wondered if anyone had seen this article on volume enhancement and thought about trying a diy version. http://www.homecinemachoice.com/new...emachoice.com/cgi-bin/displaynews.php?id=5908 From my chemistry background I have had a look around and there appear to be a few alternatives, activated carbon does indeed have the largest surface area of most adsorbants, but this is not used to best effect at atmospheric pressures. Zeolites and silica offer greater surface area and faster adsorbtion rates around atmospheric pressure than charcoal - a fact not mentioned in the associated patent after a very quick look on a friday afternoon at work. I may give this a go when I can get some adsorbants from work (weeks holiday at the moment), but a 3x increase in effective volume seems well worth the effort, especially for sub projects. Any ideas on how to approach this would be welcomed?? I may have to invest in a spl meter and experiment . Kev.