DESCRIPTION
The Shure Power Master is a solid state booster power
amplifier capable of delivering 100 watts RMS to an 8-ohm
load. It has been designed specifically for use in conjunc-
tion with the Shure VA300-C and VA302-C Series Vocal
Master Amplifiers.
When used as a booster amplifier in conjunction with
the Shure Vocal Master Amplifier, the Power Master will
effectively increase area coverage, provide higher sound
levels and increase reserve power. Several Power Master
Amplifiers may be interconnected to provide even greater
power when required. This unit is ideally suited for use in
theatres, auditoriums, stadiums, college field houses, hotel
ballrooms, convention halls and wherever maximum cover-
age with reserve power is required.
Silicon transistors and similar solid-state devices are
used throughout the unit. The circuitry design protects the
solid-state components and eliminates the need for special
operating precautions. All components are of the highest
quality and are operated well within their respective tol-
erances to assure maximum stability under normal use
conditions.
The PM300 is listed by Underwriters’ Laboratories, Inc.,
and CSA Testing Laboratories listed as certified.
P M 3 0 0 S e r i e s Power Master
EQUIPMENT DESIGNED FOR USE WITH THE PM300
SERIES POWER MASTER AMPLIFIERS
VA300-C
Vocal Master Console
VA302-C
Vocal Master Console
VA302E-C
Vocal Master Console
VA302E6-C
Vocal Master Console
VA300-S
Vocal Master Speaker Column
VA301-S
Vocal Master Monitor Speaker
P300R
Rack Panel Mount Accessory
GUARANTEE:
This Shure product is guaranteed in normal
use to be free from electrical and mechanical defects for a
period of one year from the date of purchase. Please retain
proof of purchase date. This guarantee includes all parts
and labor.
SHIPPING INSTRUCTIONS:
Carefully repack the unit and
return it prepaid to the factory. If outside the United
States, return the unit to your authorized Shure Service
Center for repair. The unit will be returned to you prepaid.
SERVICE:
If information or service should be required,
contact your local Shure Vocal Master dealer explaining
your difficulty in detail. In addition, the Shure factory
service department will be ready to assist you immedi-
ately upon request.
Operating Instructions
Input Connections:
Two parallel-wired input connectors are provided on the
rear panel of the Power Master. These connectors are
standard phone jacks (J1 and J2).
The Power Master may be driven to full rated output, to
an 8-ohm load, by any control-center amplifier, preampli-
fier, or microphone mixer which is capable of delivering
one volt across a 40,000-ohm load.
When using a Shure VA300-C or VA302 Series Vocal
Master Console as the control amplifier, connect the cable
supplied with the Power Master to the jack marked “To
Tape Recorder” on the VA300-C,* or to the jack marked
“Aux. Hi Level Output” on the VA302 Series Console, con-
nect the other end of the cable to one of the jacks marked
“High Impedance Parallel Inputs” on the Power Master.
Since the two input jacks of the Power Master are wired
in parallel, one jack may be used as an auxiliary, high level,
output to feed the signal to another Power Master or other
booster amplifier. Tape recorders may also be fed from
one of the input jacks of the Power Master to the recorder’s
high impedance auxiliary input. (When used in this man-
ner, the inputs are serving as a junction or “Y” connector
for the Power Master source.)
Additional Power Master Amplifiers may be added to the
system by interconnection from an input jack on one Power
Master to an input jack on another Power Master.
When used in conjunction with a Shure VA300-C or
VA302 Series Vocal Master Console, a setting of approxi-
mately “7” on the volume control (M6) of the Power Master
will provide equal output from the Vocal Master Console
and the Power Master when each is connected to equiva-
lent speaker loads.
Up
to a total of 15m (50 ft) of single conductor, shielded,
low capacitance cable (such as Belden #8401, 8410, or
8411) may be used to interconnect the Power Master
Amplifiers and the preamplifier. Where longer cable
lengths are required, it is suggested that the Power Mas-
ter Amplifiers be driven by a 600-ohm line from a mixer
or control center amplifier, such as the Shure M67 or
M63, to avoid high frequency signal loss.
Output Connections:
Two parallel-wired output connectors are provided on
the rear panel of the Power Master. These connectors are
standard phone jacks (J3 and J4).
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 dam-
age to the speakers or amplifier will occur, but thermal
shutoff of the amplifier may result. NOTE: With the am-
plifier driven at or near full power, pilot lamp will dim
or vary in brightness; this is a normal condition.
It should be noted that various speaker loads will affect
the output power of the amplifier. See Figure 3, Page 4 to
determine amplifier output power for the given speaker
load.
WARNING:
Do not interconnect the speaker
output
jacks
or the speaker cables between two Power Master
Amplifiers or the Power Master and any other ampli-
fier. This may result in damage to one or both ampli-
fiers, and is not covered by the Guarantee.
*NOTE: Although most VA300-C Vocal Master Consoles have a “phone-
type” “To Tape Recorder” jack, a limited number of early pro-
duction Consoles have a “phono-type” jack for this function.
If an early Vocal Master Console is used, an adapter (such as
the Switchcraft No. 336A) should be added, or one end of the
connecting cable rewired with a phono plug (such as a Switch-
craft No. 3502).
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