Duo-Art Vacuum Measurements
By Pete Knobloch
I received the vacuum gauge and was relieved that the 0 adjust was setting at about 4.5 inches on the accompaniment setting. I thought it might be much higher because of problems in the valves as people had suggested earlier.
Because of my playing with the accordion distances the night before, I changed the Theme pneumatic distances so that it would more closely track the accompaniment accordion. At level #15, the two levels were 20 inches and 30 inches which was to great a difference.
Before proceeding, I checked for leaks between the Accompaniment and Theme sections due to bad leather in the 1 way valves. Changing the Theme regulator made no changes to the 0 setting of 5 inches on the Accompaniment.
I believe the atmosphere intake or "spill" hole is in great shape. A square piece of muffler felt is pushed into the hole with a 1\4-inch hole punched in the center and glued into place. All 4 corners of the felt remain unglued and not trimmed. 2 of the felt corners are stuffed into the center of the spill hole which decreases the flow of air even more. This allows adjustments to be made to how much air enters into the spill hole.
Adjustments before testing: I took vacuum readings on the accompaniment side at level #1, #2, #4, and #8 and made changes to the Theme side to match the vacuum levels (plus some) so there wouldn't be such a big difference. I didn't measure distances at this time. I just turned the nuts on the accordions so the vacuum readings were close.
I then took the following readings at the different levels #0 to #15. The crash valve was disabled in these tests because when it opens up, the vacuum level would jump up to 40 or more inches.
* Values used to somewhat balance the vacuum levels.
Accompaniment Vacuum numbers (Inches of Water).
#0 - 5
#1 - 5.5 *
#2 - 6.3 *
#3 - 7.5
#4 - 9 *
#5 - 10
#6 - 11
#7 - 12
#8 - 13 *
#9 - 14.5
#10- 15.5
#11- 16.5
#12- 17.5
#13- 18.5
#14- 19.5
#15- 20
Theme Vacuum numbers (Inches of Water).
#0 - 5.5
#1 - 5.9 *
#2 - 6.6 *
#3 - 7.9
#4 - 10.2 *
#5 - 10.8
#6 - 11.2
#7 - 12.3
#8 - 13.5 *
#9 - 14.8
#10- 15.7
#11- 16.5
#12- 17.9
#13- 18.7
#14- 19.5
#15- 20.5
After taking these readings, I removed the regulator and measured the distance that each accordion was compressing.
Accompaniment Accordion setting (inches)
#1 - .042
#2 - .082
#4 - .178
#8 - .365
Theme Accordion setting (inches)
#1 - .054
#2 - .091
#4 - .155
#8 - .305
The Accordion distances are much smaller than the specified .0625, .125, .25, and .5 inches.
Is 20 inches of water for a piano playing at intensity #15 normal? It is still playing very loud. I just found a sound meter so I can give a somewhat quantifiable loudness value later.
|
(Message sent Thu 22 Aug 1996, 15:09:45 GMT, from time zone GMT-0400.) |
|
|
Mechanical
Music Digest™ Archives
