Department of the Army Technical Manual TM 10-751
Organist's Manual for Electronic Organ
AN/TNP-1
Department of the Army • December 1949
SECTION V
SPECIAL OPERATING TECHNIQUE
18. Combining Harmonic Drawbars
To understand the technique of combining harmonic drawbars, it is necessary to recognize that all interesting musical tones are combinations of a fundamental tone and a number of related tones called harmonics. Since altering the relative volumes of related tones alters the quality of the fundamental tone as well, groups of controls known as harmonic drawbars (see par. 4a (2) (a)) have been built into the electronic organ as means for combining and altering at will the relative volumes of fundamental tones and eight of the related harmonics of each.
a. DRAWBAR CONNECTIONS. Connections between harmonic drawbar groups and the playing keys of the two separate manuals are completed through the preset adjust keys, A# and B, on each manual (see par. 4a (1) (b)). The set of 2 nine drawbar groups to left of center controls the tone qualities for the upper manual; the set to right of center, for the lower manual. Preset adjust key A# connects its particular manual to the left nine-drawbar group of its set; adjust key B, to the right group of the set (see app. III).
b. DRAWBAR CHARACTERISTICS. Each group of draw-bars consists of nine independent drawbar controls representing a fundamental tone and eight related harmonics in a pattern that is the same for every individual playing key on the affected manual. (see fig. 5).
c. TESTING DRAWBAR CHARACTERISTICS. Test the effect of individual drawbars using the following procedures:
(1) Press down adjust key A# on both upper: and lower manuals, thus closing contacts permitting use of the left draw bar group for each manual.
(2) Hold down middle C on the upper manual and slowly pull drawbar No. 3 of the left drawbar group through each of its eight settings, noting volume increase with each change of setting. Release middle C but leave drawbar No. 3 all the way out.
(3) Play on the upper manual the first of the sequence of notes indicated in figure 5. Pull drawbar No. 1, serving the lower manual, all the way out and play middle C on the lower manual, noting that the tone, an octave lower than middle C, sounds on the lower as well as on the upper manual. Push drawbar No. 1 all the way in.
(4) Play on the upper manual the second of the sequence of notes indicated in figure 5. Pull drawbar No. 2, serving the lower manual, all the- way out and play middle C, noting that the tone, a fifth above middle C, sounds on the lower as well as on the upper manual. Push drawbar No. 2 all the way in.
(5) Repeat the general procedure above, playing on the upper manual the remaining seven notes of the sequence, alternating each note with middle C played on the lower manual using drawbars No. 3 through No. 9 in, sequence. Each time middle C is played on the lower manual the tone sounded is the same as that played on the upper manual and is consistent with the characteristic tone indicated in figure 5 for that particular drawbar.
d. DESIGNATING DRAWBAR COMBINATIONS. Since the setting for each harmonic drawbar must lie between 0, its OFF position, and 8, its full volume setting, the relative setting of all nine drawbars may be represented by a nine-digit number, each digit between 0 and 8, inclusive. Thus the designated drawbar combination, 00 6633 200, represents a volume setting of 0 for drawbars 1,2, 8, and 9; of 6 for drawbars 3 and 4; of 3 for drawbars 5 and 6; and of 2 for drawbar 7.
Note. Throughout the remainder of this manual drawbar settings will be designated as illustrated above. Pedal settings will be represented by two-digit numbers, as 3 1, representing in like manner the volume setting for each of the two pedal drawbars.
e. OPERATING DRAWBARS. In order to use drawbar groups, proceed in the following manner:
- (1) Select desired harmonic drawbar combination (see app. IV).
- (2) Pull each drawbar to desired setting, using tips of thumb and index finger to grip drawbars.
- (3) Depress tone selection adjust keys connecting prepared drawbar group to its particular manual (see a above; app. III).
- (4) Operate organ manuals according to procedures established in paragraphs 12 through 16.
19. Obtaining percussive effects
The electronic organ is a nonpercussive instrument and its electrically produced tones immediately cease when playing keys are released. The organ swell pedal, however, provides an excellent means for obtaining unusual percussive effects.
a. CHIME EFFECTS. To obtain chime effects, proceed in the following manner:
- (1) Open wide the tremolant and swell pedal controls.
- (2) Set drawbars according to one of the following designations: 00 1600 000; 00 2700 000; 00 3800 000 (see par. 18d).
- (3) Depress the desired manual keys. As they sound, quickly reduce the swell pedal to the halfway position to produce the effect of a rapidly dying away hammer blow. Then, with manual keys still down, slowly reduce the swell pedal the remainder of the way to produce the effect of a dying away chime tone.
- (4) Release manual keys and open the swell pedal wide to prepare for the next chime.
b. VIBRA-HARP EFFECTS. To obtain vibra-harp effects, proceed in the following manner:
- (1) Open wide the tremolant and swell pedal controls.
- (2) Set drawbars according to one of the following designations: 00 1600 000; 00 2700 000; 00 3800 000; 00 5000 000; 00 6000 000.
- (3) Use the pedal technique designated for chime effects (see a (3) above), sustaining successive notes of arpeggios or broken chords but slowly reducing the swell pedal setting during the successive notes.
c. CELESTE-HARP EFFECTS. To obtain celeste-harp effects, proceed in the following manner:
- (1) Close the tremolant control and open wide the swell pedal control.
- (2) Set drawbars according to one of the following designations: 00 1600 000; 00 2700 000; 00 3800 000; 00 1800 000; 00 2800 000.
- (3) Use the pedal technique designated in a (3) above.