June 1999Cromolin VC Damping Material
by Marc Mickelson
Depending on whom you ask -- Doug Blackburn for the affirmative and the resident skeptics on rec.audio.opinion for the negative -- vibration and resonance do or do not play a part in the sound a component makes. Of course, there are those in the middle of the road too, and I consider myself one of these. Having owned a CAT preamp, for instance, and knowing how carefully designed and built it is and how great it sounds, I have a more than a feeling that controlling resonance and vibration has some beneficial sonic effect. However, hearing the CAT with and without its tweaks is not possible, so theres no way to test the theory. Ive used bags of sand for a long time, and they improve the sound of my system, although not in an earth-shattering way. Then again, there are plenty of damping products on the market, and some people hear tremendous differences when using them.
To have some sense of closure on this issue, I decided to take on a review assignment that is certainly less sexy than evaluating a new amp or pair of speakers: test and write about Cromolin VC damping material, which is an attempt at a high-end solution to a high-end problem and costs an equivalent amount of money: $69.95 for three 5 3/4"L x 1 7/8"W strips. Given that each strip resembles a large piece of chewing gum, I admit that I was a little skeptical from the beginning. Would Cromolin turn out to be a high-priced placebo, or would its effects be obtainable through other cheaper means?
What it is
The notes that come with Cromolin are interesting. From them I gleaned that Cromolin is actually something called Cromoloy alloy, a constrained-layer damping material. Once affixed to a surface, the Cromolin strips are said to convert mechanical motion to heat, but do so more effectively than other damping materials (foam rubber, Sorbothane, etc.) because they force "shearing deformation" as opposed to "compression deformation." What this seems to imply is that Cromolin works more laterally -- across the surface -- than other materials, effectively covering a larger area. None other than Don Wadia Moses, founder of Wadia Digital, provides much of the commentary, outlining some of uses for Cromolin and even graphs of measured effects.
Media Access, the distributor of Cromolin, suggests dividing the surface to be treated into thirds and then applying the strips at the intersections, meaning two strips per surface. I decided to treat the bottom plates of my Lamm ML1 amps; they're large and clangy, so I used three strips on each. I later treated my Lamm L1 linestage, two strips on the top plate. If you have hot-running equipment, youll want to make sure not to block ventilation holes with Cromolin. Media Access has sold custom-trimmed pieces for treating heat sinks, which can ring like crazy, so if you have special needs, they can probably help you.
One side of each Cromolin strip is coated with an adhesive and backing, while the other has a thin, clear protective film on it. Once you identify where each strip will go, you remove the backing and press the strip into place. Next rub the handle of a screwdriver over the exposed side of the strip to adhere it to the surface fully. You will scuff the surface, but theres no worry because the protective film is still in place (and you probably won't see the Cromolin anyway). Once youve finished with the screwdriver handle, peel off the film. Cromolin is permanent, so be sure you have it placed correctly the first time because you wont get a second chance.
What it does
The effects of Cromolin are immediately and easily discernible because they fall into one general area: detail. You not only hear more detail, but the relationship between the various foreground and background details is more pronounced. The best way to hear this is to listen to a small-scale performance thats very tastefully miked -- anything from the remasters of Time Out [Columbia/Legacy CK 65122] or John Coltrane and Johnny Hartman [Mobile Fidelity UDCD 740] to Greg Browns fine Further In [Red House RHR CD 88] will do. Theres a noticeable increase in clarity, and this is due to everything being a bit more there. The warbling tones of Browns voice on "Where is Maria" sound all the more vivid, as do the cymbals throughout Time Out.
Of course, more detail pays dividends other than simply exposing more of each instrument or performer. The space rendered on every recording is more a part of the entire presentation, as it should be, and the soundstage is portrayed with greater precision, even with pinpoint accuracy on some especially impressive discs. I love what the Cromolin-treated equipment does for Buena Vista Social Club [Nonesuch 79478]. Its intrinsic sense of the performers occupying distinct places in my room is all the more enhanced.
Are there other things you can do to damp unwanted vibrations and resonances? Yes. Bright Star Little Rocks work like a charm and reportedly offer the added benefit of curtailing the effects of RFI and EMI. They're also more expensive than Cromolin. One of my favorite cheap tweaks is Ziploc baggies filled with sand, but damping this way can get ugly because you need a lot of baggies -- in my experience, at least 100 pounds worth -- to hear a discernible difference. I use sand bags on top of my speakers and CD transport, on the transformers of my amps, everywhere I can place them easily. I know some people also like using bags filled with lead shot or even a sand-and-shot mixture. Finally, theres mortite, a sticky and dense compound that you can find at your local hardware store and put on the chassis of your electronics (some people even use it inside equipment). I havent tried it, but I know others swear by it. Beware, though, that it could stain your equipment, and I suppose the mortite could melt if used inside a really hot-running component Yuck.
What I think of it
Cromolin is certainly effective. In fact, its the single most potent damping material Ive used. Its also easy to affix inside (or outside) your component, and there is more than a bit of science behind it, so its not just a simple compound repackaged for audiophiles and carrying a commensurate price tag.
The question, then, is not whether Cromolin works -- it does. Instead, you need to decide whether the effects I describe are worth $70 to you. What Cromolin does is certainly as noticeable as swapping one digital cable for another, and there are few digital cables that cost as little as $70. But also keep in mind that there are other ways to damp your equipment, and they work too. Both of the DIY methods I've mentioned are cheaper than Cromolin, but they are not as easy to use or as effective. I suggest experimenting before you run out and buy Cromolin, but if you like what you hear, Cromolin is a worthwhile next step.
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