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Symposium Acoustics's Rollerblock Junior
Feet by Symposium Acoustics
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Symposium introduced lateral ball bearing isolation with the original Rollerblock® in 1997; since then, Symposium's Rollerblock® Series 2 has been
the standard of excellence for ball bearing isolation in the high end audio industry. Many rave reviews and customer comments reinforced their position as
the premier ball bearing isolation device. However, it became evident that there was a need for a lower cost "introductory" ball bearing isolation
device designed with the same audio expertise and commitment to quality as the original Rollerblock. Thus, Rollerblock Jr. became a reality.
Rollerblock Jr. consists of of 6 tops and bottoms and 3 center bearings, to make 3 "Double
Stacked" isolator/coupler units. Each top and bottom is constructed of black anodized, aircraft alloy aluminum, and has a 1.875" diameter (4.76 cm)
and 5/8" (1.58 cm) thickness. These dimensions were carefully chosen to make Rollerblock Jr. easy to use and set up, yet strong enough to withstand the
rigors of use under heavier equipment such as large amplifiers and heavy loudspeakers. The special cup interior has been designed so that the top and bottom
"sandwich" is stable with the ball inserted in the center, making for easy setup. The bottom and top are flat and suitable for all equipment
chassis, as well as flat surfaces and carpeting.
Version 1.1 introduced
After its first production run, Rollerblock Jr. was modified to include a 1/4-20 threaded hole dead center in the opposite side from the bearing cup. This
threaded hole allows the receptacle to be screw-mounted to many existing equipment foot fastener systems, and facilitates secure fastening with "hanger
bolts" into wood cabinets, etc. Also, the alloy material of the blocks was upgraded to 6061 aircraft aluminum. Cup sphericity and all other geometric
relationships were maintained.
Standard Rollerblock Jr. is supplied with 3 chromium
steel balls, with Super-precision Grade 10 Tungsten Carbide balls available as an optional upgrade. This configuration is known as "Rollerblock
Jr.+", with Tungsten bearings included.
is effective with virtually all components, especially digital sources (CD players and transports), preamplifiers, and amplifiers, but can also be used to
isolate and couple entire shelves and platforms, turntables, power supplies (including AC "line conditioners") and loudspeakers. Rollerblock Jr.'s
virtues, like the original Rollerblock Series 2, are subtractive in nature. That is, rather than attempting to compensate for an existing problem or
deficiency in a system through the introduction of new resonance, Rollerblock Jr. is designed (as are all Symposium products) to remove the cause of
resonance and distortion. Footer devices and accessories should not create another problem by adding a new resonance; many will thicken bass and lower
midrange with artificial bass overhang, lending a false "warmth" and impression of superior bass, which eventually becomes fatiguing, damaging
timber accuracy and transient response of the entire music system.
Proper installation results in increased transparency, dynamics and musicality, properties which include better harmonic separation and
reduction of vibration-produced excessive sibilance. Further, one may expect to discern greater clarity between instruments in the sonic field, and better
defined bass performance with more accurate timbral balance.
The purpose of a ball bearing isolation device is to laterally isolate a component from external mechanical waves (vibration) without
inducing additional colorations or distortions (which can be induced through poor choice of materials, which in turn may resonate or vibrate, inducing new
distortions in the component being treated). While it may seem that any sort of ball-and-race bearing will do (such as "marbles and spoons"),
proper execution requires care and precision. The careful engineering of the problem is the difference between a "toy" and an essential component,
and if not done correctly, will create new problems.
A Few of the Problems - and their Solutions
bearings create noise, called chatter, as they roll upon a surface. This noise is directly transferred into the component, and can become a secondary source
of distortion. If chatter is not adequately reduced, the "cure" can become worse than the "disease." Devices which use more than one ball
induce more noise than devices with fewer balls, all things being equal. Accordingly, Rollerblock Jr., like all Rollerblock devices, use the fewest number of
balls possible - one per device - to ensure the lowest possible chatter. Further, not only is the ratio of the ball diameter to the cup critical for the best
compromise between mechanical stability and performance, but so is the absolute size of these elements. Symposium pioneered the lateral plane ball bearing
device for use with active components; since 1996 we have experimented with many different combinations and found that a 1/2" ball with our standard cup
sphericity offers the best solution for real-world performance. Many positive reviews and a virtual avalanche of positive responses from owners seem to
confirm these findings.
For this reason, Rollerblock Jr. employs the same basic ball and cup relationship which is so successful in the
state-of-the-art Series 2+ Rollerblock. Experiments with different cup sphericity’s and ball materials have suggested that while different resonant
conditions may be created, lateral isolation performance is no better, and in most cases, worse.
Rollerblock Jr. uses two cups of similar sphericity, positioned in opposition to each other, with a single ball in between. This
"double stack" design was invented and first described by Symposium in our original patent on the Rollerblock, which was filed in 1997 and predates
all descriptions of similar "DIY" ("Do It Yourself") devices by several years. The use of a cup, as opposed to a flat surface race, has
several advantages when operated without external force fields to damp ball motion (Symposium has since obtained a patent for magnetic bearing bias and
stabilization; at present, this technology is employed in the Symposium Isis Rack. For a further technical discussion of the theory behind ball bearing
isolation devices, please click here.
Body Material and Mechanical Drainage
The material used in the Rollerblock body is critical to non-resonant, neutral performance: Rollerblock Jr.'s robust aircraft alloy construction resists
inherent resonance and also transmits energy through itself and out of the component to mechanical "ground" (in other words, the support surface),
for best sonic results.