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July 2006
Enjoy the Music.com Review Magazine
Sound Dead Steel Isoplatmat
Review By Rick Becker
Click here to e-mail reviewer


Sound Dead Steel Isoplatmat  Sound Dead Steel is not the kind of stuff that might be of interest to Harley Davidson owners, but audiophiles? Reading the various emails that were sent to me by Les Thompson, I learned that SDS is not another rock band from England. Rather, it is a technology company specializing in noise abatement. Their particular specialty is bonding thin layers of steel or aluminum together with a 50 to 100 micron layer of viscoelastic polymer and then cutting, folding and mutilating this material into various industrial uses where very high levels of noise are problematic for the workforce. If you are an audiophile, with high disposable income and sensitive hearing, you are probably unfamiliar with such environments. But someone at SDS must be an audiophile. They count among their customers Linn, B&W, ARCAM and dCS. And they also manufacture and market their own Isoplatmat for turntables, as well as a variety of plates for dampening other components and loudspeakers.

The initial review of the Isoplatmat came out in Hi-Fi World in January 2005, and was quite favorable, but I'm always a little suspect of British products reviewed in British magazines. The audio industry in Great Britain seems to be somewhat insular and self-protective. The correspondence with Les was minimal and proper. In fact, I wondered if the initial information he sent was a shotgun invitation to all reviewers rather than an inquiry directed specifically to me. But perhaps a bottle I had thrown into the Atlantic had landed in England and word of my particular interest in vibration control was spreading. I responded with enthusiastic interest and was immediately told a review sample was to be sent. A month later, I sent a follow-up inquiry asking if they indeed did send me a review sample. And three weeks after that, to my surprise, it arrived right before three days of prime listening time over the Memorial Day weekend. Perfect timing!


The Playing Field

Unlike the reviewer for Hi-Fi World magazine, I only have one functional turntable, an old Linn Sondek with a Sumiko MMT arm threaded with some fancy cable and a Clearaudio Virtuoso Wood moving magnet cartridge. The phono stage is standard equipment on my CAT SL-1 Mk III preamplifier. The Linn is mounted on a solid oak wall shelf with a Symposium Acoustics Svelte Shelf on top of the wood, and three Boston Audio Design TuneBlocks between the Svelte Shelf and the Masonite bottom of the Linn. Three-inch squares of stainless steel increase the contact of the tungsten carbide ball bearing with the bottom of the Linn. And my secret weapon is the Boston Audio Design carbon graphite Mat 1 which I nominated for Accessory of the Year for 2005. I don't mean to set this up as a re-enactment of the Revolutionary War, and for sure, I'm not about to dump all my British Invasion LPs into Boston Harbor. My analog rig isn't state of the art, but it is decent enough to differentiate the various turntable mats that have come my way over the past few years. What is at stake here is retrieving the music from the grooves with the assumption being that the more you retrieve; the more you will enjoy the music.


The Playing

Right from the start it was clear that the Isoplatmat was a major league player. This surprised me a bit as the fit and finish of the product was... what's the right word?...uh, "questionable"? It felt like an LP made out of steel and it looked like too much paint had been applied, causing the finish to wrinkle randomly as it dried. The surface was shiny and somewhat slippery, although the disc never got away from me during all the handling in the course of the review. It looked rather "low-tech" and there were burrs of polymer on the inside edge of the hole which I reamed out with a pencil. But what worried me more was the diameter of the disc, which fit tight to the thin outer lip of the platter on the Linn. Fortunately, not only was the Isoplatmat perfectly round, but the hole in the center was exactly in the center. To check to see if the mat was sitting flat on the platter, I placed the removable outer ring of the platter on a kitchen countertop and centered the mat on it. While I sighted across the surface of the mat, Linda pressed down near the center of the mat repetitively. There was a small, but visible deflection indicating the mat was not making full contact with the surface of the platter, but rather was supported by the outer rim. I shot an email off to Les.

It is difficult to image a turntable mat "breaking in", but I seemed to enjoy the music more the second day. From the very first, there was vastly improved focus over the standard felt mat that comes with the Linn. And there was even more focus than was achieved with the Boston Audio Design Mat 1. The background was quieter, the bass deeper and tighter, and the soundscape was more clearly defined and larger than with the Mat 1. Pace and rhythm were additional stellar attributes with the Isoplatmat. My foot bopped along with the music without any conscious intent. What didn't work quite so well for me was the edge of the music. The attack and decay were lightning fast, but also fatiguing in the long run. Not when playing only one or two sides, but after four to six sides in a row, this edge began to wear on me. If I had had the slightest headache, listening with the Isoplatmat would have been totally uncomfortable. In contrast, while the BAD Mat 1 was a little softer in this regard, I can listen forever with it.

The difference is kind of like walking along the rim of the Canyon de Chelly in Arizona. The Mat 1 holds back and stays a little further away from the edge, allowing you to fully enjoy the splendid vistas as you walk along. The Isoplatmat, on the other hand, ventures closer to the edge where you are wise to pay attention to every footstep, lest you experience a thousand foot freefall into the canyon. The advantage of being this close to the edge is that you can see more of the canyon floor or deeper into the grooves, if you will. Of course the fall from your listening chair is not as severe, but the Isoplatmat reveals every note of the music, forcing you to pay close attention.

Another slight difference emerged in the soundscape. The front of the soundstage with the Isoplatmat was closer to the listening chair, but still slightly behind the loudspeakers. With the Mat 1, it was back at the front wall, and the soundscape was noticeably deeper. The notes of more distant instruments, being slightly less focused, made them seem even further away. For readers not familiar with my system I should note that virtually every component is supported with some kind of vibration absorbing isolation device. If your rig is less critically tuned, you might not experience the edge to the music that I mention here. On the other hand, it might be worse. As I've noted over the years, having some sort of vibration absorbing device under every component has a synergistic effect. Bringing out the best of each component multiplies the effect of treating just one component. Moreover, a thousand dollars spent on vibration control footers for your system will probably go a lot father than spending another grand on a single component.

This change in the soundscape also brings up two other characteristics that I like to differentiate. Improving focus is like putting your prescription eyeglasses on, which is rather obvious. Improving transparency, however, is more like taking your sunglasses off. Some components do one, but not the other. The Isoplatmat improved both focus and transparency, which is why I think the soundscape moves a little closer and compresses the depth of the soundscape somewhat.

Both of these mats are definitely big league additions to your analog rig, rivaling the expenditure of one or more thousand dollars on a cartridge upgrade, or upgrading the table itself. Depending on how well the rest of your system is balanced in terms of both component quality and vibration dampening, one of these mats may be preferable to the other. Realizing that my turntable was highly tweaked in this way, I stripped it down to just the Linn with its felt mat sitting on the solid oak shelf. The focus took a big dive, and under these circumstances, adding the Isoplatmat provided more benefit and less edge than when the table was more highly dampened. For approximately $128 US, plus shipping from England, this is the biggest value upgrade for my Linn, short of building my own wall-mounted shelf. I proceeded to tweak the rig further with the addition of the BAD TuneBlocks and stainless steel plates, but left out the Symposium Acoustics Svelte Shelf feeling that I had reached the point of greatly diminished returns. Besides, I had another use for the Svelte. I also tried the combination of the original felt matt on top of the Isoplatmat. This latter combination softened the attack of the notes somewhat, and reigned in the Isoplatmat closer to effect of using the Mat 1. Your table is most likely different than mine, so you will need to play around with it yourself to maximize its potential. And who knows, you may find you need a new cartridge in addition to the new mat. If your tonearm has adjustable VTA, you may want to play with that, too. My ear did not pick up huge differences in tonal balance as I tried the various combinations, but then, I do not have the option to play with the VTA with my rig. The Isoplatmat, by the way, looks to be slightly less than 3mm thick.

Word came back from Les that the Isoplatmat was comprised of two layers of different thicknesses of aluminum with the polymer between. It is also available with stainless steel plates at a higher price since stainless steel is more expensive and much more difficult to work with. It does give you a silver metallic finish, however, and should be slightly thinner since it lacks the topcoat. The black coating on the standard version is powder coat paint that hides the inevitable scratches in the aluminum plates that are the byproduct of the manufacturing process. Les did not give me permission to shave off the paint from the edge, but if I had, the mat would have fit neatly within the rim of the Linn platter and made contact over the entire surface of the mat. Les suggested this was not necessary (except to improve the VTA, in my opinion) and that Origin Live, a very highly regarded British turntable manufacturer, recommended using the Isoplatmat with pieces of cork beneath it. (Origin Live? Sound Dead Steel? What's going on over there? Is Britain still a land of Cults? It reminds me of the days of Mods and Rockers). Using cork coasters beneath the Isoplatmat, the edge I heard on the music was reduced slightly. Using three coasters rather than four seemed optimal in my case. I should also note that the edge of an LP record extends slightly beyond the edge of the Isoplatmat, making it easy to lift the record off the turntable. I tried, but could not determine if the thick outer edge of the LP, which just caught the edge of the Isoplatmat, kept the outer grooves from contacting the Isoplatmat. This would be another reason for trimming down the outer edge of the mat.

I also tried the Isoplatmat with a variety of LPs from the 1980's, 70's, 60's and 50's, noting the evolution of microphones and recording technique. With the Elvis' Golden Hits LP I had to pan the signal to the left speaker and slide the listening chair over to optimize the monaural signal. I also compared the two mats using an old Bob Dylan LP that was covered with light scratches. Even after cleaning, neither mat did much for the clicks and pops, but fortunately I'm blessed with the ability (or willingness) to listen through them. Dylan's lyrics, often obscured by his stylized singing especially on inexpensive gear, were easily heard with the more transparent Isoplatmat. And the harmonica cut right through to the bone, like his lyrics cut through to the brain.

Les, who is both the owner of the company and the audiophile behind this product, suggested that they could paint the Isoplatmat any color, even tartan, if there was sufficient demand. Tartan would be very apropos on the Linn, of course. Bold colors are everywhere in evidence with analog rigs these days, as seen in the recent show reports from Montreal and Munich. Then again, you might just want to take the mat to your local artist and have an original work of art created for your Origin Live. I like that idea. Maybe when my grandson, Izak, comes to visit I'll have him do some graffiti with his mother's nail polish. I can see it now... "Grandpa Rick Rocks!"



In the grand scheme of high-end audio, $150 or so for a turntable mat is not a huge sum and the potential benefit from the Sound Dead Steel Isoplatmat is multiplied many times over. It stood tall with the Boston Audio Design Mat 1, besting it in many parameters, but not all, on my Linn turntable. How it will fare on your table with your rig, you will have to try for yourself. You will also have to decide which of these two world-class mats suits your personal taste. While the Isoplatmat is more detailed, the Mat 1 is lusher. Also, the Linn is a suspended table; most are not. However, the review in Hi-Fi World, which used a variety of tables, bodes well for all types. While they have yet to establish a beachhead in North America, I'm told SDS has never had a return and will refund your money, less shipping, if you are dissatisfied. Les Thompson is looking to develop audio products into a thriving division of his company. Hopefully, other products such as shelves and dampening footers will become available with this technology. Let us also not forget a multitude of OEM applications such as those already taking root in some British companies. Two theories that have emerged from my reviews of various dampening products over the years are, first, the closer to the signal path the dampening technology is applied, the more effective it can be, and second, the closer to the signal path, the less costly the tweak can become. The Isoplatmat scores very high in musical refinement and in value, giving evidence to both. Bloody good show, gentlemen!


Wait... Don't Go Away! There's More!!!

Another "What if?" popped into my mind as I wrote the summary above. The next evening I tried using the Isoplatmat as a dampening plate, first under the conrad-johnson MV60SE amplifier, then under the CT-6 preamplifier, and finally, on the bottom of the Linn turntable itself with the Mat 1 on the platter. Holy Stonehenge! I'm not going to say more than that. Les is sending me samples of his plates for a follow-up review, but if I were a manufacturer of high-end audio components, I wouldn't wait for that review I would be contacting Les Thompson right now about becoming an OEM supplier, before mid-fi companies discover this stuff and catch us from behind.



Sub-bass (10Hz - 60Hz)

Mid-bass (80Hz - 200Hz)

Midrange (200Hz - 3,000Hz)

High-frequencies (3,000Hz on up)



Inner Resolution

Soundscape width front

Soundscape width rear  
Soundscape depth behind speakers

Soundscape extension into the room



Fit and Finish

Self Noise


Value for the Money



Type: Vibration isolation/reduction system

The aluminum Isoplatmat is 68 without VAT ($128 + shipping)
And the unpainted stainless option is 100 ($188 + shipping)

Sonphonon Steel HiFi Plates (all material is a sandwich construction)
Various sizes with pricing from 70 to 120


Company Information

Sound Dead Steel Ltd.
190 Kingsway South
Team Valley, Gateshead
Tyne & Wear, NE11 0SH

Voice: +44 (0191) 482 1147
Fax: +44 (0191) 482 0582
E-mail: Les-sds@btconnect.com
Website: www.sounddeadsteel.com












































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