Shure Vocal Master VA 300 Operating & Service Manual Download

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Input Connections:

Six individual input connectors are provided on the rear

panel of the Console. These connectors are standard 1/4 inch

phone jacks (22). The Console is designed to operate with any

high quality dynamic or ribbon-type high impedance micro-
phone. High impedance microphone cables should be limited

to a maximum length of 6m (20 ft) to avoid high frequency’
signal loss and to reduce the possibility of hum and noise

pickup in the cables. Standard 1/4 inch phone plugs should be

attached to the “Console end” of the microphone cables; the

center conductor of the cable should be attached to the “tip”

terminal of the phone plug and the shield of the cable should

be connected to the “sleeve” terminal. For low impedance

microphones, see page 10.

For additional microphone inputs, see page 10. For connec-

tions from electrified musical instruments, see page 10. For

connections to play back a tape, see page 9. For connections
to a phonograph, see page 10.

Six individual input level adjustment switches (21) are lo-

cated above the six input jacks. These screwdriver-slot slide

switches allow the microphone input signal to be attenuated

(reduced) before entering the preamplifier.

With the switch in the “Mic.” position, the signal from the

microphone is switched directly to the preamplifier of the

channel. With the switch in the “Inst.” position, the signal

from the microphone is attenuated by 11 db before entering

the preamplifier.

This feature may be useful when working the microphones

very close to the performer’s lips as with “hard rock” vocalists,

who may produce signals in excess of the clipping level of the

preamplifiers; in such an instance, the attenuator will generally

eliminate the distortion which would otherwise occur.

Output Connections:

Two parallel-wired “Speaker” output connectors are pro-

vided on the rear panel of the VA300. These connectors are

standard phone jacks (15).

Full rated output of the amplifier is obtained when the

speaker load is 8 ohms (two VA300-S Speakers). Speaker loads

of less than 5.3 ohms (more than three VA300-S Speakers)
should not be used with this amplifier. No damage to the

speakers or amplifier will occur, but thermal shutoff of the

amplifier may result.

It should be noted that various speaker loads will affect the

o u t p u t p o w e r o f t h e a m p l i f i e r . S e e F i g u r e 3 , P a g e 7 t o

determine amplifier output power for the given speaker load.

WARNING: Do not interconnect the speaker output jacks

or the speaker cables between two VA300 Amplifiers

or the VA300 and any other amplifier. This may result

in damage to one or both amplifiers, and is not covered

by the Guarantee.

The VA300 does not use speaker output matching trans-

formers and thus avoids the distortion, power loss and added

weight inherent in such transformers. The speaker output vol-

tage is 28.3 volts, to an 8-ohm load, for 100 watts. This allows

long speaker lines with wiring practices consistent with those

used for 25-volt speaker lines.

Up to 30m (100 ft) of #18 gauge two-conductor cable

(such as Belden #8452, 8478, 8460, or 8461) may be used to

c o n n e c t f r o m t h e V A 3 0 0 - C t o e a c h 1 6 - o h m ( V A 3 0 0 - S )

speaker. Greater cable lengths require heavier gauge wire to
avoid appreciable power loss in the speaker cable. For 30 to
51m (100 to 170 ft), use #16 gauge; 51 to 81m (170 to 270
ft), use #14 gauge; and 81 to 128m (270 to 425 ft), use #12
gauge wire. To maximize the power to each speaker, a separate
cable should be used to connect each speaker to the VA300.

Speakers:

Selection of speakers for use in a vocal music system is most

critical. The factors which most significantly contribute to an
outstanding vocal speaker system are correct frequency range,

distortion-free reproduction, and enough sound power to fully
penetrate the audience area.

The Shure VA300-S Speaker Column has been designed to

provide all of these features. It is recommended that VA300-S

Speaker Columns be used in pairs, each column having a
nominal impedance of 16 ohms, which provides an impedance
of 8 ohms when two are used. Each column utilizes two

special IO-inch speakers and four special 8-inch speakers, and

has a total speaker cone area of 2,310cm² (358 in²) per
c o l u m n . T h e V A 3 0 0 - S S p e a k e r C o l u m n d e l i v e r s v i r t u a l l y

uniform penetrating power over a 140° angle in the horizontal
plane and a 65° angle in the vertical plane. The rear-ported

enclosure of the VA300-S contributes to its highly directional

pattern,

which is critical in achieving maximum audience

penetration and reduction of feedback.

The Shure VA301-S Speaker Column is intended primarily

for use as an “on-stage monitor.” While this speaker meets all

of the criteria for an excellent vocal system speaker, its area of

coverage is more localized than that of the VA300-S. The

nominal impedance of the VA301-S is 32 ohms, so that when
used in conjunction with two VA300-S Speaker Columns, the

total system impedance becomes 6.4 ohms. An integral volume
control on the VA301-S permits its use on-stage as a monitor
at the highest possible sound level without feedback.

The following list shows various speaker combinations and

the resultant impedance loads which are suitable for use with

the VA300 Vocal Master:

QUANTITY and SPEAKER MODEL

1 VA300-S

2 VA300-S

3 VA300-S

1 VA301-S

2 VA301-S

3 VA301-S

4 VA301-S

5 VA301-S