Things in audio are ever changing, though sometimes, it seems, only slowly. In the area of amplification, not much has changed in a very long time. In fact, amplification seemed to stall for many years, at a high degree of sophistication, if not quite perfection. Solid-state amplifiers came along a few decades ago, with the promise of a closer approach to perfection. Many listeners were eager to embrace transistor amplifiers, which offered freedom from the unpredictable reliability of tubes (particularly output tubes). Solid-state amps also held out the promise of better, more extended bass response and ever-lower levels of distortion, in a smaller, lighter, more powerful, and potentially cooler-running package. Nevertheless, most serious listeners concluded long ago that transistor amplifiers did not fulfill the promise of better sound quality, nor did they fulfill their other promises, as many became bulky, heavy, and, often, extremely hot in operation. Then, lo and behold, the circle was completed, and an avalanche of tube amplifiers, large and small, re-entered the high-end marketplace.

Although it is not usually stated, it is accurate to say that transistors are switching devices, not amplification devices. In push/pull, Class "A" operation, each half of the output device used (in pairs) to obtain amplification is partially open all the time. In other words, it is always drawing power, which is an inefficient method, though one capable of providing excellent sound. In Class "B," the complementary pairs are allowed to switch on and off (very rapidly), which results in cooler and more efficient operation, but usually greater distortion. Most amplifiers are accurately described as Class "A/B." In that configuration, the amplifier operates in class A at low output levels, but shifts to Class B when higher power is demanded. In Class "D," the output transistors are either fully on or fully off. That is where the phrase "switching amplifier" comes from—Class D amplifiers are analog, not digital, despite the "D" designation. The many Class D amps now emerging repeat the promises of the early transistor amps. They are at least four times more efficient than other classes of amplifier. They also offer very high power output without excessive heat, in a very compact package. If you have recently added a self-powered subwoofer to your system, chances are that it has a class D amplifier. If so, you have learned about the advantages of class D amplification, with its high power efficiency over a portion of the musical range.

Red Dragon Audio's Leviathan amplifiers ($5995/pair) are particularly well constructed, with attention to fine detail. Even the small wooden shipping containers are solidly impressive. Designed by Ryan Tew, the Red Dragon Leviathan seems simple, but is a sophisticated exercise in understatement. Fine-grained and beautifully finished wood comprises all four side panels, and the entire amplifier is only five-and-a-half inches high (10 x 5.5 x 14.5 inches). Though doing so is not recommended, many users will be tempted to use the amplifiers on their sides, to show off the laser-cut dragons that glow red on the stainless steel top panels when the amps are turned on. Stainless steel was chosen for the top and bottom panels because the amplifiers sounded better than they did when Tew tried aluminum or other metals. The power output of the relatively lightweight Leviathan (20 pounds) is high, at one thousand watts into four-ohm loads, half that into eight-ohm loudspeakers.

The Leviathans use a number of shielding methods to control interferences. All Class D amplifiers feature switching outputs, and the switching results in very high-frequency radiations that can invade nearby components, including wire. This is one of the reasons why Class D amplifiers can sound very different in different systems. My Purist Audio Anniversary power cords, with their superb shielding, seemed to be helpful. The Leviathans' rated frequency range, from DC to 38 kHz, is almost certainly an attempt to limit very high-frequency response that can cause EMI and other interferences. With the Red Dragon amplifiers—and other switching amplifiers—I recommend experimenting, far more than usual, with all aspects of placement, including the arrangement of all wiring.

The Leviathans are supplied with screw-in mounting points and contact discs, which are meant to transfer vibrations to the (hopefully solid) surface on which the components are placed. I also recommend trying absorbent feet or pads. I noticed slight differences between these two types of devices in my system. The Leviathan features truly balanced (not pseudo-balanced) circuitry. The only negative in this well-thought-out design is that if your source components have RCA outputs (all of mine do), adapters must be used on the amplifiers' XLR inputs. I urge Ryan Tew to consider changing to RCA inputs, or at least offering them as an option. If all of the electronics in a system are not operating in balanced mode, the advantages of having balanced operation in the amplifiers are lost. Using adapters also adds inches to the depth of the amplifier, and can affect placement.

Hooking up the Red Dragon amplifiers was simple and straightforward. Except for the need to use RCA-to-XLR adapters on the inputs, everything was solid, stable, and confidence inspiring, but even after many hours of burn-in, these attractive looking amplifiers sounded a bit strange. I called Ryan Tew and asked if any unusual procedures were required to get them to sound their best. He responded that he did not know how many hours of burn-in time that this pair of amplifiers had been given, and that 500 hours or more were needed. He suggested that they be given more burn-in time, so I put in another hundred hours, using Purist Audio Design's well-known System Enhancer Rev-B CD. Many more listening sessions, adding another fifty to a hundred hours, resulted in a very slight but definite improvement in sound quality. It seemed as if there was no end to the improvements gained from usage, although they were subtle at best. At no time were there any unusual noises—no pops, static, turn-on or turn-off noises, just a pair of very powerful amplifiers doing their job effortlessly.

When I started my listening sessions (admittedly too soon) with the Leviathans, I was disappointed, and much of my disappointment involved the top third of the audio spectrum. Early solid-state amplifiers were also disappointing, but the reason for my disappointment with the Leviathans was the polar opposite of the reason for the disappointment with early transistor amps. With the Red Dragons, I heard a rounded-off top end and a congestion that was readily apparent with large-scale orchestral music. The amplifiers never sounded irritating or harsh, but they did obscure fine detail and were lacking in micro-dynamics. Full orchestral dynamics were never lacking, but the sense of instantaneous transient response and life-like sparkle was noticeable by its absence.

Low-end fullness, over most of the bass range, was always apparent, and sometimes a bit of added fullness gave a pleasant hint of mellowness. This mellow touch was aided by the Dragons' lack of edginess in the top end. These characteristics were barely noticeable on unfamiliar recordings, but were more apparent on often-played recordings. Audio engineers that have not brought out Class D amplifiers tell me that what I hear is a result of the interplay between very high-frequency switching noise and efforts to filter that noise. My guess is that it is correct to call the switching noises generated by Class D amplifiers their Achilles heel. The goal is to eliminate the switching noises without seriously affecting the top end of the musical spectrum.

I respect Ryan Tew's accomplishments with the Leviathan amplifiers. His first commercial product is an amplifier that, if memory serves, is better than the early offerings of major manufacturers in the beginning of the solid-state era. To Ryan I say that this is an auspicious beginning. Now design an amplifier that offers extended high-frequency response while eliminating switching noises, without any deleterious side effects. Karl Lozier

More to come on the Red Dragon Leviathans by Dave Clark, Bob Levi, Danny Kaey, and Greg Weaver....

Red Dragon Audio
474 West 500 South
Provo, Utah 84601
TEL: 801. 361. 7138
web address: www.reddragonaudio.com