Bryston BP-173 line preamplifier Page 2

So I switched from the Constellation Stereo 1.0 to a Mark Levinson No.534 ($20,000), which had just arrived for review. To my delight, the new amp produced a more neutral tonal balance, along with transparency, clear highs, and bold dynamic contrasts. The midbass and midrange were smooth and grainless and, most important, didn't overpower the bass.

The bass response of the BP-173–No.534 pairing was unusually strong and extended. The full weight of pedal chords captured on good recordings of pipe organ pressurized my listening room. John Rutter's A Gaelic Blessing, with Timothy Seelig conducting the Turtle Creek Chorale and the Dallas Women's Chorus (CD, Reference RR-57CD), delivered the leaden density of the organ's lowest notes while separating the various ranks of choristers. The deep synthesizer notes in "Silk Road," from I Ching's Of the Marsh and the Moon (CD, Chesky WO144), had impressive weight and solidity. Daniel Rossi's sustained organ-pedal chords in the second movement (Poco adagio) of Saint-Saëns's Symphony 3, "Organ," with Antonio Pappano conducting the Orchestra of the National Academy of St. Cecilia (CD, Warner Classics 0190295755553), were appropriately powerful.


The Bryston preamp also favored percussion recordings, such as Mark Walker's drum solo in "Nardis," from Patricia Barber's Café Blue (SACD/CD, Premonition/Blue Note/Mobile Fidelity Sound Lab UDSACD 2002): It teased Michael Arnopol's double-bass notes apart from the drum kit's cymbals, kick drum, tom-tom heads, and rims. It also fully reproduced the impact of the frenzied bass-drum strokes that conclude Shostakovich's Symphony 5, in the recording by the Pittsburgh Symphony Orchestra led by Manfred Honeck (24-bit/96kHz WAV, Reference Fresh! FR-724, footnote 3). It also captured the ambience of the recording venue, Pittsburgh's Heinz Hall for the Performing Arts, including the sounds of the performers catching their breaths between notes in the first movement, Moderato – Allegro non troppo, making the music all the more realistic and compelling. The BP-173 easily resolved the differences in timbre between clarinet, bassoon, and contrabassoon as they played above the tremolo of the violins (footnote 4).

Subtle distinctions of vocal timbres were revealed when I played Eriks Ešenvalds's The Doors of Heaven, with the Portland State Chamber Choir directed by Ethan Sperry (24/88 WAV file from CD, Naxos 8.579008), a recording engineered by John Atkinson that's so good I chose it as one of my "Records to Die For" for 2018. As I listened to The First Tears, the Portland singers were clearly positioned on a wide soundstage, echoing each other as they sang Ešenvalds's setting of an Inuit tale of Raven. The voice of each of the three male vocalists had a distinct vocal timbre, and emanated from a position on the soundstage distinctly different from the other two. Similarly, Harry Connick, Jr.'s voice in "Don't Get Around Much Anymore," from the When Harry Met Sally . . . soundtrack (CD, Columbia CK 45319), was smooth and pure, without sounding tubby or nasal.


The BP-173's extended, transparent upper register captured the shimmering cymbal sounds that begin "The Mooche," from Rendezvous: Jerome Harris Quintet Plays Jazz (CD, Stereophile STPH013-2); made it possible for me to distinguish the delicate harp and celesta notes from the massed strings and percussion in the third movement of the Shostakovich symphony mentioned earlier; and created a compelling illusion of a waterfall spilling into a pool in the opening of "Running Water," from the I Ching album.

I matched the levels of the BP-173, Bryston's own BP-26 with MPS-2 power supply ($5390), and the Mark Levinson ML-7 ($4400 when new, ca 1984), all driving the Mark Levinson No.534 power amp. I also consulted the notes I took last year while listening to the Mark Levinson No.526 preamplifier. That ultra-expensive ($20,000) preamp has a built-in DAC and MM/MC phono section.

While all of these preamps have controls for volume, balance, source selection, and mute, only the ML-7 and BP-26/MPS-2 have toggle switches for Mono/Stereo, High/Low Gain, and Polarity/Invert. The ML-7 has no balanced inputs or outputs, and uses only CAMAC connectors, which require adapters for RCA plugs. Only the BP-173 and No.526 can be fully operated with a remote-control handset.

To listen to LPs, I used my Sutherland Engineering Vibe phono preamplifier ($895), though the ML-7 (footnote 5) and BP-26 have optional MC phono modules. BP-173 owners who use only MC cartridges will need to buy MM module ($750) and TF-2 step-up transformer ($1500) to listen to their LPs.

With some CDs, SACDs, and digital files, the BP-173's dynamics, punchy bass, slam, and soundstage depth matched those of the Mark Levinson ML-7 and the Bryston BP-26 and what had noted about the Mark Levinson No.526. However, neither the Bryston preamps or the ML-7 consistently bettered the No.526's clarity, air, transparency, transient response, and freedom from midrange grain. Of course, the No.526 costs almost four times as much as a fully optioned BP-173.


Until now, I'd never changed reference components during a review. I've been missing out. Finding the combination of Bryston's BP-173 and the Mark Levinson No.534 power amp was a stroke of serendipity that let me enjoy sound quality almost as good as ML's No.526 with some recordings at a fraction of its cost. Indeed, the BP-173 costs less than any solid-state preamp listed in Class A of the April 2018 edition of "Recommended Components."

Among new, high-value, line-level preamplifiers, the BP-173 is a welcome find. Driving the ML No.534, it produced engaging, detailed, tonally captivating, utterly natural sound that approached reference quality. Its deep bass extension, dynamic range, soundstaging, and speed were so good that I forgot about the review sample's lack of a phono or digital inputs, the absence of Internet connectivity for firmware updates, and the omission from its standard kit of Bryston's BR2 remote control. Matched with a top-quality, compatible power amplifier, the BP-173 is the bargain preamplifier to beat—but before buying, be sure to audition it with a variety of power amps. Strongly recommended.

Footnote 3: I'm not alone in loving this live recording, which in 2018 won Grammys for Best Orchestral Performance, Classical, and Best Engineered Album, Classical.

Footnote 4: Honeck's superb liner note describes how Shostakovich, fearful of being imprisoned in a Siberian labor camp by Stalin, scored a passage in the third movement, Largo, with "a clarinet, bassoon, and contrabassoon [to play] an emotional song of lament, as if somebody is completely lost in the most deserted, cold ice and left to mourn his own fate."

Footnote 5: In 1984, Mark Levinson supplied each ML-7 preamplifier with a pair of L-2 phono boards, for MM and MC cartridges with outputs of >0.3mV. The L-2 boards had microswitches for changing the gain (38 or 44dB), and switchable input impedance (825 or 50k ohms). Also available were user-installable MC phono boards: the L-3A board, with 53dB gain for medium-output (0.2–0.3mV) MCs; and the L-3 board, with 66dB gain for low-output (0.1–0.2mV) MCs. Both MC boards had a fixed input impedance of 825 ohms. My ML-7 has L-2 and L-3A boards.

Bryston Limited
677 Neal Driv
Peterborough, Ontario K9J 6X7
(705) 742-5325

Ortofan's picture

... "superbly well engineered" and "it is difficult to see how a preamplifier could perform any better on the test bench", is it sufficient to derive the full benefit of 24-bit hi-res recordings?
A noise and distortion level of 0.001%/-100dB is barely equivalent to 16-bit resolution. Even the -120dB level only equates to about 20-bit resolution. The LSB for 24-bit encoding is on the order of a level of 0.00001%/-140dB. Does any preamp come close(r) to achieving this level of performance?

dalethorn's picture

Mind-boggling. So whatever the preamp is capable of with the best-case 1 khz test tone, you run a typical 24-bit recording through it and try to hear the preamp's contribution to the sound? No argument here, just trying to imagine how all that breaks down in the real world.

Gnib's picture

I`m very curious about this follow-up on the DAC and phono modules.

dalethorn's picture

"Cubed models employ an array of 12 active devices for the first 6dB of gain. Developed by the late Dr. Ioan Alexandru Salomie, this array acts as "a super-linear" input buffer to filter out audio- and radio-frequency noise, particularly anomalies that originate in the power line, reducing the overall noise and distortion to less than 0.001%."

Well, I thought Ortofan's questions were simple enough, but the array (no pun intended) of issues aren't going to make things easy. Ignoring any photo stages (can I?), the "array of 12 active devices" acting on the "power line anomalies" is interesting. I'd prefer to filter my power elsewhere, but who knows? Maybe these guys have tricks that their competitors don't.

allhifi's picture

Cubed's IBG (Input Buffer/Gain) circuit may be advantageous in main amplifier stages but may not be particularly suitable for preamp's 'Input' stage.

Bryston's 'Cubed' series amplifier's clearly have an articulation/ resolution capability previous series lacked.

Interestingly, the "SST" series was a MAJOR improvement over ST series, but by many accounts, the SST2 was a step back?
Apparently, changes were made to the 'Input Stage' in the SST2 -not well received by many accounts. Yet it "measured" better to Bryston ! Go figure.
Come (near) full-circle, the new "3" series employs a circuit that, interestingly, has Bryston talking 'audiophile' language previously dismissed as superfluous, imaginary -not relevant/important -or "measurable" Go figure.

I suspect IBG-circuit doesn't correlate well in line-stage applications.
While many line-stage (preamp) designer's appear to be employing lower-and-lower gain 3,6, 9 db., Bryston continues with 12-18 db.? designs.

Stick with the 3B/4B3 (Cubed) amps; quite an accomplishment for Bryston.

peter jasz

allhifi's picture

dalehorn: I suspect you are referring to Bryston's noise level/vs./source resolution ?

If so, the "breakdown" in the real-world is obvious via listening evaluations.


dalethorn's picture

Interesting - In any case, these proprietary techniques don't reveal enough to do much besides just listening for any anomalies. If I were engineering these things, I'd like to explore ways to both shape and filter noise (if that makes sense), to try to make it less apparent psychoacoustically. How that would look from a whole-system perspective I have no idea.

allhifi's picture

Indeed, what you say makes complete sense (re: noise attenuation)

It's unclear why makers don't consider using 'Balanced' power/ transformers in their designs -or AC Re-generation, as noted in ML's No.52 preamp.

The Balanced (Symmetrical) AC power supply I'm using (Blue Circle MR-800/1200) offers up excellent 'performance' with any/all components connected/powered. (I use on for 'sources', the other for amplification)

I have recently acquired an Exact Power SP-15 -sitting idle currently.
The SP-15 has a single, substantial 1.8-2KVa that may prove beneficial for main amplification -eventually to replace the 1200 watt Blue Circle.

The improvements in (particular lower/mid frequency) resolution is dramatic, and most welcome -when compared to wall AC power.

Yet, at busy AC-usage times of the day, one can easily hear the polluted line's impact upon SQ; a lumpy, slow sound. It happens regularly.

I suspect an AC Re-generator (PS Audio P-3) would work extremely well in low-power applications, particularly 'digital' gear where SQ improvements are incredible.