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Equipment Review

June 1999

Cromolin VC Damping Material

by Marc Mickelson

cromolin.jpg (5686 bytes)


Review at a Glance
Sound Greater foreground and background detail as well as a better sense of the relationship between the two; space "is more a part of the entire presentation" and "the soundstage is portrayed with greater precision."
Features Constrained-layer damping material; comes in pre-cut strips that are easy to affix to equipment.
Use Easy to determine where to place the strips; permanent; custom sizes available.
Value There are cheaper ways to damp equipment, but Cromolin is simple to use and more effective.

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 there’s no way to test the theory. I’ve 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, you’ll 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 there’s no worry because the protective film is still in place (and you probably won't see the Cromolin anyway). Once you’ve 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 won’t 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 that’s 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 Brown’s fine Further In [Red House RHR CD 88] will do. There’s a noticeable increase in clarity, and this is due to everything being a bit more there. The warbling tones of Brown’s voice on "Where is Maria" sound all the more vivid, as do the cymbals throughout Time Out.

dB's Take

I went Cromolin-ing one night. First location: a 4" x 6" metal plate behind the terminals and tweeter/midrange controls of my speakers -- it has a papery resonance. There is an open area on each plate that's 1" square, so I cut 1"-square pieces of Cromolin and stuck one on each plate. There was a subtle improvement in the smoothness and roundness of female vocals, sax, trumpet and other sounds within that frequency range. It was like a little rough edge was removed.

Next I went to work on the plastic cabinet of the video monitor that is nearly permanently ensconced between the two main speakers. This would be an interesting test, treating a part of my listening environment. I placed two full-size Cromolin strips at the 1/3 points on the tapered side panels, the largest flat panels in the cabinet. Another listen revealed an audible clearing-up of the entire soundstage. In addition, some bass energy that apparently had been missing in action appeared for the first time, revealing bass detail that was either missing or not as apparent without the Cromolin strips. I applied a 1" Cromolin square to the smallish flat rear panel of the monitor, which resonated quite noticeably on its own. This was another improvement in the same direction as the strips on the side, though not quite as great in magnitude. But it was enough to hear previously hidden metallic harmonics in sounds like bells and steel drums, which gave these sounds an improved sense of realism.

Next I applied some 3" pieces to the 1/3 points of the left and right side panels of the monitor. These are vertical panels to the left and right of the monitor screen, the flat (not tapered) sides of the monitor. This improvement was at least as large as applying the full-size Cromolin strips to the larger tapered side panels. The total improvement in clarity of the whole soundstage was now getting quite noticeable. Bass was not improving as much as the mids and highs, but there were some small gains down low.

That's where I stopped. This all took no more than 45 minutes, including the time to listen for changes in the soundfield after each application. I'd say this material is quite effective. It isn't inexpensive, but considering the price of the strips I used and the level of improvement system-wide, I'd say Cromolin offers very good value. It is what it is claimed to be: a constrained-layer damping material. There's no magic. It is an engineered product that works as designed -- without mystery. Just find things in your system that resonate and apply some Cromolin. It's hard to make a mistake with this stuff.

...Doug Blackburn

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, there’s 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 haven’t 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, it’s the single most potent damping material I’ve used. It’s also easy to affix inside (or outside) your component, and there is more than a bit of science behind it, so it’s 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.

...Marc Mickelson

Cromolin VC Damping Material
Price: $69.95 USD per package of three strips.

Media Access
2660 County Road D
Woodville, WI 54028
Phone: (800) 830-1575

E-mail: paul@mediaacc.com
Website: www.mediaacc.com

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