SOUNDBOXES VIII: MIGHTY LITTLE WONDERS FROM YESTERYEAR – Entry Level Vintage Amplifiers from Sansui and Luxman

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

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