Better Sound Through DSP?
By Jon Iverson February 23, 2004 — Back in January of 2002, we reported that loudspeaker manufacturer NHT and DEQX (then known as ClarityEQ) had begun to co-develop a new line of active loudspeakers using DEQX's custom digital room correction technology. It's two years later, and NHT says it is finally ready to unveil the first speaker system incorporating digital signal processing (DSP) developed during the alliance.

NHT says that its first DSP-based system will consist of small satellite speakers, a unique powered subwoofer, and an outboard electronic component housing a DSP processor and class-D amplifiers. The company notes, "The system is designed as a platform for driver correction, digital crossover designs, and overall phase correction, representing an open platform that will allow further software upgrades in the form of DSP-based features as they become available."

According to NHT, the satellite speakers in the system will sport a 5.25" woofer and 1" tweeter and will be sold separately so that a variety of multichannel systems can be assembled. The system's compact subwoofer features two opposed 10" active drivers powered by a 400W class-D amplifier.

In order to simplify system placement, the subwoofer will incorporate both wireless (digital 2.4GHz transmission) and wired inputs. NHT claims the wireless transmitter allows two-channel wireless transmission for either stereo bass or multiple home theater subwoofers.

The heart of the system is described as a DSP processor/amp component, containing four class-D amplifiers that will provide bi-amplification of the stereo channels. Driver frequency response and equalization, phase response correction, and linear-phase crossover will be accomplished via proprietary, low-latency digital processing.

NHT's Jack Hidley says low-frequency room correction is based on DEQX technology and notes that the system also has fully integrated digital crossovers adjustable for up to 300dB/octave slopes. He adds that driver frequency and phase response corrections and the "linear phase" crossover are accomplished with low-latency digital processing. Hidley notes that "boundary controls" will appear on the front panel so that the frequency response of the system can be "easily optimized" based on room position. USB and microphone inputs on the DSP processor are intended to provide advanced users and installers direct access to the DSP's room correction software.

According to NHT's Chris Byrne, "Loudspeaker drivers have come as far as any mechanical technology can take them. After all the refinements and improvements of the past 60 years, DSP presents a path for correcting system behavior that will allow us to meet consumer demands for higher performance, smaller systems that are flexible in placement considerations and ultimately lead to significantly enhanced room correction."

NHT's DSP system should be available in the summer of 2004.