SOUNDBOXES VIII: MIGHTY LITTLE WONDERS FROM YESTERYEAR – Entry
Level Vintage Amplifiers from Sansui and Luxman
Sansui AU-101,
Sansui AU-2900, Sansui AU-70 and Luxman L30
The quartet
of vintage integrated amplifiers featured in this review is not the stuff that
makes headlines in most ‘self-respecting’ Hi Fi magazines that sell
internationally. What I do hope to highlight in this short post is the beauty
of unearthing potential from the category dubbed ‘budget vintage gear’!
There is
no better way to start than by posting a souvenir photograph of the test
session following the completion of the ‘recapping’ and speaker terminal
modification of the Sansui AU-101. The latter was connected directly to the
powerful Vienna Acoustics Baby Grand Beethoven speakers that boasted these
specifications:
Three-way, floorstanding, bass-reflex loudspeaker.
Drive-units: 1.1" hand-coated, silk-dome tweeter; 6" X3P midrange;
two 6" X3P Spider-Cone woofers. Bass function: impulse-optimizing QB3
(Quasi-Butterworth). Crossover frequencies: 150Hz, 2.3kHz. Crossover:
three-way, 6dB and 12dB Bessel. Frequency range: 30Hz–22kHz. Sensitivity: 91dB.
Impedance: 4 ohms. Recommended amplification: 40–250W
Read more at https://www.stereophile.com/content/vienna-acoustics-beethoven-baby-grand-symphony-edition-loudspeaker-specifications#iAFFDhPpcw0pC4YP.99
Read more at https://www.stereophile.com/content/vienna-acoustics-beethoven-baby-grand-symphony-edition-loudspeaker-specifications#iAFFDhPpcw0pC4YP.99
Compare
the expectations raised by the Baby Grand Beethoven’s profile with the Sansui
AU101’s specifications and you’ll be amazed by the unbelievable results I am
shortly to describe [BTW, ignore ALL the unconnected
background equipment like the D’Agostino amplifiers, Power Regenerators, Martin
Logan speakers, YbA equipment etc., except for the YbA CD player on the forward left, and the GIGAWATT PF-2 power distributor
on the lower left]. And here are the Sansui AU-101’s specifications:
Power output: 15 watts per channel into 8Ω (stereo)
Frequency response: 20Hz to 60kHz
Total harmonic distortion: 0.8%
Input sensitivity: 4mV (mic), 3mV (MM), 200mV (DIN),
200mV (line)
Signal to noise ratio: 65dB (MM), 75dB (line)
Channel separation: 45dB (MM), 45dB (line)
Output: 200mV (line), 30mV (DIN)
Speaker load impedance: 4Ω to 16Ω
Semiconductors: 18 x transistors, 4 x diodes
Dimensions: 407 x 115 x 278mm
Weight: 5.9kg
According to most websites and audiophile reviews, the Sansui AU-101 (1973-5) integrated amplifier incorporates many
of the state of the art features of the technically more powerful, but older
AU-555A from 1970-71, including an all silicon solid state design, professional
arrangement of controls and a satin black control panel. [I have owned the
AU-555A before and can tell you that the power output between the two amps is
THE SAME when tested with the same speakers! And you can read my review of the
AU-555A on this blog by typing AU-555A in the search bar.] Like all other AU triple
digit series amplifiers, the AU-101's tonal quality has been perfected and
proved not only by precision electronic measuring instruments, but also by
repeated listening tests in a wide variety of environments. Although touted as
a ‘budget’ model by Sansui at the time, this amplifier has proven to be an
evergreen classic in reproducing a glorious analogue sound from any source fed
into it! It is easily compatible with any speaker – have heard it paired with
JBL, Focus Audio, ProAC, Vienna Acoustics, Pathos and Emmespeakers. Also, like
most Sansui solid state amps, it adds a nice tinge of Tube-like smoothness and
body to music. It has a pair of RCA outputs each for AUX (Tuner/CD player/MP3
player), PHONO, and TAPE (can be used also for Tuner/CD player/MP3 player). In
terms of electrical design, the AU-101 exhibits a clear simplicity of circuit
boards and integrated wiring.
In the test above, I used mostly three
compilation albums to sample different types of music in one intense round. In
keeping with this blog, I don’t always go for so-called ‘Audiophile standard’
rock, pop, jazz and classical discs, just simply what a down-to-earth Hi Fi fan
would listen to!
1.
Various Artistes (Euge
Groove, Frayne, Nancy Wilson with Joe Sample, Peter White, David Benoit, Joyce
Cooling, Warren Hill etc.) The Love
Project on Narada Jazz, USA, 2003.
2.
Paul Mauriat – The Best of Paul Mauriat Volume One – on
Philips Universal Music Hong Kong 2000. A HDCD remaster.
3.
Luigi Boccherini – Guitar Quintets Volume 2 – by Zoltan
Kocsis and the Danubius String Quartet on Naxos.
Lead
vocals sounded superb in their natural placements – not forward – just
immediately to the back of the floor standing Beethoven Baby Grands. They
exhibited clear dimensionality and depth, even soul, rendering them immensely
listenable. For instrumentals with a fairly large ensemble of 20-25 players,
the soundstage was engaging even if instruments could not be picked out
clearly. Scale and majesty of the arrangements were heard evidently. Soloists
that were meant to be at the front of the recording venue could still be
identified even if the rest of the soundstage was fuzzy in the mind’s eye.
Nonetheless, the overall presentation was warm, nearly tube-like, very much in
keeping with the ‘Sansui sound’ from the 1960s and 1970s. The AU-101 handled high
volumes with ease and I did not need to engage the loudness function at all,
nor did I feel tempted to turn up treble and bass. Paul Mauriat’s 1970s
instrumental renditions ‘Feel Like Makin’ Love’ and ‘El Bimbo’ were reproduced authentically with clear
accents on the funky basslines and disco beats where they turned out as
intended by the maestro himself. For the Boccherini recording, I found the
sweet spot by just tweaking bass and treble simultaneously by one notch into
the positive zone, but the overall sonic picture of a chamber-like recording
venue was reproduced realistically even with tone controls set to neutral. For
a 15Watt 1970s ‘budget amplifier’, this is most impressive.
The AU-2900 from Sansui’s 1976-7
‘Professional Series’ was no less impressive. All of the warmth with good
proportions of the treble and bass were near impeccable. Being part of the
renowned Professional series from Sansui’s mid-1970s attainments, one might
have expected a midrange knob but the AU-2900 did not offer one. This was a
minor drawback especially for those of us who absolutely swear by the lively
and full bodied presentation of vocals and string passages. The soundstage too
was not as precise as the AU-101, let alone the AU-2900’s higher numbered
siblings. But the extra two Watts i.e. 17 Watts at peak power at 8 Ohms, lent
the volume controls an awesome feel of sonic power, much more than the AU-101
did. Here are the specifications of the AU-2900.
Power output: 15 watts per channel into 8Ω
(stereo)
Frequency response: 10Hz to 40kHz
Total harmonic distortion: 0.3%
Damping factor: 50
Signal to noise ratio: 90dB (line)
Channel separation: 57dB (MM)
Dimensions: 400 x 120 x 240mm
Weight: 5.7kg
Year: 1976
That
said, the AU-2900 is a daring example of exquisite Sansui engineering packed
into a budget frame. Mind you, it can fill more than a small room the size of a
high end Hilton hotel executive suite. The AU-2900 is known to have driven
Mission, Focus Audio and JBL speakers comfortably. I ran the 2900 hitched up to
the massive 8 Ohms PATHOS Frontiers Prime and Copernicus Emmespeakers floor
standing speakers and the sound was spacious without a hint of strain since I
never needed to turn the volume beyond the nine o’clock position. Any higher in
volume, one might start developing hearing problems after repeated listening!
That said, when I compared the 2900 to the AU-7900, which is slightly over
three times the power output, the 2900 revealed some limitations. The
soundstage was much more detailed and richer, and the 7900 managed to elicit an
emotional response from listening to soul and operatic vocals that the 2900 did
not. This difference I suppose is reflected in the 7900 selling at roughly
twice the price of the 2900. Nonetheless, the AU-2900 exhibits the classic look
of the Professional series with its unmistakable black fascia, punctuated by
silver aluminium knobs and push-buttons that convey the aura of 1970s Japanese
Hi Fi glory. Like the AU-101, the 2900 exhibits a characteristic simplicity in
its topography of circuit boards.
Revellers of the entry level vintage
sound might have also chanced upon Sansui’s venerable direct precursor of the AU-111
Tube integrated amp. This is a very pretty looking machine with an all-silver
front with dark yellow glow lighting in its VU metre displays. The Red Light
Power lamp is unarguably ‘sexy’ considering this is a 1964 production! To me,
the AU-70 evokes the ‘space age’ feel of the first generation of popular Sci-Fi
films in the 1960s. Silver metal was symbolic of futurism although one might
think of it as kitschy and bland today. Whatever one’s opinion of the exterior,
this is a tube integrated amplifier dedicated 100% to music. What about its
specifications?
Power output: 25 watts per channel into 8Ω
(stereo)
Frequency response: 10Hz to 80kHz
Total harmonic distortion: 0.95%
Input sensitivity: 0.9mV (mic), 1.1mV (MM),
50mV (line)
Signal to noise ratio: 52dB (line)
Speaker load impedance: 8Ω to 16Ω
Valve complement: 4 x 7189, 2 x 6AN8, 3 x
12AX7
Dimensions: 405 x 320 x 142mm
Weight: 13.7kg
Year: 1964
Its
complement of tubes visually match many of today’s all-tube amps of the likes
of FezzAudio, Unison Research, Manley, and newer competitors like Auris Audio.
As I listened to the AU-70, I kept in mind the www.Sansui.us website’s one
liner declaration that this kit excelled in vocals to the point where after one
session with the Beatles LP or CD on the AU-70, one could never revert to solid
state amplifiers ever again. Well, was it true to my ears? It scored roughly
60% on this claim.
I was bowled over with virtually all the vocals I played through
it. Since mine were all CD, partial streaming (from Smart Phone via Bluetooth
LOGITECH adapter/receiver with RCA connections) sources, the vocals were
already rather
well refined in the recording studio. The AU-70 performed an
additional miracle on all of them. On smooth jazz vocals of the likes of Nancy
Wilson, Jeffrey Osborne, Kenny Lattimore, Frayne, Patti Austin, James Ingram,
and Luther Vandross, the soul was reproduced with an added zing to it. Like the
solid state Sansuis higher up on the technological rung, this was hard to
explain except that the more emotive parts of singing grabbed me in an
inexpressible way. When I switched to classic vocals of a Streisand, Karen
Carpenter or Michael Buble, the AU-70 showed why it was a classic that has
withstood the test of time: each of these singers demonstrated an expressive
tinge that was at once intimate and underappreciated before. At some points,
listening to great vocalists on the AU-70 beat even sitting in front row
concert seats. It was that good! But I noticed I needed to keep the unique
‘presence’ switch on throughout to sustain the intimacy and warmth of the
‘Tubey sound’, while keeping the loudness switch off. I must however warn the
reader that to hear this level of potential, I had all the 6AN8 and 12AX7 tubes
replaced with mid-budget ones, and kept two of the stock 7189s, while switching
two of the remaining 7189s for Mullard versions. I did not dare upgrade the
tubes further having spent nearly US$190.00 on recapping and replacing the odd
transistors. But the experience proved rewarding especially if one listened to
vocals most of the time. What about instrumentals? The AU-70 excelled once
again with the highly digitally recorded smooth jazz of the likes of Euge
Groove, Everett Harp, Peter White, Joyce Cooling and Kenny G! The digital
perfection of saxophones, guitar and booming bass were toned down in a sweet
analogue-like manner. In fact I’d say the bass was beautifully rhythmic. If
however, you are into classical piano and violin of the likes of Lang Lang,
Jeno Jando, Vladimir Horowitz, Anne Sophie Mutter, or Midori, forget about the
AU-70. The recordings universally sounded flat and lifeless even with the
loudness and presence switches turned on. Mantovani, Paul Mauriat and Ronnie
Aldrich sounded almost in limbo between mono and stereo. Instrumentals with
lots of percussion recorded before the 1980s fared badly too. So this is a
mixed verdict for the AU-70: great for all kinds of vocals and some very
contemporary instrumental recordings, and probably will sound great with hard
rock and pop as well, but ditch this for other instrumentals. Perhaps I’ll try the
AU-111 when I have the funds! Two final operational warnings need to be heeded
especially if you intend to acquire the AU-70. It runs very, very hot after
just 15 minutes of operation so it is best to take the cover off even in winter
indoor conditions, and keep a quite fan or airconditioner turned on during
listening. Like all Class A tube amplifiers, there are characteristic light ‘popping’
and ‘ticking’ sounds as the tubes cool down after you power off the set. A few
restorers in Singapore have also complained that some of its transistors are
hard to find, but this may not be the case elsewhere in the world. My test
model arrived second hand and barely functioning from Peru, but looked very,
very pristine inside, and the final restoration was done in a Singapore shop.
Finally, the Luxman L30 offers a nice contrast to the three
entry level Sansuis. Its chief characteristic is the fluidity of music! The
specifications of the L30 appear on paper to overtake everything the preceding
three Sansuis boast of.
Power output: 32 watts per channel into 8Ω
(stereo)
Frequency response: 15Hz to 50kHz
Total harmonic distortion: 0.05%
Damping factor: 90
Input sensitivity: 2.5mV (MM), 150mV (line)
Signal to noise ratio: 64dB (MM), 83dB
(line)
Semiconductors: 27 x transistors, 8 x
diodes, 2 x zener diodes, 1 x led
Dimensions: 440 x 160 x 225mm
Weight: 7kg
Conversations
that I have gathered from Hi Fi enthusiasts older than myself recall that around
1976, Luxman, better known as Lux Corporation of Japan, had promoted itself as
the better representation of Hi Fi luxury than its rivals Pioneer, Marantz,
Sanyo, Akai, SONY, and even Sansui. The richly lacquered original Rosewood
casing spoke of this aspiration. Although Luxman also dabbled in a range of
tube integrated amplifiers, solid state amps were what they were more strongly
remembered for. Like its rivals, the L30 also boasts a loudness switch and
frequency filters for low and high. Controls were also packaged for controlling
treble and bass for each of two channels of stereo as featured in the neat set
of four similar sized knobs. Mono and stereo were also options at the flick of
a nifty silver rod-like lever. The silver and Rosewood exterior took some
getting used to since I was not accustomed to seeing such a combination in
1990s and 2000s stereo design.
The sound of classical music was however the best genre for
proving that the L30 merited its status as entry level ‘high end’ for the
Luxman range back in the mid-1970s. The Boccherini guitar quintets proved
sublime, detailed and outright mesmerizing, especially if one has attended
classical concerts in places like historic palace chambers, churches, dedicated
brick-mortar-and-wood panelled concert venues and the like. The comparisons
between live classical music and the recorded simply blends into one another through
the diodes, wiring and transistors of the L30, facilitated no doubt by a square
boxed C-core transformer typical of that era. Every pluck of the guitar strings
by Zoltan Kocsis evoked effortlessness and natural resonance on the budget
Naxos recording. Switch the music to something with extreme pop-variations like
Paul Mauriat and Smooth Jazz and the L30 begins to lose lots of ground to the
aforementioned Sansuis. While detail and significant transparency were still
being conveyed, the intimacy and body of complex musical performances seemed to
be lost. Instead, uptempo instrumentals and vocals took on a ‘liquid’
soft-focussed quality that took off a lot of edge to soul, jazz and orchestral
pop. I am not fully convinced this is a good thing unless one wishes that most
of the music was meant to fill spaces in the background of daily chores,
reading in a library or simply plugging awkward silences in an ongoing
conversation. When playing Paul Mauriat’s disco-esque arrangements, and say,
Euge Groove’s saxophone grooves in ‘The Love Project’ CD, the bass was fairly
tight and rhythmic, but the emotion of the performance simply did not engage me
sufficiently to want to listen to an entire disc. In short, I’d vote the L30 as
a champion of classical instrumental music, and not a recommendation if you
need an all-rounder!
So, there you have it. Budget, entry level, vintage integrated
amplifiers are not to be sneezed at. They were mostly engineered for an
intensely discerning music consumer in the 1970s. For most of the amps reviewed
in this post, each has a character of its own. If life is richer because it
allows the sampling of varieties within varieties, these entry level vintage
amplifiers are definitely worth a try, and if you own one and desire to hear
its fullest potential, go for a thorough recapping service before putting them
through their paces with your music. As a good friend once advised, 30-40 year
old capacitors are almost at the end of
their lifespan and must be replaced to preserve the integrity of the sound of
vintage into the next century! And oh, one last thing to note: no need to
always use hyper expensive power cords to connect the amplifier to the power
distributor, Luxman and Sansuis often operate best with a stock copper power
cord!
ALAN
26
December 2017