First Sounds: Harmonic Resolution Systems RXR and R-Shelf

by Roy Gregory | December 30, 2015

hen it comes to equipment reviews, the audio industry exists in a bizarre state of laissez-faire: guidance for reviewers is minimal; guidance for readers is pretty much nonexistent. Ever since the "How To Read The Absolute Sound" feature disappeared from the pages of TAS, there seems to be an ongoing assumption that everybody knows how it is, what it is, and what you can get from a review. It’s an assumption that has a number of serious consequences. Not only have we developed a chronic (and inappropriate) reliance on reviews, investing them with an authority and importance they simply can’t justify, at the other end of the scale we generally fail to extract or recognize some of the most useful information they contain.

In the case of TAB reviews, how often do you skate over or simply ignore the Associated Equipment listing at the bottom of the page? It’s there for a reason, providing the essential context for the review itself, but also as a guide to the changing audio landscape that surrounds the reviewer. For example, make a longitudinal study of the equipment listings on my reviews and you can learn an awful lot about what’s happening in my system, what I’m working on, how my thinking is evolving and what’s coming up in terms of product coverage. That listing helps you to appreciate that individual equipment reviews are nowhere near as discrete as we tend to assume -- and that, try as we might, we can only listen to systems not individual components.

But perhaps most important of all, within the ever-changing system(s) with which a reviewer works, there are certain constants -- anchors on which not just the system(s) but also the evolving thinking rest. Take that longitudinal tour and one of the ever-present components that entered my system well over a year ago and has remained there ever since is the Harmonic Resolution Systems (HRS) RXR rack -- along with a variety of the company’s shelves, platforms and other equipment-support products. And my point is? After a year and a half, you might be forgiven for assuming that the rack has simply arrived, been installed and that’s as far as it goes -- the very essence of fit and forget -- but nothing could be further from the truth. In fact, the RXR and other HRS components are the subject of a review that in its own way has been at the center of virtually everything I’ve done in the last year. Getting on for two years is an awful long review period for any product, but in a very real sense the RXR has been the vessel at the heart of what has become a protracted voyage of discovery -- both for Mike Latvis of HRS and yours truly. Not bad for a component that makes a virtue of immobility and that goes beyond passive into the realm of the inert.

For years we’ve been getting equipment support wrong -- the thinking, the language and the products concentrating on the concept of equipment isolation. But read my Stillpoints review and you’ll appreciate that what we need to isolate isn’t the equipment but the signal -- and that’s a completely different problem. Your rack might sit between the floor and your equipment, but that equipment sits between itself and the signal. If we are going to take the notion of mechanically isolating the signal seriously -- and we definitely should -- then any equipment-support strategy needs to consider not just isolating the equipment from mechanical feedback, it needs to also provide a way of dealing with energy generated within the equipment itself, a mechanical grounding path that leads self-generated vibration and airborne energy away from the delicate signal that’s passing through your electronics and cables. This internal energy can be even more damaging than the external, structure-borne energy we’ve all been worrying about, which is why equipment couplers and support surfaces can have such a dramatic impact on system performance. But the bottom line is that to do the job properly, you need to deal with both problems -- and once you do, the musical gains can be huge.

Which is exactly where the HRS RXR comes in. Most companies offer a solution to either one problem or the other. Pneumatic isolators such as the Townshend Seismic Sink concentrate almost exclusively on the external sources of energy, while products like the Stillpoints and Nordost’s SortKones deal with internal energy. The HRS products are one of the very few equipment-support solutions that take both issues seriously (now more than ever, with the arrival of the new HRS Vortex footer). But to do that you have to get your conceptual model clear and your priorities right, as well as your ground paths and dissipation technology in the right place. Which helps explain why this has been such a protracted process, as HRS and I have compared notes and experiences, theory and practice -- with both sides learning along the way. Meanwhile, sitting quietly at the center of this maelstrom of system-tuning analysis and activity has been the RXR -- unsung hero and prime instigator of the whole darned exercise.

But first, a quick tour of the HRS range for those unfamiliar with the products and their nomenclature. The HRS support system consists of frames into which you can place a variety of different support platforms, with the RXR and R-Shelf adding an extra option in each category, bringing the total number of frames to four as well as four shelf options -- although there are further options within the shelves themselves. In fact, my one complaint about the HRS products is that for a range that is so logically and systematically structured, the model identifiers are so obscure as to be actively confusing. Racks/frames (in ascending order of price) are named RXR, SXR, SXR Signature and MXR; platforms start with the R-Shelf and rise through the R3X, S1 and M3X.

Given the plethora of alphanumeric acronyms, it’s easy to miss the significance of this rack -- which is, of course, why I’m writing this piece in advance of the review proper. It looks neat, classily unobtrusive (and a lot more like furniture than the SXR racks in particular), but there’s a whole lot more to it than meets the eye. Anybody familiar with HRS’s more established racks, with their massive machined-aluminum frames, might readily conclude that the RXR is just a cost-cutting exercise, seeking to offer the same horizontal framework but built from cheaper material. Well, they’d be right about one thing: the RXR was born out of a desire to offer a more affordable solution, but the key word here is solution. It needed to be more affordable, but it wasn’t acceptable to sacrifice performance. What at first glance looks like a simple wooden structure is anything but, with mixed-material construction throughout. The uprights are profiled maple hardwood sleeves wrapped around thick aluminum plates, drilled with ladders of locating holes for the shelf frames. The frames themselves take the same form as those of the SXR and MXR racks, the outer hard-maple picture frame concealing a multi-layer horizontal composite structure front and back, manufactured from a sandwich of polymer damping material and composite wood ply, a new "environmentally green" HRS damping material, with metal-plate reinforcement top and bottom. Each upright is supported on a pair of deep conical feet, with another at each corner of the lowest frames. On the double-wide rack I’m using that adds up to a total of 14 independently adjustable and lockable feet.

The end result is a product that uses a carefully selected set of materials to create a frame that is versatile, configurable and has exactly the mechanical characteristics required. The aluminum posts ensure the strength and integrity of the frame, while allowing the shelves to be securely adjusted for height, The wooden elements may not have the structural rigidity of the machined-aluminum ones (and won’t carry the same extreme loads), but the 14 feet ensure that each structural element is held stable and that the rack can’t twist. Keeping the same footprint as the SXR/MXR shelves, incorporating similar broad-bandwidth isolation technology and the dispersive nature of the wood as opposed to the aluminum main frame members, means that in real terms the RXR frame gives away very little -- and I do mean very little -- in terms of performance to its bigger (and much more expensive brothers) and it can still be used with the full range of HRS isolation platforms. Unless you have an unlimited budget, the advent of the RXR will allow you to exercise much greater flexibility in selecting and matching platforms to your components’ requirements and system priorities. In fact, the biggest single compromise with the RXR is its load-carrying capability: an RXR simply won’t support the same total mass as the SXR or MXR racks -- except that given the mass that the RXR will support, it’s only systems with components well into the three-man-lift category that are going to stretch its capabilities.

Talking of platforms brings us to the other piece of this equation: the R-Shelf, another piece of deceptively simple engineering genius. HRS used a very thick high-density custom-pressed composite plate material and it is supported on three large square pads of the same energy-dissipation material used inside the RXR frame, a second, narrow slab of the composite forming a stiffening spine down the center of the shelf. The result is a support platform that sits within the depth of the horizontal frames, flush with the top edge of the frame, creating an especially neat and incredibly cost effective support solution -- because, just like the RXR rack, the R-Shelves punch way above their financial weight.

Now consider that the RXR rack is itself totally modular. You want to rearrange the spacing or add extra shelves? Not a problem. Don’t have the height to accommodate new bigger equipment? Simply replace the uprights. Have certain key components that are more sensitive to external noise? Select one of the more sophisticated isolation platforms. That’s the real beauty of the RXR rack and the R-Shelf. Together they offer the performance that has made HRS a worldwide brand when it comes to audio racks at a price that is significantly more affordable than the existing models. But by increasing the scope and price range of the HRS system as a whole, allowing users to mix and match a wider range of frames and support shelves/platforms, they don’t just drop the barrier to entry, they also make the established models more configurable and cost-effective too. How much more affordable? Consider this: a standard four-shelf SXR frame will set you back $6495; with a quartet of R3X platforms weighing in at $1395 each, you end up with a grand total that’s a shade over $12,000 -- for the previous entry-level four-shelf rack. A dimensionally identical RXR frame will set you back $4595 and -- here’s the kicker -- the R-Shelves are $495 each, adding up to a shade over $6500. That’s not just an awful lot of performance for the money; it’s a massive increase in the flexibility and configurability of the support system as a whole, allowing you to focus and allocate your budget where it really matters.

The HRS solution is a model of engineering elegance -- but then that should come as no great surprise, given that HRS head Mike Latvis comes from a solid engineering background with a CV that includes quality assurance and certification for nuclear power systems and decades of design, development, production, and engineering management of products for isolation, resonance control, and motion accommodation in aerospace applications. Consider just for a moment the amount of energy there is in trying to reduce the rotor head in a Black Hawk helicopter to its constituent parts and you begin to appreciate just why the HRS audio racks constitute a genuine engineering solution that depends on using just enough of the right materials in exactly the right way to optimize cost and performance -- and why it is that the RXR rack and R-Shelf can deliver so much of the performance that was only previously available from the much more costly HRS solutions.

Of course, bigger budgets allow you access to not just more-sophisticated materials but also just more materials, allowing racks like the MXR and platforms like the M3X to offer even more-effective broad-bandwidth isolation, but what the RXR rack and R-Series shelf do is nail the fundamentals and absolutely get the priorities right. Which brings me straight back to the duality of the challenge facing equipment supports. The R-Shelf might not offer the same degree of isolation as the M3X, but it takes up less vertical space and arguably looks neater, but most important of all, it offers one hell of a termination to couplers and mechanical grounds. In sonic terms, you can almost hear it sucking spurious, destructive energy out of your electronics’ casework. What the R-Series shelf signals is a new appreciation of relative priorities when it comes to supporting the system. It might sacrifice absolute isolation -- relying on the supporting frame for help in that regard -- but it does a fantastic job of dissipating internally generated energy once you get it outside the chassis -- energy that might well be very low in amplitude but just happens to be right where your delicate audio signal is, and it’s by placing that technological solution exactly where it’s required that the R-Shelf can be so incredibly cost effective. It’s not the first grounding platform that HRS has offered (you can convert any R-, S- or M-series platform to a grounding as opposed to isolation configuration by swapping in the optional G-series feet), but what the R-Shelf is is by far the cheapest. As such, it doesn’t just add a new more affordable option to the HRS line; it broadens and rebalances the range of solutions too, placing new emphasis on grounding equipment as opposed to simply isolating it.

And that has significant implications, because it means that the R-Shelf and RXR offer a perfect solution for those who have already invested in quality couplers for their system. By improving the termination for those couplers you improve their performance and, in turn, further improve the performance of your system. Using the RXR rack and R-Shelves will significantly drop the noise floor of your system, improve dynamic range and resolution, as well as its range of tonal color and the harmonic character of instruments. What it does is reduce the blurring and compression (temporal, dynamic and harmonic) caused by spurious energy and mechanical feedback. As you will see once you get to read the full review, that’s just the start. Work with the range of different platforms, chassis dampers and couplers to really configure the support solution to the specific needs of the equipment in the system and the results can be absolutely remarkable. But the best thing of all is that what the HRS support solution delivers is your system, sounding more like itself. After all, a rack can’t improve the quality of your source components, amplification or the signal you are feeding them, but it is an essential part of ensuring that they perform at their best.

The RXR frame might not be the whole story, but the fact that it has been at the center of my system for as long as it has is a story itself. In a very real sense it’s the core element that brings all the strands together, a product that makes a virtue of doing nothing -- quietly. Like they say in Hollywood, Never underestimate the strong, silent type.