Volume adjuster for air operated musical instruments

A volume adjuster for an air operated instrument such as an electric organ includes a shutter valve which can be slid across the delivery duct of the instrument blower by means of a slider movable in a linear guide on a flat keyboard surround so as to permit fine adjustment of the volume.

The present invention relates to a volume adjuster for air operated musical 
instruments such as electric organs and the like having a body equipped 
with a keyboard, a reed chamber extending below and parallel to the 
keyboard and a blower arranged to supply air to the reed chamber. 
It is known to provide for adjustment of the volume of the sounds generated 
by an electric organ of the aforesaid type by controlling the air delivery 
from the blower, using a control mechanism acting upon a valve in a 
delivery port connected to the outlet of the blower. Such a mechanism 
generally includes a number of levers and mechanical linkages operable by 
a control located outside of the body of the instrument and generally 
positioned out of the plane of the instrument keyboard. 
Such a volume adjustment mechanism, although widely used, has various 
disadvantages, among which the most serious is the inevitable inertia with 
which the levers and mechanical linkages of the mechanism oppose any 
movement required to effect operation of the valve controlling the 
delivery of the blower. A further disadvantage is the difficulty of 
regulating precisely the degree of opening or closing of the valve, 
particularly after the organ has been in use for some time, in consequence 
of which the volume adjustment may in practice have only two settings, 
namely full volume and minimum volume. A further disadvantage is that 
because of the number of levers and connections in the mechanism, failure 
can easily occur due to breakages, disconnections or distortions of the 
levers or linkages. 
Yet another not inconsiderable disadvantage is the laborious and hence 
uneconomical construction and assembly of a volume adjustment mechanism of 
the mechanical type. 
The main object of the present invention is to provide a volume adjuster 
for air-operated musical instruments, for example electric organs and the 
like, having structural and functional characteristics which avoid the 
above-mentioned disadvantages of the prior art volume adjustment 
mechanism, as well as being simple, reliable and easily operated. 
According to the present invention there is provided a volume adjuster for 
air-operated musical instruments, such as electric organs and the like, 
having a main body equipped with a keyboard, a reed chamber extending 
below, and parallel to the keyboard and a blower arranged to supply air to 
the reed chamber through a delivery duct, characterised in that the volume 
adjuster includes an elongate slider in a rectilinear guide in a flat 
keyboard surround, and a valve member affixed to the said slider and 
movable thereby transversely across the said delivery duct between 
positions of minimum and maximum obstruction of air flow through the said 
delivery duct.

Referring to the drawings, there is shown part of the main body 1 of an 
electric organ equipped with a keyboard 2, a reed chamber 3 extending 
below and parallel to the keyboard 2, and a further chamber 4 within the 
said body 1 spaced laterally from and disposed above the reed chamber 3. 
The chamber 4 has a bottom wall 4a which is coplanar with a flat keyboard 
surround 13. Within the chamber 3 there is arranged a centrifugal blower 5 
driven by an electric motor 6. The blower 5 has a delivery duct 7 which 
communicates with the reed chamber 3 via a vertical duct 8 made in the 
said main body 1 and via an opening 9 formed in an end wall of said 
chamber 3. 
Within the reed chamber 3 there are formed, in a known way, a number of 
resonance chambers 10, with each of which a resiliently flexible reed 11 
cooperates. Each resonance chamber 10 communicates with the outside of the 
chamber 3 through a respective outlet aperture 12 in an upper wall 3a of 
the aforesaid reed chamber 3. The keyboard 2 comprises a number of 
conventionally mounted keys 2a which individually control valves (not 
shown) which normally close the respective outlet apertures 12. Each valve 
can be opened by depression of the respective key 2a to permit air flow 
from the reed chamber 3 through the respective resonance chamber 10, 
causing vibration of the associated reed 11. 
The bottom wall 4a of the chamber 4 is formed with a groove 14 extending 
laterally with respect to the keyboard 2 and parallel to the keys 2a. An 
elongate slider 15 is slidable in the said groove 14 and is formed with a 
finger-operable key 16 at one end which is adjacent the flat keyboard 
surround 13 and accessible therefrom. The other end of the slider 15 
carries a valve shutter plate 17 which passes through slots 7a, 7b made in 
opposite walls of the blower delivery duct 7. The valve shutter plate 17 
has a shape and transverse dimensions corresponding to the shape and 
transverse dimensions of the said delivery duct 7, whilst the length of 
the slider 15 is such it can be moved from a position in which the shutter 
plate 17 does not interfere with air flow through the delivery duct 7 
(FIG. 3) to a position in which the shutter plate 17 completely closes the 
said delivery duct 7. 
Upon the flat keyboard surround 13 there is affixed by cutting, sticking or 
other means, a graduated scale 18 in a position alongside the groove 14. 
The finger-key 16 of the slide 15 carries a mark of indicium 16a which 
cooperates with the graduated scale 18. 
By movement of the slider 15 and thus of the valve shutter plate 17 it is 
possible to shut off completely the air delivery from the blower 5, or to 
regulate the air flow through the blower delivery duct 7, according to the 
desired volume of the sound generated by the electric organ. The degree of 
shutting-off of the duct 7 by the valve shutter plate 17 can be pre-fixed 
and pre-selected, by bringing the mark 16a on the key 16 into coincidence 
with a pre-fixed and pre-selected mark on the graduated scale 18.