Musical Laboratory*'s Paeonia Rev. 2.3 Passive Preamplifier, Bosangwha Rev.2.3 Monoblock Amplifiers And
Bosangwha "Dual" Power Supply.
Review By Steven R. Rochlin
to e-mail reviewer.
As a man who nurtures a Koi
fish pond and Lotus flowers, have enjoyed sitting back and watching Musical
Laboratories* go from a small pod to rising above the water and reaching
full bloom. While high-end audio is a niche in and of itself, we have
sub-niches that are filled with everything from big and heavy solid-state
amplifiers to single-driver highly efficient full range loudspeakers. Musical
Laboratory* chose their path by fulfilling the dreams of those seeking the joys of the purest of sound via minimal parts count and silver gold foils for wiring. Their elegant circuit design is then placed within equally
beautiful cabinetry. In fact visitors within my home have wondered if what
is placed on my equipment stand were jewel boxes. In a sense they are
right as the aural output from these Musical Laboratory* products could be
considered akin to the high-end audio equivalent of a carefully crafted
to the company's documentation, Musical Laboratory*'s "inspiration comes from Eastern spirituality and the long
tradition of Japanese minimalism. Masaoki Shiki (1867 - 1902, pictured
here) was a young poet who challenged the orthodoxy of Japanese poetry of his day, which had become bloated and unreadable. Shiki is credited with inventing a
new grammatical structure, the Haiku, in which only a few words were used to
perfectly capture a moment of consciousness or to describe something in the natural
As a reviewer who was among the first to
'rediscover' single-ended tube amplification via the Audio Note Ongaku,
then following suit with such minimal solid-state device companies
including 47 Laboratory (reviewed
here) and Final Laboratory (reviewed
here) both in mid to late 2000. So as i have patiently sat back
and watched Musical Laboratory* grow and flourish, i felt it was time to
see what their recently released Revision 2.3 system was capable of. After
all, it has been about nine years since first reviewing my first single
chip solid-state amplification.
Add to that, once you have seen the sheer magnificence
of the Korean lacquer casing decorated with an iridescent Abalone mother of pearl
pattern you are hooked. There is little doubt that Musical Laboratory*
products easily find their place within the most elegant of homes.
Visually, they are both modest and distinctive yet never garish. Quiet
beauty nearly always finds attraction without the need to scream
"Hey, look at me!" This is the same as the Lotus flower, with an
inner beauty that unfolds each morning to reveal it's true essence.
"less is more" philosophy takes hold as the Paeonia preamplifier
is purely passive, without any amplification device in the signal's path.
Unlike most passive preamplifiers where the output signal from the source
component (phonostage, CD player, etc.) is attenuated, in the Paeonia's case it is the
input signal that is attenuated in order to regulate the output from the device.
This is why in the picture to the right there are two volume controls so
that there is one for each source. One advantage of this technique is that
since each source can be adjusted independently, audiophiles may choose to match
volume levels for ABX testing. Another advantage is that — since some sources
have a higher output than others — when switching inputs there is no
sudden high level output due to the volume being set for the previous
The Paeonia preamplifier is based on a 'direct
wire' approach, whereby the signal passes through just one passive component
— a naked audio resistor — from input to output. This is made possible by the implementation of a classical shunt circuit, which effectively
takes potentiometers out of the
'direct' signal path. Note that the potentiometers used still influences (to a
lesser extent) the sound, but is claimed by Musical Laboratory* "to not
degrade the overall performance of the device as is generally the case when following a
schematic". The Paeonia uses Sfernice cermet pots and the whole device
in Revision 2.3 is wired using the company's proprietary silk-insulated silver gold
As for the Bosangwha monoblock amplifier,
those who spent time on the Internet DIY audio forums years ago all well
aware of the awe of what Junji Kimura of 47 Laboratory had done by creating the 4706 Gaincard. Soon
came the Gainclone sub-culture and debates ensued. By harnessing the power of
miniaturization and combining it with some clever implementation skills, Junji had shown everyone there was another path.
Musical Laboratory* wanted to continue the change begun by 47 Laboratory and subsequently
brought forth their first revision of the Bosangwha.
When the 4706 Gaincard was released in 1999,
there was little doubt that this was an optimized design with a total
signal length that was perhaps the shortest ever realized in a production
high-end audio amplifier. In fact Musical Laboratory* readily admits they used one
within their lab as a reference so they could see were possibilities for
improvement may be accomplished. "What followed subsequently was a process of deconstruction, in which different parts of the amplifier came under
scrutiny, " says Malcolm of Musical Laboratory*. "It became increasingly clear that the magic and musicality of the LM3875 power op amp lay less within implementations of the chip, than within the chip itself. The challenge became how to let out more of the inherent musicality that was encoded inside the chip."
As such, they looked at the power supply
too. Junji of 47 Laboratory had made a good decision to isolate the power section from the signal section, into a separate module called the Power Humpty.
Musical Laboratory* felt back then that the transformer-based supply of the original could be improved upon.
They also knew what batteries could do, and thus my review of the Final
Laboratory unit shows there were improvements. The same can be said for
DIYers who chose to experiment with a battery power supply of their Gainclones.
Of course batteries in and of themselves are not necessarily the complete
and final answer (no pun intended).
And so this led Musical Laboratory* to
devising a switch mode power supplies (SMPS) that offered highly regulated
yet quiet power plus extra dynamic headroom. "Of course there are issues with using this technology in audio also, so these first had to be carefully
addressed" says Malcolm. "But we found that even a stock OEM SMPS module, when partnered with a Gainclone at specific voltages, could give up extremely good
results and this discovery became the basis for our Mono PS. Using the same reductionist logic that we applied to the Gaincard, we now applied this to the new power supply technology. This culminated in a specifically, from-the-ground-up, audio SMPS module that we collaborated with an OEM on, and which is the basis of our
Dual PS. The Dual is more powerful, has improved filtering, a feedback network, nearly 100 kHz switching frequency and large output capacitance. It is our reference PS and is designed to drive the Bosangwhas in combination with typically 8+ Ohm load loudspeakers from 88dB?w/m and up sensitivity."
While much experimentation had already been done on the DIY forums regarding
the signal side for the Gainclone circuit, Musical Laboratory* found that by swapping out a commonly accepted resistor for a new-generation
'naked' audio resistor, they could improve voice articulation. The really interesting part, according to the company, had nothing to do with passives. It was the discovery that, after they simplified the Gainclone circuit, widened and improved specification of the tracks and use of an exotic PCB substrate the Bosangwha's (aural?) signature changed to what it is now.
So Where Are We Now?
Revision 2.3 has changes that include some
mechanical and construction improvements, fully Silver Gold foil wired and
holographic counterfeit protection. They also now use low impedance potentiometers
and implement Sfernice P11s configured in a shunt arrangement. The Paeonia
Revision 2.3 changes allow for better tracking at low listening levels, improved channel
balancing and is said to be more detailed. Bosangwha Revision 2.3 is their latest advancement in
miniaturized amplification technology, taking the Gainclone concept to the next level
based on the legendary sounding LM3875 from the National Semiconductor
Overture series. Power to the amplifiers is delivered by a separately located SMPS power supply
module which connects via two Litz-wired umbilical DC cables. Changes
include the use of the company's Silver Gold conductor foils for both input and output,
holographic counterfeit protection and new high-speed PCB substrate was selected from a number of exotic substrate
materials tried. Improved specification of copper tracing on the board improved
and further simplified the circuit layout, thereby reducing resistance further. A larger ground plane with single ground connection
was able to be achieved. Joining the party are handmade next-generation low noise audio resistors in the signal path
and DC offset is limited to around 2mV. Unlike many high-end audio
products that use WBT or other heavy-duty loudspeaker binding posts,
Musical Laboratory* chose to employ low mass, non-metallic loudspeaker connections made from
nylon 6.6 with PTFE washers. The foil wire for signal output is directly
wrapping around this binding posts for a large and very direct connection
Lastly, the Bosangwha Revision 2.3 comes with a choice of
two power supplies, with one using the entry-level SMPS module and is housed in a sleek aluminum
case. All internal wiring is implemented using Teflon insulated military specification silver-coated copper wiring. A three-stage mains isolation circuit is
employed after the mains switch which prevents any unwanted switching noise
from being conducted back into the electricity supply. Connection to the monoblock
amplifiers is via two Litz-wired umbilical power cords — one per channel
— using military specification cable and state-of-the-art gas-tight power
connections. This power supply module can drive the Bosanwhas at 18 watts
each and is suitable for those systems using full range driver or high-sensitivity
(more than 93dB/W/m) loudspeaker systems.
Under review is their uprated Dual SMPS power
supply based on the same design as Musical Laboratory*'s Mono SMPS. The Dual SMPS uses a
purpose-built audio SMPS, which they personally we collaborated on. This SMPS is capable of driving
the Bosangwhas to 48 watts, which is close the chip amps full output rating. Prior to the introduction of the Dual, the
company claims that the magic of the Bosangwhas was perhaps only available to those of our customers with high-sensitivity
loudspeakers (not less than 93dB/W/m).
With the Dual power supply, this sound is now available to
their customers with a wide variety of loudspeakers that have lower
sensitivity (88 to 92 dB/W/m). What must be noted is that because of the levels of current the Dual is capable of
delivering, they do not recommend using the Dual with 4 Ohm loudspeakers.
Ideally, loudspeakers should present an 8 Ohm load to the amplifier. The Dual can be used by both
very high and more normal sensitivity loudspeakers of course. In fact Musical
Laboratory* recommends the Dual's use, as it is their reference power supply.
The Music Blooms
While i could easily sum up this review right here
and now is a few well-chosen words, am sure it would fall short of what i
truly want to say about the Musical Laboratory*' Paeonia Rev. 2.3 passive
preamplifier and Bosangwha Rev.2.3 monoblock amplifiers. My main focus
will be on the amplifiers, as the passive preamplifier is first-class and
transparent enough to easily justify purchasing it with the amplification.
In fact even if you do not purchase the Bosangwha Rev.2.3 monoblocks,
those who have not tried their hand at passive preamplification and want
something pre-built with exquisite jewel-box type looks should serious
consider it. When it comes to visual styling, the Musical Laboratory*
units received the highest of praise.
The Paeonia preamplifier has excellent
channel-to-channel accuracy and plenty of range to set the volume from
silent to quite loud on my Audio Note AN-J/SPx silver crossover with
silver wire loudspeakers. While my DIY passive employs the DACT stepped
attenuator, there are moments where one finds themselves desiring one of
those between settings. While i am not sure what brand of attenuators are
used by Musical Laboratory*, they are of the track variety and so you get a virtually limitless
range of adjustment. My source during the review was either the FrankenDAC (not a
commercial unit) or my new processional audio 24-bit/192kHz
recording/playback device. Much of the source material was either lossless
ripped music or recently recorded source material from my personal
recordings with the aid of a pair of hand-matched lab grade Earthworks
microphones. The only mechanical drawback with the Paeonia preamplifier is
the lack of right/left channel balance, which i virtually never use anyway
so it makes sense to eliminate it out of the analog circuitry for signal
purity sake. Wiring was
Kimber Select all silver units with WBT connectors.
The Paeonia preamplifier has very little
sound of its own. What difference i could detect was perhaps a very small
amount of warmth as compared to the DIY DACT passive unit. There really is
not that much more to say about this passive preamplifier, which is as it
should be. As the analog signal only needs to travel though a few silver RCA jacks, some silver gold foil wire minus the potentiometer, there really is very little to get in the
signal's way. So basically you get out what you put into it.
Since every single source component i know of can easily drive virtually
every high-end audio amplifier, there is no need to double check the
source unit's output capabilities. With that said, it is time to dig in to
the truly interesting amplification units.
The Bosangwha Rev.2.3 monoblock amplifiers
are the most recent generation of the now-famous single-chip solid-state
amplifiers. As i said near the beginning of this review, was the first to
review the Gaincard and then followed up with the battery-powered Final
Labs unit. As history shows, once my review of the 47 Labs Gaincard came
out, the high-end audio industry seemed to catch fire about these single
chip solid-state amplification units. While my then system was a different room equipped with
Avantgarde Acoustic Duo hornspeakers, direct comparisons today would be
So starting fresh, per se, what i can say is there is much similarities
and of course some differences.
If there is one thing that always seems to bring joy
to my ears is how smooth these single-chip units sound. It is not at the
expense of resolution, far from it! There is layer upon layer of intricacies
resolved by the Bosangwha Rev.2.3 monoblocks. Add to that, the soundstage
width and depth were truly of reference quality, extending way back behind
the speakers while also going slightly past the far edges in width.
Extension into the room was quite good too. During properly recorded
minimally-mic'ed orchestral music there was layer upon layer of instrument
groupings, just as there is within live performances.
Tonally, i would call it harmonically
neutral to a very small touch of warmth. It could be the Kimber cables... or not. Yes i did try other cables
and they had their signature and so my favorite Kimber Select got
the nod for the most neutral of the bunch. At no time did i feel the music
was dry or lifeless, unless of course i happen to be plying source
material that is known to be recorded this way. Special notes are that
acoustic bass had a great balance of string and body while bass drum has a
nice thump/tone sound. The critical midrange was very lifelike and evenly
balanced with the lower frequencies.
Moving up the registers i found that the
uppermost frequencies were highly resolved and very balanced with the
midrange and bass. On commercially-recorded music the highs were very good
and nicely extended to a point. Ok, perhaps missing on that very teeny tiny last bit
of extension yet am at odds to say it is the Musical Laboratory* unit's
fault given the 'live versus Memorex test' that can be done here, plus when
playing my drums and percussion system i am
sitting much closer to the actual instrument than the microphones. Add to
that, whatever electronic gear may be between the live acoustic event and the
recorded device's output 'gets in the way' per se. So getting back to commercially available
recordings, all sounded very impressive and, as said before, extremely
As noted within my 47 Labs Gaincard review,
"It is more than transparency, more than correct harmonics, it is a
freedom from what i call "beat" which is generally heard only
during true live acoustic musical performances. If you are a drummer, it
is the difference from playing the 4/4 beat and playing "in the
pocket". There are very, very small timing cues which while not
perfectly on the downbeat, they are playing a very small amount before or
after the exacting beat timing which gives the music a unique feel, or
soul." The Musical Laboratory* units also feature this great freedom.
So as a natural extension of this lack of
imposed beat, the PRAT (pace, rhythm and timing) was extremely delightful.
Rock music rocked, free-from jazz from Miles Davis or Coltrane breathed
life into the listening room and great classical music was brought forth
as such. Small inflections came though not as an obvious shouting of
"look at me" more than simply just being there... which always
brings a smile to my face and joy to my ears.
Overall transparency is very impressive.
While the Musical Laboratory* top-line power supply is being used, as is
my Furman Sound IT-Reference balanced power unit, there does seem to be an
extremely small bit of a lacking of translucent sound when played at soft
levels. It almost makes me wonder if a battery power supply would perhaps
provide that tiny bit of improvement. At normal listening levels this is
virtually a non-issue.
Turn It To 11!!!
So is the system perfect, well... a few small
quibbles would be the ability to turn the volume up to rock concert
levels. Yes there was plenty of volume for small jazz and classical
orchestra music. You see, there are times when i wanted to crank up the
tunes and the Bosangwha Rev.2.3 monoblock amplifiers went into a
soft-sounding clipping 'mode'. It showed me that the
Audio Note AN-J/Spx might need a bit more oomph within my dampened room.
This is not necessarily a fault of the electronics more than the
realization that while i do wear ear protection when playing my acoustic drum set, the possible volume levels that can be achieved when i
briefly go sans ear protection can get truly extreme. My suspicion is that if the Avantgarde Acoustic
Duos hornspeakers were back within my system then this criticism would not have made
itself known, as the difference between the Audio Note's 93dB/W/m
sensitivity and that of the 101dB/W/m Duos is a drastic increase in volume
level given the same wattage.
Now before those of you with 92dB/W/m
loudspeakers write of the Musical Laboratory* units, please understand i
am referring to very loud volume levels of the like that could be
dangerous to your hearing if you are exposed for more than 30 minutes! To
make this clearer, the United States of America law is such that you
can legally be exposed to 95dB SPL for four hours, yet only one hour at
105dB within the workplace. How loud can my acoustic drums get you ask?
Very, very loud... which is why i generally wear hearing protection
about 90 percent of the time. So if you love rock rest assured your
90dB/W/m speakers with 8 Ohm load should be fine with the uprated power
supply. If you want the same deafening volume level of a legendary The Who
concert from the mid-1970's.... So the great news is that if you ever do
reach this extreme level of volume, the clipping here did not fry my
speakers, which can happen with some amplification devices when stressed
to the maximum.
The Bosangwha Rev.2.3 does have a
personality achieving a very likable and enjoyable experience. Musical
Laboratory* is the Ying to certain Super High Wattage solid-state amplifier
Yang. While all generalizations are wrong, to be fair there are probably quite a few
great-sounding super high-wattage solid-state units. Some of the ones i have heard have
this slightly dry and overly controlled (read: heavy-handed) handling of
the music. So from my experience of three different single chip
solid-state units seem to all have a personality of delightfully letting the
music flow. Add to that, extremely small microdynamics s are resolved with
great ease. i could easily discern small inflection that are totally lost
with some gear.
The Joyous Jewel Boxes
My review period lasted an extra month or so as Enjoy
the Music.com's Superior Audio magazine is bimonthly. As luck
would have it, the Musical Laboratory*'s Paeonia Rev. 2.3 passive
preamplifier, Bosangwha Rev.2.3 monoblock amplifiers plus Bosangwha "Dual"
power supply arrived during a time period that provided me additional time
to assess their capabilities. The sound is truly engaging and never one to
offend given proper source material. While they will not become the main
amplification units for heavy metal bands trying to fill a soccer stadium,
proper speakers with sane load should be no problem.
The sheer smoothness and ability to resolve
top to bottom both in frequency and dynamics is outstanding. If you have never heard a
properly designed single chip solid-state amplifier, the Boswangwa Rev.
2.3 should be on your
short list for a listen. Imaging is of reference quality and would be
virtually impossible to beat. Hour upon hour of music flowed throughout my listening
room and the stunning soundscape capability had me hearing deeper (per se)
into the music. It is truly an honor to be able to have enjoyed these
units within my listening room. Give these monoblocks a listen, as you may
find yourself hooked!
Type: Single chip solid-state monoblock amplifier
and passive preamplifier
Frequency Response: 20Hz to 20kHz (+-0.25dB)
THD + N Maximum: 0.064, with a minimum of 0.023
SNR: 114dB @ 40W
Orange LED power indication
High-speed PCB substrate
Next-generation audio resistors used in the signal path
DC Offset protection
Proprietary high-purity Silver Gold foils using air dielectric in the signal
Inputs: two stereo pair solid silver inputs via RCA connectors
Output: One stereo pair via solid silver output RCA connections
stereo pair for Aux. version
Audio Note chrome-plated brass volume controls
Vishay Sfernice P11s used in shunt - fake law configuration
Silk insulated Silver Gold wiring throughout the device
Dimensions: 4.5 x 4.5 x 3.4 (WxDxH in inches)
Price: Bosangwha + Mono PS $2900
Bosangwha + Dual PS $3300
Paeonia (with Aux. outputs)
Voice: +352 621 762648
E-mail : firstname.lastname@example.org