|The Audio Research LS17
Preamplifier and the Grand Unified
Things tend toward integration; physics and
chemistry; gravity and quantum theory; and
perhaps more valuably for you and me, tubes
and transistors. While tube-ophiles and
transistor-ophiles argue ardently for the
relative merits of these two technologies, the
technologies themselves have gotten along
famously under the hoods of such storied
pieces as the Counterpoint SA-12/SA-100 and
more recently, the Moscode 401HR amplifier.
The former was my very first high-end
amplifier and to the best of my recollection,
was a marvelous symbiosis - marrying a
midrange slightly honeyed by a couple of 6DJ8s
to the potent, weighty bass of a solid-state
The Counterpoint SA-100, the Moscode 401HR,
and now the Audio Research LS17 pre-amplifier.
Yup, she’s a hybrid, and a beautiful one at
that; a lovely blend of JFETs and 6H30 super
tubes designed to capitalize on the best
properties of both.
While word count and training (intellect?),
limit me to a brief description of the
technicalities of such a fusion, a JFET or
Junction Field Effect Transistor has
particular objective advantages in
certain applications over, say, its bipolar
transistor cousin in that it offers a very
high input impedance (which makes for a good
input stage) and is less noisy/more linear
than bipolar transistors to boot. Some people,
not the least of whom are employed at the
Audio Research facility, apparently feel JFETs
have subjective advantages as well!
The 6H30 tube too, in the view of such
industry luminaries as BAT, and now Audio
Research themselves, offers gains over a 12AX7
or a 6DJ8 (more standard preamp fare)
including improved linearity and significantly
extended tube life; up to 5000 hours in the
case of the LS17 preamplifier.
Downsides? In a manner of speaking, that
“increased linearity” that looks so sexy on an
engineer’s oscilloscope, could translate, for
some, into less of that sexy tube sound.
Solid-state fans call this “neutrality” and
tube fans call this “if I wanted a solid-state
preamp - I would have bought one!”
Meet and Greet
The star of this show arrived well-packed and
intact - just the way I like ‘em. As a matter
of fact, the source of my LS17 informed me
they have not had an issue with significant
shipping damage involving an Audio Research
product in roughly a decade! Either that’s
some amazing luck or testament to the security
of ARC’s packing.
Having just hefted my trusty ModWright 9.0 SE
(now tube-rectified) off its perch on the
Apollo equipment rack, plucking the LS17 from
its Styrofoam cocoon, I noted immediately the
sharp contrast in weight of the two units. The
ModWright was considerably chunkier feeling
and made the ARC feel like a Technics receiver
or a “My First Sony” if you like.
Must be a case of the ‘hybrids’ I thought; the
ModWright being a tube unit through and
through (with a mighty toroid power supply to
boot). I popped the top on the 17 to inspect
and install the 6H30s and noted a sleek
interior layout utilizing AR’s proprietary
capacitors. I carefully installed the 6H30s
with the supplied tube dampers-- two per side-
and closed her up.
The LS17 entered a system comprising at
various times, a Lector CDP 7TL Mk. 3 CD
player, a Lector CDP 0.6T mk. 2 CD player, a
Parts Connection Level 2 Mod Raysonic CD128
player and depending upon my mood, an ARC
100.2 solid-state amplifier or a VTL ST-150.
Speakers were my usual Proac Response 2.5s and
my room is treated with Eighth Nerve Response
Series products. The system is wired with JPS
Labs cables, including bi-wire Superconductor+
Petite speaker cables and the remarkable
Superconductor 3 interconnects. The terrific
value-for-money Stereovox Firebird and Audio
Art cables get subbed in from time to time as
A word about these new JPS ICs-- they are
remarkable musical conduits, leaving
vanishingly small fingerprints on the signals
they touch. I’d love to review ’em- but to do
that, you gotta be able to describe what they
sound like. Good luck with that one--
damned if I can hear much of anything so far
but the often times starkly distinct
signatures of my other components and
that‘s as it should be. Truly a
laudable achievement, Joe!
Once settled into my system, the LS17 proved
remarkably reliable and easy to use. By way of
comparison with my ModWright pre, the 17 has
remote power on/off and a much more precise
and finely-graded 104 step volume attenuator.
This degree of precision with regard to remote
volume adjustment allows you easily to dial in
from the comfort of your listening perch the
exact level at which a particular recording
sounds most ‘live’. The coarseness of the
attenuation steps in using the ModWright’s
remote volume control (no issue with manual
operation of same) was one of my few gripes
with this otherwise wonderful pre and I
understand Dan’s more upscale unit, the 36.5
(which uses 6H30 tubes… hmmm), addresses this
issue handily. An upgraded volume control is
apparently available for the 9.0SE as well.
Since I had just finished breaking the LS17 in
for approx. 150 to 200 hours, and since it was
a sunny Sunday morning and since a certain
highly anticipated used Sony boxed set had
recently arrived from Amazon.com, I decided to
listen to Murray Perahia playing some Mozart
piano concertos - a lot of them! I immediately
noticed an increase in ‘ping’ and ‘hammer on
string’ in the upper registers of the piano,
along with a increase in the hall sound. The
LS17 had just turned on a few more lights in
the venue in which Perahia was performing.
Stage width and depth were roughly equivalent
to the ModWright player, though there seemed a
slight diminishment in terms of dynamic
fortitude - particularly microdynamic.
In other words, my initial impressions of the
ARC LS17 were that it portrayed more detail
than my ModWright pre, though was a bit more
delicate- a bit more reserved dynamically.
As I listened more widely over the next few
weeks, to everything from John Lee Hooker, to
‘We Three’ [Prestige/New Jazz PRCD-30162], a
new Prestige re-master, the differences in the
ARC and the ModWright sound came to be
patently apparent. Essentially, the ModWright
sounded more like you’d expect an excellent
tubed preamp to sound and the ARC sounded
more akin to some of the excellent
solid-state preamps I‘ve heard in the
In almost all of the recordings I listened to
where a concert hall was the recording venue,
the ARC pre lit up more of the hall itself.
The placement of singers within that space was
more precise than via the ModWright and
instrumental outlines were sharper. I could
more easily place the locations of singers
involved in duets and quartets etc.
The ARC showed me that the ModWright does make
some attempt to please its owner by warming up
the mids/midbass a bit. Comparatively, the
ModWright also slightly blurs the focus - but
just slightly - as compared with both the
excellent solid-state preamps I’ve heard and
more germanely, as compared with the LS17.
Mind you, I make no value judgment in terms of
these perceived differences. I am certainly
not of the “accuracy is best” school. I am in
fact increasingly of the “the sound that most
appeals to me is best” school and try to
recruit members all of the time for same.
Continuing, while the ModWright seemed to have
more midbass weight and thereby could be more
‘dramatic’ with certain symphonic works etc,
it seemed to have perhaps a slightly softer or
at least somewhat less prominent and defined
lower bass than the LS17. The very
lowest bars on the stringed bass in Bill
Evans’ “Sunday at the Village Vanguard” for
example, seemed to shake things around the
room a bit more via the LS17 than via the
The ModWright on the other hand, seemed to
have, as previously noted, the edge if not in
macro dynamics, then in microdynamics. String
quartets such as the Emerson’s playing of
Schubert’s work [DG 289 459 151-2] seemed more
dynamically nuanced via the ModWright. It was
the same with the Mozart’s piano concertos.
They seemed a little more ‘lively’ via the
The SWL9.0SE though has achieved its
well-deserved following due in no small
measure to its superb dynamics and gusto, so I
kind of expected this. In fact I haven’t
really heard too many preamps surpass or even
equal my ModWright dynamically and that
includes the delightful, though less weighty
and punchy Shindo Aurieges L I heard recently.
Viva La Difference
During my time with the ARC LS17, it served as
the nerve center for systems comprising both a
solid-state amp and a tube amp along with
three different CD players. Changes among
components were quite apparent via the
ModWright. They were even more starkly so via
the ARC. This preamplifier is quite revealing
of sonic differences among ancillaries,
immediately revealing the tonal and spatial
differences between my assorted amps, wires
and CD players.
I gradually began to feel that, like a good
therapist, the LS17 seemed not to want to tell
me too much how to live or what to do, but
rather to let my system be more or less itself
and speak with its own voice.
Along these lines, the LS17 made recordings
sound more drastically different from one
another than I’m used to. For example, Mitsuko
Uchida’s rendition of the Beethoven Emperor
piano concerto under the baton of Kurt
Sanderling [Philips 289 462 586-2] was
revealed to be notably worse than I thought!
Via the ModWright it was reasonable - not
great - but reasonable. Via the LS17 - well,
it was uninteresting at best; un-dynamic, flat
and poorly balanced; an unmistakable mistake.
Uchida’s touch is wonderful in it too (if a
shade too delicate for my tastes as compared
with say, Eugene Istomin); a shame.
On the flip side, it wasn’t until I heard it
via the LS17/VTL combo that I realized what a
great re-master of the 1952 performance of the
Beethoven ’Eroica’ with Furtwangler at the
helm [EMI 7243 5 67490 2 3] was-- terrific
instrumental texture with absolutely no edge!
And on it went, with John Mayer’s Continuum
[Aware/Columbia 8287 679019-2] sounding more
human and reach-out-and-touch-it than I’d ever
heard it before and Menuhin’s older violin
concertos sounding more brittle than I’d ever
heard them before. Two edges to this
Colors of the Wind
The Audio Research LS17 is certainly among the
finest pieces of gear I’ve heard in terms of
disappearing into a system. It does not have
the crystalline clarity of say, the Sonic
Euphoria PLC preamp (now discontinued) I heard
a few months ago, but then again in my system,
the LS17 is more dynamic than that unit was
and makes for a more involving listen. By the
way, a lack of dynamic punch is in my book
subtractive - preventing me from calling
something like the PLC, with as much detail as
it portrays, entirely transparent to the
In broad terms, the ARC did not sound quite as
warm as my tube-rectified ModWright SWL 9.0
SE, and lacked just a bit by comparison in
terms of drama and perhaps even scale at
times. It countered though, with noticeably
greater focus, detail and instrumental
separation, along with perhaps a touch more
low bass and better definition thereof.
The ModWright imposed more of itself on the
sound and as such, with say my VTL amp and a
Lector player in the system, could therefore
contribute to a touch too much warmth at
times. Similarly, albeit to perhaps a lesser
degree, the ARC in combination with the
solid-state amp and the more detailed Raysonic
player could be a bit over the top up top
with certain recordings.
Trouble is - I was shamelessly and inexcusably
not invited to any of the recording sessions
depicted by my CD collection, and therefore
can’t for the life of me tell you how any of
them are really supposed to sound -
just how they‘ve sounded on various systems
I‘ve heard through the years.
The fact that the ModWright and pieces like
the Sonic Euphoria do some things better than
the LS17 prevent me from using overused
phrases like ’totally transparent’ and
‘nothing between you and the music.’ In
absolute terms then - I know there is yet more
on my recordings.
However, I suppose the ARC LS17 is the kind of
piece that had me trying somewhat hard to
describe its specific sonic signature-
particularly as it relates to tone - from the
get go. In this sense, I did not find it
emotional or colorful or what have you.
Rather, I found it a well built, suavely
functional box that had an above-average knack
for telling me how colorful or emotional the
rest of my boxes were. If this is the essence
of what a preamp is supposed to do, then the
ARC LS17 does it beautifully.
As always, I bid you peace.
+0-3dB, 0.5Hz to 160kHz at rated output
(Balanced, 200k ohms load)
Distortion (THD) Less than .01% at 2V RMS BAL
Noise & hum 2.2uV RMS residual IHF weighted
balanced equivalent input noise with volume at
1 (101 dB below 2V RMS output).
Gain Main output: 18dB Balanced output (12dB
Record output: 0dB (Processor input: 0dB SE).
Input impedance 120K ohms Balanced, 60K ohms
Output impedance 700 ohms Balanced, 350 ohms
SE Main (2). 20K ohms minimum load and 2000pF
Output polarity Non-inverting.
Maximum inputs 24V RMS BAL.
12V RMS SE.
Rated outputs 2V RMS 1Hz to 100kHz into 200K
ohm balanced load (maximum balanced output
capability is 15V RMS at less than 0.5% THD at
Power supplies Electronically regulated low
and high voltage supplies. Automatic 50 sec.
warm-up/brown-out mute. Line regulation better
Tube complement (2) 6H30 dual triode. (Hybrid
JFET/tube audio circuit, solid-state power
Power requirements 105-130VAC 60Hz (210-260VAC
50/60Hz) 50 watts maximum.
Other Rotary volume selector (104 steps, 20
LED indicators) and rotary input selector.
Push buttons: Power, Monitor, Proc, Mute. Also
remote buttons: Bal 1, Bal 2, Aux, Tuner, CD.
Dimensions 19" (48 cm) W x 5.25"(13.4 cm) H
(standard rack panel) x 12"(30.5 cm) D.
Handles extend 1.50" (3.8 cm) forward of the
Weight 13 lbs. (5.9 kg) Net; 23 lbs. (11.5 kg)
3900 Annapolis Lane North
Plymouth, Minnesota 55447
Phone: (763) 577-9700
Fax: (763) 577-0323