March 2004Song Audio SA-300 MB Mono Amplifiers
by Marc Mickelson
Single-ended-triode amplifiers are rather like antique automobiles. They require special commitment from their owners that more contemporary designs don't. Going SET means that you have chosen a speaker that's sympathetic to the amp's idiosyncrasies, namely low output power and high output impedance. SET-loving audiophiles often turn to horn-loaded speakers because of their high sensitivity and easy load. However, horns often have obvious colorations due to their physical configuration, and I have to say that I cannot remember hearing a horn-loaded speaker that didn't sound like one to some extent, especially with vocals. I remember vividly sitting with Doug Schneider during CES 2003 and listening to a top-of-the-line Avantgarde speaker system complete with massive subwoofers. The dynamic range of this speaker system was simply awesome -- without peer -- and the bass impact was tastefully crushing. On instrumental music, especially full orchestra, the sound of this system was unmatched at CES. But then I requested an Aimee Mann cut, and it took all of two microseconds to hear Mann's voice overlaid with the ubiquitous-with-horns cupped-hands coloration. It wasn't prominent, but it was definitely there. This was a sad moment indeed.
Thus, speakers appropriate for use with SET amplifiers are often as limited as the amplifiers themselves. I've fudged a bit in the past, using Lamm ML2 SET amps, which output 18 honest watts, along with Wilson Audio WATT/Puppy 6 and 7 speakers, whose sensitivity is greater than 91dB (by our measurements). This combination is wonderfully involving -- it makes beautiful music. But it's very costly, which has put me on the trail of a less expensive alternative that captures the essence of SET magic without the colorations.
And then at last year's Son & Image show in Montreal, I heard Song Audio's electronics driving Loth-X speakers (which Song Audio distributes in Canada). Song Kim, from whom Song Audio takes its name, was treating those in his room to comparisons of his EL34-based SA-34 SB integrated amp (which was named a Select component on Ultra Audio) and SA-300 MB monoblocks, which use the much-revered 300B output tube. The high-sensitivity Loth-X speakers use single Fostex drivers instead of horns. While I could still hear compromises, mostly in terms of bass extension, there certainly were no problems with vocals, which sounded exceptionally present and lively. I talked with Song Kim then and there about hearing his mono amps with my Wilson Audio WATT/Puppy 7 speakers, and this review was born.
Anatomy of a Song
The SA-300 MB single-ended-triode, no-negative-feedback mono amplifiers use single 5UG4, 6SL7 and 300B tubes to produce a claimed 8W each. A pair of the amps costs $4000 USD, a seemingly fair price when you consider that the amps use proprietary transformers and include Song Audio 98% pure-silver power cords with Wattgate and Marinco connectors. They are especially long, lean and lovely amps, mostly mirror-polished chrome, cool-green acrylic, and glass. The SA-300 MB measures 18 1/4"L x 5 7/8"W x 6 3/4"H and weighs 25 pounds.
Bias is set manually by Song Audio for the tubes supplied with the amps, although you can check the bias with a volt/ohm meter and make adjustments. Before sending me the amps, Song Kim asked me to check the voltage in my house, and he adjusted the amps accordingly. Song Audio doesn't currently supply a manual with the SA-300 MB, but I understand that one is in the works.
Connection and operation are utterly simple. Around back, the amps have good-quality speaker binding posts (4- and 8-ohm pairs), an RCA input, and an IEC power-cord receptacle. On the front are the on/off and standby switches, the latter of which keeps the tube filaments electromofied. Simply keep the amp in standby, then turn it on when you're good to go, although I found that 30 minutes of true warm-up time improved the sound noticeably.
Review system and considerations
My audio system resides in a big new listening room (20' x 29' with a 10' ceiling), but its elements are the same as they ever were: Wilson Audio WATT/Puppy 7 speakers, Lamm ML1.1 mono amplifiers, Lamm L2 Reference preamp, Esoteric DV-50 universal A/V player, Zanden Model 5000 Mk III DAC, and Mark Levinson No.37 CD transport. Interconnects and speaker cables were from Nordost (Valkyrja and Valhalla), DH Labs (Revelation and Q-10), and Shunyata Research (Aries and Andromeda). Power was smoothed and soothed by a Shunyata Hydra Model-8, with a passel of Shunyata power cords also in use. I also listened with the amps plugged directly into the wall, which Song Kim suggested. I used Song Audio's supplied silver power cords with the SA-300 MBs as well as Song Audio's SA-1 two-box preamp. The Lamm amps and preamp sat on custom-made Silent Running isoBase 3.0 bases, which themselves sat on two two-shelf Michael Green Designs racks.
Wilson Audio states that the minimum amount of power for the 91.5dB-sensitive WATT/Puppy 7s is 8 watts, the rated output of the SA-3000 MBs. Other speakers on hand were ProAc Response D38s. ProAc speakers are generally believed to be a rather tube-friendly load, so I thought I'd give the D38s a go with the Song Audio amps even though the speakers' sensitivity is stated as 90dB/W/m. For both speakers, I tried the 4- and 8-ohm outputs, preferring the 8-ohm connections by a small margin.
The results? The power output of SA-300 MBs was at the very edge of acceptability with the Wilson WATT/Puppy 7s. I suspect that even one less watt, which represents 12.5% of the amps' manufacturer-stated output, would have been too little power, hamstringing the speakers with severely truncated dynamics and an inability to play at even moderate levels. With the ProAcs, the amps didn't work at all, sounding completely underpowered.
The moral of this story is self-evident: use these amps, and any low-power SET amps, with appropriate speakers. Once again, Song Audio is the Canadian importer of Loth-X speakers, and I'm sure other true high-sensitivity designs would work as well. Don't expect the SA-300 MBs to mate well with any old speaker, and don't trust what every company tells you regarding the sensitivity of its speakers. Often estimates are off by multiple dBs, and you're left wondering where all of your volume went.
We'll always have Montreal
Right off the bat, you have to adjust your idea of what high-end sound is when listening to the Song Audio SA-300 MB amps. They are not about bass impact and dynamic capabilities, but rather midrange palpability, smoothness and sweetness. They seduce, not blow away. They are amps for listeners who enjoy the small things about reproduction more than sheer power and slam, even with speakers like the WATT/Puppy 7s, which can sound powerful and slamming with an appropriate amp. With the Song Audio amps, however, the Wilson speakers sound smaller and more romantic, and they ultimately show how flexible they are. There are very few speakers that can sound good in such different ways with such different amplifiers.
Back to Montreal and a discussion I had with Ross Mantle, who reviewed the Song Audio SA-34 SB integrated for Ultra Audio. Ross has a seriously big brain -- maybe that's why he's a neurosurgeon -- and when you discuss something with him, it's hard not to see his point, even if you're not in full agreement. In Montreal, Doug Schneider, Ross and I debated the merits of voluptuousness. In Dr. Mantle's view, music good enough to be recorded is generally voluptuous -- plump, tactile, sensuous. Therefore, trying to strip away that quality from audio reproduction is like "trying to pretend that the sole purpose of a woman's leg and thigh is merely to hold up her body," says Ross. Audio systems that present music without voluptuousness are said to be "clean," "accurate" and "neutral," while systems that sound voluptuous "add euphonic coloration" that was present in the original recording session.
We all have our ideas about which position is correct -- I see the efficacy of both, though not equally. But in this debate, the SB-300 MB amps come down clearly on the side of voluptuousness. While the discussion of most amps begins at the frequency extremes, with the SA-300 MBs, it's everything that happens in between the bass and treble that matters most. The ravishing midrange of these amps brings vocalists to life in ways that no other amp I've heard can. The mids are gentle and full in character, but with what seem like strategically added glints of vitality. Vocalists have a round and nimble sound that compels you to listen. If you are a blues fan and don't have Buddy Guy's Blues Singer [Silvertone 01241], run out and get it. Aside from the earnest and involving performances contained on it, Blues Singer is very well recorded, offering scads of space and air. The Song Audio amps lessen these a bit, but they make up for it to my ears with the gorgeous portrayal of Guy's voice. The recording itself doesn't sound full, but the Song Audio amps add a bit of weight through the mids and into the upper reaches of the bass. I'm sure this is not accurate sound, but it sure sounds good!
Interestingly, I didn't find that the midrange went overboard by sounding chesty or plump. It is slightly dark in an absolute sense, but it wasn't plodding or opaque. Greg Brown, whose cavernous voice is a perfect test for too much midrange warmth, released a collection of traditional/public-domain tunes a few weeks ago called Honey in the Lion's Head [Trailer Records TR0035]. It's a fine-sounding disc, and the Song Audio SA-300 MBs bring a different kind of excitement to it -- not based on sheer power but rather on intimacy. Brown's voice emerged from between the Wilson speakers with wonderful presence and, I have to admit, voluptuousness. The sound was more tame than with any other amp I had around at the time, but never anemic or dead. I especially love "Railroad Bill" from Honey in the Lion's Head, although hearing Brown's wife, Iris Dement, sing background vocals on "Jacob's Ladder" is a treat, as is Brown's singing "On Top of Old Smokey."
But all was not midrange splendor. The treble was missing some of the liveliness and sparkle of other amps, even some SET designs, and immediately made me wonder if the load of the Wilson Audio speakers was to blame -- I noticed none of this in Montreal with the Loth-X speakers. Even so, the dimensionality of the amps, their ability to cast a soundstage with a believable rendition of width and depth, was intact. Blues Singer proved this, and Private Astronomy [Edge Music B00000907-02], Geoff Muldaur's tribute to Bix Beiderbecke, drove it home. As good as Private Astronomy sounds, however, the music demands most of the attention. It's authentic and expertly played jazz that drew me in on an intellectual level. I wanted to figure out its "system" -- it has a mathematical mien not unlike, in my opinion, Bach. If I heard Private Astronomy only on the Song Audio amps, I would be satisfied with it, but over, say, the Lamm ML1.1s, it's obvious that the SA-300 MBs are not bringing forth all of the high-frequency energy on the CD.
The bass was another point of concern. It was full and reasonably weighty, but it lacked depth and real authority. I'm not talking about solid-state authority, but even the sort of power that other tube amps can muster. The various Jacques Loussier Trio CDs on Telarc are always interesting listening -- Loussier's jazz renditions of mostly Baroque music are another intellectual treat. The discs can also startle with low-frequency outbursts. On Baroque Favorites [Telarc CD-83516], for example, Albinoni's Adagio for Strings in particular, drummer André Arpino cuts loose, but this is somewhat subdued over the SA-300 MBs. Perhaps SET proponents will read this and wonder what I expect from 8 watts, especially driving speakers with two 8" woofers. But that's the point in my mind. The WATT/Puppy 7s are capable of bass with pit-of-the-stomach power, but not with these amps, alas.
Because of its ups and downs, I can't consider the Song Audio SA-300 MB a product that audiophiles of all predilections should consider. This is an amp only for SET aficionados, not John Q. High End. Proponents will likely have speakers more sympathetic to the SA-300 MBs' quirks, and will certainly have greater love for the luscious 300B-based midrange of which these amps are capable. Those in the solid-state camp would find these amps grossly deficient of power and therefore completely unacceptable. To each his own -- and because of each our hobby has its diversity.
Versus the ML2s
But then there are those rare products that can seemingly create common ground where only differences existed. The Lamm ML2 monoblocks are such a product, and while not everyone will love them or even respect them given their $29,290-per-pair price, with speakers like the WATT/Puppy 7s, the Lamms produce music that's very hard not to enjoy.
I won't dally by comparing every aspect of the ML2s' and SA-300 MBs' sound -- the Lamm amps sound more accomplished in every way except one, the midrange. The 6C33C output tubes of the Lamm amps are known for their more linear sound than the 300Bs of the Song Audio amps, and that's how the ML2s sound -- less warm and dark. However, it's impossible to deny the appeal of the SA-300 MBs' midrange, with its mixture of presence and dexterity. It's truly beautiful.
If I could, would I take the midrange of the SA-300 MBs and introduce it into the sound of the ML2s? I don't think so -- it would skew the rest of the wonderful sound that the Lamm amps produce. But I wouldn't mind visiting that midrange every now and again, especially when I have some new Ella Fitzgerald remasters or a new Patricia Barber SACD.
It's undeniable that loving SET sound means making SET concessions -- unless you have a lot of money to throw at the issue. And even then, as with my CES 2003 experience, the outcome may not be everything you hope it to be. I can't say that the Song Audio SA-300 MB amps somehow bridge the performance gap between less-costly SET designs and the Lamm ML2s, which are still the best amplifiers I've heard in my system. But they certainly do have their charms, not the least of which is their seductive midrange. Frequency extremes, at least with my speakers, were not the SA-300 MBs' bag, but this should be no revelation.
To use another analogy, amps like the SA-300 MBs are for audio gourmets who appreciate a very well-made cream sauce more than enjoy gorging themselves on the meat and potatoes. Song Kim is a chef of the first persuasion, and a good one at that.
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