles assert that, in the age of computer-based audio, the optimal sound
will be achieved with no preamp at all.
mismatches and you don’t use a turntable, you don’t really need one. Do you
need a separate box for volume attenuation? Many of today’s D/A converters and
CD players have volume controls. Of course, a simple potentiometer will also do
the trick. Do you need source selection? Just add a simple switch. Indeed, some
audiophiles assert that, in the age of computer-based audio, the optimal sound
will be achieved with no preamp at all.
Yet, for the sake of convenience, not to mention tradition, most audiophiles are
reluctant to do without a preamp. If that’s how you feel, whether or not to get a
preamp is only the first decision you’ll have to make. You next have to figure out
which preamp to buy, and that’s where it gets tricky. A preamp can have an enormous
impact on a system’s sound. And unlike, for example, some source components, a
preamp can be devilishly difficult to match to your system.
reluctant to do without a preamp. If that’s how you feel, whether or not to get a
preamp is only the first decision you’ll have to make. You next have to figure out
which preamp to buy, and that’s where it gets tricky. A preamp can have an enormous
impact on a system’s sound. And unlike, for example, some source components, a
preamp can be devilishly difficult to match to your system.
So after experimenting with a few preamps in my system, all of them from reputable
audio manufacturers, I decided that the subject of this review would be a preamp
made by a company known for building great ones — and Audio Research Corporation
couldn’t be a better example of such a company. Not that it doesn’t make fine
power amplifiers, disc players, and DACs (I own an ARC DAC8), but when you think
of Audio Research, you first think of preamps, particularly tubed preamps.
audio manufacturers, I decided that the subject of this review would be a preamp
made by a company known for building great ones — and Audio Research Corporation
couldn’t be a better example of such a company. Not that it doesn’t make fine
power amplifiers, disc players, and DACs (I own an ARC DAC8), but when you think
of Audio Research, you first think of preamps, particularly tubed preamps.
Not too long ago, Audio Research introduced the LS27 preamplifier, to replace the
outgoing LS26. Retailing for $6995 USD, the LS27 comes below the company’s
Reference 5 ($11,995) and above the LS17 ($3995). If you’re interested and/or very
wealthy, ARC stopped taking orders for the limited-edition Reference Anniversary
preamp ($24,000) in April.
outgoing LS26. Retailing for $6995 USD, the LS27 comes below the company’s
Reference 5 ($11,995) and above the LS17 ($3995). If you’re interested and/or very
wealthy, ARC stopped taking orders for the limited-edition Reference Anniversary
preamp ($24,000) in April.
Features
The LS27 weighs 16.3 pounds, measures 19”W x 5.25”H x 13.3”D, and comes with
a three-year limited warranty (90 days on the tubes). The front panel has two
microprocessor-driven rotary controls: with the first, the volume can be adjusted
for both channels simultaneously; the other knob selects among the LS27’s six
inputs: CD, Video, Auxiliary 1 and 2, Tuner, and Phono. The front panel and remote
control both have buttons for power on/off, mute, processor pass-through (which
lets you use an external home-theater processor), volume up/down, balanced or
single-ended inputs, mono/stereo, and monitor (which routes the monitor input
signal to the main outputs).
a three-year limited warranty (90 days on the tubes). The front panel has two
microprocessor-driven rotary controls: with the first, the volume can be adjusted
for both channels simultaneously; the other knob selects among the LS27’s six
inputs: CD, Video, Auxiliary 1 and 2, Tuner, and Phono. The front panel and remote
control both have buttons for power on/off, mute, processor pass-through (which
lets you use an external home-theater processor), volume up/down, balanced or
single-ended inputs, mono/stereo, and monitor (which routes the monitor input
signal to the main outputs).
Via only the remote, you can adjust the LS27’s display to one of nine brightness
levels, adjust the levels of the left and right channels, keep track of how many
hours the tubes have been used, adjust the gain for each of the six pairs of discrete
inputs (high, medium, low), and invert the absolute phase of the output signal.
levels, adjust the levels of the left and right channels, keep track of how many
hours the tubes have been used, adjust the gain for each of the six pairs of discrete
inputs (high, medium, low), and invert the absolute phase of the output signal.
The rear panel has eight pairs each of balanced and single-ended connectors for the
aforementioned inputs, as well as the monitor and processor inputs. There are also
two sets each of balanced and single-ended main outputs, a tape record output,
a 12V trigger, a 15A IEC connector, and a fuse bay.
aforementioned inputs, as well as the monitor and processor inputs. There are also
two sets each of balanced and single-ended main outputs, a tape record output,
a 12V trigger, a 15A IEC connector, and a fuse bay.
The LS27 is a pure class-A design with zero feedback and a fully regulated power
supply. The internal circuitry and connections are differentially balanced. Gain is
provided by a hybrid audio circuit that includes JFET transistors and two 6H30
triode tubes, the latter rated by their manufacturer to last for 10,000 hours of use.
Dave Gordon, ARC’s director of sales, states that the optimal dynamic performance
supply. The internal circuitry and connections are differentially balanced. Gain is
provided by a hybrid audio circuit that includes JFET transistors and two 6H30
triode tubes, the latter rated by their manufacturer to last for 10,000 hours of use.
Dave Gordon, ARC’s director of sales, states that the optimal dynamic performance
Audio Research
LS27 Preamplifier
www.SoundStageHiFi.com
p1
"Lacking serious sonic
faults and exceeding my
expectations for its price..."
October 1, 2011