Its undeniable that speaker selection is paramount when using a single-ended-triode amplifier, but merely ensuring that the manufacturer-rated output power of an amp is greater than the recommended minimum power for the speakers is asking for trouble. Back in March of this year, Marc Mickelson reviewed the Song Audio SA-300 MB mono amplifiers, whose rated output is 8 watts, 1 watt more than Wilson Audio specifies as the minimum for Marc's WATT/Puppy 7 speakers. While Marc was thoroughly impressed with the SA-300 MB's midrange and treble prowess, noting that "the mids are gentle and full in character, but with what seem like strategically added glints of vitality," his enjoyment was ultimately limited by the amplifiers inability to satisfy at either frequency extreme with his speakers. Both Marc and Doug Schneider had heard the SA-300 MB amps sound terrific under show conditions, but it was obvious that Marc's speakers in his large room required more power than the Song Audio amps could deliver.
It just so happened that I had two pairs of speakers that could perhaps even the score: Tannoy Dimension TD10s and Mobile Fidelity OML-2s (review forthcoming). So we arranged with Song Audio to pair the SA-300 MBs with these speakers and report the results. I was fairly certain that the Tannoy TD10s, which, after all, are descended from the ultimate in high-efficiency SET-friendly speakers, would work with the SA-300 MBs, and I had high hopes for the Mobile Fidelity speakers as well.
With the Tannoy speakers, the SA-300 MBs had more than enough juice for just about any listening scenario I could imagine. While they did eventually run out of steam at obscenely loud party levels, they had sufficient grunt to play at higher volumes than Id ever care to listen, other than to make the point that its possible to do so. Bass came through with the Tannoys distinctive tonal richness that Ive come to know and love; hard-falling bass notes, while sounding rather more gelatinous than with higher-powered solid-state amps, did not detract from the composure of the midrange or treble, with the entire audio band remaining clear and poised, even on crescendos.
I did note some frequency-response aberrations though. The upper midrange was slightly elevated in level in a reasonably narrow band, which emphasized brushed drums and the lower fundamental of cymbals, but it wasnt significant enough to curtail my listening pleasure, although it did occasionally cause some instruments to jump out in an odd manner. Id guess that the SA-300 MBs' high output impedance and the subsequent interactions with the Tannoys impedance swings are implicated here, which stresses the try-before-you-buy nature of this type of amplifier.
The second set of speakers that I powered with the Song Audio amplifiers was the Mobile Fidelity OML-2s ($1999 per pair). These are floorstanding two-and-a-half-way designs with a 1" tweeter and a pair of 6" bass/midrange drivers each. Truth be told, I wasnt expecting much from this combination of amp and speaker, but due diligence required that I give it a try. Surprise! This combination sounded better than it had any right to, and was able to play, once again, pretty much as loud as I desired. Mahlers Fifth Symphony [Philips 422 355-2], 8 watts and claimed 84dB-sensitive speakers -- I bet you wont read about that combination too often. But it worked, it worked! While there was some compression when playing the most strident peaks at full-throttle, I had no complaints worth mentioning. I noticed no overt frequency-response deviations with these speakers, and overall I ended up enjoying this combination more than the SA-300 MBs with the Tannoys.
I found that a quiet room is mandatory in order to extract the best from the Song Audio amplifiers. The need for low ambient noise levels isnt in any way due to a lack of output power -- Ill reiterate that the amps play much louder with either set of speakers than I ever care to listen. What I refer to instead is that all of the fine detail dredged up by the amplifiers shouldn't be drowned out by background noise. A noisy room wasted many of the attributes that make these amplifiers sound so good.
Although the resulting performance was quite different with each speaker, some traits were consistently evident. Everyone harps on about the "lit from within" midrange and treble that are the hallmarks of 300B-based amplifiers, but the trait that I found most endearing about the Song Audio amplifiers was their astonishing retrieval of detail. These amplifiers peel a recording like an onion. Small, inconsequential musical events display new, exciting and emotional meaning. I must have listened to Charles Minguss Ah Um [Columbia/Legacy CK 65512] hundreds of times, yet I have never been so keenly aware of how busy, integral and fluid his bass playing is. Listen to "Better Git It in Your Soul." Its a busy song, and Minguss bass can get lost in the mix because its playing as more of a lead instrument and not really contributing to the fundamental underpinnings of the piece. The Song Audio amps helped hoist the bass up, if not to the forefront, at the very least from the anonymity of the noise floor. I found it easier to follow the bass line, and the same went for every other instrument on which I chose to focus.
The midrange of the SA-300 MBs was gloriously lush, and was indeed saturated with an appropriately burnished glow. Cassandra Wilsons voice doesnt need any help in the richness department, but the Song Audio amps dont overdo it. On the cover of the Robert Johnson tune "Come On in my Kitchen" from Blue Light Til Dawn [Blue Note CDP 581357], the SA300 MBs portrayed a roundness, a juicy fullness, to Wilson's voice that didnt change its basic nature but rather simply made that rich instrument into a more expressive one.
There were times Id find myself thinking that the treble was a tiny bit rolled off in absolute terms, most notably on the highest cymbal overtones. "Yknow, that might not be absolutely accurate," right-brain Jason would say. "Pipe down," left-brain Jason would retort, "and listen to how good it sounds!" Indeed, the upper midrange and mid-treble were silky and possessed of a rich warmth. Right now its a warm, sunny Saturday morning, Ive finished my coffee, and I'm sitting on the couch listening to Mozarts Clarinet Quintet in A, K581 from Clarinet Quintets [Musical Fidelity MF014] performed by Antony Michaelson. Theres an incredible sense of peace and calm that emanates from this recording, and its suited to the Song Audio amps. The violins are edge-free yet incisive (contradictory, I know, but this dichotomy is at the heart of these amplifiers), and the clarinet has its own distinct place in the soundstage -- recessed, simple, yet incredibly expressive. This recording, on this morning, is what I imagine Song Kim would use for his TV commercial, should he plan one.
I guess Im not telling you anything you dont know when I say that these amplifiers come with their own specific set of compromises. While two of the speakers that I had in-house worked just dandy with the SA-300 MBs, circumstances could have just as easily gone the other way and left me with a system that sounded like a clock radio. I must say, though, that I loved the way these amplifiers sounded and could live with them happily. Depending on your speakers, you may well reach the same conclusion.
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