Mark Levinson 434 User manual

Owner’s Manual
Nº436
Nº434

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 ventilation openings. Install in accordance with the manufacturer’s instructions.
8. Do not install near any heat sources such as radiators, heat registers, stoves, or another apparatus
that produces heat.
9. Do not defeat the safety purpose of the polarized 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 third prong is provided for safety. If the provided plug
does not fit into the outlet, consult an electrician for replacement of the obsolete outlet.
10. The MAINS cord is intended to be the safety disconnect device for this apparatus. Ready access
to the MAINS cord shall be maintained at all times.
11. Protect the power cord from being walked on or pinched, particularly at plugs, convenience
receptacles, or the point where it exits from the apparatus.
12. Only use attachments and accessories specified by the manufacturer.
13. Use only with the cart, stand, tripod, bracket, or table specified by the manufacturer
or sold with the apparatus. When a cart is used, use caution when moving the
cart/apparatus combination to avoid injury or tip over.
14. Unplug this apparatus during lightning storms or when unused for long periods of time.
15. Refer all servicing to qualified service personnel. Servicing is required when the apparatus has
been damaged in any way, such as when the power cord or plug has been damaged; liquid has
been spilled or objects have fallen into the apparatus; or the apparatus has been exposed to
rain or moisture, does not operate normally, or has been dropped.
16. Ventilation should not be impeded by covering the ventilation openings with items such as
newspapers, table cloths, curtains, etc.
17. No naked flame sources, such as candles, should be placed on the apparatus.
18. Terminals marked with this symbol may be considered HAZARDOUS LIVE and the
external wiring connected to these terminals requires installation by an INSTRUCTED
PERSON or the use of ready-made leads or cords.
Warning!
To reduce the risk of fire or electric shock, do not expose the apparatus to rain or moisture. Do
not place objects containing liquid, such as vases, on this apparatus.
Important Safety Instructions

FCC Notice
This equipment has been tested and found to comply with the limits for a Class B digital device,
pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection
against harmful interference in a residential installation. This equipment generates, uses, and can
radiate radio frequency energy and, if not installed and used in accordance with the instructions,
may cause harmful interference to radio communications. However, there is no guarantee that
interference will not occur in a particular installation. If this equipment does cause harmful
interference to radio or television reception, which can be determined by turning the equipment
off and on, the user is encouraged to try to correct the interference by one or more of the following
measures:
•Reorient or relocate the receiving antenna.
•Increase the separation between the equipment and the receiver.
•Connect the equipment into an outlet on a circuit different from that to which the receiver is
connected.
•Consult an authorized Mark Levinson dealer or an experienced radio/TV technician for help.
Caution!
Changes or modifications not expressly approved by the party responsible for compliance could
void the user’s authority to operate the equipment.
Canada
This Class B digital apparatus complies with Canadian ICES-003.
Cet appareil numérique de la classe B est conforme à la norme NMB-003 du Canada.
3 Oak Park
Bedford, MA 01730-1413 USA
Telephone: [phone]
Fax: [phone]
www.marklevinson.com
Customer Service
Telephone: [phone]
Sales Fax: [phone]
Service Fax: [phone]
Product Shipments
16 Progress Road
Billerica, MA 01821-5730 USA
Part No. 070-630430 | Rev 6 | 07/04
“Mark Levinson” and the Mark Levinson logo are registered trademarks
of Harman International Industries. U.S. patent numbers and other
worldwide patents issued and pending.
“Madrigal Audio Laboratories” and the Madrigal Audio Laboratories
logo are registered trademarks of Harman International Industries.
U.S. patent numbers and other worldwide patents issued and pending.
©2004 Harman Specialty Group. All rights reserved.
This document should not be construed as a commitment on the
part of Harman Specialty Group. The information it contains is
subject to change without notice. Harman Specialty Group assumes
no responsibility for errors that may appear within this document.

iv
Introduction Mark Levinson
Table of Contents
Introduction
Important Safety Instructions . . . . . . . . . . . . . . . . . . . . . . . . .ii
FCC Notice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iii
Documentation Conventions . . . . . . . . . . . . . . . . . . . . . . . . .vi
Section 1: Getting Started
Special Design Features . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1
Massive Power Supply • Balanced Design • True Voltage Source •
Adaptive Bias • Extensive Protection
Unpacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
Product Registration
Installation Considerations . . . . . . . . . . . . . . . . . . . . . . . . .1-4
Placement • Rack-Mounting • Ventilation
Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-7
Warm-up & Break-in Period • Operating States • Continuous
Operation
Section 2: Basic Operation
Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1
Rear Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-3
Linking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-8
Link Connections • Constructing Link Communication Cables •
Creating a Slave Chain • Link Controls
Section 3: Troubleshooting & Maintenance
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1
Care & Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-4

v
Nº436/434 Introduction
Appendix
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-1
Declaration of Conformity . . . . . . . . . . . . . . . . . . . . . . . . .A-3
Dimensions, Nº436 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-4
Dimensions, Nº434 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-6

vi
Introduction Mark Levinson
Documentation
Conventions
This document contains general safety, installation, and operation
instructions for the Nº436/434 Power Amplifiers. It is important
to read this document before attempting to use these components.
Pay particular attention to safety instructions.
Appears on the component to indicate the
presence of uninsulated, dangerous voltages
inside the enclosure – voltages that may be
sufficient to constitute a risk of shock.
Appears on the component to indicate important
operation and maintenance instructions
included in the accompanying documentation.
Appears on the component to indicate
compliance with the EMC (Electromagnetic
Compatibility) and LVD (Low-voltage Directive)
standards of the European Community.
Warning! Calls attention to a procedure, practice,
condition, or the like that, if not correctly
performed or adhered to, could result in
personal injuries or death.
Caution! Calls attention to a procedure, practice,
condition, or the like that, if not correctly
performed or adhered to, could result in
damage or destruction to part or all of the
component.
Note Calls attention to information that is essential to
highlight.

1-1
Special Design Features
Thank you for purchasing the Nº436/434 Monaural Power
Amplifier, combining the massive power and strength of a large
power amplifier with the elegance and finesse of a small power
amplifier. This section describes some of the design features that
make this unique combination possible.
Massive Power Supply The Nº436/434 uses a large, robust power supply with a high-
capacity, low-noise toroidal transformer and four large, low ESR
(Equivalent Series Resistance) capacitors. Specifically, the Nº436
uses a 2372 VA transformer with 80,000µF total capacitance, while
the Nº434 uses an 801 VA transformer with 72,000µF total
capacitance.
Heavy, oxygen-free copper bus bars enhance the efficiency of
power distribution with the power amplifier, eliminating variances
caused by wiring harnesses, which are commonly found even in
high-performance power amplifiers. High-frequency power supply
bypass is accomplished on individual PC boards by five types of
components. As a result, a uniformly low power supply imped-
ance is seen by various circuits within the power amplifier provid-
ing the foundation for a rare combination of massive power and
extraordinary finesse.
Balanced Design A truly balanced input topology eliminates the need for an input
buffer amplification stage, allowing the source to directly drive
the first stage differential amplifier. Matched impedances are pre-
sented to the source as both signals travel identical circuit paths.
Meticulous attention to detail, including careful mirror-imaging of
circuits, minimizes magnetic field distortions that can be caused
by such a massive power delivery system. Balanced input signals
remain balanced throughout voltage gain stages, achieving rejec-
tion of common mode noise and distortion in the final, current
gain stage.
Getting Started

1-2
Getting Started Mark Levinson
Special Design Features (continued)
True Voltage Source The Nº436/434 operates as a true voltage source, maintaining the
appropriate voltage within its rated voltage output according to
the demands of the source material rather than the current
demands of the loudspeaker. As a result, the Nº436/434 doubles its
power output each time loudspeaker impedance is cut in half. For
example, the Nº436 offers rated power at 350W per channel at 8Ω
and 700W per channel at 4Ω.
To control the flow of its remarkable power capabilities to the
loudspeakers, the Nº436 uses 16 TO-3P output transistors in eight
matched, complementary pairs per channel. Similarly, the Nº434
uses eight TO-3P output transistors in four matched, complemen-
tary pairs per channel.
Although most loudspeakers cannot absorb the continuous full
power capabilities of the Nº436, many high-quality loudspeakers
require extreme short-term power levels when reproducing music
at realistic levels. The Nº436/434 can meet these demands without
power supply “sag” or sonic performance alterations, allowing
either power amplifier to reproduce music with amazing authority
and control. Power needs depend on listening habits, the listening
room, and associated loudspeakers.
Adaptive Bias The Nº436/434 uses a proprietary adaptive biasing scheme to
deliver the advantages of a Class A output stage without the asso-
ciated thermal management problems and sonic compromises.
This unique adaptive biasing scheme does not allow output
devices to be reverse-biased, replacing dynamic distortions with a
sweeter sound that provides a greater sense of ease regardless of
volume level. Contact an authorized Mark Levinson dealer for
additional information about Adaptive Bias.
Extensive Protection Designed to prevent damage to itself and associated components,
the Nº436/434 is armed with several protective features. For
example, the AC input to each transformer is fused to protect
against excessive current conditions that occur when shorted
outputs are driven. Inrush limiting prevents premature aging of
power supply components during power cycles, switching off-line
once the power supply is charged. And, a controlled-clipping
circuit prevents output devices from saturating, using wave-shaping
action to avoid the harsh, high-frequency harmonics generated by
hard-clipped output devices.

1-3
Nº436/434 Getting Started
In addition, the Nº436/434 uses state-of-the-art protections to
guard against the following fault conditions:
•Signal-related faults, including the presence of DC (direct
current) signals at the output and demands for excessive
current at the output (indicating a short-circuit). If a signal-
related fault is detected, the front panel indicator LED blinks
rapidly, remaining lit and unlit for equal intervals. The
Nº436/434 shuts itself down to protect itself and associated
loudspeakers. To restore normal operation, remove the source
of the fault. Then, power cycle the Nº436/434 using the
power button.
•Power-related faults, including over or under-voltage (±10%)
conditions at the ~ac mains connector. If AC mains voltage is
too high or too low for safe operation, the front panel indicator
LED blinks rapidly, remaining lit for longer intervals. Normal
operation will not be restored until AC mains voltage falls
back into a safe operating range.
For example, a 120V model of the Nº436/434 will operate
from approximately 108-132V, while a 240V model of the
Nº436/434 will operate from approximately 216-264V. Outside
of these limits, the Nº436/434 will activate sleep mode. When
AC mains voltage returns to the safe operating range, the
Nº436/434 can be taken out of sleep mode using the standby
button.
•Thermal-related faults, such as if the Nº436/434 becomes over-
heated. The front panel indicator LED blinks rapidly, remain-
ing unlit for longer intervals. The Nº436/434
automatically activates sleep mode and remains in sleep
mode until output heat sink temperatures drop below 85˚C
(185˚F or 358K). When temperatures return to a safe operating
range, the Nº436/434 can be taken out of sleep mode using
the standby button.

1-4
Getting Started Mark Levinson
Unpacking
Warning! DO NOT attempt to lift or move the Nº436/434 without
adequate assistance. Failure to follow the procedures included
in this section may result in personal injuries and/or product
damage.
The Nº436 and Nº434 are massive power amplifiers. The Nº436
ships at 95 pounds (43.2kg) and the Nº434 ships at 65 pounds
(29.5kg). Rear panel handles are provided for safe, convenient
lifting and moving. Proper lifting requires at least two people.
Caution! DO NOT attempt to lift the Nº436/434 from its packing carton
alone.
DO NOT attempt to lift the Nº436/434 while bending at the
waist. When lifting, stand as straight as possible using the leg
muscles to lift.
When unpacking the Nº436/434:
•DO save all packing materials for possible future shipping
needs.
•DO inspect the Nº436/434 for signs of damage during
shipment. If damage is discovered, contact an authorized
Mark Levinson dealer for assistance making appropriate
claims.
Product Registration Please register the Nº436/434 within 15 days of purchase. To do
so, register online at www.marklevinson.com or complete and
return the included product registration card. Product registration
serves no warranty purposes. Retain the original, dated sales
receipt as proof of warranty coverage.
Installation Considerations
The Nº436/434 requires special care during installation to ensure
optimal performance. Pay particular attention to the precautions
included in this section and to other precautions included
throughout this owner’s manual.

1-5
Nº436/434 Getting Started
Placement •DO review “Important Safety Instructions” and “Power
Requirements” before installing the Nº436/434.
•DO place the Nº436/434 on a solid, flat, level surface such as
a table, shelf, or floor OR bolt the Nº436/434 into a rack-
mounting system. Use a purpose-built rack-mounting system
to accommodate the weight of the power amplifier. Refer to
“Rack-Mounting” for additional information.
•DO position the Nº436/434 close to associated loudspeakers
to keep loudspeaker wires as short as possible. Use longer
interconnecting cables between the preamplifier and the
power amplifier. This is preferable because interconnecting
cables pass low-voltage signals, which transmit over distances
with greater accuracy than the high-voltage signals required
by loudspeakers.
•DO allow at least a 6-inch (15cm) clearance behind the
Nº436/434 for the power cord and signal cables to bend
without crimping or straining.
•DO see “Dimensions” for assistance with custom installations.
•DO NOT position the Nº436/434 near low-level components.
These power amplifiers are capable of producing massive
output currents, which could generate significant magnetic
fields that induce noise in some sensitive components.
•DO NOT place the Nº436/434 on a windowsill or in another
location in which it will be exposed to direct sunlight.
Caution! BEFORE moving the Nº436/434, make sure it is powered off
using the power button. Then, make sure the power cord is
disconnected from the ~ac mains connector and the electrical
outlet.
DO NOT attempt to move the Nº436/434 without adequate
assistance. Proper lifting requires at least two people.
Rack-Mounting The Nº436/434 can be rack-mounted using the optional rack-
mount kit available at authorized Mark Levinson dealers. This
purpose-designed kit provides adequate support for the power
amplifier as well as proper ventilation for the heat sinks. When
rack-mounted, the Nº436 occupies four standard rack units and
the Nº434 occupies three standard rack units.

1-6
Getting Started Mark Levinson
Ventilation The Nº436/434 uses a sophisticated ventilation system that
combines passive convection and active, fan-driven cooling to
maintain normal operating temperatures under a wide range of
conditions. Heat sinks are crosscut to allow for both horizontal
and vertical airflow, ensuring that the Nº436/434 delivers
maximum performance and reliability at all times.
When the Nº436/434 is installed in a location with reasonable
temperatures and ventilation, convection cooling alone provides
adequate heat dissipation at low and moderate listening levels.
When operating temperatures exceed a certain level, two
temperature-controlled, variable-speed fans automatically activate
to provide additional cooling.
Note The Nº436/434 fans are extremely quiet, even when running
relatively hard. In some cases, the fans may be heard when lowering
master volume after an extended period of high-volume listening.
When the Nº436/434 is taken out of standby, the fans will activate
momentarily to remove excess dust that may have accumulated in
the heat sinks.
•DO select a dry, well-ventilated location out of direct sunlight.
•DO NOT obstruct the ventilation holes on the top and bottom
of the Nº436/434 or reduce airflow through the Nº436/434.
•DO NOT place the Nº436/434 on a thick rug or carpet or
cover the Nº436/434 with a cloth, as this might prevent proper
cooling. If the Nº436/434 is placed on the floor, use a thick
piece of tempered glass to provide firm support and proper
ventilation.
•DO NOT expose the Nº436/434 to high temperatures,
humidity, steam, smoke, dampness, or excessive dust. Avoid
installing the Nº436/434 near radiators and other heat-
producing appliances.

1-7
Nº436/434 Getting Started
Power Requirements
When shipped, the Nº436/434 is configured for 100V, 120V, 220V,
230V or 240V AC power operation at 50 or 60Hz based on the
country for which it is manufactured. Before operating the
Nº436/434, make sure the ~ac mains connector label indicates the
correct operating voltage for the current location.
Caution! DO NOT attempt to adjust the operating voltage. Consult an
authorized Mark Levinson dealer if the operating voltage is
incorrect or if the operating voltage must be changed for
relocation purposes.
BE ADVISED that different operating voltages may require the
use of different power cords and/or attachment plugs. Contact
an authorized Mark Levinson dealer for assistance.
The Nº436/434 is capable of passing remarkable musical signals
regardless of signal and loudspeaker demands. On either an
instantaneous or continuous basis, these power amplifiers can
drive exceptional power levels into most all loudspeaker loads.
Depending on listening habits, loudspeaker demands, and the
number of power amplifiers present in the system – it is possible
for the electrical service to become the limiting performance
factor.
In this case, consider installing a dedicated AC circuit for the
home entertainment system. Contact a licensed electrician for
assistance. If more than one AC circuit is providing power to the
system, contact a licensed electrician to ensure that all components
are operating with the same solid, low-impedance ground reference.
Note Building regulations and electrical codes differ from location to
location, making it impossible to anticipate the requirements of high-
current AC circuits such as the Nº436/434 is capable of using.
Contact a local, licensed electrician for information.
Warm-up & Break-in Although the Nº436/434 delivers superior performance from the
Period first time it is powered on, this performance will continue to
improve as the power amplifier reaches its normal operating
temperature and various components “break in.” The greatest
performance improvements will occur within the first 25 to 50
hours of use. Sound quality will continue to improve for about
300 hours.

1-8
Getting Started Mark Levinson
After this initial period, performance will remain consistent unless
power is disconnected from the Nº436/434. Power is considered
disconnected when the Nº436/434 is powered off using the power
button; the power cord is disconnected from the ~ac mains
connector or the electrical outlet; or an extended power failure or
power outage occurs. Power is not disconnected when the
Nº436/434 is in standby or sleep mode.
When power returns, it is recommended to allow the Nº436/434
and other audio components to stabilize for about 2 minutes. The
Nº436/434 will require a brief warm-up and break-in period (not
the full 300 hours).
Operating States The Nº436/434 has four operating states:
1. Off
Power is considered disconnected from the Nº436/434.
2. Sleep Mode
Power is connected to a small power supply, communication
circuits, and control circuits. When taken out of sleep mode,
the Nº436/434 requires a brief warm-up and break-in period.
In sleep mode, the Nº436/434 consumes less than 15W of
power.
3. Standby
Power is connected to the main power supply and voltage
gain stages. Power is not connected to the output (current
gain) stage. Because voltage gain stages are kept at their normal
operating temperatures, the Nº436/434 remains warmed-up to
deliver an optimal performance. In standby, the Nº436/434
consumes about 100W of power (±5%).
4. On
Power is connected to the Nº436/434.
Warm-up & Break-in Period (continued)

1-9
Nº436/434 Getting Started
Note The Nº436 and Nº434 are designed to run somewhat warm without
causing a safety hazard. The Nº436 dissipates about 175W of heat
energy when powered on or idle (not in standby), and the Nº434
dissipates about 130W of heat energy when powered on or idle (not
in standby).
Continuous Operation The Nº436/434 should be unplugged during lightning storms and
extended periods of non-use. Otherwise, it is designed for continuous
operation. For best performance, make sure power is connected to
the Nº436/434 at all times. During normal operation, do not use
the power button to power off the Nº436/434. Instead, use the
standby button to place the Nº436/434 into standby, which
allows the power amplifier to remain warmed-up to deliver opti-
mal performance at all times.

2-1
Front Panel
The numbers in the front panel illustration shown above correspond
with the numbered items in this section.
1. Power Button
Powers the Nº436/434 on and off when the power cord is
connected to the ~ac mains connector and an electrical
outlet.
•When the Nº436/434 is powered on, pressing the power
button disconnects power from the Nº436/434.
•When the Nº436/434 is powered off, pressing the power
button connects power to the Nº436/434. The Nº436/434
automatically enters sleep mode when powered on.
Note The Nº436/434 must be powered on using the power button to
respond to remote trigger commands.
Basic Operation
power
standby
MONO AMPLIFIER
Nº436
123

2-2
Basic Operation Mark Levinson
Front Panel (continued)
2. standby button
Places the Nº436/434 into standby or sleep mode and takes
the Nº436/434 out of standby or sleep mode.
•When the Nº436/434 is powered on, pressing the standby but-
ton places the Nº436/434 into standby or takes the Nº436/434
out of standby, allowing it to remain warmed-up to deliver an
optimal performance at all times.
•Pressing and holding the standby button for four seconds places
the Nº436/434 into sleep mode. When the Nº436/434 is in
sleep mode, pressing the standby button takes the Nº436/434
out of sleep mode. When taken out of sleep mode, the
Nº436/434 automatically enters standby.
3. indicator LED
Indicates the operating state of the Nº436/434 and provides
diagnostic information if a fault condition occurs. The table
below describes all indicator LED behaviors.
See “Extensive Protection” for additional information about
fault conditions. If the Nº436/434 will not power on at all
(even to sleep mode), examine ~ac mains connections or
have an authorized Mark Levinson dealer inspect the internal
fuses (which are not user-serviceable).
LED Behavior Description
Fully lit Indicates that power is connected to
the Nº436/434 (on).
Slowly blinking Indicates that the Nº436/434 is in
standby.
Dimly lit Indicates that the Nº436/434 is in
sleep mode.
Unlit Indicates that power is disconnected
from the Nº436/434 (off).
Rapidly blinking Indicates that a power-related fault
(lit for longer intervals) has occurred.
Rapidly blinking Indicates that a signal-related fault*
(lit/unlit for equal intervals) has occurred.
Rapidly blinking Indicates that a thermal-related fault
(unlit for longer intervals) has occurred.
*Signal-related faults include significant DC offsets at the output due to either
DC in the input signal or a failed component within the amplifier OR excessive
current demands due to a short-circuited loudspeaker wire.

2-3
Nº436/434 Basic Operation
Rear Panel
The numbers in the rear panel illustration shown above correspond
with the numbered items in this section.
Caution! Never make or break connections to the Nº436/434 unless it
and all associated components are powered off and disconnected
from electrical outlets. Before making connections to the Nº436/
434, make sure the associated preamplifier master volume is set
to a reasonable level.
1. rear panel handles
Allow for safe, convenient lifting and moving of the Nº436/
434. Refer to “Unpacking” for additional information.
Caution! DO NOT attempt to lift the Nº436/434 from its packing carton
alone.
DO NOT attempt to lift the Nº436/434 while bending at the
waist. When lifting, stand as straight as possible using the leg
muscles to lift.
1 2 1
6
~ ac mains
2
1slave in slave out RS-232
trigger
in
trigger
out
MARK L EV I N S O N
M
O N O AM P L I F I E R N º 436
S / N
inputs communication
8 9
4 5 7
3

2-4
Basic Operation Mark Levinson
Rear Panel (continued)
2. fan outlet
Provides an outlet for active, fan-driven cooling. A 1/4-inch
(6.4mm) inlet between the front panel and the chassis provides
air intake for the forced-air cooling system. See “Ventilation”
for additional information.
3. loudspeaker binding posts (main outputs)
Provide audio output. Two custom-made, gold-plated, high-
current binding posts labeled + (positive) and – (negative) are
available. In general, positive binding posts are red and
negative binding posts are black.
Caution! NEVER connect power amplifier outputs to any component
other than a loudspeaker.
NEVER short-circuit power amplifier outputs.
NEVER connect power amplifier outputs to another power
amplifier’s outputs.
For best performance, use high-quality loudspeaker cables. To
connect these cables, use a high-quality spade or hook lug
soldered to the cable or crimped to the cable with extremely
high pressure.
•Connect the + (positive) binding post on the Nº436/434
to positive input on the associated loudspeaker.
•Connect the – (negative) binding post on the Nº436/434
to negative input on the associated loudspeaker.
Spade Lug Hook Lug