|
Specifications:
● Design: Integrated; 75 Watts RMS x 2
into 8 Ohms, 150 Watts RMS x 2 into 4
Ohms
● Connections: Three Sets of RCA Inputs;
One Set of Speaker Binding Post
Outputs
● MFR: 10 Hz - 120 kHz
±
3 dB
● THD+N: 0.01%; 20 Hz - 20 kHz
● S/N: 96 dB
● Dimensions: 4" H x 17" W x 14.3" D
● Weight: 28.6 Pounds
● MSRP: $1,040 USA
Burson Audio |
|
Introduction
Burson audio began 10 years ago in Melbourne, Australia, as a DIY
cooperative producing components for their members. Just two years ago, they
introduced their first commercial product.
Most of their product line
is aimed at the DIY market, with op-amp replacement modules made entirely of
discrete components, all discrete voltage regulators, and a low jitter clock
module upgrade. In addition, they make interconnect cables and three
complete products, the Burson Audio Buffer (a unity gain buffer with
discrete op-amps), the new P-100 preamplifier, and the PI-100 integrated
amplifier reviewed here.
The PI-100 is available as
a complete component, or in bare-bones version where the user supplies the
power transformer.
Burson's philosophy is based on circuits built entirely of discrete
components. No integrated circuits are used in the signal path, and special
care is paid to the design of discrete voltage regulators and discrete
op-amps. These parts, built from individual transistors, have the same
function as an IC voltage regulator or op-amp, but take hours of hand
soldering dozens of components. The advantage is the ability to tailor the
design to the application, with performance exceeding that of generic IC
designs. All transistors can be carefully matched for the best performance.
When replacing dual or quad
IC op-amps, discrete fabrication also reduces crosstalk (if done correctly).
The disadvantage is a vast increase in parts count and complexity. Usually,
only the most expensive components offer fully discrete construction, as is
found in the PI-100. For a thousand bucks USA, this is very unusual.
The small size of the company and DIY heritage make ordering a bit more
difficult for US customers. Burson sells their products directly from their
website, and on E-Bay. They have organized service locations in many
countries, including two in the USA.
As far as I know, no
warranty is offered. Shipping costs are a bit steep, but that is more than
made up for in the low cost of the amplifier itself. The packaging of the
review unit was also a bit strange, with hand cut pieces of Styrofoam that
left crumbs all over the amp, and no manual (or paperwork of any kind for
that matter) included.
The review unit came with
"120V" written in permanent marker on the top panel of the amp, which I
cleaned off with some adhesive remover. While these are small issues, they
are also easy to fix for Burson, and will make the first impression of their
products much better. While the $1,040 purchase price is quite low for an
amp of this quality, it's still a thousand dollars. The PI-100 deserves
better quality packaging, a well-written users manual, and a pristine
component upon unpacking. The DIY background of the company still shows
through.
Design and Construction
The PI-100 uses a minimalist design, with as few bells and whistles as
necessary to maintain function. The amp has three single-ended inputs, one
of which is a unity gain input that bypasses the volume control for use as a
power amplifier with a separate preamp, or with a surround sound processor.
The front panel has a source selector switch and volume pot (unlabeled), and
a power switch. The rear panel offers two sets of five-way binding posts for
speaker connection, 3 pairs of RCA inputs, and an IEC jack for AC power. No
extras like line level pre-outs, an extra set of binding posts, a tape loop,
muting, a remote etc. are offered. This is a conscious decision that rings
true with the Burson philosophy: no unnecessary features should be included.
Extra toys will only decrease the performance of the amp and increase its
cost.
Unusually, the case of the
PI-100 is custom made. Most manufacturers purchase the chassis from another
manufacturer. The PI-100 case is made by hand, out of five pieces of
aluminum plate and a thick, machined aluminum front panel, all secured with
four corner blocks. The result is a nice looking case, but with a little
more flexibility than I would like. Also, the case seems to be made of raw,
un-anodized aluminum that could require periodic cleaning to maintain an
attractive appearance.
The simplicity of design continues on the inside of the PI-100. The power
supply, including the power transformer, are in a separately shielded box
placed on the left side of the amplifier chassis, connected to a single PC
board on the right side of the amp. An aluminum heat spreader runs down the
center of the chassis, to which the output transistors are bolted. The PC
board is laid out in a dual-mono fashion, with relay switched inputs, at the
rear of the board. A fully discrete voltage regulation stage (one each for
the right and left channels), based on the design of the Burson Super
Regulator DIY upgrade module, is on the center of the board. This regulation
stage includes 40,000 µF of
capacitance ("B" in the photo below). The voltage gain stage, which is
normally based on an IC op-amp in most audio circuits, uses a fully discrete
topology (blue area surrounding "D" in the photo), similar to that used in the Burson Discrete Op-amp. The output
of this gain stage is then routed through a relay for speaker short circuit
protection, before heading to the final current gain stage ("E").
The quality of the
electronics in the PI-100 is beyond reproach. The board, layout and assembly
quality are exceptional. A wire caused my only quibble with the internal
assembly. The wire from the volume pot was trapped between the front panel
and bottom panel. This was easily fixed by removing some of the screws
holding the case together to free the wire.
Both the flexibility of the chassis and the trapped wire still were a
somewhat annoying reminder of the PI-100's DIY heritage. As with the
packaging and lack of manual, these are easy problems for Burson to fix, and
would go a long way towards eliminating the "almost done" impression of the
product. Other than the few packaging and quality control issues I found
with the PI-100, I was very impressed with the design, and hoped upon
listening that the minimalist design of the PI-100 resulted in spectacular
sound.
The Sound
I broke in the PI-100 with casual home theater listening for several weeks
before doing any critical listening. I left the amplifier on all the time.
As there were no pre-outs, I did not use the Gallo Reference SA subwoofer
amplifier, and drove only the primary voice coil of the Reference 3.1s with
the PI-100. I was immediately struck by what wasn't missing from the
presentation. My new Emotiva separates I bought after my last review are
spectacular components, that offered vast improvements in almost every way
compared to the Plinius 8150i integrated they replaced. There was nothing
about the PI-100 that struck me immediately as negative compared to the
Emotivas.
As I listened to the PI-100 more, I found several areas where the PI-100
excelled. Even though I was not using the Gallo subwoofer amplifier, the
bass performance was still very good, with great impact, weight, and
extension. Only the last octave at the low end suffered, as you would
expect. Without the Reference SA, the bass power and agility of the PI-100
was superior to that of the Emotiva RSP-1/RPA-1 combo. I could imagine that
with the Gallo amp, the bass might be too much, though. Take this into
account of your system already suffers from bass bloat.
The most impressive area of the PI-100's performance was in the accurate and
detailed presentation of timbre. Each of the PI-100's images had a
three-dimensional size, shape, and texture that were particularly
compelling. Whether it was Connie Kay's brushes on a snare, or acoustic
guitar on the Mexican rock band Café Tacuba's Vale Callampa, the
PI-100 not only reproduced the sound accurately, but the space around the
sound. The tonal texture allowed me to hear each wire of the brush on the
snare head, or the fingers moving along the neck of the guitar in a very
real and visceral way. While the Emotivas offered a cleaner, more precise
presentation of images, with fantastic tonal separation outlining every
sound, they were not able to offer the holographic 3D presentation of the
PI-100. By comparison, the Emotiva pair produced images that were precisely
located and delineated, but were a bit flat. Note that in the Emotiva
review, I praised the RSP-1/RPA-1 for this same trait, compared to my
previous Plinius 8150. The PI-100 moves this reproduction of texture to a
new level, with even more texture extracted out of every image. This is one
of the advantages of a design with very few components in the signal path.
In the soundstaging and imaging department, the PI-100 produced larger, more
realistically sized images, at the expense of pinpoint imaging accuracy.
Combined with the timbral presentation mentioned above, this resulted in
extremely realistic presentations, especially when the source material was
small in scale, like solo voices or instrumentals and small combos. With
larger scale recordings, the large image sizes could cause some spatial
confusion. Presentation of soundstage depth was excellent, and superior to
the Emotiva pair.
Depth presentation depends
very much on the accurate presentation of tonal cues, so I would expect that
the PI-100 would do well here, and it did. On many recordings that sounded
relatively planar with the Emotivas, the PI-100 was able to extract plenty
of depth information. The Emotivas did win on soundstage width and height,
with a significantly wider and taller presentation.
The midrange and treble smoothness of the PI-100 were excellent. I never was
reminded that I was listening to a sub-$1000 solid-state component. The
tonal purity was unaffected by any sort of grain or hardness that wasn't
already there from upstream sources. Both the midrange and treble were
perfectly liquid and smooth, without being TOO liquid or smooth. Some
components (not all tube, by the way) take the smoothness thing too far, and
end up killing the excitement and attack of the music where some harshness
should be there. I tested this with one of my favorite big band recordings,
Telarc's Dedicated to Diz. As a longtime bass trombone player in big
bands in secondary school and college, I know what a big band brass section
should sound like. Many times, the point is to sound the opposite of "liquid
and smooth." A stereo component needs to accurately convey this brass bite
when called for, without diluting it in candy-coated sweetness. The PI-100
does the job, bringing out the power of Slide Hampton's all-star big band in
this album.
The macro-dynamics produced by the PI-100 were particularly impressive for
an amplifier with only 75W per channel. There was some loss in slam and
attack in the low range, with no detectible loss of impact in the midrange
and treble when compared to the Emotivas. The Emotivas did produce a bit
more life and excitement in the music, leading me to conclude that the
PI-100 was bested in the area of micro-dynamics. This is not to say the
PI-100 sounded unexciting, but it did give up a little in this area compared
to the best amplifiers I have heard. Of course, the best amplifiers I have
ever heard are, shall we say, just a bit more expensive to say the least.
Conclusions
With all the characteristics taken into account, I can safely state that the
PI-100 is an excellent integrated amplifier, equaling and besting amplifiers
costing 3-5 times more. It has essentially no sonic shortcomings. The
description I give above reveals some details of the presentation that I
might prefer to be otherwise, but there are no clear flaws of any kind.
The real question is if the
minimalist design of the PI-100 meets your needs in a system context. For
me, it does not. There just aren't enough inputs, or any line level outputs
to properly drive my subwoofer amplifier. There is also the issue that the
PI-100 cannot really be auditioned in advance, nor can it be easily
returned.
Some might be bothered by
the DIY image of the amp as well. But, for me, sound quality ALWAYS trumps
appearance. If I had a simpler, two-channel-only system as I had in the
past, the PI-100 would have been perfect. If you have the luxury to have a
second two-channel-only system, or would like to build one at a reasonable
cost, the PI-100 is a great, no frills component that can be the core of a
fine system.
It would also be the
perfect integrated for someone's first real Hi-Fi setup. A PI-100 combined
with a quality universal disc player, and monitor-class speakers could make
a fabulous $2000-$3000 stereo system. I eagerly await future components from
Burson, like the new P-100 preamp. This hobby needs more performance for
less cost, and Burson is helping to deliver.
-
Chris Groppi -
Associated Equipment:
Source
Components:
Oppo Digital DV-981HD Universal disc player
Bel Canto DAC-1.1 Digital to Analog Converter
Linn LP-12 Valhalla, Ittok LV-II, Grado Reference Platinum
Amplification:
Acurus 3x100 3-channel power amplifier (center, rears)
Anthony Gallo Acoustics Reference SA subwoofer amplifier
Video Components:
Rotel RTC-965 Surround Sound Processor
Directv HR-20 HD-DVR
Westinghouse LVM-37W1 1080p LCD panel
Loudspeakers:
Anthony Gallo Acoustics Reference 3.1 (left, right)
Anthony Gallo Acoustics Reference AV center (center)
Anthony Gallo Acoustics A'Diva (rear)
Power Conditioning:
OneAC 1920VA Isolation transformer
Cables:
Nordost Red Dawn speaker cables
Nordost Flatline Gold MK-II speaker cables (2nd voice coil for Reference
3.1s)
Audioquest 4+ speaker cable (center channel)
Audioquest F-16 speaker cable (rear channels)
Nordost Blue Heaven & Kimber PBJ interconnect
Best Deal Cables DVI & HDMI cables
Terms and Conditions of Use
|