Quest Engineering PB-4120 User manual

PROTECT
CH 1CH 2CH 3CH 4
CLIP
-20 dB
SIGNAL
POWER
POWER AMPLIFIER
PB-4120
ON
OFF
Owner’s Manual
PB-4120

WARNING

1
PB-4120
Introduction ………………………………………………………… 2
Features ……………………………………………………………… 3
Front Panel Controls ………………………………………………… 4
Rear Panel Controls ………………………………………………… 5
Connections ............................................................................... 6
System Set Up ..……………………………………………………… 7
Output Wiring Guide .................................................................. 8
Specifications ....……………………………………………..……… 9
Block Diagram ……………………………………………………… 10
Table of Contents
Table of Contents

2
PB-4120
Introduction
Welcome
Thank you for purchasing the PB-4120 constant voltage power amplifiers from Jam
industry Technologies! The PB-4120 have been designed to provide robust, clean out-
put with low distortion and wide dynamic range, along with the dependability demand-
ed by the most professional design engineers and audio installers. The PB-4120 is
enclosed in a convenient 2 rack-space chassis and feature highly efficient Class D
power cores with universal power supplies that operate from 100 – 240 volts, at 50
or 60 Hz. Each of the channels reach full power of 120 watts at 4 ohms, but they can
also run at 70 or 100 volts thanks to their internal, high performance, toroidal match-
ing transformers. Front panel controls and displays include a Power switch with LED
indicator, as well as independent channel input level controls. The amplifiers include
front panel Signal, Peak and Protection LED indicators to help you set the correct
operating levels. Euro block input and output connectors are provided to insure easy
connections and maximum flexibility. To keep the amplifiers running cool, their designs
employ internal wind tunnels with forced-air cooling via an internal fan, which greatly
reduces the chance of thermal and overheating problems. Multi-stage protection for
power-up, over-heating, over-current, short circuit, low output impedance and DC volt-
age, assures high reliability under the most demanding situations. 19-inch rack mount
design and convenient carry handles facilitating easy installation in any rack. Optimized
for commercial installations, houses of worship, live sound venues and for driving small
and medium-sized live PA systems, the PB-4120 will deliver reliable power. The Its’
advanced technology, clear sound and reliable performance makes them ideal for any
small PA or any distributed sound system installation.
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PB-4120
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PB-4120
MULTI-ZONE POWER AMPLIFIER
Introduction

3
PB-4120
Features
• Theamplifierdelivers120wattsofcleanpowerperchannelat70/100voltsand4Ohms,
with4x120watts.
• ClassDamplifieroperatingat85%efficiencyusinguniversalpowersupplieswithpower
factorcorrectionandcapableofoperatingfrom100-240V,50or60Hz.The PB-4120
amplifiersgeneratevirtuallynoheatandthankstotheirlowcurrentdraw.
• Built-in70/100voltoutputtransformerswithflatfrequencyresponsefrom40Hzto20kHz
provideconstantvoltagefordistributedspeakersystems.
• Independentinputlevelcontrolsforeachchannelallowprecisionadjustmentsandthe
includedsecuritypanelprovidesprotectionfromunwantedadjustment. 
• Clean,crispsound-Impressiveaudiospecificationssuchas0.04%THD,dynamicrange
of105dB,crosstalkof80dB,andfrequencyresponseof10Hzto25kHzguaranteeultra-
cleansoundquality.
• LEDsignalindicatorsforeachchannelcontinuouslydisplaypoweroutputlevelsandallow
youtocorrectforoverloading(clipping)conditions.
• Forcedaircoolingviainternalfanprovidesreliableperformancewithoutthermaland
overheatingproblems.
• Protectioncircuitry(withdedicatedLEDsforeachchannel)thatguardsagainst
overheatingorfaultywiringconditionsandalsoprevents“thumps”whenpoweringonor
off.ThismeansthatyoucanusethePB-4120withasinglepowerstrip,intowhichamixer
orotheraudiodevicesareconnected,withoutdangerofdamagetoconnectedspeakers.
• InputconnectionsforeachchannelaremadeusingEuroblockconnectorsto
accommodatebothbalancedandunbalancedsignalssources.
• OutputconnectionsforeachchannelaremadeusingEuroblockconnectorswhichaccept
12gaugewire.
• ThePB-4120canbemountedinanystandard19”rack(takingjusttworackspaces),
makingiteasytointegrateintoanyfixedortravelingPArig.
• Theamplifiersareenclosedinruggedlyconstruction(anall-steelchassiswithasleekblack
finish),standard2-space19-inchrackmountunit.
The Jam industry PB-4120 power amplifiers have been developed using the latest
technology in Class D power amplifier design. Here are some of their main features:
Features

4
PB-4120
Front Panel Controls
1. Handle - For easy transport while carrying,
or while rack mounting, the amplifier features
two heavy duty die cast handles located
conveniently on the left and right side of the
front panel.
2. Fan Vent - The amplifiers stay cool thanks
to their twin, forced-air cooling vents. Cool
air is drawn through the front panel fan filters,
reducing the temperature of the internal
components while forcing the heat out the
rear vents.
3. Clip LED - The CLIP segment lights
whenever the channel is outputting signal
at full strength. For the best signal-to-noise
ratio, the right (PEAK) segment should light
occasionally during peak levels; if it lights
frequently, you may be overloading the
PB-4120 and a distorted (“clipped”) signal is
probably being output.
4. Protection LED - This goes on for
approximately one second, whenever the
PB-4120 is powered on and then turns off
. The Protection LED will also light when
overheating or other severe problems occur.
It is normal for the Protection LED to fade
slowly when the amp is powered off. When
lit, no signal is provided to any connected
speakers, thus muting them and preventing
any “thump” from occurring.
5. Signal LED - The front panel LED
indicators continuously monitor the power
PROTECT
CH 1CH 2CH 3CH 4
CLIP
-20 dB
SIGNAL
POWER
POWER AMPLIFIER
PB-4120
ON
OFF
output level for the corresponding channel.
The SIGNAL LED lights whenever output
signal is present.
6. Power switch - Use this to power the
Amplifier on or off. The internal LED lights
whenever the Amplifier is powered on.
Front Panel Controls
1 3 4 5 62

5
PB-4120
Rear Panel Controls
CH 4
SPEAKER OUTPUT
PUBLIC ADDRESS POWER AMPLIFIER
PB-4120
-120dB
ADJUST
LINK
CH 2
INPUT
OFFON
HPF
400Hz
-120dB
ADJUST
LINK
CH 3
INPUT
OFFON
HPF
400Hz
-120dB
ADJUST
LINK
CH 1
INPUT
OFFON
HPF
400Hz
DESIGNED AND ENGINEERED IN KOREA
WARNING
DO NOT EXPOSE
THIS EQUIPMENT
TO RAIN OR
MOISTURE
CAUTION
FOR CONTINUED
PROTECTION AGAINST
RISK OF FIRE, REPLACE
ONLY SAME TYPE FUSE
AVIS
RISQUE DE CHOC
ELECTRONIQUE NE
PAS OUVRIR
ATTENTION
UTILISER UN FUSIBLE
DE RECHANGE MEME
TYPE
CH 3
COM
CH 2 CH 1
-120dB
ADJUST
LINK
CH 4
INPUT
OFFON
HPF
400Hz
~ AC INPUT
100~240V 50/60Hz, 118W
COM
100 V
(83 )
22 V
(4 )
70 V
(41 )
COM
100 V
(83 )
22 V
(4 )
70 V
(41 )
COM
100 V
(83 )
22 V
(4 )
70 V
(41 )
100 V
(83 )
22 V
(4 )
70 V
(41 )
1. Fan - This internal fan provides vital cooling to
your PB-4120. Make sure that both the front and
rear panels are kept free of all obstructions and
that cool, fresh air is accessible at all times. Also,
try to ensure that the Amplifier is used in a dust-
free environment.
2. Input connectors - Connect incoming signals
to these electronically balanced connectors. We
recommend the use of balanced three-conductor
cabling wherever possible (unbalanced two-
conductor signals can also be inserted into these
inputs, but you’ll get better signal quality and less
outside noise and hum if you use balanced lines).
The SZ Series accepts input levels of any strength
but needs at least 0 dBu to achieve maximum
power.
3. Link Output Connectors - Connect out going
signals from these jacks.
4. AC input - Connect the supplied heavy-gauge
3-pin “IEC” power cable here.
5. Euroblock Output connectors - Use these
to connect each channel of the PB-4120 to
4-ohm or 8-ohm loudspeakers, or to one of the 70
and 100 volt outputs if you are using a constant
voltage system .
6. Channel input level controls - These
controls allow you to precisely adjust the
input level of the signal arriving at the
rear-panel input connectors. At their fully
counterclockwise position, the signal is
attenuated by -12 dB. At their fully clockwise
position, the signal is at unity gain (that is,
no attenuation). When 0dBu of signal arrives
at the input jacks and the Channel input
level controls are set to their fully clockwise
position, the Amplifier delivers full power
output.
7. High Pass filter - It can be allowed toggle on
and off the HPF.
WARNING!: Each of the amplifier channels can
run only one output configuration at the same
time. Operating amplifiers using 4 ohm and 70 or
100 volt concurrently may cause damage to the
amplifier or connected speakers, and may void
your warranty.
Rear Panel Controls
15 36
4 2

6
PB-4120
Connections
The following diagrams illustrate various wiring set ups for 4 ohm, 8 ohm and 70 Volt operation.
8 Ohm Operation (One 8 Ohm speaker per amplifer)
70 Volt Operation (Four speakers per amplifer with their line transformers set to 25 watt)
8 Ohm Operation (One 8 Ohm speaker per amplifer)
Connections
CH 4
SPEAKER OUTPUT
PUBLIC ADDRESS POWER AMPLIFIER
PB-4120
-120dB
ADJUST
LINK
CH 2
INPUT
OFF ON
HPF
400Hz
-120dB
ADJUST
LINK
CH 3
INPUT
OFFON
HPF
400Hz
-120dB
ADJUST
LINK
CH 1
INPUT
OFF ON
HPF
400Hz
DESIGNED AND ENGINEERED IN KOREA
WARNING
DO NOT EXPOSE
THIS EQUIPMENT
TO RAIN OR
MOISTURE
CAUTION
FOR CONTINUED
PROTECTION AGAINST
RISK OF FIRE, REPLACE
ONLY SAME TYPE FUSE
AVIS
RISQUE DE CHOC
ELECTRONIQUE NE
PAS OUVRIR
ATTENTION
UTILISER UN FUSIBLE
DE RECHANGE MEME
TYPE
CH 3
COM
CH 2 CH 1
-120dB
ADJUST
LINK
CH 4
INPUT
OFFON
HPF
400Hz
~ AC INPUT
100~240V 50/60Hz, 118W
COM
100 V
(83 )
22 V
(4 )
70 V
(41 )
COM
100 V
(83 )
22 V
(4 )
70 V
(41 )
COM
100 V
(83 )
22 V
(4 )
70 V
(41 )
COM
100 V
(83 )
22 V
(4 )
70 V
(41 )
CH 4
SPEAKER OUTPUT
PUBLIC ADDRESS POWER AMPLIFIER
PB-4120
-120dB
ADJUST
LINK
CH 2
INPUT
OFFON
HPF
400Hz
-120dB
ADJUST
LINK
CH 3
INPUT
OFFON
HPF
400Hz
-120dB
ADJUST
LINK
CH 1
INPUT
OFFON
HPF
400Hz
DESIGNED AND ENGINEERED IN KOREA
WARNING
DO NOT EXPOSE
THIS EQUIPMENT
TO RAIN OR
MOISTURE
CAUTION
FOR CONTINUED
PROTECTION AGAINST
RISK OF FIRE, REPLACE
ONLY SAME TYPE FUSE
AVIS
RISQUE DE CHOC
ELECTRONIQUE NE
PASOUVRIR
ATTENTION
UTILISER UN FUSIBLE
DE RECHANGE MEME
TYPE
CH 3
COM
CH 2 CH 1
-120dB
ADJUST
LINK
CH 4
INPUT
OFFON
HPF
400Hz
~ AC INPUT
100~240V 50/60Hz, 118W
COM
100 V
(83 )
22 V
(4 )
70 V
(41 )
COM
100 V
(83 )
22 V
(4 )
70 V
(41 )
COM
100 V
(83 )
22 V
(4 )
70 V
(41 )
COM
100 V
(83 )
22 V
(4 )
70 V
(41 )
8 Ohm8Ohm8Ohm8Ohm
CH 4
SPEAKER OUTPUT
PUBLICADDRESS POWER AMPLIFIER
PB-4120
-120dB
ADJUST
LINK
CH 2
INPUT
OFFON
HPF
400Hz
-120dB
ADJUST
LINK
CH 3
INPUT
OFFON
HPF
400Hz
-120dB
ADJUST
LINK
CH 1
INPUT
OFFON
HPF
400Hz
DESIGNEDAND ENGINEERED IN KOREA
WARNING
DONOT EXPOSE
THISEQUIPMENT
TORAIN OR
MOISTURE
CAUTION
FORCONTINUED
PROTECTIONAGAINST
RISKOF FIRE, REPLACE
ONLY SAMETYPE FUSE
AVIS
RISQUEDE CHOC
ELECTRONIQUENE
PASOUVRIR
ATTENTION
UTILISERUN FUSIBLE
DERECHANGE MEME
TYPE
CH 3
COM
CH 2 CH 1
-120dB
ADJUST
LINK
CH 4
INPUT
OFFON
HPF
400Hz
~ AC INPUT
100~240V 50/60Hz, 118W
COM
100V
(83 )
22V
(4 )
70V
(41 )
COM
100V
(83 )
22V
(4 )
70V
(41 )
COM
100V
(83 )
22V
(4 )
70V
(41 )
COM
100V
(83 )
22V
(4 )
70V
(41 )
4 Ohm4Ohm4Oh
m4
Ohm

7
PB-4120
The following is a typical constant voltage system setup for a small restaurant using the Jam industry Preamplifier
power amplifier along with an S zone feeding several audio zones with paging and music. The first two channels
are connected to four wall-mounted speakers in each of the Dining Rooms with their transformers set to a 25 watt
tap. The third channel powers two speakers in the outside Bar area with their transformers set to 50 watt. The fourth
channel powers small speakers in the lobby with a 12 watt tap.
System setup
System setup
PM-10/2
CH 4
SPEAKER OUTPUT
PUBLIC ADDRESS POWER AMPLIFIER
PB-4120
-120dB
ADJUST
LINK
CH 2
INPUT
OFFON
HPF
400Hz
-120dB
ADJUST
LINK
CH 3
INPUT
OFFON
HPF
400Hz
-120dB
ADJUST
LINK
CH 1
INPUT
OFFON
HPF
400Hz
DESIGNED AND ENGINEERED IN KOREA
WARNING
DO NOT EXPOSE
THIS EQUIPMENT
TO RAIN OR
MOISTURE
CAUTION
FOR CONTINUED
PROTECTION AGAINST
RISK OF FIRE, REPLACE
ONLY SAME TYPE FUSE
AVIS
RISQUE DE CHOC
ELECTRONIQUE NE
PAS OUVRIR
ATTENTION
UTILISER UN FUSIBLE
DE RECHANGE MEME
TYPE
CH 3
COM
CH 2 CH 1
-12 0dB
ADJUST
LINK
CH 4
INPUT
OFF ON
HPF
400Hz
~ AC INPUT
100~240V 50/60Hz, 118W
COM
100 V
(83 )
22 V
(4 )
70 V
(41 )
COM
100 V
(83 )
22 V
(4 )
70 V
(41 )
COM
100 V
(83 )
22 V
(4 )
70 V
(41 )
COM
100 V
(83 )
22 V
(4 )
70 V
(41 )
4
3
2
1

8
PB-4120
Thereareseveralwaystointerfacetheamplifers,dependingonyourexactsystemset-up.Formost
smallinstallation14to16gaugezipcordcanbeusedformostsmalltomediumsizeinstallations.
Followthecablediagramsbelowforconnectingtotheinputofyouramplifier.
Output Wiring Guide
100 V
(83 )
70 V
(41 )
25 V
(5.2 )
COM
4 OHM
100 V
(83 )
70 V
(41 )
25 V
(5.2 )
COM
4 OHM
100 V
(83 )
70 V
(41 )
25 V
(5.2 )
COM
4 OHM
100 V
(83 )
70 V
(41 )
25 V
(5.2 )
COM
4 OHM
Output Wiring Guide
4 and 8 Ohm Wiring Guide
25 Volt Wiring Guide
70 Volt Wiring Guide
100 Volt Wiring Guide
SHOCK HAZARD SYMBOL
WARNING!!! - PAY ATTENTION TO THE WARNING SYMBOL AND AVOID ELECTRICAL SHOCK.
DO NOT HOLD OR TOUCH THE COMMON AND 70 OR 100 VOLT WIRE CONNECTION WHILE
OPERATING THE AMPLIFIER.

9
PB-4120 Specifications
Necessary modifications are carried out without notice.
Specifications
All channels driven
8 ohms ............................................65 Watts
4 ohms ............................................118 Watts
Current Consumption(115VAC)
@1/8 rated power 4ohms................................0.6A
@1/3 rated power 4ohms ...............................1.6A
@ rated power 4ohms, max. .............................5.0A
Input Sensitivity (Balanced Line Input) ........................1.0 + 0.2Vrms / 10Kohm
Frequency Response (50Hz~18kHz)..........................+1.5/-3dB
Dynamic Range ..........................................>90 dB A-weighted, typical
THD+N (AES17 20kHz brickwall filter, Rated output) .............Less than 5%
S/N Ratio (AES17 20kHz brickwall filter) .......................90dB
Residual Noise (AES17 20kHz brickwall filter) ..................-70dB
Input Clipping ...........................................+26dBu
Connectors (each channel)
Input: ...............................................XLR jack
Output: ..............................................Euroblock
Controls ...............................................AC power switch,Channel volume, HPF
Indicators...............................................Power on(blue),Protection(red)
..................................................Signal(green) for each Ch.,Cilp(red) for
each Ch.
Protection ..............................................Short circuit,Thermal,Current limit,DC
offset,Current inrush,RF protection, Turn
on/Turn off muting
Cooling ................................................Continuously variable speed, fan forced air
Transformer Rating .......................................118 Watts
Input voltage ............................................28.28 Vrms 100 watts / 8_load
Output Tap 1: Voltage .....................................70.7 Vrms 50_ load
Output Tap 2: Voltage .....................................100 Vrms 100_ load
Output Tap 3: Voltage .....................................20 Vrms 4_ load
Power Requirements ......................................100/115/220/230/240 VAC, 50/60 Hz
Construction ............................................All Steel
Dimensions(WXHXD) ......................................482mm X 88mm X 432.8mm
Net Weight .............................................17.8kg

10
PB-4120
Block Diagram
Block Diagram

11
PB-4120
Block Diagram