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Unpacking and placement

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.

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.

Unpacking

Placement

Ventilation

Custom installations

PRECAUTION

Summary of Contents for 23.5

Page 1: ...arance 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 t...

Page 2: ...ses 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 F U S E F USE F U S E PUSH PUSH AC mains fuses AC connector Output right Output left Nº23 5 DUAL MONAURAL AMPLIFIER WARNING HAZARDOUS VOLTAGES AVAILABLE INSIDE DISCONNECT AC MAINS CABLE BEFORE REM...

Page 3: ...ote 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 ...

Page 4: ... 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 XLR type male line mount connector you may purchase pre shorted RCA type inputs from your Mark Levinson dealer Insert a pre shorted RCA type connector into each RCA type input...

Page 5: ... 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 Balanced normal non in...

Page 6: ...gs Lug connection Pigtail connection We confidently recommend Madrigal binding post lugs made of oxygen free copper with gold over silver plating These lugs are available for round cable see your Mark Levinson dealer for more information Note Many lug connectors are designed to be crimped onto the cable However soldering usually ensures a better electrical connection If you have no experience in s...

Page 7: ...is available for polarity identification Figure 7B Pigtail connection 1 2 12 7mm Speaker cable Solder Tin 5 8 15 8mm shrink tubing 8 Follow this procedure for the remaining speaker connections Note This procedure may also be used for the speaker end of the cable depending upon the type of speaker terminal When the speaker cables are complete connect the left channel positive or red output post of ...

Page 8: ... you won t be using it for a long period see Important Safety Instructions The Nº23 5 is designed to be power cycled that is turned on and off without affecting its longevity After the amplifier is turned on after being left unpowered allow for about one hour of warmup before expecting optimal sonic performance Under certain conditions an electrical malfunction or inadequate ventilation the Nº23 5...

Page 9: ...elow Balanced bridged operation PUSH PUSH Loudspeaker Nº23 5 From preamplifier balanced main output Balanced bridging cable Right channel Left channel Figure 9 Connections for balanced bridged operation 1 For balanced bridged operation you ll need a special three ended cable You may fabricate such a cable according to Figure 10 it s also available through your Mark Levinson dealer as part of a bal...

Page 10: ...e Nº23 5 to the positive or red input terminal of the appropriate loudspeaker Connect the right channel positive or red output post of the Nº23 5 to the negative or black input terminal of the same loudspeaker 4 Repeat this procedure for the other Nº23 5 to be bridged If your preamplifier provides only single ended output follow the steps below Single ended bridged operation PUSH PUSH Loudspeaker ...

Page 11: ... rear view 2 1 3 Signal ground shield Right channel XLR male line mount rear view Signal hot center conductor 22 guage buss wire 22 guage buss wire Note If fabricating the bridging cable be sure to use high quality audio interconnect cable such as Madrigal HPC 3 Connect the left channel positive or red output post of the Nº23 5 to the positive or red input terminal of the appropriate loudspeaker C...

Page 12: ...mmend therefore that you clean all speaker connection with denatured alcohol at least once a year See your Mark Levinson dealer for other ways to optimize connections 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 Clea...

Page 13: ...e 67V rated line voltage 8Ω Frequency response 3dB 4Hz 140KHz Input impedance 50KΩ shunted by 1 5nF Voltage gain 26 9dB Power consumption Typically 225W idle 1200W rated power 8Ω Overall dimensions See Dimensions Shipping weight 105 lbs 48kg Connector complement 2 RCA type connectors 2 XLR type connectors 4 five way binding posts 1 IEC mains connector For more information see your Mark Levinson de...

Page 14: ...27 32 198 9 5 3 4 146 6 5 16 160 7 5 8 193 8 19 482 6 1 3 4 44 4 1 3 4 44 4 1 TYP 25 4 1 2 TYP 12 7 4 3 16 122 5 29 32 22 9 5 8 15 9 3 8 9 5 3 8 9 5 23 32 18 5 8 15 9 7 64 2 8 1 3 64 26 4 1 1 2 38 1 Figure 13A Dimensions Nº23 5 top view Figure 13B Dimensions Nº23 5 side view ...

Page 15: ...15 ...

Page 16: ...o Laboratories Inc All rights reserved Madrigal Audio Laboratories Inc 2081 South Main Street P O Box 781 Middletown Connecticut 06457 USA Telephone 203 346 0896 or 344 9300 Fax 203 346 1540 is a registered trademark of Madrigal Audio Laboratories Inc ...

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