Performance Advantage…

Using Grand Prix Audio adaptors and Apex cones on HRS racks

By Roy Gregory

I’ve long been a fan of the HRS RXR rack. It’s been a permanent part of my main system for a number of years now and over that time I’ve grown to really appreciate its virtues. I like its mixed material construction. I like its practicality, with modular, expandable topology and a range of upgradeable shelf options. I like its understated, even-handed sonic signature and I like the fact that it accepts even monster units like the Wadax Reference DAC. But there’s one thing that I really, really don’t like and that’s the cones on which it stands.

It’s a numbers game…

On the face of it, how much can a pointed cylinder of aluminium get wrong? They attach to meaty, half-inch threaded posts so that you can level the rack. They come with metal discs to protect your floor. What else is there? Well – quite a lot actually. For starters, on my double-wide RXR there are 14 feet. Yep – 14. A standard, single bay RXR has eight. Great for spreading the load, not quite so good when it comes to getting that load evenly distributed. Talking of load, the feet take the form of cylinders with shallow conical sections at the bottom: no holes for pry bars – no flats for a spanner. Get the rack loaded down with serious kit and adjusting these suckers isn’t for the feeble or faint hearted. The locking collars are similarly devoid of any tooling to offer mechanical advantage, which means they’ll never be more than finger tight. And to compound the problem the threads on the mounting posts have such a course pitch that small adjustments are difficult and effective locking of the feet almost impossible. The end result is, that no matter how often I tweak up the cones or tighten the lock rings, a few weeks later and at least six of the fourteen feet are no longer in firm contact with the ground and most of the lock rings have worked loose. None of which would matter unless you actually want your rack to sound good, stay sounding good and stay level! I’ve discussed this with HRS, but so far to no avail.

Apparently I’m not the only one to notice this issue and I recently discovered that a number of customers had approached Grand Prix audio with a request to produce an adaptor that would allow them to use GPA’s Apex footers/cones under their HRS racks. Too good an opportunity to miss, I added my name to the list and sat back, confident that I’d finally found a solution to my on-going battle with my reluctantly level rack.

What duly arrived can only be described as typically Grand Prix Audio. Each adaptor consists of a beautifully finished, polished stainless steel sleeve and a black anodised lock ring that screw onto the HRS mounting posts. The lock rings are drilled to accept a pry-bar and the adaptor sleeves have spanner flats on their lower shoulders, flanking the domed recess that interfaces with the ball at the tip of the Apex footer: Simple, beautifully executed and effective. The only challenge was installing them. For most customers that presents an opportunity to rip down, clean and service their system, but for the review I needed to conduct a before and after comparison, preferably without powering down the system. With a low profile jack, some air bags and a little ingenuity I soon had the rack stood on the apex feet and my first surprise. The GPA adaptors made levelling the rack considerably quicker and easier, the spanner and flats giving a perfect sense of both rotational angle and load pressure, while the lock rings span down and fixed the height of each adaptor with a really satisfying solidity: So far, definitely so good.

Getting real…

But the real proof of the pudding was in the listening and whilst I expected an improvement, I wasn’t ready for the scale of that improvement. With the Apex footers in place, a whole layer of low-level grunge was removed from the system. The soundstage became more clearly defined and even more separate from the speakers. Instrumental focus, dimensionality and separation improved and so too did instrumental timbre, texture and harmonic identity. But the most significant benefit was in terms of timing, with an increased musical fluidity, articulation and sense of flow. Listening to Alina Ibrigimova playing the Passacaglia/Cadenza from Shostakovich’s First Violin Concerto (Hyperion CDA68313 – an acid before and after test if ever there was one) the increased sense of instrumental presence and drama was immediately obvious, from the tension in the pacing to the skin texture on the timps. But the entrance of the solo instrument capped even that, Ibrigmova’s playing taking on a completely new sense of poised intensity and human agency, an almost physical shape to her bowing and her musical line. Musically the result was not just dramatically more, err, dramatic – it was more lucid, more communicative and more engaging. This was the very definition of bringing the performance home, a fundamental improvement in musical coherence and communication that affects anything you play, from Thomaso Albinoni to Zoot Sims, ABC to ZZ Top.