Crown POWER-TECH 3 User manual

Models:
Power-Tech 1, 2 & 3
Some models may be exported under the name Amcron .
®
©2000 by Crown International, Inc., P.O. Box 1000, Elkhart, Indiana
46515-1000 U.S.A. Telephone: [phone]. Power-Tech amplifiers
are produced by the Professional Audio Unit of Crown International,
Inc. Trademark Notice: Power-Tech
™is a trademark and
Amcron ,
®
Crown ,
®
IOC
®and
ODEP
®are registered trademarks of Crown
International,Inc.Othertrademarksarethepropertyoftheirrespective
owners.
125351-4
02/00
POWER-TECH™

WORLDWIDE
SUMMARY OF WARRANTY
The Crown Audio Division of Crown International, Inc., 1718 West
Mishawaka Road, Elkhart, Indiana 46517-4095 U.S.A. warrants to you,
the ORIGINAL PURCHASER and ANY SUBSEQUENT OWNER of
each NEW Crown1product, for a period of three (3) years from the date
ofpurchasebytheoriginalpurchaser(the“warrantyperiod”)thatthenew
Crown product is free of defects in materials and workmanship, and we
further warrant the new Crown product regardless of the reason for
failure, except as excluded in this Crown Warranty.
1
Note: If your unit bears the name “Amcron,” please substitute it for the
name “Crown” in this warranty.
ITEMS EXCLUDED FROM THIS CROWN WARRANTY
This Crown Warranty is in effect only for failure of a new Crown product
whichoccurredwithintheWarrantyPeriod.Itdoesnotcoveranyproduct
which has been damaged because of any intentional misuse, accident,
negligence, or loss which is covered under any of your insurance
contracts. This Crown Warranty also does not extend to the new Crown
product if the serial number has been defaced, altered, or removed.
WHAT THE WARRANTOR WILL DO
Wewillremedyanydefect,regardlessofthereasonforfailure(exceptas
excluded), by repair, replacement, or refund. We may not elect refund
unless you agree, or unless we are unable to provide replacement, and
repairisnotpracticalorcannotbetimelymade.Ifarefundiselected,then
you must make the defective or malfunctioning product available to us
freeandclearofallliensorotherencumbrances.Therefundwillbeequal
to the actual purchase price, not including interest, insurance, closing
costs, and other finance charges less a reasonable depreciation on the
product from the date of original purchase. Warranty work can only be
performed at our authorized service centers. We will remedy the defect
and ship the product from the service center within a reasonable time
after receipt of the defective product at our authorized service center.
HOW TO OBTAIN WARRANTY SERVICE
Youmustnotifyusofyourneed forwarrantyservicenot laterthanninety
(90)daysafterexpirationofthewarrantyperiod.Allcomponentsmustbe
shipped in a factory pack. Corrective action will be taken within a
reasonable time of the date of receipt of the defective product by our
authorized service center. If the repairs made by our authorized service
center are not satisfactory, notify our authorized service center
immediately.
DISCLAIMER OF CONSEQUENTIAL AND INCIDENTAL
DAMAGES
YOU ARE NOT ENTITLED TO RECOVER FROM US ANY
INCIDENTAL DAMAGES RESULTING FROM ANY DEFECT IN THE
NEW CROWN PRODUCT. THIS INCLUDES ANY DAMAGE TO
ANOTHER PRODUCT OR PRODUCTS RESULTING FROM SUCH A
DEFECT.
WARRANTY ALTERATIONS
No person has the authority to enlarge, amend, or modify this Crown
Warranty. This Crown Warranty is not extended by the length of time
whichyouaredeprivedoftheuseofthenewCrownproduct.Repairsand
replacementpartsprovidedunderthetermsofthisCrownWarrantyshall
carry only the unexpired portion of this Crown Warranty.
DESIGN CHANGES
Wereservetherighttochangethedesignofanyproductfromtimetotime
withoutnotice and with noobligation to make correspondingchanges in
products previously manufactured.
LEGAL REMEDIES OF PURCHASER
NoactiontoenforcethisCrownWarrantyshallbecommencedlaterthan
ninety (90) days after expiration of the warranty period.
THIS STATEMENT OF WARRANTY SUPERSEDES ANY OTHERS
CONTAINED IN THIS MANUAL FOR CROWN PRODUCTS.
9/90
NORTH AMERICA
SUMMARY OF WARRANTY
TheCrownAudioDivisionofCrownInternational,Inc.,1718WestMishawaka
Road, Elkhart, Indiana 46517-4095 U.S.A. warrants to you, the ORIGINAL
PURCHASER and ANY SUBSEQUENT OWNER of each NEW Crown
product,foraperiodofthree(3)yearsfromthedateofpurchasebytheoriginal
purchaser(the“warrantyperiod”)thatthenewCrownproductisfreeofdefects
in materials and workmanship. We further warrant the new Crown product
regardless of the reason for failure, except as excluded in this Warranty.
ITEMS EXCLUDED FROM THIS CROWN WARRANTY
ThisCrownWarrantyisineffectonlyfor failure of a new Crown product which
occurred within the Warranty Period. It does not cover any product which has
been damaged because of any intentional misuse, accident, negligence, or
loss which is covered under any of your insurance contracts. This Crown
Warranty also does not extend to the new Crown product if the serial number
has been defaced, altered, or removed.
WHAT THE WARRANTOR WILL DO
We will remedy any defect, regardless of the reason for failure (except as
excluded), by repair, replacement, or refund. We may not elect refund unless
you agree, or unless we are unable to provide replacement, and repair is not
practicalorcannotbe timely made. If arefundiselected, then you must make
thedefectiveormalfunctioningproductavailabletousfreeandclearofallliens
orotherencumbrances.Therefundwill be equal to the actualpurchaseprice,
notincludinginterest,insurance,closingcosts,andotherfinancechargesless
a reasonable depreciation on the product from the date of original purchase.
Warranty work can only be performed at our authorized service centers or at
the factory. We will remedy the defect and ship the product from the service
center or our factory within a reasonable time after receipt of the defective
product at our authorized service center or our factory. All expenses in
remedying the defect, including surface shipping costs in the United States,
will be borne by us. (You must bear the expense of shipping the product
between any foreign country and the port of entry in the United States and all
taxes, duties, and other customs fees for such foreign shipments.)
HOW TO OBTAIN WARRANTY SERVICE
You must notify us of your need for warranty service not later than ninety (90)
days after expiration of the warranty period. All components must be shipped
in a factory pack, which, if needed, may be obtained from us free of charge.
Corrective action will be taken within a reasonable time of the date of receipt
of the defective product by us or our authorized service center. If the repairs
made by us or our authorized service center are not satisfactory, notify us or
our authorized service center immediately.
DISCLAIMER OF CONSEQUENTIAL AND INCIDENTAL DAMAGES
YOU ARE NOT ENTITLED TO RECOVER FROM US ANY INCIDENTAL
DAMAGES RESULTING FROM ANY DEFECT IN THE NEW CROWN
PRODUCT.THIS INCLUDES ANYDAMAGE TO ANOTHERPRODUCT OR
PRODUCTS RESULTING FROM SUCH A DEFECT. SOME STATES DO
NOT ALLOW THE EXCLUSION OR LIMITATIONS OF INCIDENTAL OR
CONSEQUENTIAL DAMAGES, SO THE ABOVE LIMITATION OR
EXCLUSION MAY NOT APPLY TO YOU.
WARRANTY ALTERATIONS
Nopersonhastheauthoritytoenlarge,amend,ormodifythisCrownWarranty.
This Crown Warranty is not extended by the length of time which you are
deprivedoftheuseofthenewCrownproduct.Repairsandreplacementparts
providedunderthetermsofthisCrownWarrantyshallcarryonlytheunexpired
portion of this Crown Warranty.
DESIGN CHANGES
We reserve the right to change the design of any product from time to time
without notice and with no obligation to make corresponding changes in
products previously manufactured.
LEGAL REMEDIES OF PURCHASER
THIS CROWN WARRANTY GIVES YOU SPECIFIC LEGAL RIGHTS, YOU
MAY ALSO HAVE OTHER RIGHTS WHICH VARY FROM STATE TO
STATE. No action to enforce this Crown Warranty shall be commenced later
than ninety (90) days after expiration of the warranty period.
THIS STATEMENT OF WARRANTY SUPERSEDES ANY OTHERS
CONTAINED IN THIS MANUAL FOR CROWN PRODUCTS.
9/90
Telephone: [phone]. Facsimile: 219-294-8301
Telephone: [phone]. Facsimile: 219-294-8301
THREE YEAR
FULL WARRANTY
YEAR
3
YEAR
3

WARNING
TO REDUCE THE RISK OF ELECTRIC
SHOCK, DO NOT EXPOSE THIS
EQUIPMENT TO RAIN OR MOISTURE!
Magnetic Field
CAUTION! Do not locate sensitive high-gain
equipment such as preamplifiers or tape decks
directl above or below the unit. Because this
amplifier has a high power density, it has a strong
magnetic field which can induce hum into unshielded
devices that are located nearby. The field is strongest
just above and below the unit.
Ifanequipmentrackisused, werecommend locating
the amplifier(s) in the bottom of the rack and the
preamplifier or other sensitive equipment at the top.
C A U T I O N
RISK OF ELECTRIC SHOCK
DO NOT OPEN
A V I S
RISQUE DE CHOC ÉLECTRIQUE
N’OUVREZ PAS
À PRÉVENIR LE CHOC
ÉLECTRIQUE N’ENLEVEZ
PAS LES COUVERTURES.
RIEN DES PARTIES
UTILES À L’INTÉRIEUR.
DÉBRANCHER LA BORNE
AVANT D’ENLEVER LA
COVERTURE EN ARRIÈRE.
TO PREVENT ELECTRIC SHOCK DO
NOT REMOVE TOP OR BOTTOM
COVERS. NO USER SERVICEABLE
PARTS INSIDE. REFER SERVICING
TO QUALIFIED SERVICE PERSON-
NEL. DISCONNECT POWER CORD
BEFORE REMOVING BACK PANEL
COVER TO ACCESS GAIN SWITCH.
IMPORTANT
THE POWER-TECH 1 AND 2 REQUIRE CLASS 2 OUTPUT WIRING.
THE POWERTECH 3 REQUIRES CLASS 1 WIRING IF USED IN THE
BRIDGE MONO OR PARALLEL MONO MODES.
Theinformation furnishedinthismanualdoesnotincludeallofthedetailsofdesign,production,orvariationsofthe
equipment. Nor does it cover every possible situation which may arise during operation or maintenance. If you
needspecialassistancebeyondthescopeof this manual, please contact your authorized Crownrepresentativeor
our Technical Support Group.
Crown Audio Technical Support Group
Plant 2 SW, 1718 W. Mishawaka Rd., Elkhart, Indiana 46517 U.S.A.
Phone: [phone] (North America, Puerto Rico and Virgin Islands) or 219-294-8200
Fax: [phone] Fax Back (North America only): 800-294-4094 or 219-293-9200
Fax Back (International): 219-294-8100 Internet: http://www.crownaudio.com
Lightning Bolt Symbol:
This symbol is used to alert the user
to the presence of dangerous
voltages and the possible risk of
electric shock.
Exclamation Mark Symbol:
This symbol is used to alert the user to
refer to the instruction manual for
important operating or maintenance
instructions.
Printed on
recycled paper.

Power-Tech Series Power Amplifiers
Page 4 Reference Manual
CONTENTS
1 Welcome ................................................... 5
1.1 Unpacking..................................................................... 5
1.2 Features ........................................................................ 5
2 Installation................................................. 6
2.1 Stereo 6
2.2 Mono 6
2.3 Input Sensitivity Adjustment ......................................... 8
2.4 Additional Load Protection ........................................... 8
2.5 Required AC Mains....................................................... 8
3 Operation................................................... 9
3.1 Precautions................................................................... 9
3.2 Indicators...................................................................... 9
3.3 Protection Systems ....................................................... 9
3.3.1 ODEP................................................................. 9
3.3.2 Ultrasonic and RF Protection ............................. 9
3.3.3 Drive Protection................................................. 9
3.3.4 TransformerThermalProtection ...................... 10
3.3.5 Fuses and Circuit Breakers .............................. 10
3.4 Controls...................................................................... 10
3.5 Filter Cleaning ............................................................ 10
4 Specifications ............................................11
5 Accessories ............................................... 17
5.1 MT-XLR ...................................................................... 17
5.2 MT-BB ........................................................................ 17
6 Service ....................................................18
6.1 Worldwide Service ...................................................... 18
6.2 North American Service .............................................. 18
6.2.1 Service at a North American Service Center .... 18
6.2.2 Factory Service ................................................ 18
Important Safety Instructions
1) Read these instructions.
2) Keep these instructions.
3) Heed all warnings.
4) Follow all instructions.
5) Do not use this apparatus near water.
6) Clean only with a dry cloth.
7) Do not block any ventilation openings. Install in
accordance with the manufacturer’s instruc-
tions.
8) Do not install near any heat sources such as ra-
diators, heat registers, stoves, or other appara-
tus that produce heat.
9) Do not defeat the safety purpose of the polar-
ized or grounding-type plug. A polarized plug
has two blades with one wider than the other. A
grounding-type plug has two blades and a third
grounding prong. The wide blade or the third
prong is provided for your safety. If the provided
plug does not fit into your outlet, consult an elec-
trician for replacement of the obsolete outlet.
10) Protect the power cord from being walked on or
pinched, particularly at plugs, convenience re-
ceptacles, and the point where they exit from
the apparatus.
11) Only use attachments/accessories specified by
the manufacturer.
12) Unplug this apparatus during lightning storms
or when unused for long periods of time.
13) Refer all servicing to qualified service person-
nel. Servicing is required when the apparatus
has been damaged in any way, such as power-
supply cord or plug is damaged, liquid has
been spilled or objects have fallen into the ap-
paratus, the apparatus has been exposed to
rain or moisture, does not operate normally, or
has been dropped.

Power-Tech Series Power Amplifiers
Page 5Reference Manual
1.1 Unpacking
Please unpack and inspect your new amplifier
for any damage that may have occurred during
transit. If damage is found, notify the transportation
company immediately. Only you may initiate a claim
with the carrier for shipping damage. Even if the unit
arrived in perfect condition, as most do, save all
packing materials so you will have them if you ever
need to transport the unit. NEVER SHIP THE UNIT
WITHOUT THE FACTORY PACK.
1.2 Features
❏Rugged, professional power amplifier built for the road.
Mounts in EIA standard 19-inch (48.3-cm) rack.
❏Quick-access front panel power switch and level
controls. Turn-on delay for loudspeaker protection.
❏The patented
ODEP
®circuitry and
Grounded Bridge
™
design combine to provide performance and reliability
that surpass all traditional designs.
❏Easy to read signal presence (SPI) and distortion
(
IOC
®) indicator for each channel.
❏High damping factor provides superior control over
low-frequency drivers for a clean, accurate low end.
❏Safe with any load. Bridge-Mono and Parallel-Mono
modes make it easy to optimize the amplifier’s perfor-
mance for a wide range of loads.
❏Complete protection against shorted outputs, mis-
matched loads, overheating, input/output DC and high-
frequency overload; full internal fault protection.
❏Balanced phone jack inputs with internal three position
sensitivity switch and front-panel level controls. XLR
and barrier block input connectors are optional.
❏Efficient heat sinks and self-contained forced-air
cooling system dissipate heat quickly and evenly for
extra amplifier protection and greater output power.
❏Three year “No-Fault” full warranty protects your
investment and guarantees its specifications.
1 Welcome
Congratulations on purchasing a Crown Power-
Tech
™amplifier.
Power-Tech amplifiers are compact,
professional stereo power amplifiers engineered to
meet the most demanding sound reinforcement
needs. They compare very favorably to more expen-
sive amplifiers, providing uncolored sound and signal-
to-noise ratios commonly associated with recording
studios.
This manual will help you successfully install and
use your amplifier—we strongly recommend you read
all instructions, warnings and cautions. If you plan to
operate in one of the two mono modes, be sure to
read the Mono section. Also for your protection,
please save your bill of sale since it is your official
proof of purchase.
Fig. 1.1 Power-Tech Front and Back Panels

Power-Tech Series Power Amplifiers
Page 6 Reference Manual
2 Installation
Always remove power from the unit and turn the level
controls off (fully counterclockwise) when making or
breaking connections. This reduces the chance of
blasts that can cause loudspeaker damage.
The guidelines below are provided to help you quickly
get your amplifier installed and ready to go. Be sure to
follow the instructions in Sections 2.1 and 2.2 for the
selected mode of operation. Additional information on
input sensitivity, load protection and required AC mains
is provided in Sections 2.3, 2.4 and 2.5.
1. Install the amplifier in an EIA standard 19-inch
(48.3-cm) rack or place it on a stable surface. Your
amplifier is 19 inches (48.3 cm) wide, 3.5 inches
(8.9 cm) tall and 16 inches (40.6 cm) deep behind
the mounting surface. IMPORTANT: Make sure
the unit has adequate ventilation.
2.1 Stereo
1. Turn down the level controls (fully counterclock-
wise) and turn off the amplifier.
2. Set the back panel stereo/mono switch to Stereo.
3. If present, remove the Parallel-Mono jumper.
4. Connect the input and output cables as shown in
the first example in Figure 2.3.
5. Turn on the amplifier and adjust the level for each
channel with the front panel controls.
CAUTION: Never parallel the two outputs by directly
tying them together, and never parallel them with the
output of another amplifier.
2.2 Mono
Your amplifier’s mono modes provide double the power
of Stereo mode in a single channel. In Bridge-Mono
mode, the outputs are wired in series for twice the output
voltage. In Parallel-Mono mode, the outputs are
paralleled for twice the current capacity.
Bridge-Mono mode is provided for loads with an
impedance greater than 4 ohms. Parallel-Mono mode
should be used with loads of 4 ohms or less.
B R I D G E - M O N O
1. Turn down the level controls (fully counterclockwise) and
turn off the amplifier.
2. Set the back panel stereo/mono switch to Bridge-Mono.
3. If installed, remove the Parallel-Mono jumper wire.
4. Connect the input and output cables as shown in the
second example in Figure 2.3. Only use the Channel 1
input.
5. Make sure the load is balanced (neither side shorted to
ground) and do not use the black (–) binding posts.
6. Turn on the amplifier and adjust the level. Only use the
Channel 1 level control.
P A R A L L E L - M O N O
1. Turn down the level controls (fully counterclockwise) and
turn off the amplifier.
2. Set the back panel stereo/mono switch to Parallel-Mono.
3. Install a solid, 14-gauge (2-mm2) or heavier jumper wire
across the two red (+) binding post outputs.
4. Connect the input and output cables following the third
example in Figure 2.3. Only use the Channel 1 input.
5. Turn on the amplifier and adjust the level. Only use the
Channel 1 level control.
CAUTION: With Parallel-Mono wiring, do not switch to
Stereo or Bridge-Mono mode until the output jumper wire
is removed.
IMPORTANT: The Channel 2
IOC indicator will remain lit
when operating in Parallel-Mono mode.
Fig. 2.2 Power-Tech Input Wiring
2. Use high-quality loudspeaker cables to connect
the load to the amplifier’s outputs. Do not use
shielded cable.
3. Use shielded cables to connect audio sources to
the amplifier inputs. Either balanced or unbal-
anced wiring can be used as shown below. (XLR
connectors are available with the MT-XLR acces-
sory, see Section 5.)
Fig. 2.1 Do NOT Block Air Flow

Power-Tech Series Power Amplifiers
Page 7Reference Manual
Fig. 2.3 Three System Connection Methods

Power-Tech Series Power Amplifiers
Page 8 Reference Manual
2.3 Input Sensitivity Adjustment
The input sensitivity switch inside the amplifier is set to
0.775 volts at the factory.* It can be changed to 1.4 volts
or a voltage gain of 26 dB as follows:
1. Turn off and unplug the amplifier from the AC source.
2. Remove the access cover on the back panel.
3. Locate the labeled access hole for the sensitivity switch.
4. Set the switch to the desired position.
5. Replace the access cover plate.
When set to 26-dB gain, the Power-Tech 1 requires a
2.1-volt input, the Power-Tech 2 requires a 2.6-volt input
and the Power-Tech 3 requires a 3.3-volt input to deliver
full output into an 8-ohm load.
Fig. 2.4 Input Sensitivity Switch
2.4 Additional Load Protection
To protect against excessive power, a fuse can be
added in series with each loudspeaker cable. A single
fuse can protect the entire system, or one can be used
for each driver. High-frequency drivers (tweeters) are
usually more sensitive to large voltage peaks, while low-
frequency drivers (woofers) are typically most sensitive
to the heat from average (RMS) output power. To protect
your tweeters, we recommend that you use a high-speed
instrument fuse like the Littlefuse 361000 series. To
protect your woofers, we recommend using a slow-blow
fuse that more closely represents the thermal response
ofyour woofer. Use Figure 2.5 to find the correct valuefor
either type of fuse.
Example: (A) Choose the peak music power for the
loudspeaker (such as 75 watts). (B) Find the
loudspeaker impedance (8 ohms). (C) Draw a line
between points A and B. The line intersects the middle
scale at the correct fuse value (1.5 amps).
2.5 Required AC Mains
All Power-Tech amplifiers are shipped with an appropri-
ate line cord and plug. The standard cord and plug for
Fig. 2.5 Loudspeaker Fuse Nomograph
Fig. 2.6 AC Mains Cords and Plugs
each model are listed by country (or region) in
Figure 2.6. When possible, use a power receptacle on
a dedicated circuit, and always make sure it will
provide the right voltage with sufficient current. We do
not recommend operating your amplifier with voltages
greater than 10% above or below the unit’s rated
voltage. For example, if your amplifier is rated for
120 VAC, the line voltage should not exceed 132 VAC.
* Factory setting for international models is 1.4 V.

Power-Tech Series Power Amplifiers
Page 9Reference Manual
3 Operation
3.1 Precautions
Although your amplifier is protected from external faults,
the following safety precautions are recommended:
1. There are important differences among the Stereo,
Bridge-Mono and Parallel-Mono operating modes.
Please refer to Section 2 for additional information.
2. WARNING: Do not change the position of the
stereo/mono switch unless the amplifier is first
turned off.
3. CAUTION: In Parallel-Mono mode, a jumper is
used to connect the red binding post outputs.
Be sure to remove this jumper for Bridge-Mono
or Stereo mode, or high distortion and exces-
sive heating will occur. Also, make sure the ste-
reo/mono switch is set to the proper position.
4. Use care when making connections, selecting sig-
nal sources and controlling the output level. The
load you save may be your own!
5. Do not short the ground lead of an output cable to
the input signal ground. This will form a ground
loop and may cause oscillations.
6. Operate the amplifier from AC mains of not more
than 10% variation above or below the selected
line voltage and only the specified line frequency.
7. Never connect the output to a power supply
output, battery or power main. Such connec-
tions may result in electrical shock.
8. Tampering with the circuitry by unqualified person-
nel or making unauthorized circuit changes may
be hazardous and invalidates all agency listings.
Remember: Crown is not liable for any damage that
results from overdriving other system components.
3.2 Indicators
When lit, the amber enable indicator shows that the
amplifier has been turned on. It is driven only by the low-
voltage power supply and does not indicate the status of
the high-voltage supplies.
The signal/ IOC indicators flash green in sync with the
audio input signal, and flash yellow if the input waveform
differs from the output by more than 0.05%. IOC reports
any distortion over 0.05% introduced by the amplifier
including harmonic distortion, intermodulation distortion
and clipping distortion.
3.3 Protection Systems
Power-Tech amplifiers have extensive protection
systems, including ODEP , ultrasonic/RF protection, drive
protection, transformer thermal protection and fuses or
circuit breakers to protect the power supplies.
3.3.1
ODEP
Crown invented ODEP to keep the amplifier working
under demanding conditions and to increase output
efficiency. To do this, Crown established a rigorous
program to measure each transistor’s safe operating
area
(SOA). Intelligent circuitry was then designed to
simulate the instantaneous conditions of the output
transistors. Its name describes what it does: Output
Device Emulation Protection, or ODEP . In simple terms,
ODEP compares transistor conditions to their known
SOA. If more power will be asked of them than they can
deliver under the existing conditions, ODEP limits the
drive until conditions fall within the SOA. Limiting is
proportional and kept to an absolute minimum—only
what is required to prevent output transistor damage.
Under normal conditions, no limiting is required and
ODEP is transparent to the audio signal.
ODEP makes possible a quantum leap in output
efficiency and reliability—with ODEP , the show goes on.
3.3.2 Ultrasonic and Radio Frequency Protection
An amplifier’s slew rate only needs to be large enough to
deliver the maximum voltage at the highest required
frequency. Higher slew rates actually allow undesirable
ultrasonic and radio frequencies to be reproduced. By
design, Power-Tech amplifiers have a controlled slew
rate to limit the highest frequencies that they reproduce.
Limiting occurs well above 20 kHz, so there is no audible
affect on performance. This approach protects the
amplifier from radio frequencies and can even protect
some sensitive loads (including some tweeters).
3.3.3 Drive Protection
The drive protection system temporarily removes output
drive to protect the amplifier and its loads. Drive
protection can be activated in two situations. First, if
dangerous subsonic frequencies or direct current (DC)
is detected in the amplifier’s output, the unit will activate
its DC/low-frequency protection circuitry which puts the
amplifier in drive protection mode. This protects the
loads and prevents oscillations. The unit resumes normal
operation as soon as the amplifier no longer detects
dangerous output. Although it is extremely unlikely that
you will ever activate the amplifier’s DC/low-frequency
protection system, improper source materials like
subsonic square waves or input overloads that
excessively clip the input signal can activate this system.

Power-Tech Series Power Amplifiers
Page 10 Reference Manual
The amplifier’s fault protection system will put the
amplifier in drive protection mode in rare situations
where heavy common-mode current is detected in the
output. The unit should never output heavy common-
mode current unless its circuitry is damaged. Activating
drive protection helps prevent further damage.
3.3.4 Transformer Thermal Protection
All
Power-Tech amplifiers have transformer thermal
protection. This protection circuitry is activated in
unusual situations where the unit’s transformer
temperature rises to unsafe levels. Under these
abnormal conditions, the unit removes power to the high-
voltage transformer. The fan will continue to run in all
units except those with 220/240 VAC transformers. The
amplifier will return to normal after it cools to a safe
temperature.
It is very unlikely that your Power-Tech amplifier will ever
activate transformer thermal protection as long as it is
operated within rated conditions. Your amplifier is
designed to keep working under conditions where other
amplifiers would fail. But even when you exceed the
limits of a Power-Tech amplifier, it still protects itself—
and your investment—from damage.
3.3.5 Fuses and Circuit Breakers
Your amplifier’s low-voltage power supply is protected
by an internal fuse, and its high-voltage power supplies
are protected by a circuit breaker. The circuit breaker is
built into the power switch for all Power-Tech 1 ,
Power-Tech 2 and 220/240 VAC Power-Tech 3
amplifiers. The circuit breaker is located on the back
panel of 100/120 VAC Power-Tech 3 amplifiers. With
rated loads and output levels, the circuit breaker will only
shut down the amplifier in the incredibly rare instance of
a catastrophic amplifier failure. Other protection systems
such as ODEP keep the amplifier operational under most
other severe conditions. The breaker can also shut down
the amplifier in situations where extremely low-
impedance loads and high output levels result in current
draw that exceeds the breaker rating. Again, this should
only be possible when operating outside rated
conditions , like when the amplifier is used to drive a 1
ohm load, or when driving a severely clipped signal.
A
Power-Tech amplifier will not blow its fuse or trip its
breaker unless something is wrong. In the rare event that
an internal fuse blows, please refer the unit to a qualified
technician. If a breaker trips, try to identify and correct
the problem before resetting the breaker. The breaker for
the Power-Tech 1 and 2 can be reset using the front
panel power switch. The circuit breaker for a
Power-
Tech 3 can be reset using the back panel reset switch.
If the problem persists, refer the unit to a qualified
technician.
3.4 Controls
The power switch and level controls are located on the
front panel so you can easily turn the amplifier on or off
and adjust the amplifier’s output level. When making any
setup or wiring changes, don’t forget to turn the amplifier
off, turn the level controls down and disconnect the
power cord. The stereo/mono switch on the back panel
is used to select Stereo, Bridge-Mono or Parallel-Mono
operating modes. Be sure to leave Channel 2 turned
down when using either mono mode. The input
sensitivity switch located inside the back cover plate is
used to set the amplifier’s input sensitivity (see Section
2.3 for information on changing this switch). And the
Power-Tech 3 has a back panel reset switch that is
used to reset the circuit breaker that protects the power
supplies.
3.5 Filter Cleaning
A dust filter is provided on the unit’s air intake. If it
becomes clogged, the unit will cool less efficiently and
may produce lower output levels. To clean the filter, use
a Phillips screwdriver to remove the three screws that
secure the front grille. Use mild dishwashing detergent
and warm water for best cleaning results. Be sure the
filter is dry before you reinstall it. Replacement filters may
be ordered from the factory.
Dust filters are not 100% efficient—depending on the
local environment, the internal heat sinks of the amplifier
will benefit from periodic cleaning by a qualified
technician. Internal cleaning information is available
from our Technical Support Group.

Power-Tech Series Power Amplifiers
Page 11Reference Manual
4 Specifications
The following applies to units in Stereo mode with 8-ohm loads and an
input sensitivity of 26 dB unless otherwise specified.
Standard 1 kHz Power: refers to maximum average power in watts at
1 kHz with 0.1% THD.
Full Bandwidth Power: refers to maximum average power in watts
from 20 Hz to 20 kHz with 0.1% THD.
120 VAC, 60 Hz Units: refers to amplifiers withdedicated transformers
for 120 VAC, 60 Hz power mains.
International Units: refers to amplifiers with special multi-tap
transformers that make them configurable for several AC mains
voltages and line frequencies.
Performance
Frequency Response: ±0.1 dB from 20 Hz to 20 kHz at
1 watt.
Phase Response: ±10 degrees from 10 Hz to 20 kHz at
1 watt.
Signal-to-Noise: A-weighted, better than 105 dB below
full bandwidth power. Better than 100 dB below full
bandwidth power from 20 Hz to 20 kHz.
Total Harmonic Distortion (THD): Less than 0.05% at
full bandwidth power from 20 Hz to 1 kHz increasing
linearly to 0.1% at 20 kHz.
Intermodulation Distortion (IMD): (60 Hz and 7 kHz
4:1) Less than 0.05% from less than 171 milliwatts to full
bandwidth power.
Damping Factor: Greater than 1,000 from 10 Hz to
400 Hz.
Crosstalk
Power-Tech 1 : Greater than 75 dB below full bandwidth
power from 50 Hz to 2 kHz, rising linearly to greater than
60 dB at 20 kHz.
Power-Tech 2 : Greater than 90 dB below full bandwidth
power from 50 Hz to 2 kHz, rising linearly to greater than
66 dB at 20 kHz.
Power-Tech 3 : Greater than 90 dB below full bandwidth
power from 50 Hz to 4 kHz, rising linearly to greater than
70 dB at 20 kHz.
Controlled Slew Rate: Greater than 13 volts/ms.
Voltage Gain: 20:1 ±3% or 26 dB ±0.25 dB at the
maximum level setting.
Power-Tech 1 : 54:1 ±12% or 35 dB ±0.5 dB at 0.775-volt
sensitivity; 30:1 ±12% or 30 dB ±1 dB at 1.4-volt
sensitivity.
Power-Tech 2 : 66:1 ±12% or 36 dB ±0.5 dB at 0.775-volt
sensitivity; 36:1 ±12% or 31 dB ±1 dB at 1.4-volt
sensitivity.
Power-Tech 3 : 84:1 ±12% or 38 dB ±0.5 dB at 0.775-volt
sensitivity; 46:1 ±12% or 33 dB ±1 dB at 1.4-volt
sensitivity.
Power
Output Power: The following specifications are
guaranteed minimums for standard 1 kHz power from
120 VAC, 60 Hz North American units. For
international power specifications see the matrices that
follow.
Power-Tech 1
Stereo mode (both channels driven):
305 watts into 4 ohms.
220 watts into 8 ohms.
Bridge-Mono mode:
605 watts into 8 ohms.
445 watts into 16 ohms.
Parallel-Mono mode:
605 watts into 2 ohms.
440 watts into 4 ohms.
Power-Tech 2
Stereo mode (both channels driven):
460 watts into 4 ohms.
325 watts into 8 ohms.
Bridge-Mono mode:
910 watts into 8 ohms.
660 watts into 16 ohms.
Parallel-Mono mode:
920 watts into 2 ohms.
655 watts into 4 ohms.
Power-Tech 3
Stereo mode (both channels driven):
760 watts into 4 ohms.
540 watts into 8 ohms.
Bridge-Mono mode:
1,525 watts into 8 ohms.
1,090 watts into 16 ohms.
Parallel-Mono mode:
1,530 watts into 2 ohms.
1,080 watts into 4 ohms.
Load Impedance: Safe with all types of loads. Rated for
4to 8 ohms in Stereo, 8 to 16 ohmsinBridge-Monoand2
to 4 ohms in Parallel-Mono mode.
Required AC Mains: Power requirements are provided
on each unit’s back panel. 120 VAC, 60 Hz and 100/120/
220/240 VAC, 50 to 60 Hz (unconvertible) units are
available. Rated AC mains voltages are ±10%.
Quiescent power draw is 90 watts or less.
Power-Tech 1 : 100 and 120 VAC units draw up to 6
amps of current; 220 and 240 VAC units draw up to 3
amps.
Power-Tech 2 : 100 and 120 VAC units draw up to 10
amps of current; 220 and 240 VAC units draw up to 5
amps.
Power-Tech 3 : 100 and 120 VAC units draw up to 15
amps of current; 220 and 240 VAC units draw up to 7
amps.

Power-Tech Series Power Amplifiers
Page 12 Reference Manual
You must provide sufficient AC power to the amplifier.
Amplifiers do not create energy—they require proper
voltage and current to deliver the power you expect.
Low-Voltage Power Supply: A ±24 VDC fanformer
supply (fan motor winding) regulated to ±15 VDC.
AC Connector: An appropriate AC line cord and plug
are provided. North American units have a standard
3-wire, 15-amp grounded connector (NEMA 5-15P).
Controls
Power: A front panel push button switch used to turn the
amplifier on and off. It is also a circuit breaker for the
power supplies in the Power-Tech 1 and 2 .
Level: A front panel rotary potentiometer for each
channel used to control the output level.
Stereo/Mono: A three-position back panel switch used
to select Stereo, Bridge-Mono or Parallel-Mono mode.
Sensitivity: A three-position switch inside the back
cover plate used to select the input sensitivity for both
channels: 0.775 volts or 1.4 volts for standard 1 kHz
power, or 26 dB voltage gain (see Section 2.3).
Reset ( Power-Tech 3 only): A back panel push button
used to reset the circuit breaker that protects the power
supplies.
Indicators
Enable: This red indicator shows the on/off status of the
low voltage power supply.
Signal/ IOC :Each channel has a two color indicator that
flashes green to show signal presence and yellow if the
amplifier causes distortion of 0.05% or more.
Input/Output
Input Connector: Balanced 1/4-inch phone jacks (refer
to Section 5 for XLR and barrier block connectors).
Input Impedance: Nominally 20 K ohms, balanced; 10 K
ohms, unbalanced.
Output Connector: Two sets of color-coded binding
posts.
Output Impedance: Less than 10 milliohms in series
with less than 2 microhenries.
DC Output Offset: Less than 10 millivolts.
Output Signal
Stereo: Unbalanced, two-channel.
Bridge-Mono: Balanced, single-channel. Channel 1
controls are active; Channel 2 controls should be turned
down and not used.
Parallel-Mono: Unbalanced, single-channel. Channel 1
controls are active; Channel 2 controls should be turned
down and not used.
Protection
Power-Tech amplifiers are protected against shorted,
open or mismatched loads; overloaded power supplies;
excessive temperature; chain destruction phenomena;
input overload and high-frequency blowups. They also
protect loudspeakers from input and output DC, as well
as providing protection from turn-on/turn-off transients.
If operating conditions are unreasonable, the patented
ODEP circuitry proportionally limits the drive level to
protect the output transistors, particularly in the case of
elevated temperature. A thermal switch imbedded in the
transformer protects the power supplies from overload.
In the rare event that a transformer overheats, the
thermal switch removes power, waits until the unit has
cooled to a safe temperature and then resets itself.
Turn On: Four-second delay with no dangerous
transients. Contact us if you need to change the delay.
Construction
Durable black finish on steel chassis with special “flow-
through” ventilation from front to side panels.
Cooling: Internal heat sinks with forced-air cooling for
rapid, uniform heat dissipation.
Dimensions: Standard 19-inch (48.3-cm) rack mount
width (EIA RS-310-B), 3.5-inch (8.9-cm) height and
16-inch (40.6-cm) depth behind the mounting surface.
Approximate Weight: Center of gravity is 6 inches (15.2
cm) behind front mounting surface.
120 VAC, 60 Hz Units:
Power-Tech 1 : 30 pounds (13.6 kg) net; 34 pounds
(15.4 kg) shipping weight.
Power-Tech 2 : 33 pounds (15.0 kg) net; 37 pounds (16.8
kg) shipping weight.
Power-Tech 3 : 36 pounds, 8 ounces (16.6 kg) net; 40
pounds, 8 ounces (18.4 kg) shipping weight.
International Units:
Power-Tech 1 : 31 pounds, 2 ounces (14.1 kg) net; 34
pounds, 9 ounces (15.7 kg) shipping weight.
Power-Tech 2 : 35 pounds, 12 ounces (16.9 kg) net; 38
pounds, 13 ounces (17.6 kg) shipping weight.
Power-Tech 3 : 37 pounds, 3 ounces (16.6 kg) net; 40
pounds, 15 ounces (18.6 kg) shipping weight.

Power-Tech Series Power Amplifiers
Page 13Reference Manual
Crown specifications are guaranteed for three years.
In an effort to provide you with as much information as possible about the high power-producing capabilities of your amplifier, we have
created the following power matrices.
Minimum Power Specifications
Crown’s minimum power specifications represent the absolute smallest amount of output power you can expect from your amplifier when it is
driven to full output under the given conditions. Some spaces in each matrix may be left blank because the same guarantee is not provided
for those conditions—however, your amplifier will perform well under all conditions listed in each matrix.
When measuring power, 0.1% THD appears to be the industry standard for distortion. Two of the maximum average power specifications
shown in each minimum power matrix are measured at 0.1% THD so you can easily compare Crown specifications to those of other
manufacturers. But this high level of distortion actually allows for some clipping, which is undesirable. Because of this, a maximum average
power spec at 0.05% THD is included in each minimum power matrix, which represents non-clipped conditions. Although most
manufacturers do not give you power specifications at 0.05% THD, we encourage them to provide these specifications so you will have a
more realistic representation of the way amplifiers should be used in the real world—without a clipped output signal.
Many manufacturers publish power specs with a tolerance of ±1 dB or worse. This means their amplifier can deviate more than 20% in output!
A 100-watt amplifier would meet their specification if it only produced 79.4 watts. Other manufacturers qualify their specs by saying they are
“typical,” “subject to manufacturing tolerances,” “single channel driven” or that they are specified with “fuses bypassed.” Each of these
statements effectively removes any performance guarantee. In fact, some manufacturers use these tactics to generate large power numbers,
and they don’t even print a disclaimer. We take a different approach at Crown—our amplifiers are guaranteed to meet or exceed their
specifications for three years. Further, because our published specs are set below our “in-house” measurements, you can expect every
Crown amplifier to exceed its published minimum power specs. We believe you should get what you pay for.
Minimum Power Notes:
All minimum power specifications are based on 0.5% regulated AC mains with THD of less than 1.0% and an ambient room temperature of 70° F
(21° C). Standard EIA power (RS-490) is not shown here because it is identical to FTC Continuous Average Power. International units with multi-tap
transformers are specified for the worst-case transformer tap (normally 100 VAC, 50 Hz).
1. A 1-kHz sine wave is presented to the amplifier and the output monitored for nonlinear distortion. The level is increased until the THD reaches 0.1%. At
this level the average power per channel is reported.
2. A sine wave is presented to the amplifier over the range from 20 Hz to 20 kHz and the output monitored for nonlinear distortion. The level at each
frequency is increased until the THD reaches 0.1%. At this level the average power per channel is reported.
3. A 1-kHz sine wave is presented to the amplifier and the output monitored for nonlinear distortion. The level is increased until the THD reaches 0.05%. At
this level the average power per channel is reported.
4. A 1-kHz sine wave is presented to the amplifier and the output monitored for nonlinear distortion. The level is increased until the THD reaches 0.1%. At
this level the average power per channel is reported.
Fig. 4.1 Power-Tech 1 Minimum Power Matrix

Power-Tech Series Power Amplifiers
Page 14 Reference Manual
Fig. 4.2 Power-Tech 2 Minimum Power Matrix
Fig. 4.3 Power-Tech 3 Minimum Power Matrix

Power-Tech Series Power Amplifiers
Page 15Reference Manual
Maximum Power Specifications
Crown’s maximum power specifications represent the largest amount of output power you can expect from your amplifier when it is driven to full
output under the given conditions. These specifications can be used to prevent loudspeaker and hearing damage.
The maximum power matrices include specifications for single cycle and 40-millisecond burst sine waves. Burst signals act like large transient
peaks that are present in common source signals. Loudspeakers can respond to a single cycle burst, so the single cycle burst specifications
should be used to help you protect your loudspeakers. In contrast, a 40-millisecond burst represents the typical response time of the human ear.
Your ear will not respond to the entire dynamic change of a burst that lasts less than 40 milliseconds.
The specifications are provided at 0.05% THD because this represents a low distortion condition. To help you operate your amplifier within these
tolerances, Crown’s premium amplifiers include an input/output comparator that shows when the amplifier has exceeded 0.05% THD. Operating
the amplifier at levels higher than 0.05% THD can result in output power levels that are higher than those listed in the maximum power matrices.
Maximum Power Notes:
All maximum power specifications are based on 0.5% regulated AC mains with THD of less than 1.0% and an ambient room temperature of 70° F
(21° C). International units with multi-tap transformers are specified for the best-case transformer tap (normally 240 VAC, 60 Hz). Although it is an
unusual condition, your amplifier can function well with AC mains voltages up to 10% over the rated line voltage. With overvoltage conditions, your
amplifier may be capable of delivering instantaneous power levels up to 20% greater than the specifications in the matrix. Maximum power testing
conditions are very demanding and sometimes result in the activation of the amplifier’s ODEP protection circuitry. In the following matrices, spaces
are left blank when ODEP limiting prevents the output power level from significantly exceeding the unit’s minimum guaranteed specifications.
1. A single cycle sine wave is presented to the amplifier and monitored for nonlinear distortion. The average power during the burst is
reported. Loudspeakers must be able to withstand this level if they are to be safely used with this amplifier.
2. A 40-millisecond sine wave burst (10 percent duty cycle) is presented to the amplifier and monitored for nonlinear distortion. The average
power during the burst is reported. This power level is a measurement of the amplifier’s maximum transient power that can be perceived
by the human ear.
Fig. 4.4 Power-Tech 1 Maximum Power Matrix

Power-Tech Series Power Amplifiers
Page 16 Reference Manual
Fig. 4.5 Power-Tech 2 Maximum Power Matrix
Fig. 4.6 Power-Tech 3 Maximum Power Matrix

Power-Tech Series Power Amplifiers
Page 17Reference Manual
5 Accessories
There are two accessories available at the time of this
printing: the
MT-XLR and the MT-BB . Important: The
MT-XLR and MT-BB must be installed at a Crown
Factory Service Center or the Crown factory.
5.1 MT-XLR
The MT-XLR is an accessory panel that provides two
standard 3-pin female XLR input connectors. The
MT-XLR accessory makes it easy to quickly change
connections in a system that uses standard XLR
connectors. It can also be used in systems that need to
daisy chain an input signal from one amplifier to another.
Because the
MT-XLR connectors are in parallel with the
amplifier’s built in phone connectors, an input signal fed
to either input can be fed to another amplifier from the
unused connector for that channel.
5.2 MT-BB
The MT-BB is an accessory panel that provides barrier
strip input connectors. An
MT-BB accessory might be
desirable in applications requiring bare wire
connections. It can also be used to daisy chain an input
signal from one amplifier to another just like the MT-XLR .
Fig. 5.2 MT-BBFig. 5.1 MT-XLR

Power-Tech Series Power Amplifiers
Page 18 Reference Manual
Crown Audio Customer Service
Technical Support / Factory Service
Plant 2 SW, 1718 W. Mishawaka Rd., Elkhart,
Indiana 46517 U.S.A.
Telephone: [phone]
800-342-6939 (North America,
PuertoRico, andVirgin Islandsonly)
Facsimile: 219-294-8301 (Technical Support)
219-294-8124 (Factory Service)
Fax Back: 219-293-9200 (North America only)
800-294-4094 (North America only)
219-294-8100 (International)
Internet: http://www.crownaudio.com
6 Service
This unit has very sophisticated circuitry which should
only be serviced by a fully trained technician. This is one
reason why each unit bears the following label:
CAUTION: To prevent electric shock, do not remove
covers. No user serviceable parts inside. Refer
servicing to a qualified technician.
6.1 Worldwide Service
Service may be obtained from an authorized service
center. (Contact your local Crown/Amcron
representative or our office for a list of authorized service
centers.) To obtain service, simply present the bill of sale
as proof of purchase along with the defective unit to an
authorized service center. They will handle the
necessary paperwork and repair.
Remember to transport your unit in the original factory
pack.
6.2 North American Service
Service may be obtained in one of two ways: from an
authorized service center or from the factory. You may
choose either. It is important that you have your copy of
the bill of sale as your proof of purchase.
6.2.1 Service at a North American Service Center
This method usually saves the most time and effort.
Simply present your bill of sale along with the defective
unit to an authorized service center to obtain service.
They will handle the necessary paperwork and repair.
Remember to transport the unit in the original factory
pack. A list of authorized service centers in your area
can be obtained from our Technical Support Group.
6.2.2 Factory Service
To obtain factory service, fill out the service information
page found in the back of this manual and send it along
with your proof of purchase and the defective unit to the
Crown factory.
For warranty service, we will pay for ground shipping
both ways in the United States. Contact Crown Factory
Service or Technical Support to obtain prepaid shipping
labels prior to sending the unit. Or, if you prefer, you may
prepay the cost of shipping, and Crown will reimburse
you. Send copies of the shipping receipts to Crown to
receive reimbursement.
Your repaired unit will be returned via UPS ground.
Please contact us if other arrangements are required.
2. To ensure the safe transportation of your unit to the
factory, ship it in an original factory packing con-
tainer. If you don’t have one, call or write Crown’s
Parts Department. With the exception of polyure-
thane or wooden crates, any other packing mate-
rial will not be sufficient to withstand the stress of
shipping. Do not use loose, small size packing
materials.
3. Do not ship the unit in any kind of cabinet (wood or
metal). Ignoring this warning may result in exten-
sive damage to the unit and the cabinet. Accesso-
ries are not needed—do not send the product
documentation, cables and other hardware.
If you have any questions, please call or write the Crown
Technical Support Group.
Always use the
original factory pack
to transport the unit.
Factory Service Shipping Instructions:
1. When sending a Crown product to the factory for
service, be sure to fill out the service information
form that follows and enclose it inside your unit’s
shipping pack. Do not send the service informa-
tion form separately.

Power-Tech Series Power Amplifiers
Page 19Reference Manual Page 19
Crown Factory Service Information
Shipping Address: Crown International, Inc., Factory Service,
Plant 2 SW, 1718 W. Mishawaka Rd., Elkhart, IN U.S.A. 46517
Phone: [phone] or 1-219-294-8200 Fax: [phone]
Owner’s Name:_________________________________________________________________________
Shipping Address:______________________________________________________________________
Phone Number: ________________________________________________________________________
Model: ________________________ Serial Number:______________ Purchase Date: ___________
NATURE OF PROBLEM
(Be sure to describe the conditions that existed when the problem occurred and what attempts were made to correct it.)
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
Other equipment in your system: _________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
If warranty has expired, payment will be: ❑ ❑
❑ ❑
❑ Cash/Check ❑❑
❑❑
❑VISA ❑❑
❑❑
❑MasterCard ❑❑
❑❑
❑C.O.D.
Card Number:___________________________ Exp. Date:_______ Signature:_____________________________
ENCLOSE THIS PORTION WITH THE UNIT. DO NOT MAIL SEPARATELY.
Detach and send with unit.