Classe Audio P-151 User manual

CLASSÉ AUDIO
P-151
POWER AMPLIFIER
P-151
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. UPGRADABLE SINGLE CIRCUIT DESIGNS:
All Classé products (all preamps and all amps) share exactly the same circuit (excluding moving
coil and moving magnet phono circuits). This means all amplifiers and all high level circuits of
the preamps are the same. The same circuit is tailored to different power levels etc. Differences
between less expensive models and more expensive models are parts quality and compliment,
power supply extravagance and the amount of filtering etc., as well as features and packaging.
This means that for years Classé has been constantly fine tuning and upgrading this circuit and
its application, thus reaching a very high level of understanding and musical achievement which
benefits all models - least expensive, most expensive, preamps and amplifiers alike.
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.

P-151
OWNER'S MANUAL
TABLE OF CONTENTS
UNPACKING & SET-UP.................................................................... 4
GENERAL CONNECTIONS.............................................................. 5
CONNECTIONS FOR REGULAR OR BALANCED INPUTS........ 7
PROTECTION CIRCUIT..................................................................... 8
SPECIFICATIONS............................................................................... 12

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UNPACKING & SET-UP
Your CLASSÉ P-151 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) Detachable linecord
2) Allen key for top plate
Please report any damage or missing parts to your dealer as soon as possible.
Place the P-151 at or near its final set-up position, allowing 8 inches at the rear for tightening
the speaker output connectors. For optimum sonic performance, we recommend the optional CLASSÉ
REFERENCE A.C. LINECORD. Consult your dealer regarding this accessory.
The power transformer in the P-151 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-151 has only one fuse, the rating of which should be as follows:
LINE VOLTAGE FUSE RATING
100 or 120 V.A.C. 6 AMP FAST BLOW 125 or 250 volts
220 or 240 V.A.C. 4 AMP FAST 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.
CAUTION: SAFETY INSTRUCTIONS
DISCONNECT AC LINE CABLE WHILE MAKING ALL 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. LINECORDS TO THE WALL OUTLETS. THIS WILL REDUCE THE POTENTIAL
SHOCK HAZARD. SEE ALSO THE 10 WARRANTY SECTION OF THIS OWNER'S MANUAL.
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 [UP] position. (Units preset at factory for STEREO.)
Use only high quality interconnect and loudspeaker cables, and make all connections tight. If
the input plugs are loose, remove them and pinch down the ground leaves slightly with pliers.
Observe correct phasing of the loudspeaker connections, and tighten.

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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 [DOWN].
The MONO "Input" is the "left channel input", as marked. The unused right channel input is
automatically disconnected. MONO output connections are marked below the connectors.
Repeat the above MONO settings and connections on the second P-151 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" or switchbox set-up. Do not use with electronic crossovers
which have a common ground.
REMOTE CONTROL: (OPTIONAL)
With a simple connection from the receiver box to the remote jack at the back of the
amplifier, (see Figure 1) the power amplifier can be turned ON/OFF from a distance (or from
another room).

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CONNECTIONS FOR REGULAR OR BALANCED INPUTS:
The CLASSÉ P-151 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, and balanced interconnects with "XLR"
connectors are also required. Regardless of the amplifier inputs used, stereo or mono operation is
still possible on the P-151.
REGULAR INPUTS
Switch the REGULAR/BALANCED switch to the position marked "REGULAR" [UP]. (The
amplifier is factory set for regular use.) Connect the regular interconnects to the RCA input jacks on
the rear panels of the P-151. The balanced connectors are automatically disabled.
BALANCED INPUTS
Switch the REGULAR/BALANCED switch to the position marked "BALANCED" [DOWN]. A
balanced preamplifier and balanced interconnects are also required. 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-151 which is wired as follows:
PIN 1: GROUND
PIN 2: POSITIVE (NON-INVERTED) SIGNAL
PIN 3: NEGATIVE (INVERTED) SIGNAL
If the pin configuration of the preamplifier differs from above, the balanced interconnects must be
modified to accommodate the different preamp.
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-151. (To remove the
connectors, press the tab above the connector.)

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MONO OPERATION
As stated before, 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.
PROTECTION CIRCUIT
The Classé P-151 is equipped with rail fuses to protect the output drivers (GDB5, 5 amps
fast-blow, fig.2, and page 10). In the event that a short circuit or other problems would occur at the
output of the amplifier, these fuses may blow in an attempt to protect the amplifier. In addition to the
fuses, the unit has a circuit for the detection of unusual distortion characteristics and/or DC content
in the incoming audio signal. There is also an AC line fuse protecting the unit. It is located at the
back of the unit immediately to the right side of the AC receptacle (see fig.1, page 9).
If the protection circuit of the unit is triggered or any of the fuses has blown, the FRONT
PANEL POWER LED will go to BLINKING GREEN.
IF THE PROTECTION CIRCUIT HAS BEEN TRIGGERED, TURN THE P-151 OFF.
After the situation which 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 FUSES AND RE-STARTING
THE UNIT WITHOUT CHECKING FOR COMPONENT FAILURE COULD RESULT IN
FURTHER, SERIOUS DAMAGE TO VITAL COMPONENTS IN YOUR AMPLIFIER.
CONTACT YOUR LOCAL DEALER.

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