Mark Levinson No 23.5 Owners manual

Unpacking and placement

Unpacking

Placement

Ventilation

Unpack your Nº23.5 amplifier and keep all packing materials for future transport. Because of the weight of the unit, handles are provided front and rear so that two people may lift and carry the amplifier comfortably and without risk of injury.

Carefully inspect your Nº23.5. If you find any damage or flaws, see your Mark Levinson dealer immediately.

To keep speaker cables as short as possible, locate the Nº23.5 as close to the loudspeakers as practical.

The Nº23.5 should be located at least three feet away from the turntable and preamplifier. Otherwise, the Nº23.5 may induce hum into these sensitive components.

The Nº23.5 may be placed in a cabinet or on a shelf, but adequate ventilation must be provided to prevent overheating. The clearance provided by the unit's feet must be maintained to allow unrestricted air flow across the heat sinks and through the vents in the bottom of the chassis (placing the Nº23.5 on thick carpeting, for example, may reduce or eliminate the clearance provided by the feet). Clearance above the unit must also be maintained to allow air circulation and to prevent heat buildup.

The Nº23.5 incorporates thermal sensors located near each group of output devices. If heat-sink temperature becomes excessive, these sensors will shut off the amplifier before damage results. After a brief cooling period, the amplifier can be reactivated via the switch on the front panel. If this occurs regularly during normal use, it indicates that the ventilation provided for the amplifier is inadequate. If there's adequate ventilation and the problem continues, see your Mark Levinson dealer immediately.

Custom installations

PRECAUTION

For custom installations and cabinetry, this information may be useful:

■ All temperature measurements are made at the top of the heat

sink, 3.5" behind the front plate.

■ Normal heat-sink temperature at idle after warm-up, with unrestricted airflow at 22°C (72°F) ambient temperature: 36.5°C (97.7°F).

■ Maximum permissible heat-sink temperature before thermal protection is activated: 80°C (176°F).

For exact dimensions, see "Dimensions."

For your protection, review "Important safety instructions" before you install your Nº23.5.

Voltage selection

The Nº23.5 is factory-set (internally) for 100V, 120V, 200V, 220V, or 240V AC mains operation. Make sure that the label on the rear panel of the amplifier indicates the correct AC operating voltage for your location).

Figure 1: Rear panel

INPUT

BALANCED INPUT

+– +–

OUTPUT

SERIAL NO.

Single-ended input (left)

PUSHPUSH

Balanced input (left)

Shorting strap

Single-ended

input (right)

Balanced

input (right)

OPERATING

VOLTAGE:

• 90 - 110 VAC~

• 105 - 125 VAC~

• 180 - 220 VAC~

• 210 - 240 VAC~

• 230 - 250 VAC~

• ~47-400 Hz

Nº23.5 DUAL MONAURAL AMPLIFIER

WARNING:

HAZARDOUS VOLTAGES AVAILABLE INSIDE: DISCONNECT AC~ MAINS CABLE BEFORE REMOVING ANY COVERS. HIGH ENERGY AVAILABLE AT LOAD TERMINALS. REFER TO OWNER'S MANUAL FOR PROPER TERMINATION INSTRUCTIONS. DISCONNECT AMPLIFIER FROM AC~ MAINS BEFORE REPLACING FUSES. MAINS FUSES: PLEASE CONSULT OWNER'S MANUAL.

DESIGNED AND MANUFACTURED IN U.S.A. BY

MADRIGAL AUDIO LABORATORIES, INC.

RIGHT CHANNEL LEFT CHANNEL

Voltage indicationShorting strap

AC mains fuses

•

AC connectorOutput (right) Output (left)

If the voltage indicated is incorrect, see your Mark Levinson dealer.

If you wish to change the AC operating voltage of your Nº23.5, see your Mark Levinson dealer.

PRECAUTION

A Nº23.5 typically uses from 225W (at idle) to 1200W (at its rated power

into 8Ω). It may be powered by a 15-ampere AC mains line. For

optimum performance into lower-impedance loads, however, it's recommended that the AC mains outlet used for the Nº23.5 be capable of supplying a minimum of 20 amperes @ 100V and 120V AC, and 10 amperes @ 200V, 220V, and 240V AC. If other devices are also powered from the same AC circuit, their additional power consumption must be considered.

Two slow-blow 250V 3AG fuses (15 ampere @100V and 120V AC and 8 ampere @200V, 220V, and 240V AC) are located on the rear panel of the Nº23.5. Replace the fuses only with the same type.

ALWAYS remove the AC cord before removing the fuses.

Signal connections

Connectors

Cables

Connection methods and

operating modes

Single-ended normal

(non-inverting) operation

The Nº23.5 incorporates RCA-type and XLR-type connectors for audio signal input.

The Madrigal-designed RCA-type connectors used for single-ended audio interconnection are a great improvement over ordinary RCAtype connectors. The gold-plated XLR-type connectors employed are of European design, and are made to professional application standards.

When connecting the Nº23.5 to a preamplifier, we recommend Madrigal Audio Laboratories HPC Interconnect Cable. HPC Interconnect Cable is available in various lengths, pre-terminated with RCA, XLR, and Camac connectors. See your Mark Levinson dealer.

The Nº23.5 can be operated in either single-ended or balanced mode. In each of these modes, the Nº23.5 can be operated either normally (non-inverting) or inverting.

Note: This manual describes the connections for single-ended normal (non-inverting), single-ended inverting, and balanced normal (non-inverting) operation. If you have questions about these or other methods of signal connection, see your Mark Levinson dealer.

Typical audio systems require that the amplifier be of the non-inverting type. This means that the output signal of the amplifier will be in phase with the input signal.

Figure 2: Connections for

single-ended normal

(non-inverting) operation

For this type of operation, connect the main outputs of your preamplifier to the left- and right-channel RCA-type inputs (noninverting) on the rear panel of the Nº23.5. Be sure that the shorting strap is inserted into the XLR-type connectors between Pins 1 and 3.

From preamplifier main output

Loudspeaker

Right

+–

Right channel

+–

Shorting strap

Nº23.5

Left

channel

PUSHPUSH

–+ –+

Left Loudspeaker

Single-ended inverting

operation

Inverting operation should be used if a phase reversal is required. In

this mode, the output signal of the amplifier will be 180° out-of-phase

with the input signal. This may be required if one component in the system inverts the signal and absolute phase at the loudspeaker is desired.

For inverting operation, the main output cables of the preamplifier must be connected to the XLR-type inputs on the rear panel of the Nº23.5. The pin assignments of these connectors are:

Figure 3: Female input

connector

Figure 4: Connections for

single-ended inverting

operation

PUSH

Pin 1: Signal ground

Pin 2: Signal + (non-inverting) Pin 3: Signal – (inverting) Connector ground lug: chassis ground

Connect the XLR-type male line-mount connector to your preamplifier's main output cable so that signal "hot" (+) connects to Pin 3 and signal ground connects to Pin 1. Be sure to also connect Pin 2 to Pin 1 inside the XLR-type male line-mount connector with a piece of copper buss wire (or similar material) at the amplifier end of the cable.

Note: If you prefer not to connect Pin 2 to Pin 1 inside the XLRtype male line-mount connector, you may purchase preshorted RCA-type inputs from your Mark Levinson dealer. Insert a pre-shorted RCA-type connector into each RCA-type input (non-inverting) on the rear panel of the Nº23.5.

After completing the cables, connect the main outputs of your preamplifier to the left- and right-channel XLR-type inputs on the rear panel of the Nº23.5. Be sure to remove the shorting strap between Pins 1 and 3 before inserting the output cable connectors.

From preamplifier main output

Loudspeaker

Right

Right channel

Left

channel

Left Loudspeaker

PUSHPUSH

+–

Nº23.5

–+

Balanced normal

(non-inverting) operation

Figure 5: Connections for

balanced normal

(non-inverting) operation

If your preamplifier is equipped with a balanced main output, it's best to wire the Nº23.5 for balanced operation, particularly if long lengths of cable are required between the preamplifier and the Nº23.5. (See Figure 3 for the pin assignments of the XLR-type inputs on the rear panel of the Nº23.5.)

Connect the XLR-type male line-mount connector to your preamplifier's main output cable according to Figure 3, carefully observing pin assignments. (Refer to your preamplifier's operating manual to verify that the pin assignments of its output correspond to the diagram above. If they don't, wire the connector so that the appropriate output pin connects to the equivalent input pin.)

When complete, connect the main outputs of the preamplifier to the left- and right-channel XLR-type inputs on the rear panel of the Nº23.5. Be sure to remove the shorting strap between Pins 1 and 3 before inserting the output cable connectors.

From preamplifier main output

Loudspeaker

Right

Right channel

Left

channel

Left Loudspeaker

PUSHPUSH

+–

Nº23.5

–+

Note: For proper balanced operation, no connector (pre-

shorted or otherwise) should be inserted into the RCA-type inputs on the rear panel of the Nº23.5.

–+

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