A/V Room Service Equipment Vibration Protectors (EVPs)

tmallin

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A/V Room Service Equipment Vibration Protectors (EVPs)
Part 1


My Anti-Vibration Experience

I suppose most audiophiles have tried a number of racks and/or accessory “feet” in an attempt to eke subjectively ever-better performance from their systems. I'm no exception. As with most types of components, my 50 years of experience in this hobby has resulted in owning, using, and comparing a variety of options.

In terms of electronic equipment racks and platforms, I've used everything from a lowly Ikea Lack table, to Sound Organisation and Target racks, Black Diamond Racing Platforms, Bright Star Audio Big Rock sandboxes, inner tube suspensions, and sand filled Little Rock weights, to the Townshend Seismic Sink, to the Arcici Suspense rack, Active Vibraplane (active only in the sense that it has an air pump which automatically occasionally operates to keep the air bladders filled and platform leveled), a Minus K platform, and Mapleshade 4” solid-maple platforms. For accessory feet I’ve used everything from felt pads and tiny vinyl bumpers, to the original Mod Squad Tiptoes and Sorbothane feet, Sims NAVCOM silencers, Vibrapods, Aurios, Symposium Rollerblocks, Mapleshade Isoblocks, Bright Star Audio IsoNodes, Golden Sound DH cones, and Walker Audio resonance control disks.

For speaker stands I've used wooden stools and tables of various heights, as well as purpose-built stands from Sanus, B&W, Sound Anchor, Skylan, Something Solid, and Tontrager, as well as some custom-built fiberglass stands filled with lead shot.

For interfaces between speakers and stands and between stands and floor I've run the gamut from felt, toweling, carpeting, Blu-tac, and Sorbothane, to Navcom Silencers, to roller bearings, short and tall Mod Squad Tiptoes, to rounded metal screw heads, to very sharp spikes of the type which tend to come with speaker stands.

Probably my complexity zenith in this effort involved the isolation system described and shown in my thread, EVS Oppo BDP-105 Mods, Ground Enhancers, Black Discus & Mounting Tweaks.

What I Haven't Tried

I have not tried the latest active suspension devices such as those produced by Herzan and Accurion. Such devices use sensors and actuators to actively counter the effects of detected vibrations at low frequencies in all six degrees of freedom with passive isolation higher up the frequency range. Active isolation is claimed to eliminate the very low frequency resonance of passive isolation systems, resonance which can actually amplify vibrations near the resonant frequency, which is typically below 5 Hz. Active isolation units are thus specified to achieve 90% or more vibration attenuation as low as about 5 Hz.

Problems With Mechanical Isolation Devices

Problems I've encountered with mechanical isolation systems include:

  • expense—many would think inordinate expense for an audio system "accessory" with prices for some of the more "serious" passive and active isolation platforms starting at about $2,000 per shelf.
  • complex and non-uniform set up; where you put the accessory feet under a component for best sonic results varies from component to component and with equipment racks how you position the equipment on the shelf can seem to make a sonic difference as well
  • lack of stability of set up; e.g., the need to keep monitoring the air pressure in air suspension systems for best performance
  • seeming lack of universality—what sounds better with one component may not with another, or what sounds better with some types of music sounds less good with others
  • lack of a reasonable technical explanation as to why a particular mechanical isolation system should work better than just plunking the component down on any old shelf using its manufacturer-supplied feet; beware of any device for which the manufacturer does not publish measured vibration attenuation results
  • vertical height or weight of the isolating system; some of the best—from Minus K, Herzan, and Accurion platforms to Mapleshade platforms and feet—take up a lot of vertical inches in equipment racks making it difficult to mount all the equipment on such devices without adding racks; others, like the Vibraplane, are extraordinarily heavy for each isolating shelf
  • weight sensitivity of the isolating devices—the Minus K platforms, for example, while demonstrably sensationally effective at isolating components, only work their best within a narrow weight range mounted atop them; change components and you’ll need to buy a new version tuned to a different load since there is no easy conversion from one weight range to another
  • and, most of all, the fact that many such isolation systems, while clearly making a difference in the resulting sound, over time do not make the grade as an overall positive difference producing overall "better" sound.

Different Sound vs. Better Sound

As with the audible effects of cables and power treatments, many audiophiles view mechanical isolation with a sizable degree of cynicism. I think that’s a healthy attitude. There are a lot of companies chasing a shrinking market. Buyers need to be able to separate marketing claims from true performance enhancements.

With audiophile tweaks you should remain skeptical unless you personally can clearly hear a sonic difference and positively classify that difference as not only different, but “better.” Most anything you do to a high-resolution audio system will make a perceptible difference in the resulting sound. But in many cases, differences are just that, mere differences, which one cannot be confident in classifying as "better" sound.

What is "better" sound? For me, from what I believe to be well-made recordings of unamplified instruments in good acoustic spaces, “better” encompasses, among other concepts, a more natural (as in true to what you would have heard live from a good audience seat during the recording session) frequency balance, a more open and organized sound field, more distinct and rounded instrumental and vocal images, “blacker” background, wider perceived range of macro-dynamics and more nuanced micro-dynamics, and subjectively lower distortion of all types, especially high frequencies nasties.

When I speak of "better" sound from here on, that's the meaning of "better" I intend. You may disagree as to what constitutes "better" sound, but I hope this definition clarifies what I mean by "better" in my comments.

[Continued in Part 2 below]
 

tmallin

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[Part 2]

My Preferences

There seem to be two basic approaches to mechanical equipment support: rigid coupling and soft/springy coupling. I know audiophiles strongly differ on this, but for many years now I have generally preferred the overall sound of soft/springy coupling to rigid coupling. I tend not to like the sound of rigidly spiking components in place, in other words. To my ears, rigid coupling, while "tightening" bass and enhancing perceived macro-dynamics, generally does these things at the great cost of tilting the frequency balance toward the high frequencies, adding layers of high frequency grunge, and generally producing a "tense" sound. Compared to the "absolute sound" of unamplified acoustic instruments played in a favorable indoor venue as heard from a good audience seat, commercial recordings are generally too bright and less full in the bass range than they should be to begin with; rigid spiking generally just adds insult to injury. For example, I generally prefer mounting speakers to stands using felt, toweling, or Blu-tac interface to using a cone or spike, and with floor-standing speakers I generally prefer the sound with the speaker sitting/floating atop the carpet rather than spiked to the floor below the carpet.

Mechanical Isolation Theory

I believe that the best paradigms for examining the effect of mechanical interfaces in audio systems are rigid body and suspended spring theory. All interfaces can be modeled as either rigid bodies or suspended springs with damping applied. In high-end audio writing I continue to hark back to the 1995 Stereophile article by Shannon Dickson, "Bad Vibes" as the most thorough discussion of the application of these theories to mechanical interfaces in audio systems known to me. This is a long article, but one worth reading carefully, at least once if not multiple times.

And don't neglect, the two Sidebars! Pay particular attention to Sidebar 1 dealing with the rigid body concept and especially Sidebar 2 which states the basic theory behind low-frequency damped spring isolation for audio system components. As stated/implied in Sidebar 2, the natural resonant frequency of a mechanical interface for audio equipment should be as low as possible, low enough for you to "count the cycles" (only possible, of course, in spring mounting with relatively low and slow damping so that you can see a few cycles of movement) after the suspension is set into visible movement by a tap or nudge.

As explained in Sidebars 1 and 2, to actually reduce vibration transmission in the audio range, a springy suspension with the lowest possible primary damped resonant frequency is the only game in town. Even the best rigid coupling will never reduce transmitted vibration; it can only hope not to amplify such vibration.

Dickson basically argues that there is a place for rigidity in supporting audio equipment, but that it can only go so far, saying it must be combined with soft spring support, such as is provided by pneumatic (air) suspensions to truly reduce vibration transmitted to and from components, especially at lower bass frequencies where the energy involved is high and the motion which can be produced by that energy is thus greater.

Here is a manufacturer's graph of the effect of the Minus k BM-8 platform I once used in terms of vibration filtering. Notice the degree of filtering and that it is quite effective even below audio frequencies. Around the typical circa 10 Hz LP tonearm/cartridge resonant frequency it is filtering out 99% of vertical vibration and 90% of horizontal vibration.

My Own Experience with Air Suspension Platforms

I will add my own experiential gloss on what Dickson says. I've found that with top-flight pneumatic suspension units like the Active Vibraplane and tuned mechanical isolators like the Minus k platform, the suspension is most sonically beneficial when used with a minimum of interfaces between the suspension and the suspended audio component. Introduce a rigid platform above the suspension between it and the audio component—even one well-thought-of by Dickson such as the Black Diamond Racing carbon fiber shelf and/or BDR cones—and the sonic signature of the overall suspension becomes an amalgam of the suspension table and the added rigid platform, with the sonic signature of the added rigid platform easily heard as degrading if not actually dominating the audible benefit.

Oftentimes the component's stock feet provide a better sounding interface between the suspension platform and component than any additional platform or footer. Horizontal placement of multiple components on a single shelf is fine—as long as you don't try to extend the horizontal platform by adding a larger shelf atop the surface of the isolation device. This is so true that stacking components atop one another directly atop the Vibraplane/Minus k is frequently sonically superior to adding a larger Black Diamond Racing Platform to the top of the Vibraplane to allow horizontal distribution of the components atop the air table.

I tried various accessory shelves to make a larger horizontal platform from the Vibraplane, including Target and Sound Organisation MDF models, plywood, maple, cherry, and granite. But Even using a high-tech shelf like the Black Diamond Racing carbon fiber composite "The Shelf" atop with Vibraplane with three BDR cones supporting The Shelf above the surface of the Vibraplane, the resulting sound is much closer to the results you get when using just The Shelf than it is to the sound of mounting equipment directly on the Vibraplane via the component's OEM feet. I had a custom "The Shelf" which was 48" long and which allowed mounting quite a few components directly on The Shelf surface without stacking. In the end, The Shelf was not beneficial in this arrangement; I found vertical stacking directly atop the Vibraplane provided "better" sound.

A more elegant means of vertically stacking components with respect to an air suspension platform was provided by the long-discontinued Arcici Suspense Rack which used air bladders under the top shelf to isolate equipment not only on that shelf but up to four additional shelves hung from that shelf. I used the Arcici Suspense in the larger listening room of my former home. Yes, at about five feet tall with a component mounted on its top shelf, it was tall enough and its pillars metallic enough to resonate from airborne vibrations and those were difficult to damp out. But when well-tuned—and that requires a lot of experimentation with the amount of air gap between the top shelf and its chassis and at least weekly topping off of the air in the bladders—the Arcici Suspense offers audible performance fairly comparable to either the Active Vibraplane or Minus k at a lower cost and for multiple components at once. If you can still find one, it is worth investigating if you don't mind the experimentation and maintenance efforts.

I had originally intended to keep using the Arcici Suspense rack in my current room. But in the move from my prior home the "movers lost" the threaded four-foot-long metal rods which were an integral part of the suspension of all the shelves from the air-bladder-supported top shelf. By the time I found the rods more than 18 months after the move (the movers had managed to bend the spring-steel rods to fit within a shorter-than-the-rods framed picture box which also held a framed picture which I did not unpack for all that time [the box was not labeled to include the rods]—not enough wall space for large framed pictures in the open-floor plan of the downstairs of my new home), I had already discarded the rest of the Arcici rack as "useless." While some Arcici Suspense Racks are still available used, as it turns out, that rack is just too big and tall to fit well in my current room anyway. In my new smaller room, I really need to keep the rack short to avoid reflections off the rack and equipment on it from tweeters and midrange drivers, especially if I put the rack in the middle of the speakers so as to keep my cabling runs as short as possible and keep all reflective surfaces (such as the rack itself and equipment on it) at least five feet from my ears in the listening position).

And, believe Dickson and me, the sound of air or other very-low-resonant-frequency suspension (such as that offered by the Minus k devices) is the best, most neutral sounding interface.

My observation of the audibility of rigid platforms atop suspension platforms perhaps accounts for why in many cases even a cheap $6 bicycle inner tube partially inflated beneath a component so as to directly contact the component chassis can in many instances challenge even a Vibraplane's benefit. Such a minimal air suspension dispenses with much of the rigid support in the suspension platform system (even the Vibraplane's stiff metal top plate) and maximally contacts the chassis so as to filter more internal vibrations from the component. This may also be part of the reason for the effectiveness of the old Townshend Seismic Sink: the internal air bladder contacts most of the top and bottom thin metal plates, absorbing or damping most of the sonic signature of the frame of the Seismic Sink itself.

[Continued in Part 3 below]
 
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tmallin

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[Part 3]

The Best, But Impractical for Me, Solution

Multiple active platforms, such as those by Herzan and Accurion mentioned above, probably would be the best solution. Of the passive isolation platforms, I highly recommend the Minus k BM-8 or another Minus k platform more suitable to the particular needs of each component. If you have a large rack with enough vertical clearance, you could fit several vertically on different shelves.

But neither my current listening room nor budget can accommodate this no-holds-barred solution. You need to figure at least a foot of vertical space for each platform and the components atop it. A five-shelf rack would thus be more than five feet high, too tall to avoid causing sound-damaging reflections from the speaker drivers in my small room. I do not have room for two shorter racks horizontally arranged. And the cost of such a rack would exceed $10,000.

What to do?

What Doesn't Produce Better Sound

Frankly, I view the claims of most high-priced audiophile-oriented racks available today as clearly contrary to the physical science of vibration as modeled by rigid body and spring theory. Such racks almost always lack any sort of published test results to substantiate their claims to isolate from vibration or absorb vibration. Most of these rely on sheer high mass, sharp points, constrained layer damping, or a combination of dissimilar materials.

We know from the physics of the rigid body concept that the best we can do with the mass, sharp points, constrained layer damping, or dissimilar materials approach is to not amplify vibrations impinging on the suspension from the structure, the air, or from within the mounted electronics. Most such platforms will in fact amplify certain vibrations and reduce others, thus acting to "tune" the suspension to resonate at certain frequencies, adding a "flavor" to the resulting sound of the equipment placed on it, not isolating the equipment at all. Yes, placing equipment on such a rack will sound different, but very probably not "better."

Some other high-priced racks rely at least in part on a "soft" springiness. However, this springiness, unlike that of the better air suspension or mechanically tuned suspensions such as the Vibraplane or Minus k, is clearly tuned to a frequency far higher than required to filter out high-energy bass vibrations.

For most such racks the manufacturers provide no measurements demonstrating the effectiveness of the vibration filtering or even claims as to the percentage of vibration filtered out. And the prices can be well into five figures for a rack. One such company's footer product costs $2,800 for a set of four footers, enough for one component. Not for me, thanks.

10% of the Money Gets Me 80% of the Way There

I thus looked for a compact and fairly inexpensive solution. I knew that most of the accessory "feet" I've used in the past were not up to the "better" sound standards set by the likes of the Vibraplane, Minus k platform, or Arcici Suspense rack.

The A/V Room Service Equipment Vibration Protectors (EVPs) caught my attention as being well-reviewed and being one of the few isolation devices aimed at audiophiles with published specs on how well the device performs, as well as details of the test procedure used to derive these specifications. I ordered a set of four medium density 2" EVPs (felt version) for my Auralic Aries G2 streamer and was impressed enough to order more for the rest of my electronics.

In the published specs, notice first the test results obtained using a solid aluminum cone of the "Tip Toes" variety. As the explanation states: "Spikes, blocks and cones are very popular and can remove some vibrations—while amplifying others. They actually couple vibrations to whatever they are touching. Think of a tuning fork handle placed against a shelf. The shelf becomes a sounding board."

This is dramatically demonstrated by the two short videos, one showing the frequency spectrum and the other the SPL of a small music box first in free air, then coupled to a glass shelf, then on a short aluminum Tip Toe, and finally on an EVP. You can hear the change in both the frequency balance and loudness of the music box in each condition. On the EVP, the music box sounds much like itself, just significantly quieter than even in free air. On the glass or aluminum cone, the frequency balance is skewed—distorted and resonant—and it sounds much louder than in free air.

Then look at the test data for transmissibility of vibration through the EVP. A/V Room Service claims that within their stated weight loading range EVPs filter out at least 80% of vibrations above 5 to 14 Hz. You can see from the graphs that at all frequencies from below the audio range on up, vibration is significantly reduced. There are no resonant spikes above the level shown by the no-isolation condition. In addition, the amount of attenuation of vibration is fairly consistent with frequency from below the audio range on up to 500 Hz, and as the explanation states, we would fully expect the transmissibility graph to remain at that constant level on up through the audio range—that's how spring-like suspensions work; once the isolating effect fully kicks in, it remains fairly constant at higher frequencies.

EVPs cost about $40 each. They typically can be used in sets of four, with such a set costing about $160, although for very lightweight equipment (such as my Benchmark DAC3 HGC) three work better and I use only one to support the very small/light box of my KanexPro Audio De-Embedder. Altogether, I'm suspending eight components with these things for less than $1,200. Still expensive, yes, but less expensive by a factor of 17.5 compared to the $2,800 set of four footers I mentioned above.

Since most of my equipment is fairly lightweight, in most cases I'm using the medium density two-inch version, specified to support between two and five pounds each. The only exception is for the 25-pound weight of my Oppo UDP-205 I am using four of the high-density two-inch EVPs, specified to support between three and nine pounds each.

A/V Room Service also publishes a Selection & Installation Tips sheet guiding users as to which model EVP to select for any given application. Since my equipment is lightweight and I wanted to be able to move the EVPs around under the equipment and move the equipment mounted on EVPs around on the shelf, I chose all felt versions and in most cases the medium density version of the smaller, two-inch model.

The EVPs take up little vertical space, being about 1.18" tall for the felt version, about 1.7" tall for the rubber versions. My 28"-short Salamander Archetype rack with five shelves actually got more than five inches shorter because the 1" high EVPs replaced the 4"-thick Mapleshade solid maple platform and 2" high Mapleshade Isoblocks I had under the streamer's stock feet supporting it atop the top shelf of my rack.

[Concluded in Part 4 below]
 
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tmallin

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[Part 4]

In my initial sonic testing of the EVPs under my streamer, I tried using the EVPs directly under the stock feet of my Auralic Aries G2 streamer. The sonic results were inconclusive compared to the Mapleshade suspension I had been using previously. The sound was definitely different, but not clearly better and also the results did not seem entirely stable or consistent from one musical selection to another or between listening sessions.

But, with further experimentation, I determined that better sound resulted when the EVPs directly contacted the under-chassis of the streamer right next but inboard of the OEM feet, rather than being placed under the existing feet of the streamer. (The Aries G2 feet are not easily removable, unlike any other audio electronics I own.) This may not be a typical result with the EVPs since the streamer's OEM feet are themselves spring-loaded and incorporate ball bearings and thus are not the typical hard rubber OEM feet most audio electronic components have.

Because of this experience, however, in using EVPs under the rest of my electronic components, I chose to remove the OEM feet and use the EVPs in place of the stock feet, not in addition to them. Since the installation tips say to "start with EVPs placed near perimeter corners or edges to stabilize weight evenly" and since this is usually where OEM feet are mounted, removing the OEM feet helped me start with EVPs directly in contact with each component's under-chassis at points of maximum structural rigidity and in places directly comparable to the sonic effect of the OEM feet, as well as in accord with the installation tips from A/V Room Service.

In my installation, removing or bypassing the electronics' OEM feet has the further advantage of making each component take up less vertical space. While the EVPs add 1.18" to the component's height, removing/bypassing the OEM feet lessens that height increase by an average of more than half an inch since the OEM feet vary from about 1/4" to 3/4" tall. The net gain in height for each component thus averages only about 0.68". As you can see by the before and after pictures below, my electronic stack is still easily accommodated by my five-shelf Salamander Archetype rack and the height of the top-most component (the streamer) dropped by almost six inches because of the removal of the Mapleshade supports.

Once I mounted the EVPs under my steamer in direct contact with the streamer's under-chassis, there was no question in my mind that the EVP-supported streamer sounded better than the streamer did on its OEM feet atop the Mapleshade devices. And the Mapleshade support was itself significantly better sounding than mounting the Auralic Aries G2 directly atop the Salamander rack on its OEM feet.

Even using the EVPs under just the Auralic Aries G2 streamer, compared to the Mapleshade support, precision and stability in left to right and front to back staging was improved. The perceived soundstage changed more from one recording to another. Small details were more audible than before, but with no increase in brightness. Bass was clearer. Mids and highs were clearer and residual digital glare, brightness, and grunge were further reduced. Transients seemed cleaner, more sudden, and more startling. Musical instruments sounded tonally yet more like themselves, both as soloists and in massed ensembles. The background was blacker. The overall presentation seemed quieter, but the range of macro-dynamic contrasts was heightened.

Mounting the rest of the electronics on EVPs further ratcheted up a sonics in the same ways a few extra notches. This is even though in two instances, under the Oppo UDP-205 and the DSPeaker Anti-Mode DX4, I also removed the Bright Star Audio Little Rock platforms from under these components, substituting just the EVPs instead.

At this point, even though A/V Room Service recommends starting with isolating the speakers on EVPs, I am not using EVPs under my speakers. Doing so would cause the ideal listening height to increase by more than an inch. That change would necessitate a new listening chair or shorter speakers stands. Since the Tontrager stands I'm using with my Harbeth M40.2 speakers come in only one height and sound better than any other stands/speaker combination I've ever used, I'm standing pat on the speaker mounting system, at least for now.

I'm sure that the amount of sonic betterment I'm hearing from using the EVPs does not equal what's possible with a full active or air suspension using devices which filter out 95+% of vibration above 5 Hz. But the EVPs' increment in sonic betterment from removal of 80% of vibrations at and below audio frequencies is clearly audible and beneficial. There are no downsides I can hear. And, for about 10% of the price of five active suspension shelves, with a physical footprint which fits my needs, the A/V Room Service EVPs are a very appreciated addition to my system. Highly recommended!
 

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Vienna

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Thank you!
 

tmallin

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I experimented with using three EVPs under each component rather than the four the manufacturer recommends. My thought was that this not only could save 25% on the cost of suspending components on EVPs, but might also result in yet further improved sonic results. Most footers I've used in the past sound best when used in threes since, as long as the center of gravity is securely placed within the area defined by a large triangle of support, such a triangular support arrangement defines and single plane and results in less unwanted "rocking" of the component on its supports. In addition, since my components are all fairly light in weight, using three instead of four EVPs would result in a higher load on each EVP, perhaps moving the load into a "sweet spot" in the EVP rated load capacity.

This experiment proved unsuccessful from a sonic standpoint. While the highs seemed a bit sweeter, they were also less filigreed and seems a bit rolled off. Imaging was just as specific, but staging seemed to contract in all dimensions, resulting in a smaller overall presentation. Bass seemingly lost both detail and ultimate extension.

I can only speculate that a significant part of the better sound the EVPs produce results not so much from isolation of the components from externally induced vibration, but from absorption of vibrations generated from within the component. By placing EVPs at each corner of the underside of the chassis, a maximal amount of such vibrations are absorbed, whereas using only three in a triangle cannot damp vibrations at all corners of the chassis. The videos shown on the A/V Room Service Website clearly demonstrate how contact of an EVP with the small music box involved in the test lowers the level of audible sound produced by the music box itself.
 

tmallin

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I had been using only three EVPs under my Benchmark DAC3 HGC (two at the back corners, one centered along front edge) because of that component's very light weight of only three pounds. Even with a TAS magazine weighting the top, the total was less than four pounds.

Using four EVPs (one at each corner) resulted in a bit of imaging vagueness and lack of centerfill. I cured this by adding three Walker Audio resonance control disks (1.2 pounds each, 1" tall by 2" diameter each) atop the center of the TAS magazine. That boosted the total supported weight to about 8 pounds and thus within the 2 - 5 pound spec for each moderate density EVP. The imaging vagueness and lack of centerfill disappeared. The result is that four EVPs now sound better than the results I was achieving before with only three under that DAC. The sound is yet cleaner overall and imaging and staging is rock solid and further expanded in all dimensions.
 

tmallin

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After my initial installation of EVPs, A/V Room Service released a new version of the EVPs labeled LD for Low Density. These are meant for supporting very lightweight components. I have adopted these where appropriate in my system. I aim to use the version of EVPs which places the weight of the component midway within the recommended weight range for the number and type of EVPs used under that component. See the EVP selection chart at this link.

Wherever possible, my strategy has been to use four EVPs per component, arranged near the four corners of the chassis bottom in direct contact with the chassis, not under the existing feet of the chassis. I remove the feet of the components where necessary to achieve this orientation. When removal of the OEM feet is not possible for me, I arrange the four EVPs centered along the edges of each side of the chassis. I continue to find that four EVPs works better than three in most situations. For VERY lightweight items, such as my TP-Link router, I carefully balance the item atop one LD EVP.

Having used the EVPs for about a year now, I've also discovered that my initial assumption that the felt versions of the EVPs would be better for me was incorrect. I have now switched over to all rubber EVPs. This is not because I find the rubber versions sonically superior. No, it is simply for practical reasons. I've found that lightweight components atop the felt EVPs tend to move around too much on the shelf or other mounting surface in response to routine contact like dusting, cable connecting/disconnecting, and operating front panel controls. I'm obsessive enough about symmetrical placement of components that this shifting of the component position is annoying, necessitating, as it does in my mind, the reorientation of the component to restore the symmetry. The rubber EVPs keep even lightweight components firmly situated. Thus, while initial symmetrical placement is a bit more difficult with the rubber version of the EVPs, for me at least, they have proved the better solution.
 

Audiophilehi

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Thank You Tom for the outstanding and detailed review. I just purchased 4 2” MD and 4 2” HD EVP’s. I currently have 3 MD EVP’s under my Aurender N100H music server and 3 HD’s under my PS Audio BHK preamp. I’m going to listen for a bit and then add the 4 the EVP to each.

The EVP’s replace the IsoAcoustics Orea’s which made a nice improvement overall. So far the EVP’s seem to take it up a notch.
 

Jim Smith

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After my initial installation of EVPs, A/V Room Service released a new version of the EVPs labeled LD for Low Density. These are meant for supporting very lightweight components. I have adopted these where appropriate in my system. I aim to use the version of EVPs which places the weight of the component midway within the recommended weight range for the number and type of EVPs used under that component. See the EVP selection chart at this link.

Wherever possible, my strategy has been to use four EVPs per component, arranged near the four corners of the chassis bottom in direct contact with the chassis, not under the existing feet of the chassis. I remove the feet of the components where necessary to achieve this orientation. When removal of the OEM feet is not possible for me, I arrange the four EVPs centered along the edges of each side of the chassis. I continue to find that four EVPs works better than three in most situations. For VERY lightweight items, such as my TP-Link router, I carefully balance the item atop one LD EVP.

Having used the EVPs for about a year now, I've also discovered that my initial assumption that the felt versions of the EVPs would be better for me was incorrect. I have now switched over to all rubber EVPs. This is not because I find the rubber versions sonically superior. No, it is simply for practical reasons. I've found that lightweight components atop the felt EVPs tend to move around too much on the shelf or other mounting surface in response to routine contact like dusting, cable connecting/disconnecting, and operating front panel controls. I'm obsessive enough about symmetrical placement of components that this shifting of the component position is annoying, necessitating, as it does in my mind, the reorientation of the component to restore the symmetry. The rubber EVPs keep even lightweight components firmly situated. Thus, while initial symmetrical placement is a bit more difficult with the rubber version of the EVPs, for me at least, they have proved the better solution.

Agreed 100% Tom. I also have had great success with EVPs under subwoofers.

Frankly, the $150 Pangea rack, when used with EVOs under each component, outperforms any of the exotic racks that I've tried.

Not nearly as good looking, though.

IMO, YMMV, etc...
 

marty

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Tom
Beautiful posts on AVR. I missed them but they were brought to my attention by highstream (Gene) when I thanked him for mentioning the AVR EVPs. Your posts on the subject are gems, as always.
Marty
 

Pallen

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Jun 25, 2018
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I had considered my tweaking days over, but on the basis of this thread, I recently purchased and tried EVP's. I can't say that I've experienced the same glowing results described by others. I guess that shows once again that every system is different.
 

audioquest4life

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Sep 23, 2020
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Glad to see a company provide technical specifications which demonstrate the effectiveness of its products. I had been looking at some 3M products which also has technical specifications listed. I think using the EVPs combined with whatever rack system one chooses, is a win win situation. Now, I am considering this tweak before I purchase a set of SRA Ohio Class platforms for my amps. My amps currently sit on a pair of custom German built Copulare amp stands. I don’t have any technical specifications for them outside that they use sand inside the columns and inside the platforms to help dampen vibrations. They look real nice and wife like the red to fit the decor.
 

tmallin

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Here is a link to a Bob Katz study on the effect of isolating floor-standing loudspeakers from the floor. The devices tested were the EVPs.


I have never used EVPs to isolate speakers from the floor. The adjustments involved in getting the speakers to be vertical once the EVPs are inserted could prove daunting. Unless the weight load is distributed just right, the EVPs will tend to differentially compress, changing the verticality of each speaker and thus the sound of the speakers at the listening position. The positions of the EVPs would have to be carefully adjusted in any comparison and rapid A/B sonic comparisons with and without EVPs under speakers would be impossible.

For supporting electronics, the situation in which I use the EVPs, small changes in level are usually not important. LP and CD spinners are the obvious exceptions.

But with speakers, getting the two speakers both positioned at the same vertical angle is obviously an important part of speaker set up. This is easy to do with solid mounting, but not easy at all with compressible supports, especially if the speakers are heavy and the support core delicate--as is the case with the EVPs. It is easy to "rip" the bellows-like core of EVPs by attempting to move them around under a heavy load. You would have to lift the speaker load first before moving the EVPs, and that will tend to move the speaker from its intended positioning in the room with respect to the walls.

While I do not doubt that placing EVPs under speakers could make differences and even clear improvements in the sound, it does not appear that the design of Katz's experiment sufficiently controlled for the likely change in verticality of both speakers between the test condition of EVPs under the speakers and control of wood blocks under the speakers. Wood blocks would not compress, whereas EVPs definitely compress under load and do so differentially depending on the weight supported by each EVP. Some of the frequency response changes noted in Katz's experiment above the bass may well have been due to the change in verticality of the speakers, not the EVPs' isolating effects.

The initial experiment conducted in Bob's larger Studio A (which Bob mentions in his comment to the Stereophile article) notes the problems with concrete slab floors in audio rooms. My prior listening rooms all either had concrete slab floors or concrete over plywood. It was obvious to my ears that spiking either floor-standing or stand-mounted speakers to such a floor was a step in the wrong direction. I greatly preferred the sound of "floating" the speakers on carpet or other "lossy" material rather than hard-couple them to the concrete. Concrete coupling rather obviously brightened the treble and produced an edge or glaze to the sound. Yes, coupling "tightened" the bass, but the sonic effects higher up the audible spectrum were disastrous.
 
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poonbean

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Jul 30, 2020
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Well, I placed 4 EVPs beneath Verity Sorastros and can say unequivocally that the improvement was nothing short of dramatic. My goal was to simply eliminate a strong room resonance at around 70hz (suspended floor) after trying countless speaker positions and room absorber locations to no effect. Not only did the EVPs remove all of that resonance (to my ears and meter), but the clarity throughout the spectrum improved significantly along with image and overall musicality. Next, I got 2" squares to go between the top and bottom cabinets, replaced the oem constrained layer. Bingo, cleaned up the articulation in the upper registers, removed some of the fat/sluggishness in the lower mids, and eliminated harshness that would occasionally seep from the ribbons. Next option will be to place these directly under the lower cabinet without the separate oem constrained layer, and then beneath other equipment and the rack itself. Couldn't be happier.
 

tima

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Thanks for the other thread pointer to this post, Tom. I have not read it all but what I read is interesting. One thing you mention more than once is along the lines of: "manufacturers provide no measurements demonstrating the effectiveness of the vibration filtering or even claims as to the percentage of vibration filtered out." What would such measurements be? I'm curious if you define a standardized component object to measure, or if doing so even makes sense? Since platforms and footers themselves sit on something, would the measurement process need to standardize on that as well? Then there is the wider external context of the room and the vibrational factors impinging on that.

Given the multiplicity of products, product materials and product construction, how much value would such measurements offer? Would we understand them? Would we be able to correlate one manufacturer's measurements with those of another manufacturer? Do you believe measurements for, say, a 150lb amplifier stand translate well for someone looking to put a platform under a CD player? Or do you simply want proof that in some way a platform or footer does something?

I'm not saying measuring is not worth doing. The vibration control portion of the industry has, seemingly, not embraced it thus far. For the most part, demonstrating or acknowledging the effectiveness of a vibration control device has been left to sonic evaluation - results that matter most for the majority.

On a different topic, your post observes: "Multiple active platforms, such as those by Herzan and Accurion mentioned above, probably would be the best solution." (though you note neither your room nor your budget accomodate such solutions.) I am not a technology person but I have a somewhat technical question for you: if a component is capable of having multiple internal simultaneous resonances sometimes at different frequencies, and the component is subject to vibrations from external sources at the same time, how does an active platform deal with those? If my question makes no sense, I can handle that. :) Thanks in advance for your insight.
 
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tmallin

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For the EVPs, the test procedures and results can all be accessed from the following page: https://avroomservice.com/evp-2/ Scroll down to the part titled "How They Work" and be sure to view the videos and look at the linked white paper. These show both the measurements and subjective tests involving a music box to show the effectiveness of the EVPs in damping vibrations. As I say above in post #3 of this thread:

In the published specs, notice first the test results obtained using a solid aluminum cone of the "Tip Toes" variety. As the explanation states: "Spikes, blocks and cones are very popular and can remove some vibrations—while amplifying others. They actually couple vibrations to whatever they are touching. Think of a tuning fork handle placed against a shelf. The shelf becomes a sounding board."

This is dramatically demonstrated by the two short videos, one showing the frequency spectrum and the other the SPL of a small music box first in free air, then coupled to a glass shelf, then on a short aluminum Tip Toe, and finally on an EVP. You can hear the change in both the frequency balance and loudness of the music box in each condition. On the EVP, the music box sounds much like itself, just significantly quieter than even in free air. On the glass or aluminum cone, the frequency balance is skewed—distorted and resonant—and it sounds much louder than in free air.

Then look at the test data for transmissibility of vibration through the EVP. A/V Room Service claims that within their stated weight loading range EVPs filter out at least 80% of vibrations above 5 to 14 Hz. You can see from the graphs that at all frequencies from below the audio range on up, vibration is significantly reduced. There are no resonant spikes above the level shown by the no-isolation condition. In addition, the amount of attenuation of vibration is fairly consistent with frequency from below the audio range on up to 500 Hz, and as the explanation states, we would fully expect the transmissibility graph to remain at that constant level on up through the audio range—that's how spring-like suspensions work; once the isolating effect fully kicks in, it remains fairly constant at higher frequencies.

Another method of measuring isolation devices is shown in the Minus-k platform specs. A simple graph of reduction of vibration in dB versus frequency is shown. See, for example: https://www.minusk.com/content/tech...ibration_isolation_isolators_tables.html#BM-8

It's easy to overthink vibration isolation. Remember that it is the reduction in vibration of the isolated component that counts. Vibration can enter the component from the outside from its supports (feet, platform, room, earth) or via airborne vibrations directly from the air.

Vibration can also be generated from inside the component, usually from mechanical vibration of electrically powered devices like transformers. Electrical power tends to vibrate things at it native frequency of 50 or 60 Hz and lower harmonics of that. We can hear and feel those frequencies with our fingers and they are called hum.

The EVP videos show that the EVPs can filter out vibration originating within the device as well as from outside the device. The reduction in sound level heard from the music box itself when brought into intimate contact with the EVP is clear evidence of this.

Basically spring theory allows a passive suspension tuned to a very low frequency (below 10 Hz, for example) to filter out most audible vibrations and thus most vibrations induced by speakers playing bass frequencies at high volumes. The passive spring suspension will have a natural resonance at some low frequency (e.g., 2 Hz) which will amplify vibrations around that very low subsonic frequency. Most passive systems have to be tuned the the weight they are carrying for greatest effectiveness. That's the reason the EVPs provide such detailed weight limits for the various types and numbers of EVPs

The so-called active suspensions I mention are superior in that they use electronics to damp that fundamental very low frequency resonance so as to provide substantial isolation even from such very low frequencies. Such vibration can't originate from the audio system, but can come from nearby traffic, trains, construction, and other subterranean vibrations.

As to why most manufacturers of audio vibration isolation products don't offer measurements to show their effectiveness, one possible reason is that for most such products, reasonable measurements would not show much overall reduction in vibration and might well show just a redistribution of vibration to the resonant frequencies of the isolation product itself. As I say in a previous post in this thread: We know from the physics of the rigid body concept that the best we can do with the mass, sharp points, constrained layer damping, or dissimilar materials approach is to not amplify vibrations impinging on the suspension from the structure, the air, or from within the mounted electronics. Most such platforms will in fact amplify certain vibrations and reduce others, thus acting to "tune" the suspension to resonate at certain frequencies, adding a "flavor" to the resulting sound of the equipment placed on it, not isolating the equipment at all. Yes, placing equipment on such a rack will sound different, but very probably not "better."

In response to your last paragraph: I think the solution is to have the isolated components in intimate contact with the isolating system, whether that be EVPs or some active or passive suspension. For example, with the EVPs, put them in direct contact with the underside of the equipment chassis, ideally at the four corners if the chassis is rectangular. You may have to remove the stock feet of the equipment to do that, but if so, take off the stock feet. For best results, you don't want to add the "isolating" effects of stiff feet or even squishy feet to the demonstrably superior isolation of EVPs or other suspensions which tests show provide a high degree of uniform vibration isolation form the highest frequencies down through the lowest frequencies.

Sometimes, for chassis covers which still clearly ring or resonate when tapped with your finger (such as those made of sheet metal), I've found further audible improvements can be had by simply placing a paperback magazine (Stereophile and TAS are suitable) atop the chassis cover. You'll be amazed at how much such a lightweight damper can reduce audible sheet metal vibrations.
 

tima

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Most passive systems have to be tuned the the weight they are carrying for greatest effectiveness.

Imo, to be truly effective more than weight alone needs consideration, including size, resonance frequencies, propagation responses, material, and material construction, and the vibration control object's own context within the audio room, etc. If the solution is neither designed for the environment where it will operate nor built for the component that will site on it, its effectiveness is unknown beforehand.

I agree that whatever a component sits on will change the vibrational characteristics (dispersion, propagation, energy attenuation) of both the component and its support. When the frequency of vibration equals the natural resonance frequency of a component the amplitude of the vibration increases. What the vibration control product sits on will alter its behavior. When a vibration control product reaches its maximum resonance frequency it will direct its energy into the component resulting in larger, more complex vibrations. Knowing as much about the exact component supported enables the manufacturer to know what problems they need to solve before construction begins. Problem averaging can yield results but goes only so far.

For the Minus-k and EVP measurements you point to (thanks) each measurement is for a specific object. Won't those measurements change if the object measured changes?
 

tmallin

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Your opinion does not seem related to the physics discussed in Shannon Dickson's "Bad Vibes" article. I strongly urge you to read that article before forming your own opinions in this area. As I've said, yes, it's a long and not easy read, but much is explained there.

In addition, you seem to be arguing that anti-vibration products need to be designed with particular supported products in mind. And how would this be done by the manufacturer of the vibration isolating equipment? Custom design for each customer? Of course, "custom" work would justify very high prices, but with no guarantee of any better performance since the designer of the equipment probably would not share meaningful test results showing true reduction in vibration transmitted to or from the mounted equipment.

As explained in "Bad Vibes," basically, two concepts are combined to achieve good vibration isolation. First, the platform on which the equipment sits must be a near ideal rigid body so that it has a maximal stiffness to mass ratio, thus primarily resonating at a relatively high frequency. That is better for vibration isolation since high frequency vibrations have less energy and thus disturb the mounted equipment less. But the best that can be hoped for with a rigid body alone is to not amplify the vibrations impinging on the platform, and such platforms are powerless to filter out the high-energy very low frequency energy vibrations from low bass produced by speakers, traffic, trains, etc.

Second, to help isolate this maximally rigid platform from high-energy low-frequency vibration, this rigid platform should be isolated from its environment through a tuned and damped spring arrangement; the primary resonance of this spring-like suspension should be down around 2 Hz or less and ideally (as in the active platforms I mentioned) even that primary resonance is damped electronically. Vibrations impinging on the rigid mounting shelf at frequencies above the tuned frequency of the spring are all greatly filtered out. The EVPs can operate either below the mounting shelf or above the shelf (between the shelf and mounted component) to provide this tuned damped spring; you could also try both methods at once.
 

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