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Description and reviews 
SA-250 Main Amplifier
The Plinius SA-250 Class A power amplifier was developed following the success
of the SA-50 and SA-100 power amplifiers. Additional enhancements in the SA-250
include a much larger power transformer, substantially increased storage
capacitance, and a larger number of high current capacity output devices.
Input configuration switching allows the SA-250 to be run as a fully balanced
mono power amplifier. Two SA-250s operated in this fashion provide 1000 watts
per channel of Class A balanced pure music!
The SA-250 is switchable to AB mode for non critical listening and to Class A
setting for critical listening.
The SA-250 is constructed in a
substantial all aluminium chassis with huge Plinius designed heatsink extrusions
forming the sides of the case. An oversized power supply is housed in the centre
of the unit supplying several specialised circuit boards to the sides of the
case.
Rated at 250 watts per channel in stereo mode, the SA-250 has an awesome current
capacity. Difficult loads are driven with ease, with low efficiency ones no
problem.
Input options allow for Stereo via RCA connectors, bridged mono through RCA
connectors, XLR stereo via XLR balanced connectors, or XLR balanced mono. Signal
carrying wires are all Siltech pure silver.
As with all Plinius products the SA-250 is available in both anodised black and
anodised silver finishes.
Specifications
Power: 250 Watts per
channel into 8 Ohms, 500 Watts per channel into 4 Ohms. 1000 Watts per channel
into 8 Ohms in bridged and true balanced mono modes.
Frequency Response: DC to -1dB @ 70kHz.
Distortion: Typically < .01% THD at rated power into 8 Ohms.
Current Output: 70 Amps short duration continuous per channel. Fuse
protected.
Hum & Noise: 100dB below rated output 20Hz to 20KHz.
Input Sensitivity: 1.1 Volt RMS at 1kHz for rated output.
Input Impedance: 100k Ohms
Power consumption: 300
Watts in A/B mode (at idle); 2000 Watts in class A setting.
Dimensions: Height 275mm (10"), Width 500mm (20"), Depth 540mm
(22"), Weight 65kg (145lb).
Input Options: RCA Stereo, RCA bridged mono, XLR Balanced Stereo, XLR
Balanced Mono.
The flagship of Plinius: the
SA-250. As you can see, the amount of high quality, robust circuitry in this
amplifier makes for quite a photo. Four toroidal transformers ensure all power
demands are met. The soft start circuitry and main filter capacitors take up
space on the power supply board. To the sides you can see the output transistors
bolted directly to the heatsinks, with the side boards fitted with more
reservoir capacitance as well as the main power amp circuitry.
Centrally located on the main
board are the input rail capacitors and regulation for the 3 different supplies
to the main board. The microcontroller circuitry can be seen at the front of the
amplifier. This includes the 'ecologic' and error detection circuitry, as well
as overload (distortion) protection. Up the back of the circuit board, similar
to the SA-100 is the mute and input switching. Notice the rest of the output
transistors bolted to the top of the heatsinks.
Reviews
THE ABSOLUTE SOUND'
August/September 2000
'Put simply, this is an
excellent power amplifier and the rival of some of the best around in its price
range. It is the fourth iteration of the extremely well-received PLINIUS SA-250,
which introduced the New Zealand audio company to the US audiophile market some
years ago. The Mk IV costs $8,495, which means it is a leading competitor in a
pretty demanding arena. Its best features are deep, powerful, tightly defined
bass, and excellent depth, but there is nothing it does not do relatively well.
'As for the ability to choose between Class-A and Class-AB, I suppose it is
useful to keep the amp warmed up with a low power drain, but any audiophile is
going to listen in full Class-A.
'The first thing I should say about sound is that the PLINIUS SA 250 Mk IV
really got my attention. At this price, I take, at the very least, good sound
quality in every aspect of performance as a given. The sound of the PLINIUS went
beyond the, "ho hum, another very good power amplifier" category. I 'm
not kidding about the bass. It performed superbly with the Wilson Maxx, Dunlavy
SC-V, Thiel 7.2, and Revel Salons.
'This is a great amp for deep
pipe organs, for the kind of space music that HP likes, and camp demos like the
Jennifer Warnes recording of the "The Hunter" [Private Music
01005-82089-2, bands 1 & 8]. This also is an amp that deserves the best in
speaker cables. I found that the Kimber Select and Transparent Audio Reference
XL series worked exceptionally and expensively well, as did the new top of the
line Discovery Cable, at a more reasonable price. This amp can really control
the speaker, if you give it a chance.
'Soundstaging was also striking; the Mk IV is a highly three-dimensional
amplifier, with an excellent balance of depth, width, image size, and image
stability. It approaches the best Conrad-Johnson tube amps in getting all the
depth out of recordings that have it.
'In sum, very impressive. A product from a designer who really loves music,
knows how to listen, and truly cares about soundstage quality.
Price $8,495
PAUL BOLIN COMMENTS
' I have been able to audition some high-quality amplifiers in the last two
years, both tubed and solid-state, but none with the PLINIUS' impact in the bass.
I initially hooked up the SA-250 Mk IV to the Silverline Sonata speakers. The
Sonatas' bass is quite amplifier-dependent, but the PLINIUS seized them in a
gorilla grip and took their usable response down further than I'd heard. "Journey
to the Line" from the Hans Zimmer's Thin Red Line [RCA
09026-63382-2] showed more depth and force when the Silverlines were powered by
the PLINIUS than any of the other amps I've used with them. On my reference
Apogee Duetta Signatures, the PLINIUS was in a class by itself in bass power and
control.
'I cannot recall hearing
another amplifier that can equal the PLINIUS in the breadth, depth, and height
of the soundstage - the SA-250 Mk IV is fully competitive with better monoblocks
in this regard. Definition to the back of the stage falls only slightly short of
the best tubed amplifiers I've heard. Images are palpable and rounded:
Instruments and voices emerge life-sized and three-dimensional. Nor does this
amplifier sacrifice substance for hyped-up detailing. Even when paired with the
Jeff Rowland Coherence II line stage, unsurpassed in my experience at low-level
detail retrieval, the PLINIUS never elevated parts over the whole except when
the recording required it.
'All of the PLINIUS components offer upper-echelon dynamic performance, but the
SA-250 is special even so. Even on my inefficient, power-hungry Apogees, the Mk
IV went nowhere near its limits, even at the loudest moments. One gets the
impression that if you mounted a magnet and voice coil to a barn door, the Mk IV
would drive it to 110dB without breaking a sweat. Yet for all its muscle, the
amp is also able to capture the delicate microdynamics of instruments such as
the piano. The PLINIUS SA-250 Mk IV is a lot of amplifier for its considerable
price - both physically and sonically. For those with difficult speakers or
large rooms, it may be the best choice. But anyone who likes power music
presented with lifelike dynamics and finesse should hear this mannerly
bruiser.
'1] Like AHC, I did
all critical listening with the amplifier in Class A. The amplifier runs
murderously hot in this mode, but requires only about ten minutes of warm-up
to sound its best. Class A adds an extra degree of refinement and smoothness
over Class AB, from the lower mids upward. I recommend it for serious
listening.
--------------------
Hifi+, Roy Gregory
july/august 2000
The massive reverberent "womp"
of the drum kit toppling onto the stage rang through the house, waking the
sleeping tortoise and raising clouds dust. Clouds of dust like the ones you can
almost see, pushed out sideways on the cushion of air that shoots from beneath
the falling drums. This isn't just about volume, although the results in that
respect are extremely impressive, it's about subtlety too. Upright, the whole
drum-kit becomes a shifting pattern of vibrating air and skin, vibrating planes
that are angled precisely in space.
...............
The problem is that
expectation is fuelled by many things, and second only to a row of foot high
heat sinks comes price. If the PLINIUS amplifiers respond with gusto to
excessive application of the volume control, then they play a more circumspect
game when it comes to pricing. Six grand is a great deal of money, but when it's
buying you 250 Watts of predominantly Class A power, then it looks like a
bargain. And bargains make people suspicious. After all, the US competition from
the likes of Krell and Pass are much more expensive. Never mind, if it makes you
feel any better, the PLINIUS SA-250 sells for $8495 plus sales tax in the US, a
market where it competes quite happily with the other $9000 designs. The same
$9000 designs that cost £9000 over here. So what's in a price? A lot of profit
I hear you say and whilst it isn't quite that simple, it's certainly a salutary
lesson in the fact that the retail price of a product is no guarantee of that
product's quality, with respect to its peers or the market as a whole. There is
a tendency amongst hi-fi's conspicuous consumers to dismiss 'cheap' product and
not take it seriously. And whilst the SA-250 can hardly be described as cheap,
to underrate it would be a serious error.
....................
Controls are minimal, but also extremely sensible. The front panel sees a pair
of toggle switches, on the left a mute and on the right a bias mode selector.
With any amp of this power a mute switch is a real benefit, both in allowing you
to manipulate cables and connections without endangering your speakers or output
stage, but also to prevent catastrophic reduction of those speakers by a mishap
or failure upstream. Of course, that wouldn't be a problem if you turned the amp
off between listening sessions, but you don't want to do that. I found that it
sounded better and better over a week long warm-up period: which brings us to
that second switch. This allows you to switch between Class A and Class A/B,
meaning that you can leave the amp idling between listening sessions, drinking
about as mush power as a light bulb, then flick it to high juice Class A just
before you settle down to play. It still takes about 20 minutes to really hit
its stride, but that beats the hell out of seven days. You can of course listen
in Class A/B (perhaps while you're doing the washing-up) but once you've
experienced the Class A option, I can't see why you'd bother. Why go to all this
trouble? Look at your electricity meter with the amp running in Class A and
you'll soon get the picture.
Round the back you'll find single-ended and balanced XLR connections, along with
a four position input mode switch. That's right, real megalomaniacs can bridge
the SA-250. One kilowatt anybody? There's also four speaker binding posts a side,
and a switch to float the chassis earth. Like I said, minimal but sensible. One
small point of interest, perhaps related to the amp's easy sense of musical flow,
is that it employs two transformers per channel, connected in parallel. The
original thinking was to reduce mechanical noise (smaller transformers are less
prone to hum) but PLINIUS soon discovered a sonic benefit out of all proportion
with the cost of the modification. And they're not the only ones to move in this
direction. Maybe it has to do with cancelling mains borne problems, but whatever
the reason it's a topology which seems to offer very real benefits.
...............
We already know that the PLINIUS amps do the big-amp thing with aplomb. The
thunderous crash from Dafos (Reference Recordings RR-12) is proof enough, as is
the startled tortoise (Albert was a-kip upstairs in a back bedroom, and for
those of you who don't major on wildlife documentaries, scientific opinion tends
to the belief that the average tortoise is stone deaf!!). Given speakers with
appropriate bass extension the SA-250 is capable of both high levels and massive
dynamic swings. But there's nothing earth-bound about this bass. The attack and
texture of the individual drum beats is perfectly portrayed, as is the vibrance
and decay of the skins.
It works on a grand scale too. The deep foreboding of the pulsing double basses
that underpin the mournful tuba solo which opens the 4th movement 'Fears'
of Shostakovich' 13th Symphony 'Babi Yar' (EMI ASD 391 1) hangs in the
room, the instruments breathing in unison to their bow strokes. The subterranean
bass drum rumbles menacingly. The PLINIUS floats the soundstage convincingly,
and it does so consistently, where the recording has captured it. The bass is
powerful and warm, natural, not overblown. It's a warmth that carries through
the mid-band but diminishes as you rise, leaving upper register percussion crisp
and poorly recorded violins exposed in all their digital anaemia. The better the
recording the better it sounds, and although the PLINIUS doesn't destroy
recordings, it reveals their shortcomings without necessarily highlighting them.
But it is at the opposite end of the scale that big amps so often stumble. The
Steeplechase recording Trouble In Mind (SCS 1139) captures Archie Shepp's
tenor sax in intimate, breathy close-up, and the PLINIUS delivers the goods. But
what really impressed me was the easy way it opened out Horace Parlan's phrasing.
He constantly stretches and massages the piano's contribution, lifting it away
from the role of accompaniment and engaging Shepp's lead. The SA-250/M16L
allowed the music to unroll in front of me, the timing of the sax's
interjections perfect, the shifting patterns of the piano alternately filling in
and making space.
The other thing that I really like about these amps is their generosity. They
show no particular preference for LP or CD, classical jazz or rock. They simply
get on with the job. Experimentation with the line-stage proved it to be
impressively unobtrusive, although for some reason it really didn't like the
Jadis JA100s. The impedances look alright, so I can't explain that one. But used
together they were unfailingly enjoyable and unflappable. They even coaxed a
decent soundstage out of the NHTs, which has been a problem in m listening room.
Used with the Ars Acoustica Divas it was positively huge, precise at the front
and very wide, but a shade shallower and not quite as airy as I'm used to with
the JA30s. Nor di music have the same immediacy and presence that the Jadis
produce. But the PLINIUS amps got a lot closer than I expected them to, and are
a world away from the sterile precision that I associate with so many of their
competitors. Close enough to lead to more than one much later than intended
listening session at a time when both Victoria and I could ill afford loss of
sleep.
.............
The PLINIUS SA-250 has made me reconsider my feelings toward heavyweight
solid-state amplification. It's refreshing to know that if I ever had to go this
route then there's at least one relatively affordable contender waiting to
entertain me. And that really is the bottom line. The PLINIUS pairing is without
significant musical flaws, and gets the all important mid-range right. It brings
a performance to life, it engages, it entertains and above all, it doesn't
obstruct. If you favour the ultra precise, almost clinical presentation of some
fashionable designs, you may feel the PLINIUS sounds rather, well, dated. I
think it sounds more like music and less like hi-fi. With the SA-250 in the
system, it reminds you, just often enough, just how much power you've got on
tap. It never lets that power intrude or dominate proceedings. Rather to my
surprise, I shall be sad to see it go.
--------------------
Ultimate Audio, Dayna B.
'I use Martin Logan CLS Iiz
electrostatic loudspeakers to see how well the SA 250 handled difficult loads.
The SLS drop to a rated impedance of 1.5 Ohm, but more significantly their
impedance oscillates rapidly during musical playback. In spite of these
difficulties the Plinius SA 250 ... performed in a spectaculary musical fashion.
.. The hights were sweet, the midrange was warm and the bass was solid and
thight. .. From the beginning the tonal accuracy was sweet and natural. The
timbral purity of the instruments was very real. The Plinius could reproduce all
the instruments of the orchestra with clarity and honesty. .. The woodwinds and
brass were exceptionally well created. .. The brass instruments had excellent
blat and burnish to their sound, adding excitement to the drama that unfolded.
... Saying it was a startling performance is an understatement. ... There was a
wholeness to the orchestra that made it easy to sense the mood of the
performance itself... . If the component is that good, I don't feel like
reviewing it. Naturally with 250 watts per channel there was never any sense of
strain to the sound. Dynamic impact was shocking, with clean striking transients
of rimshots and punchiness of the kickdrum.
I believe that the Plinius SA
250 is a serious contender for the best of high-current, high power amplifiers,
able to holds its own with the Levinsons, Krells, and Cellos of the world. The
bottom line is that unless you can use an excellent solid state design dot
augmenting the bass, you can't do much better than the Plinius. If you need lots
of power, but don't want to compromise naturalness of sound, I urge you to check
out the Plinius SA 250 for yourself. You can thank me later.
--------------
Peter Moncrieff, IAR, Tomorrow's
News Today
'The Plinius sound hits all
the high points that a very good solid state equipment should. It is very
transparent, and very clean, surpassing some of the big name solid state amps.
When listening to the Plinius system on its own,, one has the comforting sense
that all the music is being revealed, with non of the veiling truncated trebles,
or other sonic shortcomings we hear all to readily in most other solid state
amps. .. The Plinius sound is among the most musically neutral of solid state
amps, coming very close to the hybrid ideal. [The Plinius has] a subtle
distinctive musical sound, that sets it apart from other solid state products.
If you 'r looking for a massive, well built amp that sounds better than the best
from Levinson, Krell etc. you should take a listen to Plinius for yourself....' 'Some
amps [f.i. Plinius] are musically neutral, with a wonderfully neutral balance
between the best of solid state sound and the best of tube sound. Some (Levinson
33H, Krell FPB 300) try valiantly to smooth and soften the hard edge typical of
solid state, attempting to sound musical, but instead they only succeed in being
vailed and defocussed.'
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