Pair of PSI Audio AVAA C20 Active Velocity Acoustic Absorber Graphite

Selling the pair (two units) for the price, will not sell individually.

Review;

"Finally I can reveal the secret I've been keeping for months. Since the June issue of STEREOPHILE has come out: with my review of the AVAA active Bass Traps. It's remarkable technology that perform so well you think it breaks the laws of physics. There's nothing else on the planet that comes close to the performance of this patented technology. Sonically it has taken my room to a level of sonic accuracy that I never thought could be attained without some serious compromise, usually and overdamped room in the mid frequency and high-frequency decay time" - Bob Katz

How it works;

The PSI AVAA C20 is an innovative acoustic solution that efficiently absorbs standing modes in the range of 15 to 150 Hz within a room. Unlike traditional passive absorbers, it achieves this with less space and greater effectiveness. When in operation, each AVAA has a similar impact to a much larger opening in the wall, with effects varying based on frequency and environment, usually falling between 5 to 20 times the AVAA's size.
Placing the AVAA in rigid corners is ideal, where room modes are most prevalent. While the device won't significantly affect initial reflections, it alters the air's impedance to draw in and "suck" low frequencies. This is achieved by measuring acoustic pressure with a microphone in front of an acoustic resistance. The resistance allows air to pass while reducing pressure. Behind this, a transducer membrane absorbs the passing air, creating specific acoustic impedance.

In function, the acoustic impedance in front of the acoustic resistance is lower than in the surrounding air, acting as a pressure sink. The AVAA's influence extends around a radius of 1 to 1.5 meters, making it more absorbent than its surface area would suggest. Effective for frequencies between 15 and 150 Hz, it's particularly useful for room modes arising from multiple reflections.
Notable features include its analog nature, absence of DSP or latency, effectiveness comparable to a perfect absorber much larger in size, and no need for calibration. The AVAA also doesn't emit sound or alter the sound source, making it suitable for various room types, including recording, mixing, mastering, and listening spaces.
Even in regular-sized studios, two AVAAs can make a significant difference.