CES 2014 - THX team up with Benchmark to create new amplifier

The audio and video company moves from certifying technology to developing it instead

by Steve Withers Jan 10, 2014 at 8:06 AM

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    CES 2014 - THX team up with Benchmark to create new amplifier
    “The market goes where it goes and we can’t always get it to go where we’d like it to go.”
    With these words Laurie Fincham of THX began to explain the process that has led the firm from certifying audio and video equipment to patenting technology that they hope will help change the audio and video industries. The first of these new products is the AHB2 a groundbreaking stereo power amplifier that they have developed in conjunction with niche audio manufacturer Benchmark. The reason that THX felt the need to develop an entirely new amplifier is to address the problem that whilst high resolution audio recordings are available in a variety of digital formats, none can be experienced to their full potential using a typical power amplifier. There are recordings available that have dynamic ranges that exceed 120 to 125 dB but it's hard to find a power amplifier that can deliver more than 100 to 105 dB of dynamic range.
    A digital amp is like putting square wheels on a car, then adding suspension to take out the bumps.
    As Laurie continued with his account of the genesis of the AHB2, he explained that Class AB amplifiers generate crossover distortion every time the output stage crosses zero volts. This crossover distortion can be especially problematic at low playback volumes. Conversely Class A output stages eliminate this crossover distortion at the expense of high power-consumption, poor damping and a limited dynamic range. THX have recently patented two technologies that address crossover distortion, virtually eliminating it while offering opportunities to improve efficiency, damping and dynamic range. This technology solves the crossover problem by combining a plurality of output stages such that one stage drives the output while another stage enters a crossover region. As a result, the distortion performance exceeds that of Class A amplifiers, whilst the efficiency exceeds that of Class AB amplifiers.

    The result of all this development is the AHB2, a stereo power amplifier that uses these THX patented technologies to eliminate most sources of distortion whilst simultaneously extending the dynamic range well beyond that of most high-end amplifiers. The AHB2 power amplifier delivers musical details without introducing the masking effects of amplifier noise. The dynamic range of the AHB2 approaches 130 dB, making it 10 to 30 dB quieter in terms of its noise floor than the typical audiophile power amplifier. We listened to the amplifier in a setup that used a Mac Mini as the source, a Benchmark DAC and KEF speakers and he results were astonishing, revealing previously overlooked nuances, dynamic ranges, textures and details in recordings we were already quite familiar with. When the sound was muted we put our ear right up to the speaker and couldn't hear anything, so the noise floor really is as low as THX claim.
    THX conceived of an amplifier with the sound quality of Class A and the convenience of Class D.
    The frequency response of the AHB2 extends beyond 200kHz to deliver the ultrasonic detail and fast transients captured by high-resolution recordings. At the other end of the audio spectrum, the low-frequency response extends below 0.1 Hz. The AHB2 has a high damping factor that augments its extended low-end to deliver solid, well-controlled bass. The AHB2 has been designed to escape the distortion limitations of classic amplifier topographies and instead allows you to experience full-bandwidth high-resolution playback. Despite the presence of cooling fins, the AHB2 also runs very cool and the fins are really only there to cater to the small minority who over-drive their amplifiers. The AHB2 can deliver 100W per a channel into 8 Ohms, 170W per a channel into 4 Ohms and 340W Bridged Mono into 8 Ohms.

    THX have developed over ten different patents related to audio technology, from amplifiers to processors to speakers and the company always gives preference to its existing licencees when looking to form a partnership. THX chose Benchmark for this project in part because the made exceptionally good DACs that would compliment the proposed power amplifier. Benchmark in turn realised that there needed to be a new kind of power amplifier that could match the performance of their DAC. The two companies worked together on the project, combining their expertise but the resulting amplifier doesn't bear the THX logo because it was felt that might overshadow Benchmark. This new amplifier was originally called the PA2 but the name was changed to the AHB2 in honour of Benchmark's founder Allen H. Burdick, who sadly passed away in September of last year. The AHB2 will be launched in the spring and will retail for around $3,000.

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