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Feet Shootout at High-Noon(?)

Part 6: continuing Mark's legendary vibration control saga

[Little Feet]
Little feet clockwise from left:
Polycrystal Reference; Avondale Basis 15; BrightStar Isonodes; Jade IsoDUO;
ERaudio steel cone; Polycrystal Isolator
Polycrystal Point Disc, centre
[Italian version]

Product 1: Jade IsoDuo Absorba Footer, from Bretz Audio
Manufactuer: Jade Audio
Approximate cost: 120euro per quartet large-size or per octet small-size
Product 2: Polycrystal Reference Isolators
Manufatcurer: Innovative Audio, distributed by UltraSystems
Approximate cost: $150 per trio
Product 3: Avondale Audio Basis Fifteen
Manufacturer: Avondale Audio
Approximate cost: 49.95 per trio
Reviewer: Mark Wheeler - TNT UK
Reviewed: August 2004 - March 2005

"YAWN, why is that guy droning on about little feet again?"
quoth plebs chorus stage-left
"Well," replies this ancient scribe, "Little Feat were a most excellent band of fine musicians performing their compositions around late-great lyricist Lowell George's words. Musically never less than superb in almost every respect until George's untimely death in June 1979. This was the catalyst for an unfortunate series of hairstyles clearly embodying their shock & grief in a postmodern foregrounding of..."
"NO NO NO, we mean the little gizmos you keep putting under your hifi"

Ever since Part 1 of my vibration control series appeared I have been hearing of more products promising a panacea to these vibration induced problems that I find has significant, and indeed, universal impact on sound quality. I would venture as far as to say that good vibration management makes more musical difference than fancy cabling. That'll get the audio-inquisitors after me with accusations of heresy.

Here are another three products each using very different technology to achieve different forms of vibration control. One of the products are variations on the Polycrystal Isolators that you read about before. PolyCrystal note their products were used at CES by Conrad-Johnson, Jadis, Krell, Pass Labs, Sonic Frontiers & VTL, which is heavy-money endorsement for inexpensive product. In the earlier tests the Polycrystal isolators majored on preserving rhythm and timing, especially with products that already have well-designed non-resonant casework. The BrightStar Isonodes excelled at reducing coloration in those products that had nasty clangy casework, and won them "best-of" awards at CES. So both these companies have some impressive credentials even with their budget lines. In those tests these two products were the winners from a field of about a dozen alternatives, most commercial but some DIY.

[Polychrystal Reference]

Polychrystal Reference & Iso3

The $150 sets of Polycrystal Reference Isolators look like they're just bigger chunks of their clever-composite material than their Iso-3 model at $65 a set, "a composite made up of multiple inert materials, crushed to the sizes of their crystalline structures and embedded in a matrix" as they say. So I checked with Robert Stein of Ultra Systems who told me that the Polycrystal Reference Isolators are indeed made from the same material as their basic Isolators. So there you have it. Robert went on to state that the difference is mainly in the quantity but also the shape is quite different. While the overall dimensions are up a little in both height and diameter, the squatter shape of the Reference type means mass per set of 3 from 65g to 190g (approx), which is nearly 3 times as much. Gramme for gramme the big ones give more polycrystal per buck, like bigger boxes of cornflakes, but will this make a proportionate difference to the sonic effects?

The Jade IsoDuo footers are one of the latest generation of more complex structures, described as "pucks cum isolators" designed to address vibration isolation and component stability by ingenious combinations of shapes and materials. Described in their press release as "The world's first Vibration Damping Footer that uses Rayco Technologies ABSORBA elastomer", tested by a UK laboratory and manufactured in Singapore. They are designed to dissipate (presumably as heat) external and internal vibrations. It is described as a "precision milled centre ring" with Absorba elastomer inserted at both ends. The key claim is that Absorba is more effective than other currently available materials at dissipating vibration and that Absorba is able to maintain this over a wider range of temperature conditions. The latter point is probably of lesser importance in audio applications as most of the global human population likes to sit in a room at 15-23C, which is a tiny range in materials terms. I have a 24 page white paper from Jade (pdf format here) explaining in detail the design considerations and materials properties (very thoroughly tested in comparison with various alternative materials and supplied as graphs). The technical arguments look secure, thorough and rigorous so these do not present as a product designed on a beermat and built in a garden shed, but as a seriously researched and engineered application.


Jade IsoDuo Absorba & the Upsetters

So the Jade IsoDuo arrives backed by data that invites the purchaser into a phenomenological encounter coloured by a priori expectation. After reading the blurb we expect to hear good things, and indeed will seek to do so, suggesting that some form of blind listening test will help subjective judgements to be based solely on the sensory experience. The Jade IsoDUO is available in 2 sizes: box of four large 37mm diameter X15mm thickness (tested); box of eight small 22mm diameter X8mm thickness, both at 120 Euro per box.

Regular readers know that I usually prefer 3 points of support over 4 for stability, but these footers are flexible enough that 4 points would make good contact, and location arrangements are comprehensively described in thorough instructions. Because 4 points would provide absorption in 4 areas of component panel they might be more effective in this arrangement so I will lay my prejudices aside and try both.

The third new product I am trying arrived as an accessory to the Avondale Audio Alpha5 cd player. The Avondale Basis 15 feet are made for Avondale audio using a combination of machined high-grade aluminium, carbon-fibre and another material. The aluminium is carefully profiled and surrounds the carbon fibre centre cylinder. At 49.95 per 3, each one of these is comparable in price to one Jade IsoDUO.

Having observed that the most dramatic differences observed are with cd players, this is where this test will start. Under the Shanling CDT100c cd player there were very distinct differences between the products in this test, and also with those tested previously. Whenever trying this type of product it is essential to examine the underside of the cd player to establish the best positions to place the supports. All these supports will only perform if they are placed in contact with a flat area large enough to cover the whole area of the isolator. Check out the centre of gravity by supporting the player on a variety of axes using one finger under each opposing side. Where these lines of balance intersect is the point of the effective centre of gravity.
The Jade IsoDUO are supplied with instructions and diagrams to accomplish this, but it applies equally to all supports. Then the isolators (whichever brand) should be approximately equidistant from this point and equally spaced on the circle thus subtended, to ensure each supports a similar weight. That is the theory and the common recommendation. It is more difficult to achieve with 3 points of contact without the player becoming quite unstable when the disc is being changed. Both the Shanling and the Arcam have centre of gravity biased rearward due to transformers, and with both these players I found optimum results with the Polycrystal products to be with two isolators close to the back, but not supporting the back or side panels, and a third below the transport axis. The Avondale Basis 15 worked similarly under the Shanling but under Avondale's own cd player worked best with one centred under the transport, one under the left rear and one halfay between front and rear near the right side; you really do have to experiment to get the best from each product under each component. The Jades work best as instructed.

The Brightstar Isonodes had not been previously tried under the Shanling. This player has an already well made chassis and the Isonodes lowered the noise floor and reduced colouration as previously. Sadly, the standard cork-composite feet did a better job of preserving rhythm & timing which I find fundamental to musical enjoyment. All the attributes of a lower noisefloor arrived with the Isonodes, including clearer vocals, midband articulation etc, but the musical message got diluted. The standard size Polycrystal Isolators make a better impression musically.

The Reference Isolators were tried next, being from the same family as one of the original test subjects. I was not expecting to hear much difference from the basic Polycrystal isolators, the phenomenology of this encounter being coloured by a low a priori expectation. Surprisingly, the difference between the Reference and standard Basic Isolator is similar in magnitude and scope as between the Basic Polycrystal feet and the composite feet fitted by Shanling. The Reference Isolator is better in areas of musical information (pitch, rhythm, timing, melody) and in mechanical respects (colouration, clarity, signal-to-noise). HiFi parameters like soundstage size, tangibility and stability also improved. Other listeners present (including an excellent guitarist/singer), with no interest in hifi equipment but deep love of music, also comment on these aspects without prompting or leading questions. Heather also notes a distinct improvement in the fuzziness parameter she proposed in the earlier tests.

[AAA5 vibration control stage 1]

The Avondale Basis 15 above platform
Polycrystal Reference Isolators below platform during the AAA5 test

The Jade IsoDuo performance was between the Polycrystal products and the Isonodes, displaying some of the advantages of each. A slightly harsher upper midrange & lower treble than the Isonodes is balanced by superior pace, rhythm & timing (PRaT) to them. The tauter bass of the Jade IsoDUO is balanced by the sweeter treble of the Isonode. Jade IsoDuo PRaT comes close to the Polycrystal, and the midrange qualities are similar despite their completely different philosophy and construction. The Polycrystal Reference bass goes deeper and tighter than the Jade IsoDUO bass, but the colouration and noisefloor are lower with the Jade IsoDUO. The IsoDUO is only slightly better than the Avondale Basis Fifteen for treble clarity.

Under the Shanling the Avondale Basis 15 is closest in character to the Polycrystal products despite being a more complicated construction like the Jade IsoDUO. There is little to choose between the basic Polycrystal Isolator and the Basis 15 on price, performance, or character despite their very different construction.

With the clangy casework of the Avondale Audio Alpha5 (AAA5 kindly on long-loan from Les Wolstenholme) the fundamental character of each product remains similar but the player itself changes the relative importance of these effects. The AAA5's major priorities are musical rather than hifi and the 3 isolation products that also major in these qualities become closer in performance. Avondale Basis 15, Basic Polycrystal & Reference Polycrystals are roughly equal for PRaT with the Jade IsoDUO but slightly ahead on bass impact and solidity. The differences are very small in this and other musical attributes like tunefulness & pitch. After listening to a wide selection of music on the Avondale I come to ambivalent conclusions. With the AAA5 I prefer each of the 3 of these products under different circumstances with different musical selections. Female vocals are most natural with the Jade, highest treble harmonics are clearest with the Polycrystal Reference, upper-bass & lower mid instruments can be more easily followed with the Avondale. And so it goes on, subtle nuances of difference that may cause one listenner to choose the Avondale, another to choose the Polycrystal and a third choose the Jade, with each believing that the others do not get close.

On balance if I were shopping for isolation feet for a high resolution cd player mounted in a resonant case I would choose the Avondale Basis 15 if the player tends toward bass-light, but I would support a bass-heavy cd source with the Jade IsoDUO. In either instance I would damp the top surface as an equal priority to feet, and the Brightstar Little Rock 5 (reviewed in Part 5 of the series) would be my cost-effective choice here.

The earlier tests established that Isonodes excel at reducing case colouration, noisefloor and fuzziness while improving hifi attributes, but the Jade IsoDUO now comes close. 4 Isonodes performed better than 3, presumably damping more chassis area, but were even better when a second set was placed on top of the AAA5 weighed down with a brick, which also helped raise PRaT parameters closer to the others. There is little to choose between 4 and 3 Jade IsoDUOs, but there is a difference. 3 Jades moved the centre of the soundstage further back than 4, and also softened the bass slightly more than 4 compared with the Polycrystal & Avondale products whose bass was both deeper and tighter. Both Polycrystal products reduced soundstage depth compared with Jade & Avondale and also brought the performers forward to the plane between the speaker fronts. The Avondale allowed an illusion of height too. Confused yet?

My test-bed Naim 42.5 board in the nasty case is no longer available as it has been returned to its Torlyte home and is undergoing counselling to come to terms with its harrowing experience in the resonant 2U rack-case. A range of other amplifiers produce consistent results. Summarised, the differences between isolation feet under amps are smaller than with cd players. The improvement wrought by plonking electronics on isolation feet is very worthwhile, again comparable to a significant cable upgrade.

I did not try turntables this time as my tests indicate that their relationship with isolation feet is as specific as cables are to systems and any opinion I might express would be worthless unless you happen to own the same turntables as me. The feet on my Gyro SE are an integral part of the design and replacing them with other products would not provide readers with any useful information. IsoDuo pioneer Terence Bretz tried the Jade IsoDuo under the solid plinth Acoustic Solid Small Royal turntable where he says it gives a very precise and firm bass extension & detailed high frequencies. If you follow my recommendations you'll have several options to try under your preferred turntable.


Vibration control is essential in optimising audio, whether high-end or modest.
With cd players it becomes a question of priority. PRaT fans with larger budgets & well-built cd players will go for the Polycrystal Reference first, the Avondale Basis 15 a close second with the standard Polycrystal ISO3 and the Jade IsoDuo coming in a close equal 3rd, all ahead of the Isonode.

If you have a cd with very clangy metalwork and PRaT is less of a priority than soundstage and neutrality then the BrightStar Isonode comes in first equal with the Jade IsoDuo. The Jade IsoDuo are better than the Isonodes for rhythm & timing, but BrightStar Isonodes lower colouration most effectively and at least cost. A set of Jade IsoDuo below the player (carefully positioned according to the instructions, and the BrightStar LittleRock 5 on top would be the next level, although a second set of Jade IsoDuo also damp the upper surface, they are less effective than either BrightStar product on the top surface and do cost more.

Conclusions with amplifiers again depend on the mechanical integrity of the hardware being supported, just like the cd player results. My own builds in wood or Torlyte cases demonstrate least differences between isolation feet and any of these will give a fair account of themselves, with taste being the final arbiter. Any are better than none, but the differences between them is very subtle with inert casework and my taste would opt for the Polycrystal Reference if cost is no object. Outboard power supplies work well with the cheap Isonode, which makes them great value in that location.

Clangy old steel boxes are a different matter where the Isonode remains most effective, with only the Jade IsoDuo coming close. Those all too common products with a good chassis base & a clangy lid benefit from different treatments above & below. Equally effective would be the Jade IsoDuo or Avondale Basis 15 sets below. The Isonodes plus brick are the killer low-budget top-damper, with the LittleRock 5 even more effective and IsoDuo also effective but slightly different character.

[AAA5 vibration control stage 2 overkill]

Stage 2 vibration overkill

You really cannot go wrong trying some of these products. Cheaper than racks, cheaper than cables, much cheaper than hardware, more musically cost-effective than eq/DSP, they are an inexpensive way to feed your audio paranoia and play for hours. These products are individual component dependent, not system dependent. The benefits of vibration control are way out of proportion to the prices on these simple products. Manufacturers should try to ncorporate them at the design stage as the improvements are cost effective in the league of haute couture capacitors, copper plating, hardwiring and low-noise resistors.

Begin by buying one set of the cheapest version of each type of these products and experiment, before buying more expensive types.

  1. Isonodes represent superb value among the squidgy types & you will need to start with two sets.
  2. Polychrystal ISO3 seem best value among the hard crystaline brands.
  3. The small Jade IsoDuo were not tested here but would be a cheaper entry to the "try to combine best-of-both-worlds" type.

Test proceedure will

  1. Audition all 3 under every component in your system, one component at a time.

  2. Is there a worthwhile difference?
  3. Which of the 3 types works best for your ears under this component?
  4. Is it worth the money compared to new software, wire or hardware? I predict always "YES"
  5. Write a legible list of what product works under what component.
  6. Repeat with Isonodes & brick on top.

With the data you have recorded, decide whether the improvement wrought by the most successful type under each component is worth that amount of money or more. If it is yes then buy some. If the answer is "worth more" then order one set of the next model up in the range (e.g. if the Polycrystal ISO3 makes a big improvement and you want more, then order the Polycrystal Reference if the expense is justified in that system location.

If the compound types (Jade IsoDuo or Avodale Basis 15) are more successful, choose the IsoDuo if the sound tends toward bass-heavy and choose the Avondale if the sound tends towards bass-light. Both manufacturers make two sizes so choose the more expensive for critical components in high-reslotuion systems and the smaller sizes for less critical, more cash-sensitive locations.

If the BrightStar Isonodes are most effective with a component consider a LittleRock 5 as the next step along this pathway to audio Nirvana.

Compared to cables these products all make much more value-for-money sense. After spending over 6 months carefully evaluating a variety of vibration isolation and tuning products (you don't get to read about the ones that didn't work) I would not be without them.

My Shanling CDT100c stands on its own cork composite feet on a small ERaudio SpaceHarmoniser & steel cone points, resting on 10mm laminated glass supported by 3 Polycrystal Reference.
A BrightStar LittleRock 5 lies on top of The Avondale Alpha 5, which sits on Avondale basis feet on an obsolete lightweight shelf. The hotrod Rotel RCD965BXdiscrete lives in a Torlyte case and stands on Polycrystal reefernce isolators on the same shelf when in use.
The Accuphase T101 tuner has some conjoined Isonodes wedged underneath and a LittleRock 4 on top.
Amplification gets a selection of treatment as appropriate too. My big transistor amplifier finaly gets a product capable of supporting its weight while simultaneously damping its chassis, so its rubber feet have been replaced by four Jade IsoDuo and the LittleRock on top. The single ended triode in a Torlyte case sits on three Polycrystal ISO3, while its power-supply squirms on three BrightStar Isonodes both on a large ERaudio platform on ERaudio steel cones.
My system now sounds better than ever.

Every component I have tried does benefit from attention to vibration control, be it isolation or damping. Until you take such measures you really have no idea how good your gear can sound...and how much play value they bring in the process.

© Copyright 2005 Mark Wheeler - www.tnt-audio.com

Part 1 - Part 2 - Part 3 - Part 4 - Part 5

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