ANALOG vs DIGITAL - Ultra High Fidelity Magazine

Our regard for Simaudio’s
Listening Feedback Room
Moon 330A Amplifier
talent for making power
amplifiers hardly needs
explaining, and it goes back
many years. Indeed, our three reference
systems are filled with them: a Moon
W-8 in the Omega system, a W-5LE
in the Alpha system, and, in the Kappa
(home theatre) system, a W-3 and a
W-4070SE. What we have long admired
is the company’s knack for making a
large amplifier that, at low volume,
sounds like a small one. Simaudio makes
large amps, but it hasn’t made many
monster amps, if you understand the
distinction.
But the amplifiers we’ve just mentioned
are breathtakingly expensive (in
the case of the W-8), or had sharply
rising costs before they were discontinued.
There are a number of reasons
for this. Simaudio cites the cost of
aluminum, though we suspect skilled
labor is probably a much bigger factor
(Simaudio’s factory is in Canada, not
China). The price-to-performance ratio
of the Moon amps remains high, but the
fact is that not everyone is going to go
for a $12,000 amp no matter how sweet
it sounds.
And that is the 330A’s reason for
being. It is considerably lower in price
than any recent Moon power amp, and
the design goal was to keep compromises
to a minimum.
The 330A is compact, much more so
than the giant amps already mentioned,
but its price tag is compact too, at
42 ULTRA HIGH FIDELITY Magazine
$3250. It is dense, however, heavier than
you might expect. It is moreover closely
related to all the amplifiers already mentioned
except the W-8, using the Renaissance
circuit that company founder
Victor Sima developed for his original
Celeste amps, and which his successors
continued to refine for years. It is fully
complementary, which means that, by
its very nature, it amplifies the positive
and negative part of the wave separately.
If you want to run one in balanced or
bridged mode, no extra circuitry is
needed, because it can operate that way
naturally.
A lot of the amplifier’s weight comes
from its toroidal power transformer,
which — as you can see from the picture
on the next page — also claims a good bit
of the innards. The eight output transistors
are of Simaudio’s own design, and
are closely matched, as they must be to
get the sort of low-level resolution that
has become a Moon trademark.
The case is flanked by two large
heat sinks. Seeing that heat rises, the
fins would seem to be the wrong way
around (vertical fins are more efficient),
but the 330A barely got warm even when
we pushed it…and we certainly pushed
it! Having examined the way the 330A
is built, we think much of the heat dissipation
is done through the slots in the
top, however, and we would hesitate to
stack anything on top.
The connectors are of good quality,
and include XLR jacks for balanced
operation. There are two “trigger”
jacks to allow a preamplifier or a surround
sound processor to turn multiple
amplifiers on sequentially — especially
useful in home cinema
systems. There is also
an RS-232 connector.
That’s pretty much a
dead standard in the
computer world, but
it is still used in some
multi-room systems,
including (of course)
Simaudio’s own.
Simaudio’s best-known amplifiers
have come with their own built-in
spikes (actually tiny cones). They could,
of course, scratch furniture surfaces,
but spikes are an effective means of
controlling vibration. No spikes here.
We thought at first glance that Simaudio
had bought the amplifier’s feet from the
same evil foot factory which seems to
supply them for audio manufacturers on
four continents. Not so. They’re metal,
not plastic. They’e still flat, though, and
if you want cones under your amp, you’ll
have to add them.
The machining and the fit and finish
is up to Simaudio’s usual standard, which
is to say first class. The jacks and the
binding posts are of good quality, and
there are of course XLR connectors
for balanced connection. There’s an
RS-232 serial plug, hardly ever found on
computers anymore, but still common
in multi-room systems. There are also
“trigger” jacks, to allow a preamplifier
or preamp/processor to turn on multiple
amps in sequence, to avoid blowing a
breaker.
The 330A has its own breaker,
though you won’t see it, because it is
self-resetting once a problem has been
resolved. It senses overheating and also
direct current in the output, but there
is no current limiting. That’s a good
thing, because in the past we’ve heard
current-limiting circuits that had highly
audible effects, and we don’t mean that
in a good way.
The 330A would have had little real
difficulty in driving the Reference 3a
Suprema speakers in our Omega system,
because it has, by most standards, plenty
of power, and the speakers are efficient,
but it would be a tough assignment
nonetheless, and the result might not be