<HTML>          List           Although there are many reasons for the usually generous sustain times heard on Mason &Hamlins all this talk of rear duplexes got my attention the other day as I tuned one of my recently bellied Mason A's. All the backscale lenths in the plain wire are generous. I found the sustain very good in the K- ovtave as is usual for these pianos with decent boards.  I also note that the first 9 notes of the first capo section had  tuned duplexes corresponding to a 6th partial and the rest of the section double octaves. By the way this 1915 ish piano had very good duplex location as all the half round duplex/bearing blocks were very well in tune and all I simply used the original  position when it was rebuilt.     All this to say that the rear string lengths of the first nine notes were quite long. Starting at about 4 inches down to about three then back up to longer lengths again. Although these segments were fairly well in tune the greater attributing factor I believe is the long backscale lengths. Other contributing factors would be wide cases/boards, good scales (mostly), good bridge location in the center of the board etc.) (As a side noteRecent discussions on Mason a's very short bass backscale lengths didn't however in this case render the tone unacceptable by any means. Tail thinning helps greatly on these pianos with conventional belly's)   Finally the question. What are adequate backscale lengths  capable of giving  increased freedom/sustain. The lengths in this case are much longer than the average stwy. It seems like 3 to five inches on any piano(in the capo) would allow more bridge and board freedom.   If I removed the duplex on the average stwyL and changed nothing but the string lentghs.(forget the tuning) what would happen?      I'm looking for suggestions and expeience from whomever.            Thanks--Dale</HTML>