Mechanical Music Digest  Archives
You Are Not Logged In Login/Get New Account
Please Log In. Accounts are free!
Logged In users are granted additional features including a more current version of the Archives and a simplified process for submitting articles.
Home Archives Calendar Gallery Store Links Info
MMD > Archives > October 1999 > 1999.10.27 > 13Prev  Next

Duo-Art Repetition Problem
By Craig Brougher

In the last letter of this thread, Robbie was wondering,

>[ Mario, could you connect a water-tube manometer to the player, and
>[ compare the suction data, of bass vs. treble?  This data will help
>[ to determine if the problem is pneumatic or mechanical.

The reason I didn't mention pressures is because that is almost never
the case.  Weak valves are very seldom seen in just one section of the
stack, and not throughout.  Mechanical resistance is more often seen
in one section than another, but that is found fairly easily underneath
the piano at the stack by just feeling the differences.  Lost motion
is also easy to detect by raising the striker and feeling it touch the

When a problem with a weak section arises, it is almost always in
connection with roll play.  Mario said they were the same notes which
were weak on the test roll.  That gave me the clue-- probably theme
(solo).  But I should have asked also if it was during accompaniment
or theme tests, or both? If it was primarily at low intensities?
And how the chord build-up tests performed at low intensities?

When a Duo-Art plays, the intensity of the note at the lower pressures
is dependent upon how many notes play at one time.  The dependency
decreases as the pressure is raised.  Everything is controlled by the
roll, so performance is determined entirely by the roll.  If the
weakness is the expression box, then a manometer would probably never
catch it because the time required to react would be during a faint
(low pressure) theme accent perforation.

However, you can test one note at a time by removing the sustain pedal
control tube, thus raising the dampers, and running the single note
test with the expression on the full length of the note compass,
slowly.  Each note should play evenly at zero intensity.  Do the same
test again by first pulling off the bass theme tube at the theme valve
box, and then the next run, pull off the treble theme TB tube, same
box, then remove both.  The themed side of the stack in each case
should be very slightly louder.  When you remove both tubes from the
tracker bar, both sides should be the same.  If, for some reason, your
treble side of the stack is not louder but the bass is, the problem
is definitely in the expression box.

Craig Brougher

(Message sent Wed 27 Oct 1999, 10:46:23 GMT, from time zone GMT-0500.)

Key Words in Subject:  Duo-Art, Problem, Repetition

Home    Archives    Calendar    Gallery    Store    Links    Info   

Enter text below to search the MMD Website with Google

CONTACT FORM: Click HERE to write to the editor, or to post a message about Mechanical Musical Instruments to the MMD

Unless otherwise noted, all opinions are those of the individual authors and may not represent those of the editors. Compilation copyright 1995-2024 by Jody Kravitz.

Please read our Republication Policy before copying information from or creating links to this web site.

Click HERE to contact the webmaster regarding problems with the website.

Please support publication of the MMD by donating online

Please Support Publication of the MMD with your Generous Donation

Pay via PayPal

No PayPal account required

Translate This Page