Vibration Isolation:
THE RETURN OF THE BLOBBY SNATCHERS

[overkill or minimum?]

A Toxic Environment for Audio

Subject: The Old Scribe revisits Vibration Control
Price: a high price uncorrected but less money than you think but YMMV
Author and bringer of calm: Mark Wheeler - TNT UK
Mo better performance from what you got, whatever the format
Test period: 1977 to February 2019

Rumbles

Sound is vibration. Audio sys tems are primarily vibration generators. Many parts of an audio system are very effective vibration detectors too. The problems were explored in part 1 or our vibration control Odyssey in 2004.

A moving coil loudspeaker is an effective microphone, being a diaphragm attached to a coil suspended in a focused magnetic field. A loudspeaker cabinet vibrating sympathy with a sound field can be detected by the drive units connected to a microphone input can also generate a further tiny signal. Fortunately the impedance relationship between driver coils and amplifier outputs usually renders this irrelevant.

Obviously electro-mechanical devices such as Loudspeakers and turntables will be subject to the effects of vibration. Most loudspeakers work (except unusual technologies like plasma tweeters) by shoving something back and forth in the air to vibrate the air molecules sufficiently for those air molecules to vibrate their neighbours until some vibrating air molecules vibrate the listener's eardrum. Hence the mechanical air shoving system needs to be in a defined position in space, otherwise the loudspeaker output will have a tendency to generate intermodulation distortion as the loudspeaker vibrates in space. This is the primary reason for the popularity of tight position control via tiny high pressure contact patches at the tip of a spike. It is also why 4 or more spikes will always be inferior to 3 spikes.

Where loudspeakers must be positioned on flat surfaces (mixing console tops for example) it is more important to protect the mixing console panels from the loudspeaker vibration than obsess about pointy contacts. Here large area absorbent mats offer the best compromise between vibration decoupling and loudspeaker position in space. Similarly, despite popular audiophile mythology, a wall proximity aligned loudspeaker will usually achieve more of its potential on a loudspeaker wall bracket that is masonry bolted to a solid wall may outperform a loudspeaker on a floor stand on a wood suspended floor; similarly a loudspeaker stand on a solid masonry floor will be better than than a bracket on partition (or drywall), which is where the floor is better than wall notion became established.

Whether on a sand filled steel framed table, or on Something Solid XR4 rack or the Origin Live Ultra wall shelf, turntables benefit most from the correct support and vibration control. Every turntable type (high mass solid plinth, lightweight subchassis, heavy subchassis, lightweight direct drive) requires a different approach. A whole article would not begin to cover the field.

Plenty of rigorous research has demonstrated that signal devices with gain are prone to vibration distortion effects. In particular valve amplifiers are strongly affected; their active devices work using wire mesh, heating elements and flimsy electrodes. These are effectively the components of a microphone. Airborne and structure borne vibration will be detected and amplified by valve (tube) gain stages, which owners can clearly demonstrate using a sine wave recorded through the amplifier while the amp is being bombarded with music from another source. The music will be clearly audible on the recording along with the highly distorted effects on the sine wave.

"But what about solid state amplification?" challenge plebs, stage left, "Surely thatís impervious to vibration"

Even the printed circuit boards (especially in ferrous cabinets) will respond similarly microphonically, whether electromagnetically or capacitively (depending on construction), because amplifiers are devices with gain indeed stuffed with devices with gain. It is easily measured, along with any effects of further vibration from the environment. The effects of vibration on amplification equipment are more obvious (and detectable in blind tests) than any interconnect cable effects.

When undertaking subjective tests for very subtle effects, reviewers and potential purchasers must be careful not to allow a belief in a phenomenon to auto-suggest perception of that phenomenon (confirmation bias). This suggestibility has been covered in these pages and has been researched by Neuropsychologists. One test includes exposing listeners to white noise and asking them whether they can detect, or not, an excerpt of Bing Crosby singing White Christmas embedded at the start of the burst or near the end. A high proportion of the population make an identification but there is never an embedded except of White Christmas at either end of the burst. The suggestion that there might be causes listeners to imagine that it is there. Your Old Scribe has taken this test and the Plebs Chorus will be pleased to know that Bing Crosby was not imagined during any of the sequences

The shelf or table begins the process of either vibration isolation (if well designed and well chosen) or of providing another opportunity to allow destructive vibration effects. Tables with 4 points of support per shelf start immediately at a disadvantage. One or two point will always be under less pressure, or even rock or chatter than the two slightly higher points that define an axis. It takes 3 points and 3 points only to define a plane. Some products like the Something Solid range, approach the problem more laterally and support the shelves flexibly.

As noted in our TNT-audio.com vibration control experiments (below), electro-mechanical devices need stability plus vibration absorption; the transducer elements need defining in space accurately to preserve information (cd players, turntables, traditional hard disc drives) so these are a good place to start experimenting.

CD players bombarded with high intensity sound have been shown to lose data at first (increasing interpolation rates) and ultimately skip or shut down. Fellow TNT scribe Maarten effectively improved CD players with Dynamat Extreme car panel dampening mats. Experiments have shown that a mixture of approaches works best with CD/SACD/DVD players, of point contact under either mains transformer or CD transport axis with absorbent support elsewhere to tame chassis resonances. The no longer available PolyCrystal Isolators remain the reference (at the time of asking RDC did not accept a review offer but were tried and were not as good) and TNT-Audio's own Stone Blocks are excellent in the solid support role and another DIY solution is in preparation. BrightStar Isonodes remain the blobby reference (Deflex/Spectra Foculpods did not respond to a review request) and there will be a DIY alternative soon.

Vibration control takes many forms Previous investigations (see below) indicate that different components require different strategies.

Terms like coupling and decoupling are routinely misused in audio writing about vibration control. semi-rigid decoupling/coupling combinations, or those products that try to combine approaches into one device.

One of the most vibration prone devises available for test is the Canor TP306 VR+. Even though there is some kind of compliant grommet between the steel chassis and the signal circuit boards, the effects of airborne vibration are clearly audible as microphony, and structure borne sensitivity is so high that some shelf types can be identified blind. However, it remains one of the greatest single-ended phono stages ever produced, and the big bottle 6SL7 and 6SN7 valves are responsible for this microphony as well as their advantages; octal base valves (tubes) tend to be more microphonic due to their larger internal structures than b9a based valves, but the smaller valves tend to suffer from more internal crosstalk due to the proximity of the two triode sections. The Canor TP306 VR+ only shows its mettle when appropriately supported by a combination of isolation products.

"Surely that is just bad design!" state plebs, stage left

The execution could certainly be better designed to isolate from vibration, but this phono pre-amp remains a benchmark, although watch these pages soon for a serious contender.

The inter-relationship between components and vibration control is brought home sharply by the differences between two single-ended triode amplifiers and the different valves tried in one of them. In that first article for TNT-Audio, Box Clever a Tim de Paravicini circuit design was shown built into a Russ Andrews Torlyte box. The mains transformer stands on 3 BrightStar Isonodes to isolate the circuit and the output transformers from any mains transformer vibration and the Torlyte box is fairly impervious to support, seeming to work best on Yamamoto PB9 & PB10 feet. The modified Assemblage SET300B (Sonic Frontiers derived design), fitted with EAR feet works better with large BrightStar Isonodes when fitted with JJ Meshplate 330b valves but with Yamamoto PB-20/PB-21 - setting bases when running Western Electric 300b valves.

[boxing clever]

Many of the major componants submitted for review have sounded better with their lids removed or with Vibration dampening devices installed.

Conclusion

Vibration control in audio systems is essential to exploit any of the potential of expensive audio components.

Every component in the system benefits from correct choice of vibration isolation and vibration control products. Whether these be products to dampen vibrations present in the audio device, or products designed to isolate the audio hardware from vibration from external sources (be they structure borne or air borne) judicious use of vibration isolation and control will have a profound effect on audio system optimisation.

Previously in TNT-audio

[move & groove]

Music enjoyed during this review Reference system
On vinyl:
  • Lightenin Hopkins: Goin Away all valve from microphone to loudspeaker with the Canor phono stage
  • Grateful Dead: One from the vault
  • Frank Zappa:: Ship Arriving too late to save a drowning witch
  • Pink Floyd: Relics, Record store day remastered from original tapes
  • Pink Floyd:: Animals
  • Dave Clark: Rise 1
  • Beethoven: Piano Concerto 5 'Emperor', Böhm conducts the Vienna Philharmonic with Pollini tinkling the ivories, worn second-hand copy
  • David Bowie: Station to Station
  • David Bowie: Cracked Actor (live LA 1974), Parlophone ltd. ed. 5 sided triple vinyl
  • LTJ Bukham: Journey Inwards
  • Dave Clarke: Archive One
  • Dave Clarke: Charcoal Eyes
  • DJ Format: Music for the Mature B-Boy
  • Billy Cobham: Spectrum
  • Billy Cobham: Simplicity of Expression - Depth of Thought
  • Miles Davis: Aura
  • Bob Dylan: Highway 61 Revisited, audiophile 180g pressing
  • Grooverider: Mysteries of Funk, quadruple vinyl box
  • Keith Jarrett: The Köln Concert
  • Gustav Mahler: 10th Symphony, Bournmouth Symphony Orchestra conducted by Simon Rattle
  • Lou Reed: Perfect Night: Live in London
  • Bruce Springsteen: Darkness on the Edge of Town
  • The Dreads if deejay was your trade the audiophile obsessive King Tubby productions 1974-1977
  • Funkadelic: Free Your Mind
  • Leftfield: Leftism, 2018 triple vinyl remaster
  • Leftfield:: Rhythm and Stealth, 10" box set
  • Widor:: 8th symphony, Nicolas Kynaston on Kreuzkirche organ Bonn
  • Wilko Johnson: Blow Your Mind, with the magnificent Norman Watt-Roy on bass
  • Bob Dylan: Blood on the Tracks
Equipment used in these reviews:
  • Turntable support: modified Origin Live Ultra wall shelf, tuned with PolyCrystal vibration control devices and 12mm laminated glass shelf
  • Turntable 1: Michell Gyro SE on PolyCrystal point discs with top hat PSU PolyCrystal point disc and BrightStar Isonodes
  • Turntable 2: Michell Orbe SE on PolyCrystal point discs with Gyropower PSU PolyCrystal point disc and BrightStar Isonodes
  • Pick-up arm 1: Hadcock 242SE Silver silver wired straight to silver bullet plugs
  • Pick-up arm 2: Michell Tecnoarm
  • Turntable 3: Audio Files Spoke Modified Linn Sondek LP12 with aerolam subchassis and triple Spoke modification
  • Pick-up arm 3: SME 309
  • Turntable 4: Garrard 401 with plywood, concrete & kiln dried sand plinth
  • Pick-up arm 4: SME 3012 Series I and aftermartket thread & weight bias assembly
  • Pick-up arm 5: SME 3012 series II with FD200 damper
  • Pick-up arm 6: SME 3009 series II
  • Turntable 4: Thorens TD160 somewhat modified & mollified
  • Pick-up arm 7: SME 3009 Series II improved detachable headshell, on the Thorens
  • Cartridges:Dynavector XX2 MkII; Benz Micro; Cartridge Man MusicMaker II; Modified Decca London; Audio Technica VM500 and VM95 ranges
  • Phono pre-amplifier 1: Canor TP306 VR+ phono-preamplifier
  • Phono pre-amplifier 2: Gold Note PH10 phono-preamplifier
  • Phono pre-amplifier 3: QHW The Vinyl phono-preamplifier
  • CD Player 1: Shanling CDT100c modified by Chevron Audio
  • CD player 2: Avondale Audio AAA5
  • Phono and CD player supports: Yamamoto PB9/PB10 feet; ERaudio SpaceHarmoniser violin plank; ERaudio steel cones; Something Solid shelf: Something Solid XR4 rack; Something Solid Missing Link feet.
  • Audio Research Reference 3 pre-amplifier
  • Vibration Control includes BrightStar Isonodes and BrightStar Little Rock on Something Solid shelf & rack
  • Integrated amplifier: Canor TP106 VR+
  • Pre-amplifier 1: Audio Research Reference 3
  • Pre-amplifier 2: Yaquim MS12B
  • Pre-amplifier 3: Naim NAC42.5 test mule in various cases powered by various DIY overkill power supplies including Sonic Link/Audiokits parts and Avondale parts
  • Pre-amplifier 4: Quad 44 with versatile tone tilting and shaping
  • Power amplifier 1: hot-rodded Assemblage SET300B Signature from the DIY wing of Sonic Frontiers
  • Power amplifier 2: Burson Bang
  • Power amplifier 3: Graham Nalty designed & built Care Music prototype
  • Power amplifier 4: Paravicini designed 4W SET3080
  • Loudspeakers: TQWP/Transmission-line hybrid passive loudspeakers (18mm & 25mm birch-plywood cabinets; long fibre natural wool stuffing; Deflex panel lined) based loosely on the late John Wyckoff's Hammer Dynamics
  • bass-mid driver and crossover (with litz-wired inductors & couture capacitors) and B&C DT400N tweeters.
  • Loudspeaker supports: Yamamoto PB-18 African ebony & ceramic loudspeaker spike receiver bases
Some wire is used to join these components together too. No interconnects cost more than 10% of the device at each end, much of it made by the Old Scribe mostly from Neutrik, Van Damme and Sonic Link/Black Rhodium components. Speaker wire is ultra-low impedance Black Rhodium S900, a prototype variation on the Black Rhodium S600 cable that came out well in Ben Duncan's objective and subjective correlation tests.

DISCLAIMER. TNT-Audio is a 100% independent magazine that neither accepts advertising from companies nor requires readers to register or pay for subscriptions. After publication of reviews, the authors do not retain samples other than on long-term loan for further evaluation or comparison with later-received gear. Hence, all contents are written free of any “editorial” or “advertising” influence, and all reviews in this publication, positive or negative, reflect the independent opinions of their respective authors. TNT-Audio will publish all manufacturer responses, subject to the reviewer's right to reply in turn.

Copyright © 2019 Mark Wheeler - mark@tnt-audio.com - www.tnt-audio.com
Images free to use or creative commons.