Solid State Power Amp Reviews

John Atkinson wrote abut the M28 in August 2015, (Vol.38 No.8):

When Michael Fremer reviewed this $30,000/pair power amplifier in the May 2015 issue, he admitted that he had difficulty getting it to sing with his Wilson Alexandria XLF speakers, especially before the review samples had broken in. "Out of the box and dead-of-winter-right-off-the-truck cold (but given a day to reach room temperature)," he wrote, "the M28s sounded more tube-like, more 'soft and loose' than 'fast and tight.' Though it was consistent in these and other regards from top to bottom, the M28s didn't exactly provide the woofer control advertised on Bricasti's website. Bass was soft and rhythmically bland."

After the amplifiers had been continuously running for a week, MF felt the Bricasti M28s' top end fully opened up, their bottom had tightened, and the overall sound was considerably more transparent. However, he still felt the M28's sonic signature was "more smooth and sweet than fast and tight."

In their "Manufacturer's Comment," Brian Zolner and Casey Dowdell of Bricasti Design felt that Michael was yearning after aspects of the sound that, in absolute terms, were unnatural. "When a listener is presented with a sound that contains an order of magnitude less distortion than their reference system," they wrote, "it takes time to hear that as a positive aspect of the sound. Distortion masks the honesty of the recording, but it also adds high-frequency excitement. The additional harmonics add volume, particularly to transient elements and elements that already have a bit of distortion in the recording." In my "Measurements" sidebar to the review, I had noted that the M28s did indeed offer very low distortion. "Even at 40% power into 4 ohms," I wrote, the highest-level distortion harmonic, the third, "lay at –90dB (0.003%)."

There was also a possible complication with Michael's reference preamplifier, the darTZeel NHB-18NS, which sounds at its best when used from its single-ended outputs, whereas the M28 prefers to see a fully balanced input signal. Michael did use the darTZeel's transformer-coupled balanced outputs, as well as its single-ended outputs, to drive the Bricastis, but that introduces another variable.

Given all of these matters, Brian Zolner asked me if I would be prepared to write a Follow-Up on the M28, especially as I still had the review sample that I had measured (serial no.1006). I agreed, and the other sample MF had reviewed (no.1007) was shipped to me after being checked out at the factory. (Zolner let me know that no.1007's bias was slightly high, but did not think this would change the measured performance.)

I was also sent an up-to-date sample of the Bricasti M1 D/A processor, which I had reviewed in February 2012. However, to avoid changing too many variables at once, I did most of my auditioning of the M28s with two balanced-output DACs with which I was familiar: Ayre Acoustics' QB-9 and PS Audio's PerfectWave DirectStream—the latter running the v.1.2.1 firmware because I was not familiar with the more recent Pikes Peak upgrade—both connected via AudioQuest's JitterBug USB cleaner. The source was a Mac mini running Pure Music 2.0 and Audirvana Plus v.1.5.12, and the speakers were first the KEF Blade Twos, then GamuT RS7s (review underway). At first, I used the DACs to drive the fully balanced Ayre KX-R Twenty preamplifier.

Mostly, I think, Michael called it correctly. Once broken in—which did indeed take a few days from completely cold—the M28s produced a wide, especially deep and expansive soundstage, with an absence of grain. The midrange sounded superbly natural, the high frequencies smooth yet detailed. With the KEFs, the balance was a little on the polite side, though the GamuT speakers proved a synergistic match. With Iván Fischer and the Budapest Festival Orchestra performing Rachmaninoff's Symphony 2 (DSD64, Channel Classics 21604), the M28s produced an enormous sweep of sound at the climaxes, with no tendency toward glare or the treble balance becoming congested, and the Tchaikovsky-esque brass scoring had just the right amount of "blattiness," in the late J. Gordon Holt's wording. The big violin tune in the slow movement—there is no punishment severe enough for Eric Carmen's stealing this tune for his 1976 hit "Never Gonna Fall in Love Again"—maintained its tonal composure as the volume increased, with no audible signs of intermodulation-type distress.

Michael's main criticism had concerned the M28's reproduction of the low frequencies. Certainly, with the Rachmaninoff, the doubles basses dug down deep. In "My Rival," from Steely Dan's Gaucho (24-bit/96kHz ALAC file transcoded from FLAC, HDtracks/MCA B0000868-36), the bass guitar and kick drum sounded rich but tight with the Bricastis, and weightier than with the Ayre MX-R Twenty amplifiers reviewed elsewhere in this issue. Certainly the weak spot of the otherwise superb Pass Labs XA60.5 monoblocks that I reviewed in January 2014 was their bass register—the Bricastis readily outclassed the Passes in that respect.

Given Bricasti's provenance—the company was founded and its products designed by Madrigal and Harman alumni who had been involved with the Mark Levinson brand—I would have loved to have been able to compare the M28s with the samples of the Mark Levinson No.33H monoblocks I purchased back in 1998, However, one of my '33Hes has had a broken power supply for several years now, and fixing it has been too long on my to-do list. (A task that is neither urgent nor important tends to get a low priority.) But the M28 didn't seem to have the rather dark balance that I remember the Levinsons having.

In my review of the KX-R Twenty, I had commented on the paradox that the system sounded better with the Ayre preamplifier than with a volume-control–equipped DAC feeding the power amplifiers directly. But in an e-mail exchange with John Marks, he had mentioned that he got great sound from the Bricasti DAC without using an intervening preamplifier. I therefore connected the PS Audio PerfectWave DirectStream DAC directly to the M28s, matching levels to within 0.15dB to those I had used with the Ayre preamplifier for the same selections of music. (The PS Audio's volume control was generally set to provide 12–20dB of attenuation.)

To my surprise, with the levels matched, the PS Audio feeding the M28s sounded slightly quieter. But there was a noticeable improvement in clarity. John Barbirolli's rather muddy-sounding 1962 traversal of Elgar's Cockaigne Overture, with the Philharmonia Orchestra in London's Kingsway Hall (ALAC file ripped from CD, EMI Classics CDM 7 64511 2), lightened up, but without the brass instruments sounding harsh. But Giuliano Carmignola and Mayumi Hirasaki's brisk performance of J.S. Bach's Double Violin Concerto, BWV 1043, accompanied by Concerto Köln (ALAC file ripped from CD, Deutsche Grammophon Archiv 0289 479 2695 5), now sounded a little too shrill. Certainly the M28's rather laid-back balance was now less polite, a little more vivid. The Channel Classics Rachmaninoff still sounded sweet—and the solo violin in the first movement was deliciously tangible—but the low instruments sounded a bit too gruff and less authoritative without the Ayre preamp in circuit.

On balance, with the PS Audio DAC I think I preferred the Bricasti M28s used with the Ayre preamp. But either way, this was definitely superbly involving sound. It was time, therefore, to replace the PS Audio with the Bricasti M1, again without a preamplifier and primarily with the M1's reconstruction filter set to "Minimum 0." With the Bricasti D/A processor driving the M28s directly and its volume-control settings ranging between "–22dB" and "–11dB," to match as closely as possible the volumes with the PS Audio both used direct and with the Ayre preamplifier for each music track, this was the best sound I obtained with the M28s. The midrange remained as sweet and detailed as it had been with the PS Audio PerfectWave DirectStream, and the highs were in better balance with the mids.

More important, the low frequencies in the Rachmaninoff were both better defined and had more weight with the M1 driving the M28s directly. Pino Palladino's Fender bass, played with the heel of his right hand damping the strings at the bridge, on Where the Light Is: John Mayer Live in Los Angeles (ALAC ripped from DVD, Sony 722727), had full weight. The PS Audio was slightly better at presenting reverberation tails in my recordings of the Portland State Chamber Choir, but the M1's more forward signature worked better with the M28s.

The M28's sound still has a more polite balance than that of the Ayre MX-R Twenty, but used in an empathetic system—particularly in one optimized for classical orchestral music—it will produce true reference-quality sound. Overall, I very much enjoyed the time the Bricasti M28s spent in my system. They worked best with Bricasti's own M1 driving them directly, particularly with the laid-back KEF Blade Twos. Yes, at $30,000/pair this is an expensive amplifier, but if you want the reliability of a solid-state design with the smooth-balanced midrange magic of tubes, and low frequencies that are sufficiently well developed, the Bricasti M28 is indeed a Class A contender.—John Atkinson