Mesa Engineering Baron power amplifier JA listens to the Baron
Giving away its professional heritage, the dual-mono Baron has a ground-lift switch for each channel, a guaranteed way of minimizing ground-loop hum. I have no idea why this often essential option is so rare in consumer amplifiers, unless it's a safety/insurance issue. I got the most hum with with one or both channel grounds connected to the system ground, so I lifted them them both for my auditioning.
I spent only a short time listening to my first sample of the Baron, which was dark-sounding as all get-out, especially in triode mode. It turned out that an early production run of 18 samples—including mine—had been fitted with a wrong-value capacitor. As I was about sit at the laptop to dismiss the amplifier in a few choice words, a phone call from Mesa's Tom Menrath informed me that a replacement was already on the way.
Chip Stern wasn't bothered by the "limitless" variations the Baron has to offer. Me, I'm made of less stern stuff. Faced with a choice of output transformer taps, four negative feedback levels, and four operating modes—triode to pentode, with two stops along the way—I spent a weekend ringing the changes with the second sample before settling down with a basic setting which seemed to work best with my Silver Signature speakers. Which was: all-triode, with the negative feedback set to the minimum setting short of none at all. All-pentode was, to my ears, a bust—intolerably bright, at least to my ears. Dynamic, certainly, and the amp played loud with only a smidgen of drive from the preamp, but the sound lacked class. And at my age, class is what I wants from a piece of electronics.
In triode mode, the class was there. Seductively sweet-sounding, in fact. Anything with female voice, anything with those most vocal of instruments, the trombone and the cello, was reproduced with a sense of "body," of being there, that made the music sing. In comparisons with the amplifier I've found to be the best in this area, the single-ended and identically priced Cary CAD-300SEI, the Baron fell a little short, but not by much. And on recordings that had been recorded so as to capture a real soundstage—Keith Johnson's neglected but sonically superb, early HDCD release of virtuoso classical clarinet pieces (Ebony Concerto, Reference Recordings RR-55CD), for example—the Baron threw a huge, spacious dome of ambience around the musicians.
It was at the frequency extremes that the Baron fell short of what I want from an amplifier. The revised amplifier was less dark-sounding than the first sample, but it was still balanced well on the mellow side of neutrality. While this generally didn't get in the way of the music on most recordings, it might be a problem in system matching. The bass was also a problem area in that it failed to kick rhythm sections along with sufficient pace. Charlie Haden's bass on the superb-sounding Ginger Baker Trio album produced by Chip Stern, for example, was just too fat, warm, and nice-sounding to kick much booty. Pleasant, yes, but the tension just wasn't there. As CS mentioned, increasing the negative feedback or changing to partial or all-pentode operation went some of the way toward alleviating this character, but I just liked the low-feedback triode mode too much to be happy with this compromise.
Chip commented positively on the Baron's dynamics. Paradoxically, while it does give an impression of controlled power, I couldn't get the amp to play loud without it starting to sound strained. In my preferred triode mode with Stage I feedback, playing the 20-bit master for Stereophile's Robert Silverman Liszt recording, which I was preparing for LP release, 20W on the meters (which I later measured as indicating a true 20W from the 8 ohm tap into 8 ohms) was about as far as I could usefully push the amplifier. Note that the Baron was not clipping; rather, the sound started to get a bit gritty, and treble grain began to intrude. When I kept the level below 20W I enjoyed what the Baron did with the music; above that level, I reached for the volume control.
"A definitive conclusion as to the Mesa Baron's rightful place in the hierarchy of great power amplifiers," Chip asks for in his part of this review. Looks like the new kid on the reviewing block don't ask for much!
With its high output impedance and progressive distortion characteristic, Mesa's Baron both gives away its music-industry pedigree and reveals its departure from the high-end amplifier norm. Its sound will vary to a much greater extent than usual, depending on the loudspeakers it is asked to drive, and mandating a careful audition before purchase. But when everything does go its way, the Baron will give its owner much musical enjoyment.—John Atkinson