Krell Launches 'Radical' New iBias High-Efficiency Class A Amplifiers

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Krell has announced what it’s calling their most revolutionary design change in its 33-year history: iBias.
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,”
“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.”


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 have always been the preferred choice of audiophiles, and they’ve been a hallmark of Krell engineering for decades,” Bill McKiegan, president of Krell Industries, said. “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 thatof 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 also incorporate internet-based technology that will delight both audiophiles and systems integrators.”