HRS SXR-1921 Three-Level Empty Frame

HRS, Harmonic Resolution Systems of Buffalo, New York, was founded by Mike Latvis, a vibration-control engineer whose previous work was in avionics, helicopter rotor systems and missile hardware, and the SXR Audio Stand is the company's approach to a problem most equipment racks ignore: a rack is not a shelf, it is a path for energy. Floor-borne vibration travels up through it into the components, airborne energy from the loudspeakers excites it, and the components themselves, transformers and motors and spinning discs, feed vibration back into it. HRS's answer is to separate the two jobs. The frame is made as rigid and well-damped as the materials allow, and the isolation happens in the bases that sit in it, each tuned to the weight and nature of the component on top. The SXR-1921-3V is the three-level frame in the 21 by 19 inch size, sold empty so that the bases can be chosen level by level.

The frame is machined from billet aircraft aluminum rather than cast or extruded, and each level is carried by six struts rather than the usual four, with HRS's polymer damping elements placed at the joints where strut meets shelf support. The six-strut geometry raises the frame's stiffness and spreads its resonances, and the polymer at the interfaces turns the energy that does reach the frame into heat rather than passing it along; HRS describes the structure as built to optimize the performance of the isolation bases rather than to isolate on its own. Threaded spikes and cups level the frame on the floor, and floor protectors are included. The shelf spacing is set by the strut length: 8 inches between levels is standard, with 2, 4, 6 and 10 inch struts included in the price and 12, 14 and 16 inch struts available at extra cost for tall components or tube amplifiers.

The frame accepts any HRS 1921 isolation base. The R3X is the base HRS fits to its standard SXR racks; the S3 steps up to the Signature level; and the M3X2 Reference is the base from the VXR, with more than 70 parts, six materials, a polished granite contact plate and feet matched to the weight of the component. Mixing them is the point of buying the frame empty: an M3X2 under the turntable and the preamplifier, S3 or R3X under the streamer and power supply. HRS's SXR Solid Brace inserts, sold as the Signature Upgrade Kit per level, add mass and stiffness to the frame later and bring it to SXR Signature specification without replacing it, and a fourth level or a second column can be added at any time.

Danny Kaey, reviewing the SXR with M3X2 and S3 bases for Fidelity, found that a CD player he knew intimately became "sonically, a whole new CD player" on the HRS, and that the detail retrieval from a turntable on an M3X base "simply wasn't what it is now" on his previous rack; the combination, he wrote, "completely eliminated the problem" of footfall and feedback. Robert Harley, reviewing the VXR, the reference frame above the SXR, for The Absolute Sound, wrote that "the sound was softer because of the reduction in hardness and glare but no less incisive or immediate" and that the stand "unlocks a wealth of hidden sonic potential". The effect reviewers describe is consistent: lower apparent noise, less hardness in the treble and a firmer, more defined bass, which is what removing vibration from sensitive circuitry should sound like.

Within HRS's stands the EXR-1921 below it is the four-strut entry system with E1X bases included, and the SXR-1921 Three-Shelf Rack is this frame supplied with three R3X bases for those who want a complete stand in one order. The SXR Signature adds the Solid Brace inserts and S3 bases, and the VXR-1921 is the reference frame, also sold empty or with M3X2 bases. The empty SXR frame is the choice for a listener who wants to specify a different base for each component or who already owns HRS bases from an earlier stand.

We plan the SXR frame most often with an M3X2 under a Linn Klimax LP12 or Clearaudio turntable and under a dCS or Boulder preamplifier, with R3X or S3 bases under streamers and power supplies, in systems where the electronics sit between the loudspeakers and footfall or feedback is a concern. HRS reviews the weight and footprint of each component before a stand ships, so send us your equipment list and we will configure the frame, struts and bases with them.