Symposium Acoustics4L ISIS RackusedSymposium Acoustics ISIS Rack - 4L Shelf Model with UpgradeThe Symposium Acoustic ISIS Rack is considered a Giant Killer in the Audiophile World, with many reviews out there. Those in the know understand how special and rare these racks are, and more so t...4900.00

Symposium Acoustics ISIS Rack - 4L Shelf Model with Upgrade [Expired]

no longer for sale

The Symposium Acoustic ISIS Rack is considered a Giant Killer in the Audiophile World, with many reviews out there.  Those in the know understand how special and rare these racks are, and more so today because if you want one you can’t find it.  If you find one, you have to pay 3 to 5 times the retail price due to material and manufacturing cost. 

This 4L model comes equipped with the Triple-Isolated 27” x 22” Turntable Top featuring LDSS Isolation. Linear Displacement Suspension System (LDSS) is Symposium Acoustics’ proprietary technology that blocks low frequency vibration from passing through the shelf from below and on to the turntable.

Features of the STANDARD Rack include:

  • Laser cut stainless steel constrained layered damped shelves with electrical grounding
  • High quality, solid aircraft aluminum legs and hardware
  • 3 precision couplers
  • Tellurium copper reversible spikes 
  • Roller-block Module with Grade 25 Chromium Steel balls
  • Compound-Isolated 24” x 20” XT Top
  • 8” and 11” Legs that Provide 9” to 10.5” Clearance Between Shelves  

, the Triple-Isolated 27” x 22” Turntable Top is normally reserved for the ULTIMATE model priced at $6,999 for the 4L. 


4L - STANDARD Model sale price $4,400

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Rollerblock Modules:

The Isis Rack system utilizes dedicated, Rollerblock® isolation modules which provide nearly perfect lateral isolation not only for the level it treats, but all levels of the rack above it. Because of its precision engineered parts complement and no-compromise materials complement, Rollerblocks have been acclaimed by professional reviewers and audiophiles around the world as an extremely effective method for reducing vibration-induced distortions in audio and video components. Its hallmark is the reduction of mechanical noise without the unwanted resonances and new distortions which cheaper, "shortcut" ball bearing systems inevitably add.

Magnetic Bias System:

Each Rollerblock module for the Isis Rack uses centrally seated, powerful neodymium magnets. This patented "Magnetic Bias" technology not only holds in place and provides precise centering of the ball bearings but also provides a frictionless restorative "bias" force for the bearing's movement.

Exclusive Features

The Isis Rack combines two innovative technologies pioneered by Symposium: the Svelte Shelf and the Rollerblock isolation system. The combination makes for a startling advance in rack technology.

Built-in Rollerblock isolation:

The Isis Rack features Symposium Rollerblock Isolation - not merely providing isolation of the shelf, but isolating the entire level (including the legs) from other levels while still maintaining a constant-density mechanical ground path (Patented). It is interesting to note that two of the requirements for proper component support - isolation and mechanical grounding - are seemingly contradictory: this is the essence of the solution that the Rollerblock Module provides.

TAS Editors Choice Awards: - Jonathan Valin, The Absolute Sound, October 2012

"···At the end of the decade I got the chance to try Peter Bizlewicz's outstanding Symposium Acoustics Isis Rack, which in its pioneering use of aircraft-aluminum cups and tungsten carbide balls, introduced a new element to resonance control - roller bearings. By using constrained-layer-damped shelves in a beautifully machined aluminum rack, with both the shelves themselves and the struts on which the shelves sit separated from one another by roller bearings, Symposium's Isis did not just turn resonant energy more efficiently into heat; it also seemed to more effectively drain that energy away without feeding it (or select parts of it) back into the items sitting n the shelves. I say this because, in the listening, there was a marked increase in neutrality and transparency when the components were seated on the Symposium stand. It was as if the sonic presentation were "deburred" - little areas of tonal, textural, and dynamic roughness (what I assume were little resonant peaks) were smoothed down into uniformity. The presentation might have been just a touch "politer" dynamically than it was via, oh, the Walker Proscenium rack (although nowhere near as polite as it was with Critical Mass' first stands), but it was also much smoother and more neutral in balance and much more subtly detailed, with absolutely top-notch resolution of very-low-level detail and superior isolation from footfalls. (I still use the Symposium Acoustics Isis rack and recommend it)."


"Svelte Shelf" Technology

Symposium's popular "Svelte Shelf" has been considered an essential component by audiophiles for years, an accessory device that some have called "compulsory." The Svelte Shelf's constrained-layer stainless steel sandwich construction provides lower distortion and a rarely heard, coloration-free neutrality. Every Isis level, whether a Standard (0.75" thick) Level or an Ultra (1.875" thick) Level, is supplied with 3 Precision Couplers, which provide excellent mechanical coupling between equipment chassis in order to make best use of the energy absorbing function of the Isis shelves.

Magnetic Bias technology

Magnetic Bias bearing technology keeps the bearings of the Rollerblock isolator units conveniently centered while lifting or changing levels, and also provides frictionless motional damping ("bias") which reduces bearing chatter, one of the causes of "bright," artificially "sweetened" sonics which can be heard with inferior ball bearing isolation feet.

Lightning Rods for Mechanical Energy:

The purpose of any rack's leg system should be to transmit energy to ground efficiently - this is called "Mechanical Grounding" and is essential for best bass performance. This pathway depends upon good mechanical conductivity - and the material makeup and design of the legs, often overlooked, is one of the keys to a rack's ultimate bass performance. Instead of the more commonly found legs which are made of wood, hollow tubing or steel, the Isis features solid legs of aircraft alloy aluminum - for unsurpassed mechanical grounding and sonic performance (aluminum posesses superior transmission efficiency to all other materials except silver or copper). The Isis offers quality you won't find elsewhere. Wood legs, or tubular metal legs, even if filled with sand or lead shot, cannot match the mechanical transmission capacity of the Isis' precision machined 1 7/8" diameter, solid aluminum leg sections.

EMI/RF "Faraday" shield design:

Because of its shelf system construction, the Isis Rack system helps reduce distortion in sensitive components by providing RF/EMI shielding for your components. Multiple stainless steel layers form a "Faraday Shield" which reduces the harmful effects of EMI and RF, especially that which is generated by proximity to certain components, such as High Definition video receivers, which can emit higher amounts of EMI and RF energy. All current Isis levels have dedicated Ground Connection posts at the rear of each shelf for electrical connection between components and shelf, and/or shelf and a dedicated electrical ground.

Shelf spacing flexibility

The modular nature of the Isis Rack allows for different component spacings determined by the leg lengths of each section, and "legsets" can be swapped out to change spacing if your spacing requirements change over time. For spacing combinations with standard legsets, please click here. If you need more space, or wish to tailor the total rack height to your particular needs, custom legsets of virtually any length are available on special order.

High energy transmission reversible leveling spikes

The interface between any rack and the floor is usually accomplished through adjustable spikes found at the bottom of each leg. Most don't give much though to this device - but in fact, the material used in the spike is critical, since it must have the fastest mechanical conductivity and efficiency possible. For this purpose, Symposium specified the second fastest metal on earth after silver, and Isis Rack leveling is accomplished through custom, heavy duty 1/2-20 Tellurium copper threaded bottom spikes. In addition, these unique spikes are reversible, with a machined flat side for hard floors, and a sharpened point side for carpets. Leveling is accomplished (even after the rack is fully loaded) by simply inserting a supplied tool through the spikes' orthogonal access holes - which makes it easy to turn the spikes under load. Locking nuts are premium brass.

"Real Engineering"

Webster's dictionary defines engineering as "the science concerned with putting scientific knowledge to practical uses." The audio art - and the art of home theater as well- is constantly advancing, and demanding new and better solutions, and even new and better science. And so, we seek the harmonious and efficient confluence of all of the requirements for the solution of a problem. Since the state-of-the-art is always re-inventing itself, state-of-the-art engineering must be equally as creative - for how else can we find new solutions for problems which were unheard of a generation ago? For this reason, while they may seem tenable upon first encountering them, relying on readily accessible solutions used in unrelated industries (automotive, industrial, military, etc), while easier, is neither adequate nor desirable for the specific and unique requirements demanded by high end audio and video systems, because the processes are different and not equivalent. For this reason, Symposium is committed to always seek the better solution, and make it available in our products regardless of its difficulty or expense.


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