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Phonographs:
To connect a” phonograph having a magnetic cartridge, and
no preamplifier, to the VA300, attach a cable from the
phonograph output to one of the six Input jacks on the
Console. Set that channel’s Input Attenuator Switch to the
“Mic.“ position. Set the Treble control for that channel at
9:00 o’clock and the Bass control at 3:00 o’clock to provide
approximate R.I.A.A. phono equalization. Use the individual
channel Volume Control to adjust the volume from the phono-
graph.
To connect a phonograph having a magnetic cartridge, and a
phono preamplifier, to the VA300, connect a cable from the
phono-preamplifier output to one of the six individual channel
input jacks on the Console. Set that channel’s Input
Attenuator Switch to “Inst.” Set the Treble and Bass controls
for that channel to 12:00 o’clock. Use the individual channel
Volume Control in conjunction with the phonograph’s level
control, to adjust the volume.
For stereo phonographs see the section on Stereo
Operation.
Musical Instruments:
Most electrified musical instruments may be amplified
through the VA300 with great effectiveness. Generally the
output of electrified instruments is greater than the output of
a dynamic microphone and therefore the individual channel
Input Attenuator Switches should be set to “Inst.” to avoid
exceeding the preamplifier input clipping level. See the section
on Input Connections for further information.
Electrified instruments may then be connected directly to
the individual Input jack. If low volume occurs, return the
Input Attenuator Switch to the “Mic.” position.
Low Impedance Microphones:
Low impedance microphones may be used with the VA300
when accessory matching transformers (Shure Model A95UF)
are added to the Input jacks (22).
The Shure Model A95UF Line Matching Transformer is
terminated at the high impedance end with a locking-type
phone plug for direct connection to the input jack; the low
impedance end is terminated with a Cannon-type, 3-pin female
connector.
The main advantage of low impedance microphones is that
virtually unlimited cable lengths may be used, whereas high
impedance microphones require that cable length not exceed
6m (20 ft).
Low impedance microphones should be wired using low
capacitance, two-conductor, shielded cable (such as Belden
#8413, #8422). When wiring Cannon-type connectors,
the cable shield should be connected to Pin No. 1 and one of
the two conductors to Pin No. 2, the other conductor to Pin
No. 3. When using several microphones, consistency of cable
wiring should be followed to insure that all microphones are
“in phase.“
To test two microphones and their cables for proper
phasing, connect them to the VA300. Talk or sing into the
two microphones while holding them 8 to 10 cm (3 to 4 in.)
apart. The amplified sound from the Speaker Column will be
10
the same when talking directly into either microphone or
directly between them if they are in phase with each other. If
the sound drops drastically, or a dead spot is found when
talking between the two microphones, one of them, or their
cables, is out of phase.
To change the phase of the one microphone, or cable, inter-
change the conductors that are wired to Pins No. 2 and No. 3
of the Cannon connector. Test all the microphones and cables
this way to insure that they are all “in phase” with each other.
Additional Inputs Using a Mixer:
If additional microphone inputs are required, a microphone
mixer (such as a Shure M68 type) or a second Vocal Master
Console may be used.
When using a microphone mixer for the additional inputs,
connect the mixer High Impedance Mic. Output to one of the
Input jacks on the VA300 Console. The individual input
control on the channel, bass, treble, volume, and reverb,
provide master control over the mixer inputs. See Figure 5.
Figure 5
When reverb and external echo are not required, the mixer
may be connected to the Echo “To Output” jack. With this
arrangement the mixer Aux. High Level Output is connected
to the Console Echo “To Output” jack. See Figure 6.
Figure 6