magazine, Vol. 2, issue 1'1997
BEST AMPLIFIER? THE LAMM ML1.
From Brooklyn (via
Russia) with love. Hand-crafted in Brooklyn, much like vintage
Marantz gear, the ML1 blends old and new technology, East and West,
to forge a sublime statement in power amplification. It is in a
real sense a child of the times, as it owes its very existence to
the political cataclysm that has reshaped the former Soviet Union.
Democracy in Russia has
definitely impacted the U.S. audio scene. First, Russian tube
production has been flowing steadily westward. Brands such as Sovtek
and Svetlana have become as familiar to tube-o-philes as GE and RCA,
and have re-populated the ranks of quality power tubes. Tube types
unknown in the West because they were developed for military
applications (e.g., the 6C33C) are now generally available. And
second, the recent influx of Russian designers has greatly enriched
high-end praxis. Meet Vladimir Shushurin -- Mr. LAMM INDUSTRIES.
Here's a man with twenty years of electronics design experience and
an intimate knowledge of Russian tube technology. Who better than
Vladimir to extract the full sonic potential of the 6C33C--a brutish
looking power triode? From MIG jets and Russian tanks, this tube has
recently found its way into audio amplifiers.
The 6C33C tube is
awesome, almost frightening in stature-- not the kind of tube you'd
want to meet in a dark alley. It's not pretty-the glass envelope is
as appealing as a cow's behind--but it's rugged, can dissipate
considerable heat, and is noteworthy for an exceptionally low output
impedance. The latter is an important parameter for output
transformer-less (OTL) designs, and helps explain the recent
emergence of the 6C33C as the king of OTL tubes.
But Vladimir actually
believes that the 6C33C is even better for transformer-coupled
push-pull applications--the major benefit being a significant
reduction of the output transformer's turns-ratio. As less turns
translates into a much more extended bandwidth, an output
transformer's eternal struggle for extension at the frequency
extremes can be easily fulfilled with the 6C33C in the circuit. The
ML1 uses two transformers: an E-I core output transformer and the
toroidal power transformer that is suspended in a special
encapsulant which almost completely absorbs even the residual
mechanical vibrations and resonances. The amp's power supplies also
incorporate three chokes manufactured by Hammond.
The ML1 chassis is
generously proportioned, oversized by design--the idea being to
provide an adequate heat sink for the output tubes which generate
considerable heat. No sea of output tubes here. (Simper is usually
better, anyway.) Just a single pair of 6C33Cs is deployed to
generate a clean 80 watts of power in to 2, 4, and 8 ohm loads.
However, there's plenty of headroom--up to 180 watts on music
signal. The output stage is biased for rich-A class-AB operation.
Very little overall negative feedback is used.
Judging strictly from
its external appearance, it would be natural to mistake the ML1 for
an all-tube unit. It is in fact a sophisticated hybrid design.
Vladimir describes himself as basically a tube man who knows
transistors. Anybody who doubts that should check out his model M1.1
monaural power amp (see
Ken Kessler's review in Issue 6).
Innovation begins right at the input stage where a 12AX7 dual-triode
is joined by a Wilson current mirror consisting of all Motorola
transistors. The driver/buffer stage following the second voltage
gain stage (12BH7 twin triode) uses a quartet of Hitachi
high-frequency MOS-FETs. These devices are factory-matched and
operated at only a fraction of their rated dissipation. Instead of
recycling old circuits from the '50s or '60s, the ML1 marries
solid-state and tube technology in order to coax the best sound
possible from the 6C33C.
Meters and pots are
conveniently provided on top of the chassis to allow monitoring and
adjustment of the mains voltage, idle current, bias voltage, and
balance. At the flick of a switch you can monitor the operating
point and status of the amp. A long-blade screwdriver is
thoughtfully included as an accessory to facilitate pot adjustments.
Expect to have to tweak the bias and balance over the first fifty
hours or so of use; it takes about that long to break in the 6C33Cs.
After that, the operating parameters will stabilize, and you'll have
little to do for the next 10,000 hours or so of use--except enjoy
the music. However, operating the tubes beyond the recommended idle
current of 0.3 amps or at elevated AC line voltage will shorten tube
An extensive array of
protective features merits attention. First, a
"soft-start" circuit protects the power supply by limiting
large in-rush currents when the amp is turned on. Second, according
to Vladimir, the design notes for the 6C33C recommend a two-minute
delay in applying plate voltage after the filaments are energized to
prevent thermal shock and extend tube life. The ML1 incorporates
such a circuit. I know of no other designer that adheres to
recommended practice. Finally, there are several fuses provided. In
addition to an AC line fuse, there's a 1.25 amp fast-blow type
(internally mounted) in the plate circuit of the output tubes, and a
thermal resetting fuse controls the internal temperature of the
power transformer. I did pop the 1.25 amp fuse on one channel while
driving the amp hard. The maximum plate current is 0.75 amps, so
that the 1.25 amp fuse should in theory be adequate. However, when
the aC line voltage drifts above 120 volts, it's possible to pop the
fuse. To eliminate the inconvenience of having to remove gads of
screws to change this fuse, a 1.5 amp rated fuse will be used in all
future product. (LAMM note: this modification has already taken
As with any other power
amp, the ML1 needs proper care and feeding to reach its full sonic
potential. It should ideally be used on a dedicated AC circuit with
a high-quality power cord but without the intervention of isolation
transformers or any other line conditioners. Plan on about fifty
minutes of play before the amp will sound its best. It takes that
long for the chassis temperature to stabilize.
Furthermore, its diet
should consist primarily of moderate impedance loudspeakers. With a
source impedance of just over 1 Ohm, its damping factor into an
9-Ohm load is a respectable 7. And, more importantly, the damping
factor remains constant with frequency over the entire audio
bandwidth. With lower impedance loads, however, the potential for
more substantial load interactions exist, and current delivery also
becomes an issue. Peak current output is about 9.5 amps into 2 ohms,
corresponding to 180 watts. That ought to be adequate for all but
the most demanding of dynamic loads. A case in point is the PBN
Audio, which wasn't entirely enamored with the ML1. PBN's Montana is
a prime example of a loudspeaker that thrives on high-current
In the reference room,
and partnered by LAMM's exceptional L1 line-stage for reasons of
synergy, the story was considerably different. The Sound Lab A-1
ESL, a notoriously difficult load, went into a protracted orgasm.
Buckle up, folks, and
hold on to your listening seat: the ML1 is lightning quick.
Transients were unleashed without any discernible hesitation. With
all that speed came incredibly control and clarity of
expression--free from that unholy trinity of transistory treble
gremlins: brightness, hardness, and textural grain. Elucidation of
sibilants was exemplary. Early digital recordings, while still
unpleasant to the ear, were nevertheless accommodated without any
further insult. Rachmaninoff's Symphony No. 1 [Decca 411657-2] came
off better than ever before. The tempestuous character of the music
was readily conveyed while the various orchestral threads were there
for the picking.
Bass definition and
impact scaled new heights with the ML1. I couldn't believe my ears.
The A-1s really kicked. Tight, real tight, bass lines with an
amazing boogie factor, and enough crunch--I'd say about an 8 on the
Richter scale--to almost make me swear off dynamic speakers. No tube
amp in my experience is capable of this level of conviction through
the lower octaves.
With such a sure hand at
the frequency extremes, it was all the more surprising to realize
that the ML1 gift-wraps the midrange and hands it to you on a silver
platter. The critical midband was always suave sounding with an
innate feel for harmonic colors. Female voice as in Her Highness
Kathleen Battle's Baroque Duet with Wynton Marsalis [Sony
SK46672] was divinely velvety, sweet, and compelling--a veritable
gestalt of a singer in my room. Reproduction of the music's hidden
nuances--micro-modulation in volume and frequency--was so good that
Ms. Battle's full palette of expression was discernible.
Listening to Eric
Clapton's Unplugged album [Reprise, 9-45024-2], it occurred
to me that Vladimir and Tube God must have conspired on this one,
for suspended before me was an almost perfect fusion of solid-state
and vacuum tube virtues: quick attack, clarity, and visceral bass
combined with textural liquidity, Cezanne-like solidity in
portraying image outlines, micro-dynamic conviction, and a
remarkable feel for ambient clues. ...let me state that such tonal
balance neutrality is an admirable trait.
...So let me get back to
the rhetorical question raised in the title regarding "world's
best" stature. The point I'm trying to underscore is that
there's no such thing as a universal power amp. Any great amplifier,
as is the case with the ML1, can only sound great when mated with an
appropriate load. The underlying fallacy of any Recommended
Components list you care to name is the notion that Class A speaker
and amplifiers will perforce yield Class A sound. Audio is about
system-building, and that's where Fi comes in with specific
recommendations that leave nothing to chance.
...Despite its 80-watt
rating, the ML1's considerable headroom can deliver the goodies into
most real-world loads, including reactive loads such as the Sound
Lab A-1. Its iron-fisted bass control, textural suaveness, excellent
detailing, and transient finesse should earn the ML1 a buss load of
converts. It stacks up well against all contenders. Do try to
audition it with the LAMM L1 line stage, as this combination really
cooks. Looking at the price tag, it should be clear that this is an
amp for the working rich. Even though it's offered at a premium
relative to the likes of the Air Tight ATM-3, the ARC VT-150, and
the Conrad-Johnson Premier 8, the ML1 deserves your full and