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MMD > Archives > November 1997 > 1997.11.17 > 09Prev  Next


Duo-Art Cross Valve
By Craig Brougher

It seems as though this subject has been the topic of debate for years,
so in Oct '86 and Jun '87 I wrote two articles in the Amica Bulletin
explaining, technically, how and why cross valves are not efficient or
desirable in any particular department.  In the article named, "The
Cross Valve, Was It A Plus?" I included a simple tester that about
anybody could make which takes any differences in gapping and valve
well turbulence between samples out of the question, and proves what
I've been saying, physically.

This absolute iron-clad test, that I have also demonstrated to Amicans
at a large meeting close to St. Louis that same year really stopped all
mouths as to whether I knew what I was talking about or not.  And I
opened it up to questions, once I had demonstrated everything I claim
about round-versus cross valves.  They're poorer in all respects.  I
respectfully suggest that Bob Taylor and others who still want to
believe things about the cross valve that is not true, read that
article in Terry Smythe's "Technicalities," Vol. V pp. 43-45.

I have restored Duo-Arts both ways, particularly if the owner did not
want them changed.  Either valve works well, and there is no difference
(initially) in the expression, sensitivity, repetition speed, or
anything else, because each valve is regulated for its particular valve
plate.  However, it might be interesting to know that the recent
Steinway concert grand restored by Mel Septon and manned by Jeffrey
Morgan during its recording session had round valve plates.  This fact
comes from the rebuilder who built the (longer) stack for Mel to
install.

As far as the ratio of valve clamping area versus pouch diameter is
concerned, Bob Taylor might consider the same question in regard to
literally dozens of other player piano valves whose ratios are even
less or very similar to the elder Duo-Art stack design.  If we were to
believe that pouch to valve ratio is responsible for "sluggish" valve
operation when changing out to round valve replacements, how is it then
that I, nor anyone else who understands how to make valves work well
have ever had the problem? I'm quite sure that Bob Taylor is not
tacitly suggesting by omission that I probably wouldn't recognize
sluggish valves.  I feel that he just didn't think to do it, since he
surely has heard my restorations in the homes of Amica, MBSI members,
and mutual friends who own my restored Duo-Arts, knowing that I have
always changed out cross valves without loss of performance or
complaint.

Craig Brougher


(Message sent Mon 17 Nov 1997, 13:39:44 GMT, from time zone GMT.)

Key Words in Subject:  Cross, Duo-Art, Valve

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