Duo-Art Vacuum Numbers
By Pete Knobloch
[ Ed. Note: Pete sent a letter earlier with numeric data, which I
[ assume is to be replaced with this most recent letter, therefore
[ I'll publish only this one. As with previous long lists of
[ data (i.e., lists of music rolls) this material will usually be
[ placed at the end of the Digest.
[
[ Please re-submit anything from the earlier letter, Pete, which
[ should accompany the data below. -- Robbie
I'm finally posting numbers on my Duo-Art Regulator that has been adjusted per the specifications. I don't know if these numbers are normal, higher, or lower than what they should be. Only that they are what my regulator seems to be putting out.
1) Both the Accompaniment and Theme distances were adjusted to compress the specified 1/2, 1/4, 1/8, and 1/16 inch. This was done using a Dial Gauge which read distances up to 1/2 inch. A wire with a hook was connected to the end of the Gauge. The hook was placed around the connecting wire rode which links the accordion pneumatic to the wood linkage arm located at the top of the regulator. A small holding rack was used above the regulator to steady the dial gauge and vacuum was applied to each section of the accordion pneumatic. This pulls down the wire on the gauge which shows how far the accordion dropped.
Note: The pull down wire has to be positioned directly above the center of the accordion.
2) The spill valve was adjusted to competely shut OFF when level #10 was seen on either the Accompaniment or the Theme. A thick piece of muffler felt was then rolled up, with a 1/4 inch hole in the center, and stuffed into the spill hole.
3) The Crash valve was adjusted to open at level #15. It was disabled when taking the initial readings.
4) The large pulley was placed on the motor. The pump speed was 112 RPM with a light load. The motor speed would slow down a little as more vacuum is called for.
Accompaniment Distance (Inches)
#1 - .0625 (1/16)
#2 - .125 (1/8)
#4 - .25 (1/4)
#8 - .5 (1/2)
Theme (Solo) Distance (Inches)
#1 - .0625 (1/16)
#2 - .125 (1/8)
#4 - .25 (1/4)
#8 - .5 (1/2)
Accompaniment Vacuum (Inches of Water)
#0 - 5.0
#1 - 6.5
#2 - 8.2
#3 - 10.6
#4 - 12.2
#5 - 13.7
#6 - 15.2
#7 - 17.0
#8 - 18.5
#9 - 19.5
#10 - 21.5
#11 - 23.2
#12 - 25.6
#13 - 29.5
#14 - 32.2
#15 - 32.2
Note: Level #14 and #15 are the same because the regulator is completely compressed. Tightening the spring some more should fix this.
Theme Vacuum (Inches of Water)
#0 - 5.5
#1 - 6.5
#2 - 9.0
#3 - 12.5
#4 - 14.6
#5 - 17.2
#6 - 20.4
#7 - 23.0
#8 - 26.0
#9 - 29.0
#10 - 33.2
#11 - 35.0
#12 - 36.7
#13 - 39.0
#14 - 42.2
#15 - 44.0
"Crash" measures 70 inches when connected and dynamic level #15 is reached.
The piano is playing at 97 dB when playing "American In Paris".
I changed the motor pulley to run at 90 RPM and reran the same test. All of the numbers shifted down slightly with the exception of the 0 adjust numbers. The #15 level vacuum levels shifted down to 31.2 and 41.5 and a crash vacuum of 58 inches of water. The piano plays at 95 dB. maximum under this condition.
I am hearing a distinct difference in many of the music played. There is defiantly more separation between the Accompaniment and the Theme (Solo) playing. I never had it adjusted at such a large separation when adjusting the piano by ear (no vacuum gauge).
There is a pronounced difference in how rapidly the volume levels can change, and they do. There is defiantly a big difference in how the piano sounds. The piano sounds (and feels like) wants to take off. You can feel the piano move when the keys are about to hit hard. The only drawback is that it would be nice to sit in the same room when my 6'5" Steinway is playing.
I have never liked playing the piano in the "Soft" mode and it is not an option for me. What this does is to move the hammer rail up closer to the strings, and it places a 2nd regulator (called the Primary Regulator "Unit C") between the pump and the main Expression unit. It does lower the volume but kills almost all the louder expression levels. It would be nice to get the best of both worlds, wouldn't it?
Do these numbers that I am posting seem to be OK or are there other problems?
Pete Knobloch |
(Message sent Wed 4 Sep 1996, 14:27:53 GMT, from time zone GMT-0400.) |
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