Hafler 9303 Owner's manual

®
MADE
USA
IN THE
PROFESSIONAL POWER AMPLIFIER
9303 / 9505
Installation & Operation
PROFESSIONAL POWER AMPL
nova
trans
®

NOTICE - IMPORTANT SAFETY INFORMATION
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
!!
WARNING: TO PREVENT FIRE OR
SHOCK HAZARD, DO NOT EXPOSE THIS
EQUIPMENT TO RAIN OR MOISTURE.
1. READ INSTRUCTIONS
AllthesafetyandoperatinginstructionsofyourHaflerequipment
should be read before power is applied to the equipment.
2. RETAIN OWNER'S MANUAL
These safety and operating instructions should be retained for
future reference.
3. HEED WARNINGS
All warnings on the equipment and in the operating instructions
are important and should be followed.
4. FOLLOW INSTRUCTIONS
All operating and use instructions are important and should be
followed.
5. HEAT
Theequipmentshouldbekeptawayfromareasofhightempera-
ture, i.e., heater vents, radiators, stoves/ovens, fireplaces, etc.
6. VENTILATION
The equipment should be used in an area suitable for proper
ventilation. Care should be taken not to impede airflow in and
around the cabinet. Do not mount on a carpeted shelf or in a
sealed enclosure. Allow for proper clearance above the equip-
ment.
7. WATER AND MOISTURE
The equipment should not be used in or around water, such as a
bathtub,sink,orswimmingarea. Also,theequipmentshouldnot
be used in areas prone to flooding, such as a basement.
8. POWER SOURCES
The equipment should be connected only to a power source of
the same voltage and frequency as that listed on the rear panel
above the power cord entry point.
9. POWER CORD PROTECTION
Powercordsshouldbearranged so they do notinterferewiththe
movementofobjectsintheroom:people,fanblades,utilitycarts,
etc. Also,careshouldbetakenthatthecordisnotpinchedorcut,
and placed so it is not in danger of being pinched or cut, as in
under a rug, around a tight corner, etc.
10. POWER CORD GROUNDING
Thepowersupplycordisofathreewiregroundedtype,designed
to reduce the risk of electric shock sustained from a live cabinet.
It is assumed to be of suitable length for most uses of the
equipment. The use of extension cords and power strips is
discouraged unless they are of suitable rating to deliver the
required total current for safe operation of all connected equip-
ment. Furthermore,extensioncordsorpowerstripsmustprovide
thesamethreewiregroundedconnection. Itisimportantthatthe
blades of the equipment’s plug be able to fully insert into the
matingreceptacle. Neverremovetheroundgroundingpinonthe
plugin anattempt to mate to a two wireungrounded receptacle:
use a grounding adaptor with the grounding tab or wire suitably
connected to earth ground.
11. NON-USE PERIODS
During periods of extended non-use, the power cord should be
unplugged from the power source.
12. CLEANING
Theequipmentshould be cleaned onlyasdetailed in theoperat-
ing instructions.
13. OBJECT AND LIQUID ENTRY
Care should be taken so that objects and/or liquids, such as
cleaningfluidsor beverages, arenotspilled into the enclosureof
the equipment.
14. DAMAGE REQUIRING SERVICE
Haflerequipmentshouldbeservicedbyqualifiedserviceperson-
nel when:
A. The power supply cord or plug has been damaged, or
B. Objects have fallen, or liquid has been spilled into the
equipment, or
C. The equipment has been exposed to rain, or
D. The equipment does not appear to operate normally or
exhibits a marked change in performance, or
E. The equipment has been dropped, or the enclosure has
been damaged.
15. SERVICING
Theusershouldnotattempttoservicetheequipmentbeyondthat
whichisdescribedintheoperatinginstructions. Allotherservice
should be referred to qualified service personnel.
16. CARTS AND STANDS
The equipment should be used with carts or stands only of
sufficient strength and stability for the use intended.
Anequipmentandcartcombinationshouldbemovedwithcare.
Quickstopsandstarts,excessiveforce,andunevensurfacesmay
cause the equipment and cart combination to topple.
– i –
The lightning flash with arrowhead symbol within an equilateral triangle
is intended to alert the user to the presence of uninsulated "dangerous
voltage" within the product's enclosure, that may be of sufficient magni-
tude to constitute a risk of electric shock to persons.
The exclamation point within an equilateral triangle is intended to alert
theuser of the presence of important operatingand maintenance(servic-
ing) instructions in the literature accompanying the appliance.

PERFORMANCE SPECIFICATIONS
9303/9505
Full Power Bandwidth: 0.15Hz to 300kHz
Signal-to-Noise: >100dB “A” Weighted
Slew Rate: 150 V/µs
CMRR: 75dB at 1kHz
Gain: +29dB max.
9303
Power Rating: 150 wpc @8 Ω, 225 wpc @ 4Ω, 450 Watts mono @ 8Ω
Distortion: 0.07% THD 20-20Hz, Typically 0.005% THD 1kHz, at rated power into 8Ω
Damping Factor: 800 (to 1kHz); 80 (to 20kHz); 20 (to 100kHz) into 8Ω
Input Sensitivity Range: 1.22 Vrms for 150W into 8Ω, 1.06Vrms for 225W into 4Ω
Dimensions: 19"W x 12-1/2"D x 3-1/2"H (excluding feet)
Weight: 36 lbs. (16.4kg)
Power Consumption: Quiescent, 84 VA; at rated power, 612 VA (150W into 8Ω, both channels driven)
9505
Power Rating: 250 wpc @8 Ω, 375 wpc @ 4Ω, 750 Watts mono @ 8Ω
Distortion: 0.1% THD 20-20Hz, Typically 0.005% THD 1kHz, at rated power into 8Ω
Damping Factor: 1000 (to 1kHz); 100 (to 20kHz); 20 (to 100kHz) into 8Ω
Input Sensitivity Range: 1.58 Vrms for 250W into 8Ω, 1.37Vrms for 375W into 4Ω
Dimensions: 19"W x 12-1/2"D x 5-1/4"H (excluding feet)
Weight: 50 lbs. (22.7kg)
Power Consumption: Quiescent, 132 VA; at rated power, 1020 VA (250W into 8Ω, both channels driven)
– ii –

TABLE OF CONTENTS
SAFETY PRECAUTIONS........................................................................................................................................... i
PERFORMANCE SPECIFICATIONS......................................................................................................................... ii
INTRODUCTION ................................................................................................................................................... 1
INSTALLATION
Location ........................................................................................................................................................... 1
AC Line ............................................................................................................................................................ 1
Input................................................................................................................................................................. 2
Balanced Input: 1/4" Tip Ring Sleeve.......................................................................................................... 2
Balanced Input: XLR................................................................................................................................... 2
Unbalanced Input ...................................................................................................................................... 2
Unbalanced Source with Balanced Input ................................................................................................... 2
Output Connections ......................................................................................................................................... 2
Monophonic Use.............................................................................................................................................. 2
OPERATION
Power Switch ................................................................................................................................................... 3
Balanced/Unbalanced Input Switch.................................................................................................................. 3
Ground Switch ................................................................................................................................................. 3
Mono Switch .................................................................................................................................................... 3
Load Fault Protection........................................................................................................................................ 3
Warm Up ......................................................................................................................................................... 3
Cleaning and Maintenance............................................................................................................................... 3
Schematic Diagram .......................................................................................................................................... 4
PC Board Layout............................................................................................................................................... 6
Parts List ........................................................................................................................................................... 7
9303/9505 Functional Block Diagram .............................................................................................................. 8
TECHNICAL INFORMATION
Theory and Operation of trans• nova ................................................................................................................ 9
Circuit Implementation..................................................................................................................................... 9
Calibration ..................................................................................................................................................... 10
Common Mode Rejection ........................................................................................................................ 10
Bias.......................................................................................................................................................... 10
WARRANTY ......................................................................................................................................................... 11

INTRODUCTION
–1 –
TheHafler 9303 and 9505 aretwo channel professionalpower amplifiers. Passivecooling with large heatsinks
isused forlowmechanicalnoise.Ourpatentedtrans•novacircuit topologyandMOSFET outputstageensures
trouble free, long term operation and is backed by our seven year warranty.
This manual contains information on using the 9303 and 9505 amplifiers. It is organized into three main
sections.“Installation”coversthelocationandconnectionoftheamplifierinthesystem.Likemanyprecision
components careful attention to the initial setup can yield dividends in higher performance and trouble-free
use.“Operation” coversthe controls and featuresof the amplifiersand how touse them toget the besteffect.
The“TechnicalInformation”sectioncontainsinformationonthecircuitimplementationandtheschematic
diagram and parts list. We strongly urge reading over the Installation and Operation portions of this manual
before putting the amplifier into service.
Thecircuitryusedinthe 9303and9505isthelatestrefinementofourtrans•nova(TRANSconductanceNOdal
Voltage Amplifier, US Patent 4,467,288) circuit. The 9303 and 9505 utilize our proprietary DIABLO (patent
applicationin progress)transconductancedriver stagewhichcombines thelinearityof ClassAoperation with
the current headroom of a Class B system. When used in combination with the robust output stage used with
these models, DIABLO yields lower high frequency distortion without the sonic penalties associated with
increasing the negative feedback.
The9303and9505havefullydifferentialinputsforuseinbalancedlinesystems.Thebalancedinputterminals
work with either 1/4" TRS phone or XLR plugs. Gold-plated RCA phono jacks are available for use with
unbalanced source components. The output terminals are gold-plated binding posts, spaced on 3/4" centers
forusewithdualbananaplugs.Forhighpowerapplications,theamplifiercanruninbridgedmonofordouble
the output voltage. Using state-of-the-art surface mount assembly equipment in our manufacturing facility
ensures consistency and reliability.
LOCATION
The 9303 and 9505 can produce considerable heat in normal operation so the primary consideration when
determining a location for the amplifiers is to allow for adequate ventilation. The large heatsinks provide
unrestricted airflow, but care must be taken to keep the slots in the bottom panel and top cover clear, as well.
Iftheamplifierismountedinanequipmentrack,makesureadjacentequipmentdoesnotimpedecoolairflow
through the amplifier bottom and out the top. The attached feet provide sufficient clearance for the bottom
whentheamplifierisrestingonahardsurface.Inadequateventilationcanshortencomponentlife,especially
when other equipment raises the ambient air temperature, so a circulating fan should be considered in tight
quarters. The power transformer can generate a substantial magnetic field, so caution should be exercised in
the placement of low level components such as a tape deck, mixer or mic preamp to avoid inducing noise in
the low level circuitry.
AC LINE
The 9303 and 9505 operate from a 120 volt, 60Hz AC power line. Connection is made by an IEC Type 320,
grounded line cord. For safety considerations only a properly grounded (earthed) receptacle should be used.
Ifagroundedcircuit isnotavailabledonotbreakoff thegroundpin;usetheproperadapter plugforatwowire
receptacle.Located inside the amplifieris the line fusewhich interrupts thepower to theamplifier. If this fuse
blows replace it only with the same type and rating fuse. The correct replacement fuse value is included in the
parts list in the “Technical Information” section of this manual. If the replacement fuse blows, this is an
indication of a fault with the amplifier. Servicing should be performed only by a qualified technician.
INSTALLATION

–2 –
INPUT
The 9303 and 9505 have input jacks for both balanced and unbalanced input signals. The unbalanced inputs
use conventional RCA phono jacks. When using the RCA inputs, the rear panel BALANCED/UNBALANCED
switchmustbesettotheUNBALANCEDposition.Thebalancedinputjacksaredualfunctionconnectorswhich
accept 1/4" TRS (Rip Ring Sleeve) phone or XLR plugs. Set the BALANCED/UNBALANCED switch to the
BALANCED Position to use these jacks. The connector pin-out is printed on the rear panel of the amp.
Balanced Input: 1/4" Tip Ring Sleeve
The1/4"balancedinputjackisconnectedaccordingtoconventionalusagewiththeTiphigh(+),Ring
return (–) and the Sleeve ground shield.
Balanced Input: XLR
The XLR balanced input jack is connected according to the IEC International Standard, with pin 2
high (+), pin 3 return (–) and pin 1 ground shield. When preparing to use the amplifier, check the
output configuration of the source unit to maintain the proper signal polarity.
Unbalanced Input
Manypopular mixersuseunbalanced RCAphonojacks forthemonitor outputs.Forshort cableruns
RCA audio patch cable can be used without any system performance penalty. Check the mixer specs
for the maximum cable length it will drive. Make sure the BALANCED/UNBALANCED switch is set
for UNBALANCED operation.
Unbalanced Source with Balanced Input
Betternoiserejectionforlongcablerunscanbeachievedbyusingatwistedpairbalancedcable from
the unbalanced source. At the source end of the cable, connect an RCA plug with the return (–) wire
and shield connected to the ground shell of the plug. Wire the plug at the amplifier end of the cable
the same as for the regular balanced input connection.
OUTPUT CONNECTIONS
The speaker output connectors are dual binding posts. These binding posts will directly accept 12 AWG wire
or banana plugs and are spaced on 3/4" centers to accept dual banana plugs.
MONOPHONIC USE
Forsystems with highpower requirements, theamplifiers canbe configured forsingle channelbridged mono
operation. To bridge the amplifier, set the rear panel STEREO/MONO switch to the Mono position; use only
theleftchannelinput,andconnectthespeakertotheredoutputbindingposts.Whentheamplifierisbridged,
theoutputisfloating.Anyspeakerwhichrequiresacommongroundfromtheamplifieroutputcannotbeused
in this application. Since a bridged amplifier shares the load between the two channels, the amplifier will
effectively drive half of the load. Therefore, for bridged mono operation we recommend using an eight ohm
load as the minimum impedance.

–3 –
OPERATION
POWER SWITCH
ThePOWERswitchis located on the front panel of the amplifier. An internal lampindicateswhenitisturned
on. Standard practice is to turn the amplifier on last and off first when switching components individually to
prevent sending damaging transients, generated in the source components, to the speakers. It is possible to
leave the power switch in the on position and switch the amplifier remotely through a power distribution
block or preamp switched outlet. When doing so make sure the switch is rated for the current required by the
amplifier.
BALANCED/UNBALANCED INPUT SWITCH
The BALANCED/UNBALANCED switch configures the input grounding when using the RCA phono input
jacks. In the UNBALANCED position the balanced differential input return (–) port is grounded inside the
amplifier. This prevents noise pickup or unstable amplifier operation caused by the open input. In the
BALANCED position the differential amplifier inputs are connected to the hot (+) and (–) incoming signal
connectors.
GROUND SWITCH
Groundloopsarecharacterizedbyahumorbuzzinthesystemandarecausedbyavoltagepotentialdifference
between two points in a ground circuit. Ground loops are aggravated when multiple paths exist for a given
circuit. Mounting components in a rack with metal rails may introduce ground loops between associated
equipment,becausetherails canestablishanadditionalgroundpath.TheCHASSIS/FLOAT switchallowsyou
to select the amplifier grounding scheme for best system compatibility. With the switch in the CHASSIS
positionallsignalgroundsare referred to the chassis and power line ground. In the FLOAT position the signal
ground is decoupled from the chassis. The position of the switch is determined by the overall noise in the
system; choose the position which gives the lowest hum.
MONO SWITCH
Conventional two-channel stereo operation is obtained with the STEREO/MONO switch in the STEREO
position. For high powered single channel use, set the switch to MONO and use the left channel input and
the RED binding posts only for the output. For thermal considerations we do not recommend using less than
an eight ohm load on the amplifier when running it in mono. When the switch is set in the mono position
the left channel (+) and (–) inputs are connected to the right channel in reversed polarity, which inverts the
right channel output.
LOAD FAULT PROTECTION
Becauseoftheself-protectingpropertiesandfaulttoleranceofthelateralMOSFETsusedinthe9303and9505,
elaborate voltage and current limiting protection schemes are not necessary. To prevent damage to the
amplifier from a fault in the loudspeaker load, the power supply B+ and B– rails are fused. Check these fuses
if the sound is garbled or there is no output. The fuses should not blow under normal use and a blown fuse
is usually an indication of a fault. The fault could be a bad connection, a problem with the speaker or a short
in the speaker line. Disconnect power to the amplifier before removing the cover.
WARM UP
Inordertoachievethebestsonicperformancefromtheamplifier,werecommendlettingitwarmupfor1hour
beforebeginninganycriticallistening.Theamplifierwillnotdeliveritsfullpotentialsoundqualitybeforethis
time has passed.
CLEANING AND MAINTENANCE
There is no requirement for regular maintenance on the electronic components of the amplifier. If the case
becomessoileditcanbecleanedusingasoftclothandamilddetergent,suchasspraywindoworglasscleaner.
If the amplifier is located in a particularly dusty environment cleaning the inside with compressed air or
vacuuming every 18 to 24 months is sufficient.

–4 –
SCHEMATIC DIAGRAM
NOTES: Unless specified otherwise
1. All resistors in ohms
2. All capacitors in microfarads
3. Component Designators:
1-99: Left Channel
101-199: Right Channel
201-299: Common Parts
301-399: Chassis/Power Supply
4. Left Channel Only Shown
5. Stereo/Mono Switch Shown in Stereo
6. Balanced/Unbalanced Switch Shown in Balanced Position
7. Chassis/Float Ground Switch Shown in Float Position

–5 –

–6 –
PC BOARD LAYOUT