DEQX Speaker Correction: RMAF’s Most Amazing Demo

At the Rocky Mountain Audio Fest in Denver earlier this month, I must have visited at least 100 demo rooms and booths. But DEQX impressed me more than any of the scores of headphones, speakers, and electronics I heard.

DEQX has been around a while; I first heard the technology in 2005, when it was incorporated into an NHT speaker system. But the company’s focus on two-channel audio and my general lack of enthusiasm for digital audio correction schemes have deterred me from giving it a more serious listen. I might have skipped the company’s room at RMAF, but happened to encounter DEQX’s public relations guy, Jonathan Scull, in the Bel Canto room right across the hall. I could hardly turn down his invitation to visit the DEQX room when it was just 20 feet away.

I have to confess that DEQX’s David Higginbottom’s initial pitch really hooked me. “You’re about to hear the best sound at the show and the worst sound at the show,” he claimed.

The company first demoed its latest digital audio processor, the $4,500 DEQX Mate, by using it with a pair of TOA paging speakers, paging speakers of course being notorious for bad sound. Yep, it was indeed the worst sound at the show, with no bass, harsh treble and blaring mids. When DEQX’s Alan Langford kicked in the DEQX Mate’s processing, though, the PA horns suddenly sounded like a decent pair of home speakers.

The demo was even more convincing when I heard the DEQX Mate’s effect on a pair of Gallo Reference 3.5 speakers. As I discovered when I measured Gallo’s Nucleus Reference Strada, the company’s hemicylindrical tweeter design delivers consistent horizontal dispersion but very uneven frequency response. I heard the same character in the Reference 3.5 — until the DEQX Mate’s processing kicked in. With DEQX, the unevenness in the treble disappeared, yet the speakers still had the super-detailed, hyper-spacious sound I loved in the Nucleus Reference Strada.

“One of our goals is that the processing is not supposed to rob any component of its sonic character,” Langford said.

What’s the secret? “This is not room correction, it’s speaker correction,” Langford explained. “The customers measure their speakers themselves — we provide the software and the dealer loans them a microphone. They move the speaker out into the room and measure it at 1 meter.” The reflections of the room are truncated from the measurement, and the resulting data is then used to create a correction algorithm for the speaker. The company can also run the process remotely for customers who prefer not to get so deep into their audio tech.

The system focuses on phase response, not frequency response. “We look for the frequency that arrives the slowest, then slow all the other frequencies down to compensate,” Langford said. “It’s a phase correction, but we do end up with flat frequency response that way.”

While the system isn’t designed for room correction per se, it does have parametric equalization that can be used for room correction. According to Langford, the company recommends using it only for frequencies below 500 Hz, where the effects of room modes are problematic and the EQ’s effects won’t change the system’s tonal character.

Yeah, $4,500 seems like a lot to spend for digital correction, especially when similar (although in my opinion, not as effective) technologies are found in many $500 A/V receivers. But at a show dominated by enthusiasts who think little of paying for the subtle difference a $5,000 digital-to-analog converter might deliver, the massive improvements that DEQX achieves make it feel like a bit of a bargain.