Selective Vibrato
Figure 7, used in early selective vibrato consoles, also has a 25 section line.
To obtain correct phasing of the vibrato and no vibrato channels, the first
part of the line is used for #1 vibrato. The vibrato switch has no off position,
and three vibrato chorus positions (Cl, C2 and C3) are included in it as well as the
three vibrato positions (VI, V2 and V3). The vibrato effect is turned on and off
each manual separately by means of vibrato swell and vibrato great tablets on the
manual assembly.
The preamplifier used with this circuit, has two separate channels into which
signals from the vibrato great and vibrato swell tablets are fed. The vibrato
signal goes through a preliminary amplifier, through the vibrato system, and then
into additional stages of amplification. The no vibrato signal also has a
preliminary amplifier, but bypasses the vibrato system and goes directly into the
additional amplifier stages. The preamplifier alone is shown in figures 20 and 20A
of Section 16, Part 2.
Line with Resistor Dividers
The vibrato line box of figure 8 employs resistors for voltage dividers at the
compensated pick-off points instead of condensers. Otherwise this circuit is
identical with that of figure 7. The line boxes of these two types are
interchangeable, and the scanners and switches are identical.
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