Lowell MA125 Скачать руководство пользователя страница 6

Instruction Sheet

IS-MA60/125/250

Issued: 3-6-18

Lowell Manufacturing Company

100 Integram Drive

Pacific, Missouri 63069 U.S.A.

Call: 800-325-9660

Fax: 636-257-6606

Click: www.lowellmfg.com

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Note:   A  push  switch  is  provided  on  channels  1  through  5  that  turns  on  the  aux input  jacks  and  at  the  same  time 
pads the XLR and screw terminal inputs for  that channel so they can  be used as  low impedance balanced line level 
inputs.   

With  the  switch  in  the  “AUX”  position,  use  either  the  aux  input  jacks,  or  the  XLR/screw  terminal  low 

impedance line level  inputs.  

Do not use both at the same time.

  When using the XLR jacks or screw terminals as 

line inputs, defeat the phantom power for that input channel.

    

MIC LEVEL INPUT CONNECTIONS

The  amplifier  includes  low-impedance  balanced  microphone  inputs.   16VDC  Phantom 
Power is available at  microphone inputs 1-5.  The amplifier is shipped from the factory 
with internal Phantom Power jumpers set “ON” for Channel  1-5.  The Phantom power 
for each microphone channel may  be  defeated by first unplugging  the  power cord , and 
then  removing  the  amplifier  chassis  cover  and  changing  the  jumper  position  for  that 
channel to “OFF” (Channel-1: jumper JP1, Channel-2: jumper JP2, Channel-3: jumper 
JP3, Channel-4: jumper JP4, and      Channel-5: jumper JP5).   The jumpers are  located 
on  the  circuit  board  that  includes  the  input  connectors.    See  the  picture  to  the  right 
which shows JP2 (for Channel-2) and JP4 (for Channel-4).

JP2

RCA Phono Plug Connection

Pin     Sleeve

Sleeve:

Shield

Pin:

Signal

GENERAL WIRING AND INSTALLATION GUIDELINES

  

DO  NOT

  run  microphone  cables  near  AC  power  wires, data  cables, telephone  cables, or  speaker  wiring  to  avoid 

picking up extraneous signals in the sound system.   

DO NOT

 run  speaker  output cables near data  cables, telephone cables, or other low  voltage wiring that could pick 

up the signal from the higher level speaker cables.  

DO NOT

 run high impedance unbalanced wiring more than 20' to avoid picking up noise and affecting the frequency 

response of the sound system.

DO

  use  shielded  cable  for  all  microphone  and  line  level  cables (except  the  balanced  600  ohm  input  line  from  a 

telephone system may be twisted pair cable).   

DO

 make sure that all speakers are wired in phase with each other .   

DO

 make sure there are no short circuits on the loudspeaker lines before connecting them to the amplifier output .   

JP4

2

3

1

GND

_

+

+

GND

_

TO INPUT

CHANNEL

MICROPHONE CHANNEL INTERNAL WIRING

LINE LEVEL “AUX” INPUT CONNECTIONS

The amplifier includes high-impedance unbalanced  auxiliary inputs  which may  be  used for  connecting the output  of 
an AMFM tuner, CD player, cassette deck, or other music program source.  A push switch is provided on Channels 
1 through 5 that selects the aux input jacks while switching the XLR and screw terminal inputs for that same channel 
to  low impedance  line level inputs.  Use the aux input  jacks 

or

 the line level XLR/screw terminal inputs but 

do  not 

use both at the same time

.  Two (2) RCA-phono connectors are provided for each aux input so stereo input cables 

can be connected.  The stereo input signal is converted internally to a mono signal .  Mono inputs need only use one 
or the other of the RCA-phono connectors.   

GROUND  LOOPS

    Any  time  two  (2)  pieces  of  equipment  (that  both  are  powered  by  grounded  AC  plugs  are 

connected by an unbalanced RCA to RCA cable, a  ground loop  is created.  In some instances, this does not  cause 
a  problem.  

In other cases this causes a “hum” or “buzz” that can be heard in the system’s speakers .  This can be 

corrected using  industry  standard  grounding  techniques , but another  simple way  to eliminate the  ground  loop  is  to 
replace the RCA to RCA cord with a Lowell TSM-ISO isolation transformer that is sold separately . 

Содержание MA125

Страница 1: ... the POWER AMP IN jack A chassis ground termination screw is available on the rear panel The front panel includes channel 1 5 volume controls treble and bass controls a master volume control a main power switch and an output level LED display Rack mounting brackets are included with each model Optional Accessories sold separately Lowell Manufacturing offers a full line of 19 equipment cabinets wal...

Страница 2: ...To completely disconnect this apparatus from the AC mains disconnect the power supply cord plug from the AC receptacle This apparatus shall be connected to a mains socket outlet with a protective earthing connection When permanently connected an all pole mains switch with a contact separation of at least 3 mm in each pole shall be incorporated in the electrical installation of the building If rack...

Страница 3: ...BS MA250 29LBS Color Black Note Black rack mounting brackets are included Speaker Level Outputs Screw terminal strip 4W 8W 25V 70V MA60 60W RMS MA125 125W RMS MA250 250W RMS Tape Outputs Dual parallel RCA phono jacks 1V 4 7kW output Preamp Pre Outputs Dual parallel RCA phono jacks 1V 600W output Convenience AC Outlet 500W maximum unswitched outlet Mic Inputs 1 5 XLR receptacle or screw terminals 1...

Страница 4: ...jack or screw terminals Circuit Breaker for Convenience Outlet 1 2 3 4 5 6 7 8 9 10 11 12 Circuit Breaker for Amplifier Earth Ground Connection Screw Power Amp Input RCA Jack Preamp Output RCA Jacks Tape Output RCA Jacks Aux 6 Level Control Aux 6 Input RCA Jacks Aux 5 Input RCA Jacks Mic 5 Aux 5 Selector Switch Mic 5 Input XLR Jack Mic 4 Input XLR Jack 4 2 13 14 15 16 17 18 19 20 21 22 23 Convenie...

Страница 5: ...amplifier operating temperature of no higher than 92o F To mount the amplifier in a Lowell equipment cabinet use standard 10 32 Phillips head machine screws like the Lowell model RS or RSP rack screws with integral plastic washers to protect the finish of the front panel of the amplifier Rack mounting brackets for the amplifier are included The AC power cord provided with this amplifier is equippe...

Страница 6: ...telephone cables or other low voltage wiring that could pick up the signal from the higher level speaker cables DO NOT run high impedance unbalanced wiring more than 20 to avoid picking up noise and affecting the frequency response of the sound system DO use shielded cable for all microphone and line level cables except the balanced 600 ohm input line from a telephone system may be twisted pair ca...

Страница 7: ... or screw terminal inputs not the Channel 1 aux inputs have the second highest level of muting priority The telephone input always mutes Channel 1 The Channel 1 XLR and screw terminal inputs mute Channels 3 6 as long as the Channel 1 mute switch is in the ON position The Channel 1 muting is active whether using the XLR or screw terminal inputs in the microphone mode with the aux switch in the MIC1...

Страница 8: ...mono outputs to two different devices such as a booster amplifier or equalizer As shown in the AMPLIFIER BLOCK DIAGRAM on page 3 the PREAMP OUT jacks are fed from the output of the master volume control In other words if you wish the levels to be adjusted as a result of changes in the setting of the MASTER volume control that may need to be adjusted due to crowd noise in a live performance the PRE...

Страница 9: ...per Between Pre Out And Power Amp In OPTIONAL 1 3 OCTAVE EQUALIZER BY OTHERS High Z Input High Z Output Type 1 Type 1 Connection to two 2 1 3 octave equalizers using Lowell PA250A booster amplifiers with similar and different types of loudspeakers Note Similar speakers are fed by the same equalizer LOWELL PA250A BOOSTER AMPLIFIER Aux In Jack To Speakers Note Jumper cords shown are not included Ins...

Страница 10: ...amage the amplifier and void the manufacturer s warranty It is also important to pay attention to the power rating of the speakers used If an 8W speaker is fed from the 8W output of an amplifier and the amplifier is turned all the way up the speaker will receive the maximum power output of the amplifier A speaker must be chosen with sufficient power handling capacity for the amplifier used For exa...

Страница 11: ...M 572 5 watt 70V 25V dual voltage transformer That means that this speaker can be used on both 70V systems and 25V systems The 8W secondary of the transformer is connected directly to the 8W input terminals on the 810 speaker The primary has transformer taps for either 70V or 25V at 0 25W 0 5W 1W 2W and 5W When a designer is mapping out the coverage of these ceiling speakers he she will determined...

Страница 12: ...ker load to no more than 106 25W Since we know from our example that 100 speakers would be required it is obvious that tapping the speakers at 1W is the best choice Some system designers feel it is best to tap the speaker transformers as high as possible Consider an example where a sound system that has a 125W 70V amplifier only has 10 speakers If the transformers are tapped at 0 25W each the tota...

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