#bryston

Design, Features & Usage

Compared to typically-spartan, even downright crude high-end amplifiers, the Bryston 4B Cubed (4B3 in shorthand) has a number of nice features:

Switchable unbalanced RCA and balanced XLR inputs

Low (23dB) and high (29dB) gain settings

Bridged mono operation

Soft start with remote trigger option

The distinguishing aspect of the Cubed series vs. Bryston’s previous line (e.g. SST2) is the Salomie input buffer. Co-developed with the late Ioan Alexandru Salomie, the circuit is said to reduce noise and distortion by 10x vs. the previous implementation and excel at immunity to RFI and power supply noise, a critical factor in today’s world where literally every device imaginable has a microprocessor and/or switching PSU buzzing away. Much has been written about the circuit in other reviews and the objective proof is in the 4B3’s superb measured performance - 0.005% THD and > 119dB S/N at full power (300W) across the entire audible spectrum.

I got the amp in black, with standard 17” front panel (no rack handles). The status LEDs glow green, but apparently this can be internally changed to blue if the customer prefers. I found the remote trigger feature quite handy when paired with the BP-17 Cubed preamp, and the switchable inputs useful for preamp/interconnect comparisons. The binding posts are of the standard 5-way insulated variety to meet EU regulations, and worked well with different sized spades. An extra pair of posts would have been nice to aid bi-wiring or my REL subwoofer hookup.

All business inside.

The 4B3 consumes a reasonable 60 watts powered up at idle - certainly not EPA EnergyStar territory, but about the same as my 60 watt Ayre AX7e integrated and just warm to the touch thanks to the generous heatsinks and extensive use of aluminum. Ecological concerns aside, I had no qualms leaving it running 24-7 in an open shelf with just a few inches of clearance above. Should you decide to do the green thing and power it down between sessions, the 4B3 consumes under half a watt on standby, and powers up quickly and smoothly. You'll hear the distinctive clicking of the soft-start circuit, and sound will start flowing within a few seconds. From a cold start, the sound takes about a half hour to get the juices flowing, and maybe an hour to reach full potential.

Setup

Preamp: I had the good fortune of having 3 very different preamps on hand during my time with the 4B3 - the companion Bryston BP-17 Cubed, the tubed Valvet Soulshine from Germany, and the Pass XP10. I found the Bryston pre to be a reasonably good match, but the Pass and Soulshine were simply better musically and both worked well, my top choice being the Pass. The 4B3's RCA input impedance is on the low-ish side (30kΩ), not the 100k+ that many tube pres seem to favor, so something to keep in mind when matching. The Soulshine did just fine, others may not.

Balanced vs. unbalanced input: for some reason, I preferred the sound of the 4B3 through its unbalanced inputs, save with the Pass preamp which doesn't fare as well unbalanced. It's hard to control for all the factors, but I had identical model of cable (DH Labs Air Matrix, Audience Au24 SX) in both RCA and XLR, and contrary to expectations I found the RCA input to sound fractionally more open and dynamic, and equally as quiet. Normally balanced operation affords you these qualities but I heard no such advantage with the 4B3. One clue is in the specs, which show drastically different input impedances for the balanced terminals - 30kΩ for positive, and a shockingly low 6kΩ for negative. This seems to indicate that it's not a differential/complementary input circuit like you'd find with e.g. Ayre or Pass, and I'd imagine this lack of symmetry compromises CMRR and some other benefits of balanced operation. I inquired with Bryston about how the circuit was implemented but didn't get a response.

High vs. low gain: Some people have commented that you can "tune" the sound of the Bryston, with the low gain (23dB) setting sounding a bit smoother and more laid back, while high gain (29dB) is more dynamic and detailed. I agree they sound different, but I had a different take: to me, high gain sounds transparent, and low gain sounds subtly dulled and veiled. For me it's a no brainer - unless absolutely necessary to attenuate, I'd always use the high gain setting. It simply sounds more truthful to me. I also inquired whether the low gain setting adds an additional attenuator in the signal path (it sounded like it to me) but again, I didn't hear back.

All the preamps, plus a DAC.

Bridged mono operation: I didn't test it, at least not intentionally, as I only had one amp on hand. I did accidentally flip the bridging switch once during playback which fortunately did not cause anything to explode. One note: if you do bridge it as a monoblock, be aware the input impedance drops to a very, very low 7.5kΩ, which I imagine will make some preamps quite uncomfortable.

Power cord/conditioner: The Bryston comes with a standard but appropriately-heavy 14-3 power cord, and it sounds quite good with it and wasn’t particularly fussy about changes. That said, I felt it was really locked in with the latest version of the Twirling Gerbil Red Electrum, a really fascinating cord made by our own MGD - bass became even more grounded, the soundstage locked in place and everything just clicked. Given that this cord isn’t readily available though, I’d say it’s worth trying a few different things (e.g. the Audience powerChord was a bit nicer than stock) but don’t worry too much - as long as you don’t use something gimmicky or too light, your amp is still going to sound good. One thing was clear though - the Bryston perferred being plugged directly into the wall vs. my Audience ar6 TSSOX conditioner. Even though the Audience is designed specifically with low impedance and high current delivery in mind, the Bryston felt constrained running through it - give it as direct a connection to the wall juice as possible.

Speaker cables: I got the impression that the Bryston prefers having a very direct connection to the speakers, working better with the heavier gauge cables I had on hand like the Cardas Clear Light or DH Labs Q-10 Signature (both 10 gauge or larger), vs. the Audience Au24 SX. I have a completely unsubstantiated theory that high damping factor amps employIng more negative feedback are more effective when there’s less between them and the speakers, whereas low/zero feedback designs (e.g. Pass or Ayre) don’t care as much and are more amenable to being tuned/voiced with lighter cables. Whatever the reason, I’d recommend sticking to the heavy stuff to maximize the Bryston’s grip on the speaker.

Speakers: I had a few speakers on hand, all of the 2-way monitor variety - Silverline Minuet Grand and SR-17 Supreme, Audiovector SR-1 Avantgarde Arreté, Role Audio Kayak. I really wish I had had a big 3-way floorstander as I’m sure the Bryston would have flexed its muscles and flourished wrangling a big speaker. My comparatively small speakers don’t provide that much of a challenge, all being amendable to low power tube amps. That said, the Bryston showed no favoritism towards any particular speaker - its voicing is essentially neutral and you’ll hear what the speaker is capable of. This is in contrast to my Ayre AX7e integrated, which clicks with the Silverline while sounding thin and unengaging with the Audiovector. I really did not think the Bryston would work at all with the Audiovector, an ultra high-resolution speaker that will megaphone any solid state liabilities like brightness, hardness or lack of body, but the Bryston impressively held its own with the unyielding Dane. I wouldn’t call it the most organic or emotive pairing, but they were quite agreeable working together. The Silverline SR-17 Supreme with Cardas Clear Light wound up being my preferred pairing, the combo bringing out wonderful midrange density and great dynamics, and most of my listening notes below reflect that setup.

Pure conjecture - I think the Bryston would be killer with a speaker like the Role Audio Enterprise - something a bit on the warm side with an silky-smooth but still-detailed soft dome tweeter that complements the transparency of the 4B3, and with some meat on the bottom end that could take advantage of the amp’s grip and power (I'm a fan of Role’s transmission lines). I’d also be curious to hear the 4B3 with a relatively inefficient but neutral speaker like something from ATC - that could be a good one, and ATC has a similar pro-audio pedigree. I’d steer clear of pairing with more forward/harder-sounding speakers, e.g. Focal Sopra or B&W or Paradigm Persona - not because the Bryston does anything wrong, but I frankly find those speakers with their metal/diamond drivers and higher-order crossovers too brittle and aggressive and in need of something more laid back (e.g. Naim) to sound anywhere near balanced.

Counterpoint: a reader reports getting great results with the 4B3, Focal Electra speakers and Crystal Cable with primarily hard rock and metal. I could see how the qualies of the 4B3 would click in such a system, particularly with harder-driving material.

The Sound

Out of the box, things were not promising. Compared to the Ayre AX7e I had been using for some time, or even an old Bryston B60 integrated, the 4B sounded drab. It wasn't bad per se, but everything was a little lacking - dynamics were a little flat, soundstage lacked depth, highs were a little glazed, midrange wasn't very dimensional, etc... even my wife couldn't help but comment, "this sounds boring." I saw a comment online describe the 4B3 as "gray," apt given what I was hearing for the first several days. A couple weeks later things were slowly improving, but not to the extent I was hoping. I was starting to get a little nervous about the conversation I'd be having with Bryston.

I fought the urge to swap other amps back in, and fortunately things continued to get better - much, much better. Despite having 100 hours of burn-in at the factory, the first 100-200 hours in my system were not at all representative of what this amp is capable of. After a month of continuous operation, virtually all of the aforementioned detractions had largely faded away; after 3-4 months and perhaps 500+ hours of music, it really started to push all the buttons. All my comments henceforth shall refer to the sound of the 4B after 6+ months in my system, and are representative of the long-term ownership experience.

With that out of the way... a standout aspect of the Bryston was how it delivered its obvious power with an easy finesse and speed. The Bryston sounds good for every one of its rated 300 watts (and actually more according to my unit's factory spec sheet)... this is an amp that revels in being cranked up, and the more watts I asked for the better it seemed to sound. But it also delivered those watts with delicacy and articulation, effortlessly revealing tons of musical detail in recording after recording without the typical detractions of high-power solid state - the glazed or harsh treble, the hard or murky midrange, the lack of rhythm and pulse. It was equally at ease floating Magdalena Kozena's vocals over delicate period accompaniment on a Mozart Aria, as it was hammering out the bass line of a Depeche Mode track. The 4B3's ability to reproduce music at realistic volume levels without strain or loss of transparency was addictive and had me cranking up number after number and pushing the limits of my neighbors' tolerance.

The treble was surprisingly delightful. In the past I've found big Bryston amps to lack refinement and resolution there, but the 4B3’s highs caught me off guard with how silky and delicate they were. Violins had just the right amount of brightness, bringing out the steeliness of the E string without sounding tinny, and triangles had realistic tinkle without popping out of the fabric of the soundstage. There was enough detail to do justice to the extremely high resolution AMT tweeters on my Audiovector monitors, but at no point did the 4B3 come close to burning my ears off the way some detailed amps can. Compared to the ol' Bryston B60 integrated, a longtime favorite that sacrifices some detail for sweetness and musicality, the 4B3 has far higher resolution in the upper registers that will bring out more energy without glare. There's no euphonic give in the high frequency response either, so if you need an amp that'll take some zing off a problematic tweeter (metal domes, I'm looking at you), look elsewhere.

Another nice surprise was how smooth and grainless the 4B3 was in the midrange, with just a hint of richness in the lower mids on things like cello, baritone, french horn or piano. It's subtle, and nothing like the bloom you'd get from a tube amp, or the coziness created by the Bryston B60 for that matter - just enough to balance out the transparency and power of the frequency extremes and keep the otherwise ruler-flat response from sounding too dry. Bryston claims the 4B3's quad-complementary output stage "mimics the characteristics of a Class-A design, but with dramatically lower distortion"; while it's not as round and juicy as true Class A designs like the Pass Labs XA30 or Valvet A4, it does approach their naturalness and smoothness much more than I'm used to from a high-power Class AB amp. I've found most gear that isn't blatantly colored to tend toward the leaner side these days, which can really put you in a pickle if you don't have something to balance it out. The 4B3 has a relaxed, generous quality to it which will help keep your system from getting too lean and bright, one of the more common traps of a modern system. I think this character of the 4B3 is summed up well in Christian Punter's extensive review on hifi-advice.com, and while I wouldn't go quite as far as he does, my listening observations largely align with his.

That warm, smooth quality might sound at odds with neutrality, but unlike some amps I've heard (ahem tubes) this came without biasing or distorting the sound in any particular way. Tonality of woodwind instruments in particular was spot-on, with the timbre of reed instruments - oboes, clarinets and bassoons - coming through distinctly and realistically. The wide variety of instrument timbres in a symphony orchestra are the toughest test for any gear and at no point did I pick up on anything nasal, bright, muffled or otherwise colored with the 4B3. True to its pro audio heritage, it gives the sense of telling it like it is with minimal editorializing and exceedingly low distortion.

Bryston makes much of the extensive lengths it went through in the Cubed series to both minimize internally-generated noise while maximizing rejection of external sources (e.g. RFI and power line noise). Whatever they did, it worked a treat. While the 4B3 is quiet at idle - with no input and your ear pressed up against the speaker, there's barely any hiss and zero hum - it's really the lack of audible noise and grain imparted on the signal that makes it sound so true and clean. Most solid state amps, including the older Brystons, always sounded a bit cloudy and grainy compared to the likes of Pass or Ayre. With the Cubed improvements, much of that has been scrubbed away, giving music a newfound sense of openness and purity approaching those venerable marques. Combined with fast, clean attacks, everything comes across with great clarity. Jason Kennedy describes this quality, along with all the usual British flourishes about PRaT etc., better than I could in his excellent review for The Ear - I recommend giving it a read.

The 4B3 also produced some of the best bass I have heard in my system. I've known Bryston amps to have big bass, but perhaps lacking in subtlety and definition. I found the 4B3 to be powerful for sure, but also tight, fast, and musically balanced. It was deep and tuneful, creating a feeling of unflappable stability with big orchestral music and heavy rock tracks. Sometimes amps with very high damping factor can sound lean, but the Bryston complemented its slam and control with just enough juiciness and resonance. String bass sounded full and tuneful without bloat, bass drum whacks had realistic impact, and pop/rock tracks had relentless drive. Some Class D amps I've heard capture pitch a bit more evenly (maybe due to their switching power supplies which reduce 60Hz colorations), but the Bryston is nearly their equal in that regard. It gripped the 6" woofers of the Silverline and Audiovector monitors and coaxed low notes of remarkable clarity and power within their physical limits.

Nits & Comparisons

Okay, so what doesn't the Bryston do right? Mostly little flaws of omission - subtle things that seem like fluff to non-audiophiles, but that the fanatics among us go through inordinate lengths and expense to obtain in the name of musical nirvana. While it's very detailed, it does gloss over some fine instrumental texture and spatial cues. While it's plenty dynamic, there are more organic sounding amps that convey more emotional swing and nuance - the electrifying climaxes of Maria Callas in a Puccini aria, the ebb and flow of the Vienna Phil in a Strauss waltz, the emotional surge of cellist Alisa Weilerstein in the Elgar concerto. While its midrange is very smooth, it doesn't have the liquidity of a fine tube or Class A solid state amp that makes instruments flow from the recording to your room. And its soundstage is a tick or two less deep and open, its images less dimensional and tactile than what those amps can convey.

Things got a little out of hand with the comparison testing...

For the most part, these are things you need to pay a lot more money to obtain, but some aspects can be had in this price range. E.g. the $4k (before it was discontinued) Ayre integrated gets more of the presence and immediacy of a voice, the sense that there's less between you and the performer - little nuances like clarity of diction, articulation of a bow stroke, pauses between phrases are a hair more convincing. Some people call this "inner detail" - not the obvious stuff, but the little things. The Bryston was a little laid back by comparison - not veiled, just less forthcoming - which will likely come as a relief to those with an aversion to harsh, forward solid state sound, but it's an omission nonetheless. The flip side is the Ayre pushes a bit too much in the other direction, sounding a little on edge and over-articulate compared to the unflappable Bryston, particularly with hyper-articulate speakers like the Audiovector. The 4B3 also has a more solid "core" to its sound - a sense of solidity and anchoring in the midrange. This is most apparent with notes around middle C (262Hz), where the Ayre lacks the natural weight that the Bryston captures nicely without sounding heavy or slow... again, a very endearing quality to those traditionally allergic to solid state.

An amp that made for a fascinating comparison was the Valvet A4 Mk. II ($8k) - a handmade, Class A solid state monoblock from Germany with minimalist circuitry and real soul. Despite being rated at just 55W/8Ω, with a reasonable load and volume level the Valvet sounds just as capable of macro dynamics as the Bryston while being noticeably more expressive within the melodies and more holographic with its soundstage. Tonally they were surprisingly close, both sounding full bodied in the midrange and extended in the treble. But the Valvet really has a way of projecting a compelling image and conveying a natural, singing quality that showcases the beauty of a tune and really pulls at your heartstrings. The resonance and ring of a soprano or flute, the halo around solo instruments, the height of the stage, the harmonics of an oboe - the Valvet captued these nuances with an uncanny ease and conviction that made the Bryston sound a little restrained and disconnected by comparison. However the Valvet doesn't have the same slam in the bass, won't drive as wide a range of speakers, and will run out of steam well before the Bryston even comes close to breaking a sweat.

I'll have more to say about the Valvet in its forthcoming review, but this isn't meant to be an indictment of the Bryston in any way - on the contrary, it proved itself a very fine sounding and satisfying amp, and I was impressed with how well it held up musically to a very special, highly tweaked-out audiophile amp costing over $1k more.

Verdict

Maybe I'm not talking to the right people, but the Bryston 4B Cubed seems to be flying under the audiophile radar. It's a very, very good sounding amp - great, even. Once properly run in, it possesses a subtly smooth and warm sound with none of the coldness or harshness one might be prejudiced to expect from such a powerful and practical solid state amp. And while not cheap, it's downright affordable compared to the astronomical price points in today's high-end market. It would be my absolute first choice for a combined music/home theater system, where it would have all the power and reliability to handle the needs of TV/movie watching while having plenty of refinement for music.

So it doesn't resolve the last few degrees of detail or stir the musical soul quite like the better high-end amps - the fuzz of the peach, the inner glow, the transcendent insight, whatever you want to call it. But those amps generally cost much more and/or have other limitations and compromises. For under $7k, the Bryston gives you musically satisfying reproduction that's easy to live with, and it will probably outlast every other piece of gear in your system. It's also a sound investment, maintaining resale value far better than average thanks to its durability, exceptional factor service and support, and of course that 20 year warranty.

Overall, I'd give the Bryston 4B Cubed 4 stars purely on sound quality, 5 for value, netting out to 4.5 stars overall. It's an amp you can set up and forget in most any system and just enjoy for years, and I came very, very close to purchasing the review unit. Ultimately my quest to get every last bit of that fuzz on the peach led me to continue my search for a reference amp, but there are times I wonder if I should have hung onto it... particularly now that I've moved to a larger space that could really benefit from the power, I have some pangs of regret sending it back. I enjoyed my time with the Bryston 4B Cubed and highly recommend giving it a listen - it might just be all the amp you need.