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Krell Unveils Radical Changes to Amplifiers

At the International CES in Las Vegas this week, Krell is unveiling a product design change to its audio amplifier line that it is calling the most revolutionary change in its 33-year history.

At the International CES in Las Vegas this week, Krell is unveiling a product design change to its audio amplifier line that it is calling the most revolutionary change in its 33-year history.

Called iBias, it is based on a patent-pending technology that uses the Class A circuitry preferred by audiophiles yet consumes far less energy than a traditional Class A amplifier does.

Because iBias technology eliminates crossover distortion, Krell says that it allows low-level details, subtleties, and the spatiality of music to come through exactly as they do in a traditional Class A amplifier. Yet iBias also allows these new amplifiers to produce “the nearly limitless dynamics” that are the hallmark of Krell’s sound.

“Class A amplifiers have always been the preferred choice of audiophiles, and they’ve been a hallmark of Krell engineering for decades,” said Bill McKiegan, president of Krell Industries. “But concerns about energy consumption have reduced some of the enthusiasm for Class A. We are now building in our Connecticut factory a new type of amplifier with musicality that surpasses that of Class A and the energy-efficiency of newer Class G and H designs. Our iBias designs deliver all of this in a surprisingly compact package–and it also incorporates Internet-based technology that will amaze both audiophiles and systems integrators.”

The new line includes seven models, each one built into a 3U-high (5.25 in/134mm) chassis with removable rack-mount ears. The model numbers of the amplifiers indicate their power in watts RMS per channel into an 8-ohm load. The line includes two monoblocks, the Solo 550 and Solo 375; two stereo amps, the Duo 175 and Duo 275; the three-channel Trio 275; the five-channel Chorus 5 and the seven-channel Chorus 7.

Class A amplifiers eliminate crossover distortion (the distortion that occurs when the audio signal shifts from positive to negative polarity) by operating the output transistors at full power all the time so they never shut off. Any energy not required to drive the speaker is dissipated through the amplifier’s heat sinks.

In an iBias amplifier, a circuit continuously measures current flow through the amplifier’s output transistors, and instantly adjusts the power (or bias) going to the transistors to suit the demands. The output transistors never shut off, yet very little power is wasted as heat. Not only does the amplifier consume less power, it runs cooler and can be built into a more compact chassis.

“The iBias amplifier is like a high-efficiency 12-cylinder automotive engine in which some of the cylinders shut down when you don’t need all that power,” McKiegan explained. “Just as that engine can run efficiently yet deliver 600 horsepower in an instant, the iBias amplifier can run efficiently yet in a matter or microseconds gives you hundreds of watts of full Class A bias for musical peaks.”

iBias amplifiers also incorporate features that make them much more practical for custom installation than most high-end amplifiers are. The amplifiers are built into relatively small, rack-mountable chassis, making them practical for use in places where a traditional Class A amplifier would likely be too large. Proper cooling is assured through the use of thermostatically controlled fans chosen specifically for their ultra-quiet operation.

In order to assure reliable, consistent operation for years, Krell has added Ethernet capability to all iBias amplifiers. Through the Ethernet connection, each amplifier can be accessed on its own web page through any device that can run a Web browser, such as a smartphone, tablet or computer. Using this interface, the dealer or customer can view heat sink temperature, fan speed, and other information, and also receive alerts for such conditions as overheating, fan failure and shorting of the output terminals.

Like the newest Krell products, including the Foundation AV preamp processor and the Connect Stream Player, the iBias amplifiers feature an industrial design with precision-machined metalwork and distinctive lines. This look is enhanced by the complete absence of visible screws or fasteners on the top, front, and sides.

All of the iBias amplifiers have begun shipping or will ship later this month.

Here are the prices:

ModelDescriptionPrice (each)
Duo 175175-wpc stereo $7,500
Duo 300300-wpc stereo $9,500
Chorus 5200-wpc 5-channel$7,500
Chorus 7200-wpc 7-channel$9,500
Solo 375375-watt monoblock$8,750
Solo 575 575-watt monoblock$11,250
Trio 300 300-wpc 3-channel$11,500