<html> <body> Dean, I should have qualified further.  I was not thinking of stabilizing the tuning (which it does even better with top and bottom covers) but of stabilizing the action.  The addition of a stringcover extends the conditioned environment into the action cavity.  Admittedly it is not as well conditioned as the underside of the board but the difference in regulation stability experienced after adding a stringcover is like that of night and day.   I suppose it might be less noticeable on a new Kawai with the Millennium action... Andrew Anderson At 04:16 PM 2/20/2008, you wrote: <blockquote type=cite class=cite cite=""> >>A DC system really can't be effective in a grand without a string-cover.   I have years of anecdotal evidence on scores of installations that say otherwise. Perhaps a string cover increases their effectiveness, but on many of my installations I don’t know how. I’m talking about pianos that had +/- 25 cent seasonal variation that went to +/- 2. Dean Dean May             cell 812.239.3359 PianoRebuilders.com   812.235.5272 Terre Haute IN  47802   <hr> <div align="center"></div> From: pianotech-bounces@ptg.org [<a href="mailto:pianotech-bounces@ptg.org" eudora="autourl"> mailto:pianotech-bounces@ptg.org</a>] On Behalf Of Andrew and Rebeca Anderson Sent: Sunday, February 17, 2008 6:43 PM To: Pianotech List Subject: Re: Whole room humidity control better than Dampp Chaser. ( Right?)   A DC system really can't be effective in a grand without a string-cover.  Even then it doesn't really help the front key-pins.  An undercover is recommended if the place has forced air heating/conditioning. My wife's concert grand wouldn't stabilize until I made both additions above. Andew Anderson </blockquote></body> </html>