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Equipment Review
November 2006

Belles 350A Reference Stereo Amplifier

by Doug Blackburn


"A sure-fire Reviewers' Choice."

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Review Summary
Sound "There is no easily identifiable character to the sound of this amp. Every recording sounds distinct -- more distinct than they sound with other amplifiers…. The 350A Reference doesn’t add, subtract, or alter anything." Still, "the 350A Reference’s bass extension, power, and control make lesser amps sound like 20-pound weaklings," and "there was no softening or roll-off," but rather "total clarity and honesty in the highs." "The midrange has got to be as close to perfection as you can get at this point in time -- assuming your definition of perfection is not altering the recording in any identifiable way."
Features "The 350A Reference is a complete internal update of its predecessor, the 350A stereo amp. The new circuit has a complementary differential input stage using bipolar transistors. The output stage uses new MOSFETs that help it deliver two times the power and current capability of the 350A -- 64 amps of current capability overall." "The 350A Reference is also AC coupled, while the 350A was DC coupled."
Use "Beware: Power conditioners with 15-amp breakers may trip when you turn on a connected 350A Reference. It is also possible that a marginal 15-amp breaker in your home’s power panel might kick off when you turn on this amp."
Value "The 350A Reference provides super-amp sound without the super-amp cost."

Sometimes the work of a single-minded designer betters that of "the big guys." There’s a certain cachet that just can’t be equaled by the increasingly corporatized names in high-end audio. Sadly, many former craftsman operations are, in fact, merely well-known names disguising corporate ownership and guidance.

Dave Belles is a prime example of a modern-day audio artisan. Over the last 30 years, Belles has had an almost continuous string of über-performing products that have gotten consistent raves from critics and customers who eschew high-end big-brand names in favor of the more personal touch. Such customers tend to be drawn to the chi of a designer who creates the entire product from top to bottom, including auditioning his work on loudspeakers he designed and built.

The Belles 350A Reference looks pretty normal for an amplifier. It is of average size and not flashy in any way, though the 1/2"-thick faceplate does give it some "presence." Some might call the appearance elegantly simple. The Reference 350A doesn't have the billet chassis, fancy finish, or gigantic size that add enough supposed content to garner a five-figure price tag, yet it is solidly built and looks the part of a mid-priced high-end amplifier.

The 350A Reference’s physical size, 17"W x 5 1/4"H x 16 1/2"D, is not large for a high-end power amp in its price range. Much of its 65 pound weight comes from the Kong-sized power supply. Lights dim in neighbors’ houses when the 350A Reference is turned on -- well, at least in your house. Beware: Power conditioners with 15-amp breakers may trip when you turn on a connected 350A Reference. It is also possible that a marginal 15-amp breaker in your home’s power panel might kick off when you turn on this amp. Belles is considering a soft-start circuit if it can be incorporated without compromising sonics. After power-up, there is no problem operating the 350A Reference from a standard 15-amp AC outlet, and I had no problems with tripping a circuit breaker on a 20-amp dedicated line.

Using this amp is straightforward. The power switch and LED power indicator are on the front. The rear panel has the RCA inputs mounted high on the left and right sides. The single XLR input connection is used only for monoblock operation. The four gold-plated oxygen-free copper binding posts are clustered closely together in the center of the back panel to allow for dual bananas to be used for stereo or mono connections. Single bananas and spades are also OK. The binding-post location does make the center of the back panel a bit cluttered because the 15-amp IEC power-cord socket is mounted below the binding posts. With bulky biwired speaker cables and a beefy aftermarket power cord, there can be a bit of crowding with all those connections so close together.

The 350A Reference is a complete internal update of its predecessor, the 350A stereo amp. The new circuit has a complementary differential input stage using bipolar transistors. The output stage uses new MOSFETs that help it deliver twice the power and current capability of the 350A -- 64 amps of current capability overall. The new output stage has no source resistors, which, according to Belles, "offers many benefits, such as less coloration" and "better control and damping of the loudspeaker load." The 350A Reference has double the power-supply capacitance of the standard 350A "to improve its dynamics and for noise reduction."

The 350A Reference is also AC coupled, while the 350A was DC coupled. The difference is essentially safety for your system. An AC-coupled amp will not pass DC to the loudspeakers, while a DC-coupled amp will if any is presented at the input. Under normal conditions, this should not be an issue, but, as we know, sometimes stuff happens. There are also sonic considerations here. AC coupling compromises the sound and may limit bass extension in the bottom octave because a capacitor has to be inserted in the signal path to block DC from passing through the amp to the outputs. Dave Belles managed to insert a capacitor that doesn’t limit the deep bass (detected by ear or by SPL meter using the DC-coupled 350A as a reference point). Thus, there’s no audible harm to the audio signal from the extra capacitor that I can detect.

The 350A Reference costs $3995, an increase of $500 over the price of the original 350A. Even with all-new circuitry inside, 350A owners can have their 350A upgraded to the Reference version. This costs $1500 and includes new circuit boards, new wiring, and a 350A Reference front panel.

Bass bounty, high-end highs, and midrange meat

Theories on building a satisfying audio system are as abundant as snow in the Rockies. Mine involves starting with an amplifier that is as clear, pure, effortless, and neutral as possible -- like the 350A Reference. There is no easily identifiable character to the sound of this amp. All recordings sound distinct -- more distinct than they sound with other amplifiers. The amp itself does not impose a near or far perspective; you get what is captured in the recording with no enhancement or alteration. The 350A Reference doesn’t add, subtract, or alter anything. There’s nothing solid-statey about the sound, nor anything remotely tube-like. And I can’t even play the "musical" card, because with the 350A Reference this is entirely up to the recording. The 350A Reference, as best as I can tell, is doing nothing to the music but amplifying the incoming signal. Perhaps some day there will be an amplifier I encounter that reveals the 350A Reference to have a little something here or there, but if there is any sonic character in the 350A Reference’s sound, it is so small that I just can’t pick it up.

Listening to the Belles 28A

After hearing the 350A Reference with three perfectly good tube preamps, I didn’t feel that any of them were revealing all the performance the amp had to offer. I have been using tube preamps exclusively for 30 years, because in that time I’ve found only one solid-state preamp that was sonically better than the tube models I'd owned: an RE Designs six-channel unit. But that really wasn’t a practical product for my needs, so I kept waiting for the day I’d find a solid-state preamp that could finally end the tyranny of tubes I’ve been living with. Then Dave Belles offered up his new 28A, a solid-state preamp complete with moving-coil and moving-magnet phono stages.

This is it -- the real deal. Never again will I stomp the floor and growl over another preamp tube gone microphonic. Never again will I sit down to listen to music knowing the preamp sounds just a little worse than it did yesterday. Never again will I have to accept tube hiss as background noise in my system. The 28A is so good that I may never feel compelled to use something different.

The 28A is a low-gain preamp and, psychologically, it’s hard to get used to the volume control being between 12:00 and 3:00 all the time. Turn a tube preamp up that high and you are often rewarded with audible hiss from the speakers. The 28A stays silent, even when cranked beyond the 3:00 position.

There’s a remote control for power, volume, mute, input selection and record monitor. All functions are available on front-panel toggle switches as well. The phono stage was fabulous with my .25Mv moving-coil cartridge -- that’s about half the output of most moving coils. Dynamics, detail and lack of noise were top-notch.

The 28A is freakishly good at everything it does. Like the 350A Reference amp, it has no color, no limits bottom or top, and no hint anywhere of solid-state sound. Nor does it have any hint of tube sound. The 28A delivers everything you could want in terms of dynamics and harmonic content. The highs set the standard for what they should sound like from a preamp. The soundstage size is strictly a function of the recording. You can have flat or huge space; whatever is on the recording is what you’ll hear.

If you are looking for a preamp with no sound and no detectable limitations, the 28A is it.

...Doug Blackburn

Still, there are many things to be said about the sound of this amplifier. For instance, the 350A Reference shares the 350A’s thundering bass extension and control. The quality of the bass your speakers will produce with the Reference’s greater-than-2000 damping factor is simply fabulous. Paula Cole’s This Fire [Warner Brothers/Imago 946424-2] is one of the rare CDs that has some serious deep bass to exercise your full-range system while the music keeps you entertained. The 350A Reference rocked the room, providing more low-end power and control than other amps I've heard, though the 350A comes close. The 350A Reference’s bass extension, power, and control make lesser amps sound like 20-pound weaklings. It is simply remarkable to hear how much better bass can be when the amplifier has a huge damping factor, bleeding-edge topology, and a power supply that can dump lots of current. I realize there are those who feel that bass isn’t all that important, but I don’t understand the sentiment. For me, great bass is one of the biggest thrills in music.

However, it takes a speaker with good bass capabilities below 40Hz to hear everything this amp can deliver. I don’t think the bass quality of the 350A Reference would be terribly obvious with an expensive two-way speaker with limited low-end extension. But hook up a speaker with strong aspirations for producing bass below 40Hz and the improved bass performance becomes obvious.

The high-frequency performance of the 350A Reference is unlike that of any amp I’ve heard so far. The highs are so problem-free and color-free that recordings I thought were a bit over-energetic and annoying in the high frequencies proved to be easy to listen to with the 350A Reference. There was no softening or roll-off; the difference was in the total clarity and honesty in the highs. Brian Wilson’s Imagination [Giant /WB 924703-2] usually comes off as too energetic in the upper mids and highs. That causes listener fatigue by the time you are four or five tracks into this disc, even when using tube components noted for their musical high frequencies. The 350A Reference reveals more detail and tonal color in the highs with no grain, dryness, or harshness. The fatigue or annoyance present with other amps never develops. There is still a lot of treble energy in the recording, but it’s simply no longer objectionable with the 350A Reference.

I was so taken aback by hearing high frequencies without identifiable shortcomings or fingerprints that I spent weeks revisiting LPs with my analog rig. Dire Straits’ 45rpm Private Investigations [Phonogram/Vertigo DSTR-101 and DSTR-112] had impressive dynamics with endless high-frequency extension and clarity. Very subtle tone and level differences were rendered with precision not present in other amps I’ve heard. Godley & Creme’s Cry [Polydor 881786-1], another 12" 45rpm single, confirmed the spectacularly un-solid-state-like high frequencies. The highs were simply neutral in every way, pristine without a hint of added color, sweetness, graininess, dryness, or roll-off.

The Power of the Orchestra - Moussorgsky [Chesky RC-30] threw all the usual symphonic torture tests at the 350A Reference. It was a pleasure not to hear another layer (or layers) of ‘"flavor" on top of Chesky’s remastering done with modern custom tube gear. The original RCA Living Stereo recording was made with Golden Age tube gear. In the past, this recording always seemed to have too much tube sound to suit me. But the unrelenting neutrality of the 350A Reference allowed all the nuance of tone and harmonics to be heard in pristine detail. I kept wanting to say the 350A Reference had amazingly fast transient response, but this wasn’t something I noticed while listening. In fact, the "speed" of the amp was a non-issue. It simply did whatever was required by the recording. Transients were just there at whatever speed was captured in the recording. The high winds, reeds and strings were superb with complete preservation of the RCA/Chesky tube sound.

Associated Equipment

Loudspeakers –  Vandersteen 3A Signature, NHT 2.3.

Power amplifiers – Belles 350A and 150A Reference.

Preamplifiers – Audible Illusions Modulus M-3A, Belles 21A, Belles 28A.

Digital – Pioneer DV-535 DVD player used as a transport, Perpetual Technologies P-1A and P-3A.

Analog – Roksan Xerxes turntable, SME V tonearm, Cardas Heart cartridge.

Interconnects – Audience Au24, Magnan Signature, Nordost Quattro-Fil.

Speaker cables – Magnan Signature.

Digital cables Audience Au24 with BNC connectors, Vans Evers Pandora with RCAs.

Power cords – Audience Power Chord for source components, Magnan Signature for preamp, JPS Labs Power AC+ and Power AC for amplifiers and power conditioners.

Power conditioners – Monster Power AVS-2000, ExactPower EP15A, ExactPower SP15A, Equi=Tech Son of Q, Jr., Equi=Tech Son of Q, Richard Gray's Power Company Model 400S, Quantum Life Symphony, AudioPrism Wave Guides.

The 350A Reference also produced a great sense of space with all the dynamics captured on this updated classic recording. Hearing this recording through the Belles 28A preamp (see sidebar) and 350A Reference amp combo made me feel that this was the first time I was hearing it without audible compromises, additions, or subtractions. The sound was presented exactly as recorded by RCA and remastered by Chesky. The complete neutrality, detail, and dynamics of the 350A Reference made this my most compelling Living Stereo listening experience so far.

I tried hard to find something in the midrange to complain about -- I am a critic after all -- but there’s nothing there but pure, clean, glistening music. The midrange has got to be as close to perfection as you can get at this point in time -- assuming your definition of perfection is not altering the recording in any identifiable way. Even the hard stuff like female vocals, reeds, unusual percussion instruments like marimba and xylophone, and massed strings were smooth, sweet, detailed and completely grain- and haze-free. Paula Cole’s vocals on This Fire can be a bit too edgy and annoying with some amps, but the 350A Reference delivered all the raw emotion of the performance without the off-putting edginess I hear with other amps.

The 350A Reference presented more layering, space, and detail in the complex mix of Brian Wilson’s extraordinary Smile [Nonesuch 79846-2], making the music even more joyous and liberating. I loved the way the 350A Reference could make me smile again when listening to this great CD in spite of what must be the 75 times I've already heard it. Again, the amp added, deleted, and changed nothing. It simply reproduced more of what was captured in the recording without altering the sound in any way.

Belles vs. Belles

The Belles 350A ($3495) was a sonic breakthrough, taking amplifier sound to a place I’d never experienced before. The 150A Reference ($2995) improved on the 350A by being more neutral, more transparent, and having marvelous high-frequency performance. The 350A Reference trumps the 150A Reference by having greater dynamic drive throughout the audio spectrum, especially in the bass. In addition, the 350A Reference provides more detail and is even quieter in operation.

The 350A Reference extended my emotional connection to every performance very noticeably. In fact, it enabled an emotional connection with many recordings I’d given up on, recordings of good music that never reached their potential to draw me into the performance with other amps. Sitting down to listen to music with the 350A Reference can cause large amounts of time to be lost due to the complete immersion in the performances. Everything the 350A Reference does is a little more spacious (unless the recording itself is 2D flat), a little more transparent, and a little prettier without being colored or softened.

Other amplifiers I’ve reviewed in the last two years (all for other publications) in the same price range pale sonically, even in comparison to the older 350A or 150A Reference. I guess that means I recommend you hear any of these amps before you buy something else.


Does it seem unbelievable that a reviewer could be speaking of a solid-state amplifier that delivers the emotion, soul, and joy of a musical performance? Everybody knows solid-state amps can’t do that, right? No amp I’ve heard has the combination of bass, midrange, and high-frequency quality; low noise levels and low distortion; loudspeaker control; and sheer neutrality of the Belles 350A Reference. This is an amplifier that should be taken seriously by anybody seeking an open window on the recorded performance. Other solid-state and tube amps consistently have characteristics I can identify with careful listening. The 350A Reference’s lack of an obvious sound makes it a useful reference amplifier, but "reference amplifiers" aren’t usually praised for their ability to deliver the emotion and energy of the performance, which the 350A Reference does by nature. "Reference amplifiers" aren’t what high-enders who value musicality over all else will typically gravitate toward, but the 350A Reference delivers reference performance from both the analytical and musical perspectives, putting it in very rare company.

Sure it might be nice to own an amplifier that is so large and imperious that onlookers can’t help but "oooh" and "aaah," but the 350A Reference provides super-amp sound without the super-amp cost. A sure-fire Reviewers' Choice.

...Doug Blackburn

Belles 350A Reference Stereo Amplifier
$3995 USD.
Warranty: Five years parts and labor.

Power Modules. Inc.
479 East Street
Pittsford, NY 14534
Phone: (585) 586-0740
Fax: (585) 586-4203

E-mail: info@powermodules.com  
Website: www.powermodules.com

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