Acoustic Revive RHR-21 acoustic resonator 1 piece

Description - Acoustic Revive RHR-21 acoustic resonator 1 piece

Acoustic Revive RHR-21 resonator - world news

This resonator has a single, but important task, to eliminate resonant vibrations in the room /flicker/ caused by inappropriate composition of walls - glass/windows, furniture - glass table, glass display case, etc. It effectively fights parasitic sounds in the room, which you then have to listen to together with the music signal and it greatly disturbs the listening comfort.

Monoandstereo magazine review 17 May 2024:

Acoustic Revive is one of the most prolific manufacturers of high-end audio when it comes to specialized, well-designed and imaginative accessories. Designed by Ken Ishiguro, these accessories always go a step further than expected. They are usually on the edge of science, but none of these Japanese products have disappointed me and I have had the opportunity to test, listen to and review quite a few Acoustic Revive products over the years.

The RHR-21 builds on Ken Ishiguro's research into Helmholtz resonance theory.

Helmholtz resonance is the name given to the phenomenon of air resonance in a cavity, named after the German physicist Hermann von Helmholtz. This resonance occurs when air is forced to move in and out of an enclosed space, causing the air to vibrate at a certain natural frequency. This principle can often be observed in everyday life, for example when air is blown through the opening of a bottle, resulting in an unmistakable resonant sound. To make the best use of Helmholtz resonance, however, it is necessary to determine exactly where the cavity ends and the throat begins and how these aspects affect the high and low resonant frequencies. How important is this distinction? The resonant frequencies for the high and low end need to be calculated accurately and it needs to be determined whether the measured frequency falls within these ranges. The resonant frequency of air columns depends on factors such as the speed of sound in the air and the length and geometry of the air column. Longitudinal pressure waves are reflected from both the closed and open ends to form standing waves. The key to understanding these standing waves is determining the nodes and counter nodes of pressure and displacement in the air column. It is quite interesting how Ishiguro has managed to squeeze the primary elements and concepts into such a small but effective device. It required a lot of out-of-the-box thinking to bring technology that is usually implemented by much larger absorbers and diffusers into a device that fits in the palm of your hand. But as you can read throughout the review, Acoustic Revive has managed to encapsulate something very unique and highly efficient, despite the size.

Music

As always, we bring you a few reference tracks and albums that sum up the strengths of the Acoustic Revive RHR-21. Most importantly, the RHR-21 was able to present music more vividly without changing direction or deviating from the energetic, harmonic integrity that is key to maintaining its flow. Zen Percussions - Yaslikazu Amemiya. Zen Percussions is, for many reasons, one of my absolute favorite albums when it comes to obscure non-mainstream music. I don't think any other album I know of comes close to the sheer immediacy, lightning speed and realistic reproduction of metal percussion and its realistic representation in acoustic space. It's a record that can instantly "break" a system because its complexity, density of overtones and thunderous energy demands a truly balanced and powerful high-end audio system. I notice the differences immediately, as the album has become deeply etched in my subconscious with many repetitions because I like and love its narrative and sonic escapism. It's just something that touches my inner soul. With the Acoustic Revive RHR-21, I was again more than pleasantly surprised at how the timbre, tone and colour matched the music and the sound projected more realistically when these units were placed in their intended locations. There was more control and natural silence, and somehow the sense of extended virtual acoustic sphericity was pushed further.

I was pleasantly surprised by the effect of the Acoustic Revive RHR-21 on the track "Underneath The Apple Tree" from the Michael Franks - Tiger In The Rain album. Particularly with the horns, the obvious foray into three-dimensional space ensured that they were not only more natural in forte, but also took on greater crispness and solidified their three-dimensionality, revealing another layer beneath the sonic collage. All too often, sound supplements can expand the musical picture. By contrast, Acoustic Revive's RHR-21 proved with Tiger In The Rain that it's not a one-off, temporary performance enhancement, but a repeated balancing act. And for many other tracks, the RHR-21 brings the nature of attention to the forefront, which is again unusual for a small surround tuner like the RHR-21.

Conclusion

Like everything that comes from the master Ken Ishiguro, these room tuners are something special. Although the Acoustic Revive RHR-21s are relatively small, they have considerable weight when you hold them in your hand. These units are made of a solid aluminum block with a perforated top and a solid brass metal base. The openings on the top of the units are precisely calculated to achieve the most effective effect. These unique devices are designed based on the concept of Helmholtz resonators and must be carefully placed in strategic locations where energy accumulates. This can be achieved either close to the loudspeakers or by finding the exact focal points where energy accumulates and needs appropriate treatment. The location of the focal point can be measured or more easily found by playing a piece of music with the beat of a basic love register. It can also be done by projecting a pure sine wave signal while sounding at around 50 80 and 150 or even 200 Hz. Using the latter methodology, I have found relatively easy to work out the points for effective operation of these devices in my listening room.

Because of its patented, unique design, the RHR-21 room tuning device, when used properly, deals with the elimination of standing waves and should be placed in areas where these waves accumulate, such as in the corners of the room, near speakers, or behind audio racks. The RHR-21 is also designed to eliminate unwanted reflections, frequency clipping and phase response in the listening room, and to reduce frequency peaks and dips that affect the color and texture of instruments and voices. The result depends on the acoustic treatment of the existing room and careful placement, but when in place, it delivers a significant improvement in resolution by effectively removing sonic unsharpness.

Once the high-end audio system is balanced and the electronics optimally tuned, it is usually time to add high-end audio accessories. Without these basic steps in tuning, voice adjustment and finally balancing the system, it is impossible for any accessory to work to the benefit of the system, but only distract the listener from the real goal, which is the best possible reproduction of the music.

Acoustic Revive is one such product that can take system balancing to a new level of performance, but it needs clever and thoughtful placement in the audio system. If this criterion is met, the RHR-21 can make a noticeable difference in sound reproduction, and when in place, it easily shows its power, and the effect is by no means subdued. It can bring much more benefit to the overall performance of a system than its proportions might suggest. This is particularly interesting because, as written in the music section, it touches on the harmonic structure of the music, more specifically harmonic density and tonal overlap, along with richer sound projection, and that in itself is a great compliment and highlight.

Interestingly, with the RHR-21 in the right places, the decay times and delays are not lightning fast, but close to reality and reflect a realistic reverberation of the tones. The Acoustic Revive RHR-21 also reduces artificial glare that too often pushes the sound into brittleness, and naturally increases brightness by somehow playing with the millisecond timing of the music without altering the accuracy or speed of the attacks. Too often the value of something is measured by how and what exotic materials are used, or by esoteric techniques. The Acoustic Revive room tuner takes raw science and brings it into the realm of the unpretentious spirit of music that saturates the listening experience. Although at first glance the Acoustic Revive RHR-21 may be perceived as a patchwork of approaches, it actually exceeds expectations. Although it is a passive device, it operates in the realm of an active apparatus and, unlike many tuning devices, easily transcends the act of merely existing.

I am pleased to award the Acoustic Revive RHR-21 the 2024 Mono and Stereo Highly Recommended Product award. ❖

full test including photos: https://www.monoandstereo.com/