IRP PA-4020B User manual

2000 041600 622-1018Ver 2.3
IRP professional sound products L.P.
1225 Greenbriar Drive !"Suite R
Addison, IL 60101 USA
800-255-6993 !"630-860-1993 !"FAX [phone] !"www.irp.net
INSTINST INSTINST
INSTALLAALLA
ALLAALLA
ALLATION &TION &
TION &TION &
TION &
OPERAOPERA OPERAOPERA
OPERATIONS MANUTIONS MANU
TIONS MANUTIONS MANU
TIONS MANUALAL
ALAL
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PP
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PA-SERIES POA-SERIES PO
A-SERIES POA-SERIES PO
A-SERIES POWERWER
WERWER
WER AMPLIFIERSAMPLIFIERS
AMPLIFIERSAMPLIFIERS
AMPLIFIERS
PP
PP
PA-4020BA-4020B
A-4020BA-4020B
A-4020B

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ContentsContents
Contents
List of Tables and Figures ................................................................................................. ii
Important Notices .............................................................................................................. 4
FCC Compliance ............................................................................................................... 5
Product Description ........................................................................................................... 6
Specifications .................................................................................................................... 7
UnPacking ......................................................................................................................... 8
MechanicalMounting.......................................................................................................... 8
Connections....................................................................................................................... 9
Trouble-Shooting................................................................................................................ 13
Warranty Provisions ........................................................................................................... 13
i

Figure1:FrontandRearPanel View..................................................................................6
Figure2:InputConnections................................................................................................10
Figure3:OutputConnections ............................................................................................. 11
Figure4: Dual-channel,70.7 voltoutput Connections..........................................................12
Figure5: Bridged mode, 70.7volt output Connections........................................................12
Table1:OutputPower versusImpedance ...........................................................................7
Table 2:Input SignalCharacteristics,Thermal Considerations............................................ 8
List ofList of
List ofList of
List of TT
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4
ImporImpor
ImporImpor
Important Noticestant Notices
tant Noticestant Notices
tant Notices
PLEASE READ THIS PAGE BEFORE OPERATING YOUR
IRP

professional sound products L.P.
POWER AMPLIFIER
IntrIntr
IntrIntr
Introductionoduction
oductionoduction
oduction
YournewIRPprofessional sound products power
amplifier has been designed and constructed to
provide years of reliable, trouble-free operation.
Please take a few moments to read the following
information before installing your new power am-
plifier.Adherence to these simpleinstructionswill
ensure that your new power amplifier will provide
you with the service and performance that you
have come to expect from IRP products.
Read all instructions prior to connecting
any ac power to your power amplifier
Ac PAc P
Ac PAc P
Ac Poo
oo
oww
ww
wer Conditionser Conditions
er Conditionser Conditions
er Conditions
ThePowerAmplifierdescribedinthismanualand
whichisintendedfor distribution in North America
is shipped from the factory setup for operation
from 115 volt, 60Hz power mains. The unit can
be rearranged for operation on 230 volt 50Hz if
required. The power amplifier should be con-
nected to an ac line source of the type described
in this manual or as indicated on the rear of the
unit.
VV
VV
Ventilaentila
entilaentila
entilationtion
tiontion
tion
When the unit is installed in an equipment rack
without forced air cooling, a maximum ambient
temperature of 45°C (113°F) should not be ex-
ceeded. Refer to Mounting Section for further de-
tails.
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The PA-4020B is enclosed in a chassis, which is
devoidof ventilation holes. Consequently,it is by-
and-large impervious to happenstance’s where
liquid or other corrosive elements can be intro-
duced into the interior of the chassis. However,
the external connections on the rear panel of the
amplifiercouldbeadverselyeffectedbyexposure
to water or other liquids. Hence, as a general
precaution, the unit should not be operated in a
location where it might be subjected to water or
other spilled liquids.
GrGr
GrGr
Groundingounding
oundingounding
ounding
The power amplifier is intended to be mounted in
a metallic enclosure which should be grounded
inaccordancewithNEC (National ElectricalCode)
prescribed procedures. When used in locations
other than the USA, adhere to local codes and
standards for specifics.
Do not make any modifications that will
defeat the grounding provisions of the unit.
OperOper
OperOper
Operaa
aa
ating Contrting Contr
ting Contrting Contr
ting Controlsols
olsols
ols
There are no user operating controls within
the interior of the chassis. Do not remove the
chassis cover. Potentially lethal electrical circuits
may be exposed when the cover is removed.
SerSer
SerSer
Service Infvice Inf
vice Infvice Inf
vice Inforor
oror
ormama
mama
mationtion
tiontion
tion
Only qualified service personnel should service
the power amplifier when:
#The power cord or line connection plug is
frayed or otherwise damaged
#Unit has been exposed to spilled liquids
#The amplifier does not appear to be
operating properly or there is a noticeable
change in performance
#The unit has been dropped or the
enclosure has been damaged
Refer all service work to a qualified electronics
technician.Contact the factory or yourauthorized
IRP dealer for further information
Removal of the cover, or other unauthorized
tampering may result in a voiding of the
warranty

5
WW
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This equipment generates and uses radio
frequency energy and if not installed and used
properly, may cause interference to radio and
television reception. It has been type tested and
found to comply with the limits for a Class B
computing device in accordance with the specifi-
cations in Subpart J of Part 15 of FCC Rules,
which are designed to provide reasonable pro-
tection against such interference in a residential
installation. However, there is no guarantee that
interference will not occur in a particular installa-
tion. If this equipment does cause interference
to radio or television reception, which can be
determined by turning the equipment off and on,
the user is encouraged to try to correct the
interference by one or more of the following
measures:
#Reorient the receiving antenna
#Relocate the amplifier with respect to the
receiver
#Move the amplifier away from the receiver
#Plug the amplifier into a different electrical
outlet so that the amplifier and the receiver
are on different electrical branch circuits
FCC ComplianceFCC Compliance
FCC ComplianceFCC Compliance
FCC Compliance
If necessary, the user should consult the dealer
or an experienced radio/television technician for
additional suggestions. The user may find the
following booklet prepared by the Federal
Communications Commission helpful:
“How to Identify and Resolve Radio-TV
Interference Problems”. This booklet is available
fromthe U.S. Government Printing Office,Wash-
ington, DC 20402, Stock No. 004-000-00345-4.

6
Fig. 1: Front & Rear Panel Views
PrPr
PrPr
Product Descriptionoduct Description
oduct Descriptionoduct Description
oduct Description
ThePA-4020BPowerAmplifierisIRP professional
sound products’latest version of the legendary
DH-4020.ThePA-4020B featuresimprovements
designed to address the needs of today’s
systems integrators. The front panel graphics
have been redesigned to match the appearance
of the other power amplifiers in the PA-Series
product line.
This new unit employs a dual monaural design
forimprovedreliability;thePA-4020Boutputpower
rating has been increased significantly. However,
the single rack space mount characteristic has
beenretained.Withconvectioncoolinganda fully
enclosed chassis, the inherent problems of fan
noise and susceptibility to environmental prob-
lems such as dust, smoke and liquids have been
reduced to near negligible levels.
Designedfor the Global Market,IRP decided that
the PA-4020B must be one of the most easily
specified and installed amplifiers available. This
iis reflected in its overall design and feature set.
Theamplifier is able tooperateon 120 or 240volt
ac power at 50 to 60Hz.
With convection cooling, when idling, the unit
draws very little power, thus producing remark-
ably little heat. Inasmuch, as it utilizes signal de-
pendentswitching power supplies, thehighlyeffi-
cient PA-4020B has one of the lowest idle cur-
rentsofanypoweramplifieravailabletotheAudio
Industry.
This highly stable discrete power amplifier has a
power handling rating of 180 watts per channel
into 8 ohms and 250 watts each channel into 4
ohms. In mono-bridged mode it will provide 450
watts to an eight ohm load. Both bipolar amplifier
sections employ switchable transient current
limiters and a turn on delay for speaker protec-
tion.
The input and output connections for this
amplifier will accommodate virtually any
permanentorportableapplication.Therearpanel
is arrayed with XLR, NeutrikSpeakon, binding
posts and removable screw terminal connectors.
Few power amplifiers available offer as much
flexibility,powerhandling,andquality performance
as the IRP PA-4020B.

7
SpecificaSpecifica
SpecificaSpecifica
Specificationstions
tionstions
tions
Frequency response:
+0, -1dB —20Hz to 20kHz
Maximum input level:
+20dBv
Maximum output level:
+20 dBm
Input impedance:
100kW
Input sensitivity:
1VRMS
Distortion:
.02% THD
Input signal filter:
40kHz, to limit input slew rate to avoid SID/
TIM distortion
Channel crosstalk:
-85dB
Output impedance:
4, 8, and 16W
Signal to Noise ratio:
>105dB below rated output, 20Hz to 20kHz
Slew rate:
20V/µsec
Damping factor:
>100
Overload recovery:
<10µsec. With no recovery anomalies
Dc output offset:
±10 mV or less
Input/Output connectors:
XLR type, Neutrik Speakon, binding post,
removable screw clamp connectors
Front panel controls and indicators:
Channel level controls (2)
Power on/off switch
Power on indicator 2 leds (green)
Temperature indicator 2 leds (yellow)
Failure indicator 2 leds (red)
Signal indicator 2 leds (green)
Current Transit Indicator 2 leds (yellow)
Rear panel controls and indicators:
Input channel connector 2 removable screw
clamp connectors, 2 XLR type 3-pin connec-
tor
Output channel connectors, each channel, two
4-way binding posts each 2 Speakon
connectors
1 Ground lift switch
1 Bridge mode switch
1 Ac line fuse
1 3-pole, grounded, male IEC connector
Maximum audio power output:
(see table)
Ac Power requirements:
120/240V ±10%, 50/60Hz (draws <20 watts
on idle, 300 watts at 200 watt output)
Dimensions:
19 in. x 1.75 in. x 14 in.
(48.3 cm x 4.45 cm x 35.56 cm)
W x H x D
Heatsinking:
two, single-piece, finned, aluminum extrusion
extends full depth on both sides of chassis
Operating temperature range:
0 to +85°C
Finish:
Thermosetting black paint/anodized
Cooling:
Passive cooling. No fans or ventilation holes;
adequately cooled by natural convection
NOTE
Power Output is average per
channel,20Hzto 20kHz. with
less than .02% THD. In Dual
ChannelMode,bothchannels
driven.
EDOMECNADEPMI REWOP TUPTUO
LENNAHCLAUD
SMHO4W052
LENNAHCLAUDSMHO8W081
LENNAHCLAUDSMHO61W521
EDOMDEGDIRBSMHO4W054
Table 1: Output Power versus Impedance

8
InitializionInitializion
InitializionInitializion
Initializion
UnpacUnpac
UnpacUnpac
Unpackingking
kingking
king
Your new IRP professional sound products L.P.
PA-4020B Power Amplifier has been carefully
packed and shipped to you in an approved ship-
ping container.
Open and unpack the unit on a clean, firm flat
surface
Removethepoweramplifierfromthe die-cut card-
board fillers and the line cord from the accessory
bag. The unit is shipped from the factory with the
front-panel (faceplate) installed.
Inspectthe unit for shippingdamageimmediately
upon receipt. If any damage is found, promptly
notify the shipping company. Only the consignee
(you) can initiate a claim with the shipping carrier
for shipping damage. In the event of shipping
damage, be sure to save the shipping carton for
inspection by the carrier’s agent.
Retainallpackagingmaterialsforuseintheevent
that the unit has to be moved or shipped at some
future time. To avoid damage and/or scratching,
transportunitstothejob-siteintheirshipping con-
tainers.
PrPr
PrPr
Product Inspectionoduct Inspection
oduct Inspectionoduct Inspection
oduct Inspection
Examine the rear panel of the device.
Appearing adjacent to the IEC power line recep-
tacle are two screened labels reading 240VAC-
3A at the top of the receptacle and 120VAC-6A
below the receptacle. Make sure your unit is
marked with a √√
√√
√in the appropriate box.
Verify that the two (green) screw-clamp connec-
tors are inserted into the amplifier input
connection receptacles and that they have not
been dislodged in shipment.
Examinethe dipswitch carefully for possibleship-
pingdamage.Verify that the Bridge/Stereo switch
is in the proper position for the intended service.
MountingMounting
MountingMounting
Mounting
The PA-4020B is intended for mounting in a stan-
dard 19”equipment cabinet and will occupy
1-RU (1.75”) of rack space. The unit is attached
to the equipment rack by using four mounting
screws inserted through the rack lug spaces at
thefrontoftheamplifierchassis.To avoid scratch-
ing the faceplate, it is recommended that a fiber
washer be installed between the screwhead and
the faceplate.
Your PA-4020B amplifier has no ventilation holes
in the chassis; hence it is fairly impervious to the
possibility of dust, dirt or other contaminates en-
tering the chassis interior. However, like all other
electronic equipment, it should be mounted in a
conditioned space to insure that it is operating in
a stable temperature and dust-free environment.
GroundingGrounding
GroundingGrounding
Grounding
Equipment racks (cabinets) and the components
installed therein should be properly grounded in
accordance with National Electrical Code (NEC)
andallotherapplicablecodesandstandards.The
third prong (green wire) of the ac line cord should
not be relied upon to provide proper grounding.
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9
For best performance and to insure that the in-
stallation is free of ground loops that can create
obnoxious noise and hum problems, a technical
ground for the audio equipment should be
installed. In such a grounding system, the audio
electronicequipmentisgroundedatonepointonly
and with reference to the ac power connection to
the building (service entry). Depending upon the
size of the facility and the distance between the
equipment rack(s) and the service entry, a rela-
tively large ground conductor may be required to
establish a solid ground.
Do not rely on the building conduit/raceway
to provide a proper ground
Variance of ground potential between the
audio equipment and the service entry
should be <.25 Ohms.
Prior to commencing an installation, the design
of a well thought-out grounding plan can elimi-
natemostproblemswithinterfering RFI (radio fre-
quency interference) and EMI (electromagnetic
interference). A properly conceived and imple-
mentedgroundingplan can save untold griefand
expense in trying to correct problems ‘after-the-
fact’.
InterInter
InterInter
Internal Equipment Rnal Equipment R
nal Equipment Rnal Equipment R
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Wiringiring
iringiring
iring
Forbestperformanceandminimuminterference,
internal rack wiring should be spaced with a
minimum of 4 inches (10 cm) between conduc-
tors having varying signal levels. That is, ac
wiring, input audio wiring, intermediate level
audio and output audio wiring should be
separated by a minimum of 4 inches from each
other.Varyingsignallevelsand/oracwiringshould
never be bundled or tie-wrapped in a common
riser.
ConnectionsConnections
ConnectionsConnections
Connections
Audio Input ConnectionsAudio Input Connections
Audio Input ConnectionsAudio Input Connections
Audio Input Connections
All input connections are made on the rear panel
of the PA-4020B Power Amplifier. Each channel
is equipped with a 3-pin, screw-clamp, barrier-
strip type connector and a 3-pin, XLR-type con-
nector. Choose which type of connector you plan
touseandconnectaccordingly. Connections may
be made to either the terminal strip or to the XLR-
type connector; but not to both.
Both types of connectors have their respective
pins marked 1,2 and 3. Connections should be
made using the AES standard as follows:
Pin 1 –ground (shield)
Pin 2 –high (+) audio signal
Pin 3 –low (-) audio signal
Use two conductor, shielded cable for all audio
input lines.
Shields should be connected to ground at their
source end and not at the power amplifier.
Cable between the source and the power ampli-
fier should not exceed 18 inches (.5 meters).
Do not locate audio input cables closer than 4
inches (10 cm) from output, intermediate, or ac
wiring. See Grounding in the preceding Mounting
Section.
Determine whether the power amplifier will be
used in dual-channel mode or in the bridged
mode.Inthedual-channelmode,connectionsare
made to both channel 1 and channel 2. If the unit
istobeusedinbridgedmode,connectionismade
to channel 1 only. Make sure the bridge/stereo
selector switch is in the proper position for the
service intended.
See figure 2 for connection information:
AA
AA
Audio Output Connectionsudio Output Connections
udio Output Connectionsudio Output Connections
udio Output Connections
Alloutputconnectionsaremadeontherearpanel
of the PA-4020B Power Amplifier. Each channel
is equipped with a 2-conductor Neutrik Speakon
connector and a pair of 4-way binding posts.
Choose which type of connector you plan to use
and connect accordingly. Connections should be
made to either the Neutrik connector or to the 4-
way binding posts; but not to both.

10
Ground
Lift
On
LMT
Off
Bridge
Channel 2 Channel 1
++
++
+
--
--
-
++
++
+
--
--
-
1 2
31 2
3
Input
Connector Input Connector
Figure 2 Rear Panel Input Connections
1 2
3
--
--
-N/
C
++
++
+--
--
-
Dual-Channel mode both Channel Inputs
1 2
3
N/
C
++
++
+
1 2
3
N/
C
++
++
+
--
--
-
Bridged mode - Connection to Channel 1 Only
○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○
○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○
240V - 3 A
120V - 6A
√√
√√
√
Input ConnectionsInput Connections
Input ConnectionsInput Connections
Input Connections

11
Output ConnectionsOutput Connections
Output ConnectionsOutput Connections
Output Connections
Useclasstwo wiringandsufficientlysizedspeaker
cable wire to minimize signal loss.
If the power amplifier will be used to drive a
constant voltage (70.7V) transmission line,
accessory output transformers will be required.
When the PA-4020B is used with constant volt-
age transformers, it will provide 180 watts at 70.7
volts from each channel. In bridged mode, the
PA-4020B will drive two output transformers to
produce 350 watts at 70.7 volts.
When used in a constant voltage mode, the
sound system should have a high pass filter (low
frequency cut) to prevent saturation of the
constant voltage transformers. A second order
(12dB/octave)Butterworthfilter at 40Hz or higher
frequency is recommended. A first order
(6dB/octave) filter may be used if it is placed at
80Hz or higher frequency.
See figure 3, 4 and 5 for connection information
++
++
+
--
--
-
--
--
-
++
++
+++
++
+
--
--
-
--
--
-
++
++
+
--
--
-
PA-4020
Balanced input noninverting - dual channel output
○○○○○○○○○○○○○○○○○○○○○○○○○○○○○
++
++
+
++
++
+
--
--
-
--
--
-
--
--
-
--
--
-
++
++
+
++
++
+
--
--
-
Unbalanced input noninverting -- dual channel output
--
--
-
++
++
+
○○○○○○○○○○○○○○○○○○○○○○○○○○○○○
++
++
+
--
--
-
++
++
+
++
++
+
--
--
-
++
++
+
++
++
+
++
++
+
Balanced input non-inverting -- bridge mode
++
++
+
PA-4020
PA-4020
Fig. 3 Output Connections

12
++
++
+++
++
+
++
++
+++
++
+
PA-4020
○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○
Fig. 4 Dual-Channel mode -- Constant Voltage 100 watts per Channel Output
Output ConnectionsOutput Connections
Output ConnectionsOutput Connections
Output Connections
++
++
+
++
++
+
DH-100
DH-100
NC ++
++
+
++
++
+
DH-100
NC
NC
1
(2)
1
2
2
3
4
3
4
++
++
+
--
--
-
70.7 volts
200 watts
Fig. 5 Bridged mode -- Constant Voltage 200 watts Total Output

13
TT
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ouble Shootingle Shooting
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SerSer
SerSer
Service and Maintenancevice and Maintenance
vice and Maintenancevice and Maintenance
vice and Maintenance
ThePA-4020Bcontainsnouser serviceableparts.
No routine maintenance is required. Inoperative
units should be returned to the factory for ex-
change or repair.
See procedure for return of defective materials.
If the PA-4020B thermal LED remains lit even af-
tertheamplifierhascooleddown,adcoffset/load
protection cycle has occurred. Cycle the on/off
switch to reset the device.
OneOne
OneOne
One YY
YY
Year Standarear Standar
ear Standarear Standar
ear Standardd
dd
d
WW
WW
Warar
arar
arrr
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rantyanty
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anty
IRP professional sound products L.P. warrants
to the original purchaser each product manufac-
tured by it to be free from defect in material and
workmanship for a period of one year from date
of sale to original purchaser, and agrees to rem-
edy any such defect, or to furnish a new part in
exchange for any part of any product of its manu-
facture which, under normal installation, use and
service,disclosessuch defect provided such part
orproductis returned by the originalpurchaserto
the IRP factory within one year from he date of
sale, with all transportation charges prepaid, and
provided that the IRP examination discloses that
it is defective.
This warranty does not extend to any IRP prod-
uct which has been subject to misuse, neglect,
accident, incorrect wiring by others, improper
installation, or to use in violation of instructions
furnished by IRP, nor to products on which the
serialoridentifyingnumbershavebeenremoved,
defaced or changed, nor to accessories used
therewith not of IRP manufacture.
IRP’s obligation under this warranty as to any
products or parts approved by IRP for remedy or
exchangeislimited,atits option, toreplacingsuch
products or parts in kind without charge to the
original purchaser, or to crediting the original
purchaserwiththe purchase price of thereturned
defective products.
This warranty is in lieu of all other warranties, ex-
press or implied, and no representative of IRP or
anyother person is authorizedtoassumefor IRP
any other liability in connection with the sales of
its product.
RR
RR
Returetur
eturetur
eturn Prn Pr
n Prn Pr
n Procedurocedur
ocedurocedur
ocedureses
eses
es
Should you encounter any problems with your
IRP product, be sure to contact either your local
authorized IRP dealer or the IRP factory before
taking it anywhere for repairs. We will help you to
identify and locate any specific malfunctions,
possibly avoiding needless shipment, or we will
instruct you as to the speediest method for
authorized repair.
If you must send your IRP product to the factory
for repair, be sure to contact the IRP Sales
Department for a Return Authorization Number.
Includethefollowinginformationwiththereturned
product:
1. Your complete name and return shipping
address
(PO box numbers are not acceptable)
2. The model number, serial number and the
Return Authorization Number.
(RA # must appear on the outside of the
shipping container)
3. A complete and detailed description of any
and all problems you experienced with the
product
Never ship the unit in any shipping carton other
than the original or a replacement supplied by
IRP. Ship to us only by a reputable carrier. Be
sure to insure the package for full replacement
value. IRP cannot be held responsible for any
damage incurred during shipment
If you need further assistance please contact us
at the address and communication numbers as
shown on the rear cover of this manual.

14
IRP professional sound products L.P.
1225 Greenbriar Drive !"Suite R
Addison,IL60101USA
800-255-6993 !"630-860-1993 !"FAX [phone] !"www.irp.net