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Emerging Technologies

TacT Audio - Room Correction & Digital Amplifiers

TacT Audio are well-known for their groundbreaking and unconventional use of digital technology in high-end audio, exemplified by their Millenium digital amplifier, and more recently, their RCS digital room correction Click for a Larger Versionsystem. The owner of TacT Audio, Peter Lyngdorf, is seen entertaining and informing CES attendees on the stack of equipment to his right comprising of an NAD CD transport on top driving an RCS 2.0 Room Correction System ($2,950) in the middle of the stack whose digital output feeds the Millenium amplifier ($9,600) at the bottom. Not seen in this picture are the Dali loudspeakers driven by the Millenium.

TacT Audio have gone after one of the holy grails of high-end audio with the RCS 2.0 correction of errors introduced by the listening environment. Namely, the RCS 2.0 seeks to ameliorate reflections from the walls, floor, and furniture in a room which cause uneven frequency response problems like boomy bass, imprecise imaging and soundstanging. How does the RCS 2.0 do this? Basically, it measures the impulse response of a room, and then applies the inverse of the room response to the audio signal so that the correction and the room errors cancel out, leaving only the audio signal. What's different about this approach from, for example, any conventional kind of equalizer is that RCS' correction varies with time whereas a conventional equalizer will apply the same change all time. This is an important distinction because reflections are a time-varying effect: a distortion due to a reflection only occurs some time after the main signal because the reflection needs time to bounce against a wall and reach the listener, and a reflection does not travel about forever because it loses energy each time it encounters a wall, furniture, or the listener. It's clear that a conventional equalizer cannot correct for reflections because it will apply its correction before the reflection arrives at the listener, and will still apply its correction well after a reflection leaves the listener. For a reflection, a conventional equalizer will be correct only at one instance in time: when the reflection arrives at the listener. At all other times, the equalizer will be coloring the sound you hear.

By contrast, the RCS 2.0 uses the impulse response of the room to determine when to send a correction, because the impulse response of a room also shows the reflection timing present in the room, and can therefore be more effective. Note that, without going into a lot of hairy mathematics, this is an extremely simplified explanation, and hopefully serves only to give the reader a sense of the significant difference between a conventional equalizer and what TacT is trying to do. There are many kinds of reflections that no system can ever correct because of physical limitations, and the simple explanation above doesn't consider this limitation.

Given all this theory, how well does the RCS 2.0 work? From my very brief listening session under show conditions, the RCS 2.0 appears to work very well indeed. Peter was holding court and I mean that only in the nicest way because Peter very much has a large room presence and seems to thrive in front of a big crowd in a live, unfurnished room with bare walls, with the Dali Click for a Larger Versionspeakers placed very close to the bare walls. The difference between room correction on and off was large, dramatic, and very much in favor of the correction. In a difficult room, the RCS 2.0 did very well.

While working room correction alone is already quite an achievement, TacT have gone further, and have made the system very easy to use, which is something I feel is as important as the main feature itself. The best feature in the world is worthless if its users gave up and never used it because it was too complicated to use. Just as importantly, true ease-of-use reflects a thoughtfulness in any design showing that the designer has moved the feature beyond a lab experiment into everyday usefulness, meaning that the designer has considered how the feature will be used in a day-to-day context, and is indicative of deeper thought and thoroughness of design in a feature. In other words, the feature itself benefits from the additional thought of ease-of-use, and, as result, is usually fundamentally better. And so it was for the TacT RCS 2.0. With a portable PC hooked up to the RCS 2.0, Peter was able to quickly and effortlessly measure from any spot in the room, and have the correction loaded and ready to go within two minutes. The RCS 2.0 even gamely tried to correct for a measurement spot right next to one of the speakers, almost flush against the wall the system was so easy to use that it was painless to experiment freely.

The RCS 2.0 base unit has 5 digital inputs and 3 digital outputs. TacT offers optional analog-to-digital convertors ($690) with 5 analog inputs, and optional digital-to-analog convertors with 2 analog outputs so the RCS 2.0 may interface with any system. The RCS 2.0 can also be used as a preamp with input switching and digital volume control. The RCS 2.0 uses 3 high-speed Motorola DSP chips for its room correction, and has 2Hz granularity. When expanded to 6 DSPs, the RCS 2.0 will have 1Hz granularity of correction. This is important for bass frequencies, wherein corrections must work on narrower Click for a Larger Versionfrequency bands than higher frequencies. TacT will also offer a conventional 16-band equalizer option for about $400 for RCS 2.0, which is useful for correcting errors in recordings.

The RCS 2.0 corrects for only two channels, and TacT Audio is set to introduce a 10-channel A/V preamp with 10 channels of room correction in March 2001. The price for the TCS (Theater Correction System), seen in above with the Millenium amplifier and a Toshiba DVD player, will be around $10,000. In addition to room correction, the TCS sports DTS, Dolby Digital, and Dolby Surround decoding, and is expandable via its modular design.

On the digital amplifier front, TacT Audio showed a prototype of its upcoming integrated digital amp, the 150 Wpc M2150, which uses the same amplification technology as the Millenium amplifier. The M2150 accepts digital inputs up to 96kHz 24-bit and is expandible to 192kHz 24-bit. Like the TCS, the M2150 will bow in March 2001 priced at $3,995, substantially less than the $9,600 Millenium. []

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Show report last updated: 23rd April 2001. 276 original images on-line.

 

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