Classe Audio P-303 User manual

CA-301 ISSUE 1 MAY ‘99
CLASSÉ AUDIO
P-303
POWER AMPLIFIER
P-303
OWNER'S MANUAL

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CLASSÉ DESIGN PHILOSOPHY
1. REPEATED LISTENING DESIGN SESSIONS:
Fine tuning of sound by exchanging and mixing of parts (transistors, capacitors, wiring, PCB
boards etc.), and adjusting many specific operating voltages within proper engineering ranges,
producing an overall sonic recipe giving the most natural harmonic realism of music typical of
instruments in a live performance.
2. CIRCUIT DESIGN:
The P-303 is based on Classé’s whole history of designing and building High End amplifiers.The
P-303 is an Ultra- High performance amplifier of incredible sonic realism capable of
transmitting to the listener the emotional essence of the music. The P-303 has a massive toroidal
transformer totalling 2 KVA, each with their own power cords and a huge storage capacity
which totals over 70000 uF per channel. The P-303 has 10 high voltage/current Bi-Polar output
devices per channel. Discrete high voltage/current voltage regulation for the pre-driver and input
sections. Also featured are heavily gold plated bars connecting supplies of the output devices.
Gold plated input and output connectors. Oxygen free copper wiring. All signal carrying cables
are shielded and have Litz type configuration. The P-303 is symmetrical from input to output
3. EXTREME LONG LIFE IN REAL WORLD CONDITIONS:
Choosing the best attainable quality parts and materials combined with the advantages of the two
above-mentioned areas provides Classé owners with years of proven trouble free reliability and
musical enjoyment.

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P-303
OWNER'S MANUAL
TABLE OF CONTENTS
UNPACKING & SET-UP..................................................................... 4
GENERAL CONNECTIONS............................................................... 5
CONNECTIONS FOR REGULAR AND BALANCED INPUTS…. 8
PROTECTION CIRCUIT..................................................................... 10
IR IN AND OUT…………………………………………………… 11
SPECIFICATIONS………………………………………………..... 14

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UNPACKING & SET-UP
Your CLASSÉ P-303 power amplifier is packed in high density, semi-rigid foam placed in a
special cardboard box. To remove the unit, open and spread all the top flaps of the box and by its
sides, lift out the entire unit and put it on a large flat surface. Take it out of the plastic bag and
inspect the unit for any concealed damage. Apart from this owner's manual, please ensure the
following has also been included:
1) One (1) detachable A.C. linecord
2) Nut driver for output connectors
Please report any damage or missing parts to your dealer immediately.
Place the P-303 at or near its final set-up position, allowing 8 inches at the rear for tightening
the speaker output connectors.
The power transformer in the P-303 is located at the front-center of the unit. Ideally, a few
feet should separate this area from components which potentially could pick up hum. These include
preamplifiers, turntables, and interconnect cables. In terms of providing adequate airspace for
cooling, a good rule of thumb is to allow 6 inches above and 3 inches on each side of the unit.
Check the Serial Number sticker on the back of the unit for the correct operating voltage.
The P-303 has one external AC fuse, the rating of which should be as follows:
LINE VOLTAGE FUSE RATING
100 or 120 V.A.C. 12 AMP SLOW BLOW 125 or 250 volts
220 or 240 V.A.C 10 AMP SLOW BLOW 250 volts

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GENERAL CONNECTIONS
A.C. LINE
Insert the linecord into the A.C. receptacle on the rear of the unit. PLEASE MAKE SURE
YOU HAVE PREVIOUSLY HOOKED UP THE SPEAKERS AND PREAMPLIFIER TO
YOUR AMPLIFIER BEFORE CONNECTING THE AC POWER CORD TO THE
AMPLIFIER.
IMPORTANT NOTE
CAUTION: SAFETY INSTRUCTIONS
DISCONNECT THE AC LINE CABLE BEFORE MAKING ANY OTHER CONNECTIONS.
"FLOATING THE GROUND” OR DEFEATING THE GROUND ON A 3-PRONG
LINECORD MAY CREATE A SHOCK HAZARD. CONNECT ALL INTERCONNECT
CABLES BETWEEN THE ELECTRONICS BEFORE CONNECTING THE A.C. LINECORD
TO THE WALL OUTLETS. THIS WILL REDUCE THE POTENTIAL SHOCK HAZARD.
STEREO
Input and output connectors are clearly marked on the back of the amplifier. Left/Right
connections are oriented from the front of the unit. Stereo output connections are marked above the
connectors. Switch stereo/mono switch to STEREO position. (The P-303 is preset at the factory for
STEREO.)
Use only high quality interconnect and loudspeaker cables, and make all connections tight. If
the RCA input plugs are loose, remove them and pinch down the ground leaves slightly with pliers.
Observe correct phasing of the loudspeaker connections, and tighten. DO NOT

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STEREO (CONTINUED)
OVERTIGHTEN the output connectors. When powering up the P-303 in stereo mode, the front
LED will blink RED for approximately 20 seconds, when the sequence is completed, will be solid
RED.
MONO
Please read through the previous Stereo section for general notes on securing good
connections, and safety tips. If the unit has been previously used in stereo, make sure it is OFF, and
remove all connections, including the AC line cable. Make sure the STEREO/MONO switch is
switched to the MONO position. NOTE: The Stereo-Mono switch will not operate if the amplifier is
turned on, you will NOT be able to change from one mode to the other, as the mode is “locked”
while the amplifier is on.
The MONO "Input" is the "left channel input", as marked. The unused right channel
input is automatically disconnected. Correct output phase MONO connections are marked below the
connectors.
Repeat the above MONO settings and connections on the second P-303 to be used for the
other channel.
Please remember that the negative output connection of a bridged amplifier is NOT a
ground. Do not use a "common ground” switch-box set-up. Do not use with electronic crossovers
which have a common ground. Connecting two bridged amplifiers to a common ground device of
any sort will cause the amplifiers to fail.

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MONO OPERATION
As stated above, either the regular or balanced inputs can be used in stereo or mono.
Connect a single interconnect, either regular or balanced, to the left channel input of each amplifier.
See the "Mono" section above for complete details. NOTE: Neither the Stereo-Mono switch nor the
REGULAR/ BALANCED switch will operate while the amplifier is turned on. You will NOT be able to
change from one mode to the other, as these modes are “locked” while the amplifier is on. To
activate the circuit, turn off the unit and engage the STEREO/MONO switch to REGULAR. If the unit has
not been turned off before engaging the switch, turn off the unit, wait for about 10 seconds, and turn
the unit on again, the circuit will then engage.

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CONNECTIONS FOR REGULAR OR BALANCED INPUTS:
The CLASSÉ P-303 power amplifier is equipped with both regular and balanced inputs.
Either one may be used SEPARATELY, BUT NOT SIMULTANEOUSLY. The balanced inputs must be
connected to a preamplifier which has balanced main outputs. Balanced interconnects with "XLR"
connectors are also required. Regardless of the amplifier inputs used, stereo or mono operation is
possible on the P-303.
REGULAR INPUTS
Engage the REGULAR/BALANCED switch to the position marked "REGULAR". (The amplifier is
factory set for “REGULAR”.) NOTE: The REGULAR/ BALANCED switch will not operate if the
amplifier is turned on; you will NOT be able to change from one mode to the other, as the mode is
“locked” while the amplifier is on. To activate the circuit, turn off the unit and engage the
REGULAR/BALANCED switch to REGULAR. If the unit has not been turned off before engaging the
switch, turn off the unit, wait for about 10 seconds, and turn the unit on again, the circuit will then
engage. Connect the regular interconnects to the RCA input jacks on the rear panels of the P-303. The
balanced connectors are automatically disabled.
BALANCED INPUTS
Switch the
REGULAR/BALANCED switch to the position marked "BALANCED". A balanced
preamplifier and balanced interconnects are also required. NOTE: The REGULAR/ BALANCED switch
will not operate if the amplifier is turned on; you will NOT be able to change from one mode to the
other, as the mode is “locked” while the amplifier is on. If the unit has not been turned off before
engaging the switch, turn off the unit, wait for about 10 seconds, and turn the unit on

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BALANCED INPUTS (CONTINUED)
again, the circuit will then engage. For use with balanced preamplifiers other than Classé, the
wiring of the 3-pin XLR connectors must be matched to that of the CLASSÉ P-303 which is wired as
follows:
PIN 1: SHIELD (Should be connected only at the preamplifier end of the cable)
PIN 2: POSITIVE (NON-INVERTED) SIGNAL, “HOT”
PIN 3: NEGATIVE (INVERTED) SIGNAL
All Classé preamplifiers and amplifiers are configured as above. Some preamplifiers from other
manufacturers have PIN-3 set as the positive or “HOT” side. If this is true of your preamplifier, and
you wish to maintain absolute phase throughout your system, the interconnects must have the wire
which is connected to PIN-3 at the preamplifier output end switched to PIN-2 at the amplifier input
end and the wire which is connected to PIN-2 at the preamplifier output switched to PIN-3 at the
amplifier input end.
Having confirmed the correct connections, plug the XLR connectors of the balanced
interconnects into the locking XLR connectors on the rear panel of the P-303. Push the connectors in
until the locking mechanism clicks. (To remove the connectors, press the tab above the connector
while pulling gently on the connector body.)

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PROTECTION CIRCUIT
A special circuit in the Classé P-303 continuously monitors the output audio signal to detect
output overload, clipping or DC content. In addition, each channel has two front end supply voltage
fuses (3/4 amp fast blow), located on the front end voltage regulation board, to protect the input
circuitry from damage due to overload
There is also an AC line fuse, located at the rear of the amplifier immediately above the IEC
receptacle.
If the protection circuit of the unit is triggered or any of the protection fuses has blown, the
FRONT PANEL POWER LED will go to BLINKING GREEN.
IF THE PROTECTION CIRCUIT HAS BEEN TRIGGERED, TURN THE P-303 OFF.
.After the situation which has triggered the protection circuit has been clearly identified and
corrected, attempt to re-start the unit. IF THE UNIT STILL GOES INTO PROTECTION MODE,
OR IF IT APPEARS THAT PROTECTION FUSES DID BLOW, CONTACT YOUR LOCAL
DEALER. DO NOT TRY TO CHANGE A BLOWN FUSE. REPLACING A FUSE WITHOUT
CHECKING FOR COMPONENT FAILURE COULD RESULT IN FURTHER, SERIOUS
DAMAGE TO VITAL COMPONENTS IN YOUR AMPLIFIER. CONTACT YOUR LOCAL
DEALER or Customer Service at the Classé Audio, Inc ---(514) 636 63 84.