June 2002 Reviewed by Anthony Di Marco	Sherbourn 5/1500A Multichannel Amplifier

Description Model: Sherbourn Technologies 5/1500A Price: $1999 USD Dimensions: 17.7"W x 17.7"D x 7"H Weight: 79 pounds Warranty: Five years parts and labor Features Monoblock construction 400VA toroidal transformer (one per channel)	Features (cont'd) 20,000 microfarads of capacitance per channel 500-square-inch heatsink per channel Auto turn on Auto biasing circuit Balanced XLR and gold-plated RCA inputs 8 bipolar output transistors per channel 30-amp current capacity per channel Detachable IEC power cord Anti-clipping circuitry 12V DC trigger

Attempting to differentiate one audio product from a sea of competitors is a difficult task. While some manufacturers choose to wax hyperbolic about features that are as thin as the stickers on their products' faceplates, Sherbourn Technologies purports to offer the consumer benefits that are considerably more substantial.

The $1999 5/1500A multichannel power amplifier stands as a prime example of this North Billerica, Massachusetts-based company’s philosophy: start with a solid design principle that dictates that the final product will require fewer in-born compromises. For Sherbourn amplifiers, this lies in what Sherbourn co-founders Ron Fone and Engne Tang refer to as true monoblock construction.

Technical details

Before examining Sherbourn’s concept of monoblock construction, let’s look at your average surround-sound receiver. Almost all of them utilize the latest DSP chip, exhibit tight build quality, and boast 100Wpc for up to seven channels. Unfortunately, not all "watts" are created equal. And, despite what the specs might say, a thousand dollars won’t likely buy you an amplifier that can simultaneously sustain 100W of high current and voltage into multiple channels, across varying frequencies and impedances. The chances are good that our hypothetical receiver shares power supplies or transformers among its multiple channels. This means that it might not deliver all its power into all its channels for sustained periods. Although the chance of needing 100W into all of a receiver's channels might be slim, there are times when one channel's requirements might prevent another from delivering the power the signal dictates -- and a clipped signal can permanently damage a loudspeaker.

One solution would be to use a completely isolated amplifier for each channel. This is common in cost-no-object systems, where each amplifier would be a completely separate unit referred to as a monoblock. A few manufacturers make multichannel amplifiers based on this same concept -- there are even a few receivers built that way -- but Ron Fone and Engne Tang believe they’ve one-upped their competition with Sherbourn's five-channel 5/1500A (a seven-channel version of this amplifier and companion processor is due out this summer). Most affordable multichannel products use a shared power supply (transformer and capacitor bank) to drive monoblock electronics. Sherbourn, however, furnishes each channel’s electronics with an individual power supply. Fone and Tang acknowledge that this same monoblock approach is offered in more expensive competing products, but by remaining specialized, manufacturing their products overseas, and employing the same monoblock module throughout their entire product line, they are able to offer the technology at an unprecedented price point.

The beast

The 5/1500A is rated to deliver 200W into 8 ohms (and 300W into 4 ohms) with all five channels driven simultaneously. Its casework won’t bowl you over with expensive sheet metal or a beefy faceplate. What might take you by surprise, however, is its weight. At close to 80 pounds, the 5/1500A isn’t easy to lug around. The absence of dedicated handles and lack of wiggle-room in its carton make setting it up a little awkward. A sturdy rack or amplifier stand is an absolute necessity for this beast.

Around back, four rubber feet allow the unit to stand on end without crushing its high-quality balanced and unbalanced audio inputs and speaker connections. Yes, you read that right: in addition to single-ended RCA-type inputs, the 5/1500A has XLR connections. According to Sherbourn, this affords greater flexibility in the unit’s placement by allowing long cable runs from processor to amp. The XLR connections are inherently better at preventing hum or RF-induced noise from clouding the signal.

Around front, a florescent-blue power LED gives the amp an upscale appearance without being distracting. Well, at least it wasn’t distracting to me. My son, however, was drawn to the LED and power switch like a fly to a zapper -- making my wife wonder where the sound went when he experimented with the nickel-sized switch.

Under the 5/1500A's well-ventilated top plate, five completely independent mono assemblies suggest where Sherbourn spent the majority of their budget. As advertised, each module sports its own double-donut-sized 400VA transformer, 20,000 microfarads of capacitance, and robust aluminum heatsink. Less conspicuous are the multiple bipolar output transistors that populate each channel. According to Tang, using eight 250V transistors not only affords the amp increased stability into reactive and low-impedance loads, but also, in conjunction with the separate transformers and plentiful heatsinks, contributes to the modules' superior thermal performance.

In class A and A/B amplifiers, a good deal of energy is lost to heat. Sherbourn maintains that the 5/1500A’s individual power supplies contribute to a cooler thermal environment than an amplifier that shares facilities, since each supply is tasked only with the demands of a single speaker.

But can this beast carry a tune?

Having an amplifier capable of a kilowatt of power into an 8-ohm load doesn’t necessarily mean that you're going to be playing music loud. Typically, loud music played through efficient speakers will consume no more than a few constant watts per channel. Yet enormous amounts of power will give you the headroom to handle musical peaks and extremely wide dynamic shifts without strain. This quality was quite audible in the listening tests.

Chapter 2 of Jurassic Park 3, for example, gives us a cell-phone-gabbing Udesky walking up to his associates, just as they test-fire a large gun. Simultaneously, Udesky finishes his phone conversation, the gun is fired, and a plane carcass is destroyed. The sound was remarkably clear and dramatic. The Sherbourn 5/1500A showed no signs of compressed dynamics -- it dealt easily with the dynamic swings and maintained its output without a hint of distortion. This rendered scenes, such as the battle between the Spinosaurus and T-Rex in chapter 6, with shocking realism.

Saving Private Ryan is filled with many examples of deep bass, such as the scene where tanks rumble into the village during the film’s finale. Bass, in particular, is an area where the 5/1500A easily outperforms most receiver-based systems I’ve heard, and, frankly, it does so to a point where using a sub with speakers like the NHT ST4 almost seems completely unnecessary. The Sherbourn's control over bass was tight and authoritative.

Speaker systems from NHT and Triad both benefited from the Sherbourn’s substantial power. But it was the NHT ST4 home-theater speaker system that seemed to be the better match for the 5/1500A’s silky, laid-back midrange and high frequencies. The combination of my Harman/Kardon receiver and the NHT system displayed an uncomfortable amount of sibilance during chapter 1 of Unbreakable. Connecting the Sherbourn to the H/K’s preamp outputs removed the sibilance and allowed the amp to dig deep into the ST4’s bass capabilities. The 5.1 image produced by the NHTs was also excellent when driven by the 5/1500A. Seamless front-to-back pans and a hyper-evocative ambience gave me goose bumps while watching Final Fantasy: The Spirits Within.

The Sherbourn’s refined sonics also served less action-centric films well. The rich Dolby Digital mix on Requiem for a Dream was more realistic through the 5/1500A than with the dimensionally flatter presentation of the Harman/Kardon’s internal amplifiers. The scene where Sara Goldfarb’s refrigerator comes alive during a drug-induced hallucination was frightening in its transient detail and clarity. Everything in the 5.1soundstage felt more tangible and focused with the Sherbourn amp.

I experienced less visceral energy when Triad’s Silver Monitors took over. Music from Howard Shore’s brilliant Lord of the Rings soundtrack [WEA 48238-2] conveyed less drama and sweetness in the treble and midrange with the two-way bookshelves. Guitar and percussion on the title track of Suzanne Vega’s Songs of Red and Gray [Universal 493111] lacked the shimmering overtones that gave the recording more dimension. Detail was still there, mind you -- though not as forward as with the NHTs. For instance, the decay of piano and the wispiness of Sunny Sumter’s vocals had less of an edge on track 4 of Mapleshade’s Music Festival [Unapix Entertainment UPX 72032].

The Sherbourn’s interaction with the Triads confirmed my overall impressions of its sound: a darker-than-neutral timbre. It displayed good detail across the frequency range, presenting vocals with good weight, and bass with healthy body and energy. It didn’t quite have the most vivid soundstage or hard-hitting slam I’ve experienced, though.

Beast versus…

I took delivery of the five-channel B&K AVR305 (younger brother to the Reviewers’ Choice-awarded AVR307) at the end of my evaluation. And despite obvious differences, this receiver competes quite well with separates-based systems. Purchase a 5/1500A and you still need a processor and quality interconnects to get the AVR305’s functionality. But the total price for both would probably rise above the $3000 retail of the AVR305. That’s the price you pay for power.

Which amplifier sounded better was a question best left to individual taste. The B&K had more zip and slam and seemed to have a better balance across the frequency spectrum. The Sherbourn tended to accentuate midrange elements, such as voices, over other portions of a performance, which benefited vocal intelligibility.

The B&K also seemed to exhibit a more natural rate of decay. By comparison, the Sherbourn’s slight lack of sparkle made bells and cymbals sound slightly flatter as their clinks and splashes faded away. The Triads, in particular, sounded more alive with the AVR305, while the NHTs favored the better qualities of the Sherbourn. The Sherbourn 5/1500A was definitely more adept at driving more lively speakers.

The Sherbourn had a slightly shy, yet immensely powerful, sonic signature. In my evaluation, the Sherbourn gave a larger-than-life presentation to everything I listened to. During Jurassic Park 3, the B&K made the dinosaurs’ footsteps seem like they were going to make a hole in my floor. By comparison the 5/1500A had more weight, but less attack -- as if the floor was flexing under the dino’s weight, rather than splintering under its step.

So will this beast fly?

Technology and competition in Sherbourn’s market space has reached a point where you either have a well-built amplifier that can differentiate itself from the crowd, or you have a dead product. Fone and Tang know this, but they also know what it takes to build a good product. They also genuinely believe in giving the customer the most for his hard-earned dollars, and in my opinion they’ve accomplished this. From an engineering/cost standpoint the 5/1500A is an impressive piece of gear that has the effortless strength and the silky-smooth demeanor of a ballerina over the speed and force of a football player. Its construction offers features that differentiate it from the crowd. Indeed, of the products currently available, I know of few that offer the same design features, and impressive power and performance, as the 5/1500A at anywhere approaching its price. 

Manufacturer contact information:

Sherbourn Technologies
19-3A Sterling Road
North Billerica, MA 01862
Phone: (978) 663-7385

E-mail: Sherbourn@aol.com
Website: www.sherbourn2.bizland.com/

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