Boulder 500AE power amplifier Page 3

For some reason or other, it seems that 40Hz is the effective low-end limit of 90% of the big loudspeakers on the market today. Some go deeper, but most do not do it well, and few do it with authority. This, I believe, is why audiophiles who do a lot of listening to what is reputedly very good equipment seem astonished when they hear stuff that sounds substantially deeper coming out of the updated Sound-Labs. With the 500AEs, the A-3's apparent low-end range is a good half-octave lower than it was with my previous reference standard, the VTL 300. The main difference is that, since there is no slight additional weight at 40Hz (as there was with the VTL), the range below that becomes more evident. With the strapped Boulders, the new Sound-Labs' low end (with the wing panels) measure flat down to a hair above 30, which sounds deeper than you can imagine. (Visitors thought the speakers were reproducing an honest 20Hz. They weren't.)

To give you an idea of the kind of bass detail I'm talking about, the last section of Walton's Crown Imperial March (Previn/RPO, Telarc CD-80125) has several closely spaced bass-drum beats, with a sustained bass line behind them which I had always assumed was from bowed double basses. With the 500AEs, I noticed for the first time that it didn't sound quite like double basses, but then it didn't sound quite like a pipe organ (my second guess) either. Curious, I phoned Jack Renner: it wasn't double basses or a pipe organ, but an Allen electronic organ. The ability to reproduce that kind of LF subtlety would not have surprised me from a good transmission line or a big horn woofer system, but it was the first time I had heard it from a full-range electrostatic speaker.

Strapping the 500AE does involve a liability, though. Because it doubles the amplifier's gain, very low-level hum that might have been inaudible in stereo mode may become quite audible, particularly if you're using a high-sensitivity loudspeaker. (This happened to me. The hum was not from the amplifier, but from the power supply of my surround decoder, which was too close to the preamp.) The gain doubling makes sense from one point of view, because it does not require any more output voltage from the preamp to get four times the power as in stereo mode. But it will probably make the 500AE unsuitable for use with any horn loudspeaker unless its inputs are padded down.

But is it "high-end"?
While listening to these for months, I've been doing a lot of thinking about the high-end tweaking mystique. Sure, it's fine when you're working with your own system, and is in fact necessary to get it working at its best. But tweaking an amplifier by ear? I dunno...

What loudspeaker system should an amplifier designer use to tell him whether his amp has a sucked-out midrange or a tipped-up high end or a slightly thin low end? Ideally, he should use several—a "representative sampling"—but this rarely happens. Most use only one speaker system for listening, so it had better be "accurate." Of course, few speakers are, and there's very little industry agreement as to which they are. But the main problem, as I see it, is that any amplifier designer who tweaks his product by ear is unwittingly doing exactly the same thing that got CBS Records and RCA and Angel in trouble during their horror years of 1960 to 1980. In trying to make a recording, or a power amplifier, sound "better" through one pair of "reference" loudspeakers, you run a real risk of making it sound less good (or accurate, or whatever) on speakers that don't sound like that reference. I won't pursue the point further here, but it has gotten me thinking. Maybe an "As I See It" will be forthcoming.

Conclusion
As you may have gathered by now, I like this amplifier a lot—not so much for its sound as for its seeming lack of it. At almost $3500, the 500AE isn't cheap, but it's a lot cheaper than a number of other amplifiers I can think of that have definite sonic signatures which, while much favored by many audiophiles, could also be construed as being colorations of various kinds. Some that come to mind: the Rowlands, which tend to sound rather laid-back; many of the Krells, which hew toward a dark sound; and the Audio Research tubed units, which tend to have some forwardness and brightness. All of these amps, of course, can sound gorgeous if the loudspeakers happen to complement their sound, but if the speakers are fairly neutral (which is what we're all supposed to be seeking, is not it?), it's more than likely that the Boulder 500AE will make acoustically produced music sound more realistic than any of these can.

I realize that relatively few rock-oriented readers will understand my insistence that a system's first requirement be that it be able to reproduce the sound of acoustical instruments. The others will no doubt wonder what the hell I hear in this amplifier that turns me on. I am also well aware that Boulder The Brand does not have the cachet among high-enders enjoyed by such names as Krell, Mark Levinson, and Audio Research. And indeed, the Boulder does not have the disarming sweetness and liquidity of those amplifiers, sounding occasionally almost a bit coarse by comparison. But so does real musical sound. After having lived with the 500AEs for several months now, and attending symphony concerts locally from time to time, I contend that what I hear reproduced from the 500AE has more of the ring of sonic truth than my recollections of those other amplifiers.

Real instruments can sound beautiful—almost magical—but they also often make lots of vulgar noises: clicks, scrapes, squawks, and buzzes, particularly when played loudly. Many audiophiles prefer their musical sound a little more tidy than that, so I won't declare the 500AE to be the best amplifier you can buy, although I will say that if I owned one, I would not be compulsively driven to audition alternatives. I won't even urge every high-endophile to run right out and listen to the 500AE, because this is not really a high-ender's amplifier at all.

The 500AE's appeal is going to be to the "serious" music lover, whose frequent exposure to live acoustical music gives him a reference point that stems more from reality than from an idealized wet dream of what music should sound like if the world was more wonderful than real. I'm not even sure the sonic excellence of the 500AE happened by design (pun intended) or by happenstance, because Boulder prez and chief designer Jeff Nelson does not meet Bob Harley's definition of a "high-end" designer (Vol.14 No.7). Jeff seems to be pretty much a meter man, as evidenced by his skepticism about the benefits of warmup and the fact that he has never proselytized to me about the brand of interconnect he uses. But however it happened, he did something right, and the result is an amplifier that I have been happier living with, for a longer time, than any other I have ever used.

Would I recommend the 500AE? Well, yes and no. If all you're looking for is "magical" sound from whatever non-acoustical fare you enjoy, I would advise listening to the 500AE, but I would strongly urge you not to buy one without auditioning it first in the privacy of your own home (footnote 4). But if you listen to live acoustical music often enough to know how unglamorously raw it can sound at times, and are fairly confident that your speakers are capable of reproducing a measure of sonic truth, then the 500AE could well be the ideal amplifier for you. (The only other amplifier I can recall that had the Boulder's ability to tell it like it is was the now-discontinued Threshold SA-1, which (interestingly) was designed the same way as the Boulder: by brilliant engineering, rather than by aural tweaking. Today, the Threshold amp most comparable in price to the 500AE—the S/350e—costs $3900, $400 more than the Boulder. It has not yet been reviewed in these pages, though the more powerful and more expensive S/550e has been, by Robert Harley in Vol.14 No.1 and by Tom Norton in Vol.14 No.9.)

Highly recommended!



Footnote 4: No one should buy any audio product without auditioning it first, but I know a lot of our readers do. What can I say?—J. Gordon Holt
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