Harmonic Resolution Systems (HRS) EXR Audio Stand
Chassis Noise Reduction
Before we dive into the review of the EXR rack, I need to take a little detour to explain the two other elements that complement the HRS system: Chassic Noise Reduction and Damping Plates.
What HRS refers to as Chassis Noise Reduction is essentially a range of Footers (Nimbus, Helix, and Vortex) and Damping Plates (in various sizes and two thicknesses) to be used respectively under and on top of audio components. The products can work with other racks (when the support surfaces have similar properties as the HRS Isolation Bases) but they are made specifically to be used with HRS stands. The Chassis Noise Reduction products are designed to reduce the noise levels on the bottom of the audio component chassis as well as reduce the component’s top chassis noise level. HRS recommends using 3, 4, or 5 footers per audio component, depending on its surface area.
Nimbus System
The Nimbus System is a broadband noise-reduction design, intended to work ideally with the HRS Isolation Base and Damping Plates. The Nimbus products reduce air-borne vibration by eliminating bottom panel resonance, while the Damping Plates work to control top panel resonance and the HRS Isolation Bases or Rack System significantly reduce the harmful effects of structure-borne vibration.
The Nimbus unit is manufactured from billet-machined aircraft aluminum and proprietary HRS polymers that feel soft to the touch and are a little sticky. There are two primary components to the Nimbus system: the all-polymer Nimbus Coupler that sits on both ends of the sandwich and an anodized aluminum Nimbus Spacer that sits in between. The combined specific amount of mass, stiffness, and damping from these components reduces chassis resonance problems and transforms residual chassis energy into heat.
Nimbus is placed directly on the shelf to support the audio component, with one of the all-polymer couplers in contact with the surface of the shelf, and another in direct contact with the bottom chassis of the component, thereby bypassing the existing component feet.
Nimbus is available as separate elements consisting of a spacer and two couplers or a complete bonded assembly. The NA in the product type stands for Nimbus Assembly which means that it is a bonded version of the Nimbus Coupler and Nimbus Spacer whereas the separate components carry the NS moniker where I imagine the S stands for “separate”. Each version is available in three heights. Just as with the Rack System, the model number incorporates the size, in this case, the height. For instance, the NA-150 that I was provided has a 1.5″ height, which is 3.8 cm. HRS makes no recommendations as to the number of Nimbus footers to use but I assume 4 will be the default.
Helix System
The Helix System is designed to reduce the negative impact of air and structure-borne vibration on the audio or video component’s performance. The Helix’s materials are not specified but appear to be a hard and non-sticky polymer underside encased in an aluminum top section. Helix is specifically designed for use with components that have stiffer (plate and billet) metal chassis construction and yields targeted performance improvements when used in conjunction with the HRS Isolation Bases.
The HRS Helix was designed specifically for use with HRS Isolation Bases. Using the HRS Helix in conjunction with another shelf that does not have the same capabilities as the HRS Isolation Bases can limit the performance benefits achieved by the Helix. As with the Nimbus, the Helix can be used in combination with HRS Damping Plates. While the Helix significantly reduces bottom chassis noise, the Damping Plates will work to reduce top chassis noise in the component.
The Helix is produced in a very low-profile design, completely invisible under most components, so it is ideal when you wish to maintain the original look of the component. This product is available only in a single variant but thanks to its adjustable Stainless Steel centerpiece it will fit a wide range of audio components. As with the other HRS products, the model number incorporates the size, in this case, the height. The HLX-090 has a .90″ ~ 1.1″ height, which is 2.3 ~ 2.9 cm. Depending on the size of the audio component, 3, 4, or 5 Helix footers can be used.
Vortex System
The Vortex System is designed specifically to obtain maximum performance from audio components designed with a stiffer chassis construction. A stiffer chassis is one that is constructed from plate or billet metal parts rather than a standard sheet metal construction. The Vortex is designed to be placed in direct contact with the component’s chassis, not under existing component feet, with the point in direct contact with the HRS Isolation Base and the large diameter in direct contact with the component chassis.
The Vortex is comprised of a Stainless steel topside and a custom hard polymer-like material underside. The custom material interface within the Vortex steel outer case is developed by HRS specifically for the Vortex primary interface and is optimized to push the limits of resolution and dynamics without brightness, fatigue, or high-frequency noise. The Vortex also contains a second custom internal element that dissipates the chassis energy as it passes through the Vortex’s non-magnetic stainless steel housing along a specific length path allowing the internal parasitic element time to deplete the energy and prevent it from returning to the system.
The Vortex system is available in two versions, the V-150 standard version with a fixed height of 1.5″ (3.8 cm), and the adjustable V-150A which allows a subtle height adjustment for precise leveling calibration purposes. Depending on the size of the audio component, 3 (all fixed), 4 (1 adjustable), or 5 (2 adjustable) Vortex footers can be used.
Damping Plates
Damping Plates are used on top of audio components to reduce chassis noise. They are precision manufactured from billet-machined aircraft aluminum and proprietary HRS polymers. A very specific amount of mass, stiffness, and damping from these products eliminates chassis resonance problems and transforms residual chassis energy into heat.
As with other HRS products, the product type indicates the size. For instance, DPX-05545 indicates a Damping Plate with a size of 5,5 x 4,5″. The Damping Plates are available in three sizes and two thicknesses. The thicker variant is 1.3″ (3.3 cm) while the thinner variant is 0.7″ (1.8 cm).
For this review, I was supplied with all three available sizes of the thicker variant: DPX-05545 (14 x 11.4 x 3.3 cm), DPX-09545 (24.1 x 11.4 x 3.3 cm), and DPX-14545 (36,8 x 11,4 x 3,3 cm).
F
HRS SXR rack with CH Precision P1 Phono Stage. Thanks to the cavity in the rack’s supporting structure, a thick HRS Damping Plate fits perfectly. In situations where there is less vertical space, the thinner Damping Plates will be ideal.
Next: EXR Rack Assembly
Once again, thanks for the in-depth examination of these components. i really like your short, astute, descriptions of how they sound.
I own CH Precision gear. The voicing of CH gear is very natural with its own support spikes in place. Music flows freely, as it does in nature.
I have tried any number of third party top plates and footers. Almost all introduce damping that clamps down and restricts flow, resulting in a loss of naturalism, and moves towards audiophile sound. None of these devices are keepers.
I gather you’re not a fan of the CH provided spike isolation system?
Artesania racks bypass component feet by design and over many years I got used to how that works and sounds. Outside of initial experiments on the floor and a few occasions where I heard my CH equipment with friends, I have no real experience using CH with its own feet or the CH Spike Option. I don’t have enough experience with it to proclaim being a fan or not. The HRS racks provided the first occasion where I seriously tried them and since I also tried a range of other footers with the CH and HRS, I would say my prefefence is more down to the combination of audio component and rack than the CH footers themselves. So, long story short, I don’t really have an opinion on the CH footers just yet.
This is a fascinating point about using HRS Chassis products with CH-Precision. I am the representative for HRS to many CH dealers in the USA. They have found that the Vortex and Damping Plates significantly improve when combined with an HRS Base. Please remember that the CH chassis design is not at fault but rather the extreme levels of fidelity that allow you to hear the results clearly.
How many Vortex footers (3 or 4) did you use under the Grimm? I’ve lately been using 4 of the Stack Audio AUVA footers to good effect with the MU1 on my HRS rack. And as you found I have been very pleased with 4 Vortex under my dCS Vivaldi APEX DAC for about a year.
Hi Steve, sorry, notifications ended up in spam somehow, leading to my late response. I tried the MU1 with 3 Vortex footers and 4 and did not discern a very large difference. Both work well but with 4 footers, I found it is very important to set the tension on the adjustable 4th footer very precisely to achieve even distribution. With the very lightweight Grimm, this can be a little tricky.
Mail filtering is unfortunately a common problem we’ve all experienced. Based on your review, and already having been using Vortex footers since late 2020, at the urging of Michael Latvis ( he’d already had experience using these under his dCS DAC with his racks), I went ahead and purchased a set of 4 and noted the immediate improvement compared to the Stack Audio AUVA feet I’d been using under the Grimm MU1. Your experience mirrors mine. I also tested the potential for additional benefit of some damping plates atop the MU1 in varied sizes and configurations to no clear effect.
Thanks for the feedback, Steve!