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Set the controls on the second VA300 Console as follows:

A n t i f e e d b a c k   S w i t c h e s   t o   “ O u t , ”   M a s t e r   R e v e r b   S w i t c h

“Out,” Individual Volume Controls to “0,” and the Master
V o l u m e   t o   “ 5 . ”   A d j u s t   t h e   E c h o   “ G a i n ”   C o n t r o l   t o
approximately 1/3 rotation from the c.c.w. off position, and

use this control as a volume control to obtain the same

amplification level from both of the VA300 Consoles. Once

the Echo “Gain” Control is preset, the output of the second

V A 3 0 0   C o n s o l e   w i l l   “ f o l l o w ”   a l l   c o n t r o l   s e t t i n g s   o f   t h e

original VA300 Console. Small changes in amplification level

on the second VA300 Console can be made by adjusting its

Master Volume Control.

An additional VA300 Console, PM300 or tape recorder can

be connected to the “To Tape Recorder” jack on the second

VA300 Console.

Microphone Cuing:

Microphone “cuing” may be preset by using the individual

Reverb “In-Out” switches to reduce the volume of, or turn off

an unused individual microphone channel. This is useful when

it is desired to preset the individual volume controls but only

have one or two microphones “live” at a time. This allows

tighter control of feedback, or additional control to avoid

pickup from off-stage microphones.

Insert an unwired phone plug into the Echo “To Output”

Jack. With the individual Reverb switch in the “In” position,

the channel will operate normally. In the “Out” position, the

channel level is reduced or turned off. The level of the “Out”
or “Cued” channel is controlled by the “Echo Gain” control;

t u r n i n g   t h i s   c o n t r o l   f u l l y   c o u n t e r c l o c k w i s e   t u r n s   o f f   t h e

“Cued” channel. Returning the individual Reverb “In-Out”

switches to “In” restores the channel to the normal level.

For remote “Cuing” on and off, plug a foot switch into the

Echo “To Output” Jack on the VA300 Console. Turn the
“Echo Gain” control fully clockwise. With the foot switch in

the “On” position, the channels will operate normally. With
the foot switch “Off” those channels switched to individual

Reverb “Out” are turned completely off. This is useful for
remotely turning on and off preselected channels (Micro-

phones). The cable used with the foot switch should be limited
to 15m (50 ft) of low capacitance, single conductor, shielded
type (such as Belden #8401, #8410, #8411) to avoid high
frequency signal loss and to reduce the possibility of hum
pickup in the cables.

Stereo Operation:*

Stereo operation may obviously be obtained by using two

VA300 systems without any interconnections. If it is desired

to have one of the microphones connected to both systems,
simply use a “Y” connector on that microphone and feed its
signal to one Input on each Console. For making stereo tapes,

the “To Tape Recorder” jacks, one on each console, may now

be connected to the left and right Auxiliary Inputs, respec-

tively, on a stereo tape recorder.

Alternatively, stereo may be accomplished by using one

VA300 system and one PM300 with additional speakers. A

connection is made from the VA300 jack marked Echo “To

Input” to an input of the PM300. Those input channels of the

Console which are to be reproduced through the VA300

*   A s   a   g e n e r a l   r u l e   s t e r e o   s o u n d   r e i n f o r c e m e n t   o f   t h i s   t y p e

i s   q u i t e   a n n o y i n g   t o   l i s t e n   t o   a n d   i s   r e c o m m e n d e d   o n l y   f o r

special effects.

12

Console speakers will require that the individual channel

Reverb “ln-Out” switches be in the “In” position. The channels
on which the switches are in the “Out” position will be heard

at the speakers connected to the PM300. This may be used for

a special echo effect, like “throwing” a voice from the rear of

the room.

Stereo recordings may also be made using one VA300

Console and one PM300. One channel of the stereo tape

recorder would be fed from the Console jack marked “To
Tape Recorder;” the other channel would be fed from the

open input jack of the PM300. NOTE: Reverberation can be

added to only those channels that are being reproduced by the
speakers connected to the VA300 Console.

A very convenient way of recording with a stereo tape re-

corder is to record the vocals on one tape channel and the

instruments on the other tape channel. Connect the VA300

“To Tape Recorder” jack to the right channel auxiliary input

of the tape recorder. A separate microphone is connected to

the left channel microphone input of the tape recorder; an

omnidirectional microphone suspended from the ceiling is

recommended.

A stereo phonograph may be connected for stereo operation

with either of the two above systems. Connect the left phono

output to one Input, and the right phono output to a second

Input. Refer to the section on 

Phonographs 

on page 10, for

Input arrangements. Set the individual Reverb In-Out switches

on these two channels to direct the sound to the left and right

speakers.

Connecting a VU Meter:

An external VU meter may be connected in parallel across

the speaker wires of the VA300 with a resistor attenuator, as

shown below. Use a true VU meter (such as Simpson Model
No. 1349) and three resistors connected as shown. The resis-

tors should be ½-watt carbon 5%, or 1% if available.

Figure 10

With an 8-ohm speaker load (two VA300-S) zero VU is 50

watts. Output power for other VU readings is shown in the

table below.

V U

Power to 8-ohm load

+ 3

100 watts

0

50 watts

- 3

25 watts

- 7

10 watts

- 1 0

5 watts

Summary of Contents for Vocal Master VA 300

Page 1: ...VA 300 OPERATING AND SERVICE MANUAL Manufactured by SHURE BROTHERS INC 222 Hartrey Avenue Evanston Illinois 60204 U S A Copyright 1978 Shure Brothers Inc AL404 RE 27A819 Printed in U S A...

Page 2: ...eble Control Action 10 db at 10 000 Hz with respect to flat setting To Tape Recorder Jack Impedance 5 000 ohms Output 19 db below speaker output nominal 2 V at 50 watts to speakers Clipping Level 4 V...

Page 3: ...to mix up to six microphones with individual control over volume tone and reverberation A solid state 100 watt R M S power amplifier is incorporated in the Console Unique cir cuitry design protects th...

Page 4: ...olume Control 9 Thermal Overload Indicator Lamp 10 On Off On Power Switch Figure 2 Rear Panel Controls and Connections Refer to Figure 2 11 Line Cord Storage Spindles 12 A C Line Cord 13 D C Fuse 3AG...

Page 5: ...O to whichever 7 8 9 10 11 On position results in the least amount of hum coming from the speakers Now turn up the other Individual Channel Volume Controls 5 which are being used By use of the Indivi...

Page 6: ...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 vol...

Page 7: ...o them A shallow broad room might require four speakers to be utilized in order to cover the extreme horizontal expanse Again if balconies were added four more speakers might be required to expand the...

Page 8: ...flat sounding voice It is often used to great advantage to reduce high frequency acoustic reverberation in reflective rooms The Master Volume control 8 adjusts the output level of the total mixed outp...

Page 9: ...perated When connected in the manner described the individual channel Reverb In Out switches will offer selective echo in addition to selective internal reverb With the Master Reverb In Out switch in...

Page 10: ...put 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 hig...

Page 11: ...TION is available Contact your Shure Dealer or the Shure Factory for further information on this Additional Power or Area Coverage In those applications which require more power than one VA300 Vocal M...

Page 12: ...tems simply use a Y connector on that microphone and feed its signal to one Input on each Console For making stereo tapes the To Tape Recorder jacks one on each console may now be connected to the lef...

Page 13: ...dge of the case and the six screws four within the plastic feet on the bottom of the case Push the amplifier slightly forward from the back to permit access to the front panel Note Uncoil the cable be...

Page 14: ...he following modifica tion if not already performed place insulated tubing over the leads of a 3 3k 1 2W resistor and solder it across the terminals to which the white and black leads of transformer T...

Page 15: ...ctive transistors and diodes may be located by use of an ohmmeter Polarity of the ohmmeter must be verified before these checks are made With a known diode orientation measure the diode resist ance in...

Page 16: ...a malfunction should occur The amplifier can be operated without this assembly To eliminate possible damage or shock hazard the plug in cables should be temporarily inserted in the nylon inserts norma...

Page 17: ...hms Read ings outside of these limits indicate possible failure 6 Reconnect lead disconnected in Step 3 Install back of cabinet tightly REPLACEMENT PARTS LIST FOR VA300 S SPEAKER COLUMN REP REPLACEMEN...

Page 18: ...A018 Potentiometer 50K R15 RKC60 1 46A020 Potentiometer 2 5K R17 R18 45EC439B Resistor 43 ohms 5 W R19 R21 R20 45EC209B Resistor 20 ohms 5 W R22 45EC129B Resistor 12 ohms 5 W R23 RKC47 1 45A38 Resisto...

Page 19: ...ALTERNATE POWER SUPPLY INCORPORATED IN EARLY PRODUCTION UNITS Figure 17 19...

Page 20: ...ume controls set to maximum 11 Master reverb switch set to OUT position except as noted Chassis Ground Preamplifier Ground 12 Individual channel reverb switches set to OUT pos Reverb ition except wher...

Page 21: ...VA300 C CIRCUIT DIAGRAM ISSUE 6 21 Figure 18...

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