Mark Levinson N28, 28 Operating Manual

Operating Manual

Mark Levinson

Nº28

Preamplifier

®

Madrigal Audio Laboratories, Inc.

15

WARNING: TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK,
DO NOT EXPOSE THIS APPLIANCE TO RAIN OR MOISTURE.

CAUTION

RISK OF ELECTRIC SHOCK

DO NOT OPEN

CAUTION: TO REDUCE THE RISK OF ELECTRICAL SHOCK,
DO NOT REMOVE COVER. NO USER-SERVICEABLE PARTS
INSIDE. REFER SERVICING TO QUALIFIED PERSONNEL.

The lightning flash with arrowhead symbol, within an equilateral triangle, is intended to alert the
user to the presence of uninsulated “dangerous voltage” within the product’s enclosure that may
be of sufficient magnitude to constitute a risk of electric shock to persons.

The exclamation point within an equilateral triangle is intended to alert the user to the presence of
important operating and maintenance (servicing) instructions in the literature accompanying the
appliance.

16

Important safety instructions

Please read all instructions and precautions carefully and completely before operating your Nº28
Preamplifier.

1. ALWAYS disconnect your entire system from the AC mains before connecting or disconnecting

any cables, or when cleaning any component.

2. This product is equipped with a three-conductor AC mains power cord which includes an earth

ground connection. To prevent shock hazard, all three connections must ALWAYS be used. If
your electrical outlets will not accept this type of plug, an adapter may be purchased. If an
adapter is necessary, be sure it is an approved type and is used properly, supplying an earth
ground. If you are not sure of the integrity of your home electrical system, contact a licensed
electrician for assistance.

3. AC extension cords are not recommended for use with this product. If an extension cord must
be used, be sure it is an approved type and has sufficient current-carrying capacity to power
this product.

4. NEVER use flammable or combustible chemicals for cleaning audio components.

5. NEVER operate this product with any covers removed.

6. NEVER wet the inside of this product with any liquid.

7. NEVER pour or spill liquids directly onto this unit.

8. NEVER block air flow through ventilation slots or heatsinks.

9. NEVER bypass any fuse.

10. NEVER replace any fuse with a value or type other than those specified.

11. NEVER attempt to repair this product. If a problem occurs, contact your Mark Levinson® retailer.

12. NEVER expose this product to extremely high or low temperatures.

13. NEVER operate this product in an explosive atmosphere.

14. ALWAYS keep electrical equipment out of the reach of children.

17

From all of us at Madrigal Audio Laboratories, thank you for choosing the Mark Levinson® Nº28
Preamplifier.

A great deal of effort went into the design and construction of this precision device. Used properly, it
will give you many years of enjoyment.

18

Table of contents

Front panel ...................................................................................................1

Rear panel ................................................................................................... 2

Unpacking and placement .......................................................................4

Unpacking .............................................................................................. 4

Placement ............................................................................................. 4

Ventilation ..............................................................................................4

Voltage selection ........................................................................................5

PLS-228 bottom-panel label .......................................................... 5

Set-up and installation ................................................................................6

Connectors and cables ....................................................................... 6

Internal adjustments: line gain ............................................................. 6

Line gain settings ............................................................................ 6

Internal adjustments: phono gain ....................................................... 6

Phono gain settings (high-gain option) ....................................... 6

Phono gain settings (low-gain option) ......................................... 6

Internal adjustments: cartridge loading ............................................. 7

Cartridge loading settings (high-gain option) ............................ 7

Cartridge loading settings (low-gain option) .............................. 7

Internal adjustments: optional load terminals ................................... 7

Terminating the optional load ...................................................... 7

Internal adjustments: varying the input capacitance ...................... 8

Making the internal adjustments ......................................................... 8

Nº28, internal adjustments ............................................................. 8

Power connection and system activation ......................................... 9

AC power cord polarity ................................................................. 9

Care and maintenance ...........................................................................10

Specifications ............................................................................................11

Phono section ...................................................................................... 11

Line section .......................................................................................... 11

Dimensions................................................................................................. 12

Dimensions, Nº28, top view.......................................................... 12

Dimensions, Nº28, side view ......................................................... 12

Dimensions, PLS-228, top view ..................................................... 13

Dimensions, PLS-228, side view .................................................... 13

19

CD

PHONO/

AUX 2

TUNER

AUX 1

INPUT SELECTOR MONITOR SELECTOR RECORD SELECTOR OUTPUT LEVEL

TAPE 1

TAPE 2AUX 3

TAPE 1

MADRIGAL AUDIO LABORATORIES

Nº 28

PREAMPLIFIER

INPUT

MONITORDEFEATTAPE 2

4

3

2

1

OFF

1 2 3 4

Front panel

1 INPUT SELECTOR

Selects one of the seven inputs: CD, TUNER, PHONO/AUX 1, AUX 2,
AUX 3, TAPE 1, or TAPE 2.

2 RECORD SELECTOR

Selects between the program source (selected via the INPUT
SELECTOR), and either of two tape monitor inputs (selected via the
MONITOR SELECTOR).

In the DEFEAT position, the tape outputs are disconnected.

5

6

7

8

9

10

In the INPUT position, the tape outputs are connected while still
monitoring the selected source.

In the MONITOR position, the selected tape machine can be
monitored without affecting the signal at the tape outputs.

Note: Because of the switching arrangement employed in
the Nº28, we recommend that while making a critical
recording you don't operate the RECORD SELECTOR switch.

If you wish to monitor the signal from tape, set the RECORD
SELECTOR to MONITOR and use your tape machine's monitor
switch to switch between input and tape.

3 MONITOR SELECTOR

When the RECORD SELECTOR is in the MONITOR position, this selects
between the TAPE 1 and TAPE 2 inputs.

4 OUTPUT LEVEL

Adjusts volume at the main outputs.

The OUTPUT LEVEL control doesn't affect the tape outputs.

1

BALANCED MAIN

RIGHT LEFT

MAIN

TAPE 1

TAPE 2

POWER
SUPPLY

INPUT

CD

RIGHT LEFT

PUSH PUSH PUSH PUSH

AUX 2

RIGHT LEFT

INPUTSOUTPUTS

LEFT

GND

TAPE 1

TAPE 2

AUX 3

TUNER

AUX 1

PHONO/

RIGHT

7

PRECAUTION

3

2

1

4

568

Rear panel

Disconnect all associated equipment from the AC mains BEFORE
making any signal connections and applying power to the Nº28.

Note: All left-channel RCA-type inputs and outputs are at the top of
the rear panel, and all right-channel RCA-type inputs and outputs are
at the bottom of the rear panel.

1 PHONO/AUX 1

If your Nº28 is equipped with the phono option, connect your
turntable's right-channel and left-channel signal leads to these
inputs. Connect the tonearm ground lead to the GND binding post
next to the inputs.

If your Nº28 isn't equipped with a phono option, these inputs will
accept signal leads from any line-level source equipment.

2 TUNER

Accepts right-channel and left-channel signal leads from a tuner
or other line-level source equipment.

3 AUX 3

Accepts right-channel and left-channel signal leads from line-level
source equipment.

4 TAPE 1, TAPE 2 (INPUTS)

Accept right-channel and left-channel signal leads from the tape­output connectors of a tape machine. These inputs can also be
used with other line-level source equipment.

5 AUX 2, CD

Accept right-channel and left-channel balanced signal leads from
a CD player or other source equipment with balanced output.

The pin assignments of these XLR-type female input connectors
are:

PUSH

21

3

Pin 1: Signal ground
Pin 2: Signal + (non-inverting)
Pin 3: Signal – (inverting)
Connector ground lug: chassis ground

2

Refer to the operating manual of your balanced-output line-level
source to verify that the pin assignments of its output connector
correspond to the Nº28. If not, wire the cable so that the
appropriate output pin connects to the equivalent input pin.

Note: If you won't be using the Nº28's balanced inputs and
need more single-ended inputs, it's possible to fabricate a
cable to connect line-level sources with single-ended output
to these balanced inputs:

Male RCA

(connect to

source)

22-guage

buss wire

1

3

Male XLR

(connect to

2

Nº28)

6 TAPE 1, TAPE 2 (OUTPUTS)

Connect these outputs to the right-channel and left-channel tape
inputs of your tape machine.

These outputs are unaffected by the OUTPUT LEVEL control on the
front panel of the Nº28.

7 MAIN

Connect these outputs to the right-channel and left-channel
inputs of your power amplifier or electronic crossover.

These outputs are affected by the OUTPUT LEVEL control on the
front panel of the Nº28.

8 BALANCED MAIN

If your power amplifier is equipped with balanced input
connectors, it's best to connect it to the Nº28 via these connectors,
particularly if long cable lengths are required.

Connect the right-channel and left-channel BALANCED MAIN
outputs of the Nº28 to the appropriate balanced inputs of the
power amplifier.

The pin assignments of these XLR-type male outputs are:

Pin 1: Signal ground

12

3

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

Refer to your power amplifier's operating manual to verify that the
pin assignments of its input connector correspond to the Nº28. If
not, wire the cable so that the appropriate output pin connects to
the equivalent input pin.

3

Unpacking and placement

Unpacking

Placement

Ventilation

PRECAUTION

Unpack your Nº28 Preamplifier and keep all packing materials for
future transport. Locate and remove all accessory items from the
cartons.

Carefully inspect the product for damage and flaws. If you find any,
see your Mark Levinson dealer immediately.

Place the Nº28 as close as possible to the source equipment, thus
keeping interconnect cabling as short as possible. It may be placed
on a shelf or in a cabinet where it's convenient to operate.

A two-meter DC cable is provided to connect the PLS-228 to the Nº28.
This allows you to place the PLS-228 so that it won't induce hum in the
Nº28 and other sensitive components. Other associated equipment
should also be placed so that it doesn't induce hum in the Nº28 and
other sensitive components.

Be sure to allow 3 to 4 inches of clearance above both the Nº28 and
the PLS-228, to allow heat dissipation through air circulation.

Mechanical drawings are included in this manual to facilitate special
installations and custom cabinet work (see "Dimensions").

For your protection, review "Important safety instructions" before you
install your Nº28.

4

Voltage selection

The PLS-228 is factory-set (internally) for 100V, 120V, 200V, 220V, or
240V AC mains operation @ 50 or 60Hz. Make sure that the label on
the bottom of the PLS-228 indicates the correct AC operating voltage
for your location.

PLS-228 bottom-panel

label

PLS-228 POWER SUPPLY

AC INPUT

Voltage

indication

WARNING:

OPERATE THIS DEVICE, REFER TO
OWNER'S MANUAL FOR PROPER
OPERATING INSTRUCTIONS AND SAFETY
PRECAUTIONS. HAZARDOUS VOL T AGE
AVAILABLE INSIDE; DISCONNECT AC~
MAINS CABLE BEFORE REMOVING COVER.

MAINS
FUSES:

BEFORE ATTEMPTING TO

OPERATING VOLTAGE:

90 – 110VAC~

105 – 125VAC~
180 – 220VAC~

100 – 120VAC~
2A SLO–BLO 250VAC 3AB
200 – 240VAC~
1A SLO–BLO 250VAC 3AB

SERIAL NO.

DESIGNED AND MANUFACTURED IN U.S.A. BY

MADRIGAL AUDIO LABORATORIES INC.

210 – 240VAC~
230 – 250VAC~

~50 – 60HZ

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

If you wish to change the AC operating voltage of the Nº28/PLS-228,
see your Mark Levinson dealer.

The Nº28/PLS-228 can be powered by a normal 15-ampere AC mains
line. If other devices are also powered from the same AC line, their
additional power consumption must be taken into account.

5

Set-up and installation

Connectors and cables

Internal adjustments:

line gain

The Nº28 incorporates RCA-type and XLR-type connectors for audio
signal input and output.

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 Nº28 to source equipment and power
amplifiers, we recommend Madrigal Audio Laboratories HPC
Interconnect Cable. HPC is available in various lengths, terminated
with RCA, XLR, and Camac connectors. See your Mark Levinson
dealer for more information.

The Nº28 offers internal gain adjustment of the line amplifiers, in 6dB
steps via two single-pole miniature rocker switches. These switches
have been factory-adjusted at 6dB/single-ended and 12dB/
balanced operation. In practice, you should have enough gain so
that normal listening is possible with the OUTPUT LEVEL set at
approximately 6.

If you wish to increase the line gain, see "Making the internal
adjustments;" refer to the table below for the proper switch positions
for each gain setting.

Line gain settings

Internal adjustments:

phono gain

Phono gain settings

(high-gain option)

Phono gain settings

(low-gain option)

Switch Gain

#1 #2 Single-Ended Output Balanced Output
Off Off 18dB 24dB
Off On 12dB 18dB
On Off 6dB 12dB
On On 0dB 6dB

The Nº28 is available with either a high-gain or low-gain phono option.
Each option offers two internally adjustable gain settings via two
single-pole miniature rocker switches, one for each channel. The high­gain and low-gain phono options have been factory-adjusted at the
lowest gain settings (58dB and 38dB, respectively).

If you wish to increase the gain, see "Making the internal adjustments;"
refer to the tables below for the proper switch positions for each gain
settings.

Switch

#1 #2 Gain Nominal Cartridge Output (3.54 cm/sec)
On Off 58dB .2mV - .6mV
Off On 64dB .2mV and Lower

Switch

#1 #2 Gain Nominal Cartridge Output (3.54 cm/sec)
On Off 38dB Greater than 2.0mV
Off On 44dB 2.0mV and Lower

6

Internal adjustments:

cartridge loading

The high-gain and low-gain phono options offer internally selectable
cartridge loading via four single-pole miniature rocker switches, one
for each channel. The high-gain and low-gain options have been

factory-adjusted at 825Ω and 47KΩ, respectively.

If you wish to change the factory-adjusted cartridge loading, see
"Making the internal adjustments;" refer to the table below for the
proper switch positions for each load setting.

Cartridge loading settings

(high-gain option)

Cartridge loading settings

(low-gain option)

Internal adjustments:

optional load terminals

Terminating the

optional load

Switch 30Ω 100Ω 825Ω 10KΩ Optional

#1 On Off Off Off Off
#2 Off On Off Off Off
#3 Off Off On Off Off
#4 Off Off Off Off On

Switch 825Ω 10KΩ 22KΩ 47KΩ Optional

#1 On Off Off Off Off
#2 Off On Off Off Off
#3 Off Off On Off Off
#4 Off Off Off Off On

Resistance values other than those listed above can be
accommodated via the optional load terminals. Load resistors can be
inserted into these terminals, allowing virtually any load desired.

Optional load

Solder

component

Solder

PC board

See "Making the internal adjustments;" refer to the "Cartridge loading
settings" tables for the proper switch positions for the optional load.

Because the inherent input resistance (all switches off) is in parallel with
the optional load terminals, use this formula to calculate the actual
resistor needed:

R = 1/ (1/RD - X)

RD = Desired Resistance in ohms

X = 0.00002 for Low-gain Phono Option,

0.0001 for High-gain Phono Option

Note: We recommend precision metal-film resistors; see your
Mark Levinson dealer.

7

Internal adjustments:

varying the input

capacitance

If you wish to vary the input capacitance of the phono option to
obtain the optimal value for a particular cartridge, a capacitor may
also be inserted into the optional load terminals (see "Terminating the
optional load" and "Making the internal adjustments").

Because the inherent input capacitance (all switches off) is in parallel
with the optional load terminals, use the following formula to calculate
the actual capacitor needed.

Making the internal

adjustments

Nº28, internal adjustments

C = CR - CT - C

P

C = The capacitor value

CR = Recommended capacitance value

CT = Tonearm capacitance including leads

CP = Preamplifier inherent shunt capacitance

(Low-gain phono option = 100pf; high-gain phono option = 1000pf)

Note: We recommend high-quality polypropylene, polystyrene
or Teflon capacitors; see your Mark Levinson dealer.

1. Make sure all associated equipment is disconnected from the AC
mains, and that the PLS-228 is disconnected from the AC mains.

2. Using a 5/64" Allen key, remove the eight 6-32 flat-head socket­cap screws securing the Nº28's top cover. Carefully lift the top
cover and remove it.

1234

OFF

Cartridge loading
(right channel)

Optional load pins

Phono gain
(right channel)

12

O
N

O
F
F

3. Adjust the gain switches (using a ballpoint pen or similar

4. Reassemble the Nº28.

8

Cartridge loading
(left channel)

Optional load pins

Phono gain
(left channel)

Line gain

instrument) and install optional loads as desired.

Power connection and

system activation

AC power cord polarity

Be sure all associated equipment is disconnected from the AC mains.

After making all signal connections and internal adjustments, connect
the ten-pin DC cable from the rear panel of the PLS-228 to the
connector on the rear panel of the Nº28.

Connect the AC cord to the male IEC connector on the rear panel of
the PLS-228, then connect the AC cord to the AC mains.

To PLS-228 To AC mains

132

2

1

3

1 = Line (hot)
2 = Neutral
3 = Earth ground

The LED on the PLS-228 will light; after about five seconds, the LED on
the Nº28 will flash. After the LED begins flashing, turn the OUTPUT LEVEL
knob on the front panel of the Nº28 to its lowest (OFF) position (the LED
will stop flashing).

Allow the Nº28's circuitry to stabilize for 1 to 2 minutes, then connect all
associated equipment to the AC mains and activate it.

For optimal sonic performance and longevity, the Nº28/PLS-228 is
designed to remain powered at all times (a power-on/power-off
switch isn't provided).

Note: If AC mains power to the Nº28 is interrupted, the main
output will be muted. When power is restored, the main output
will remain muted and the LED will flash until the OUTPUT LEVEL
knob is turned to its lowest (OFF) position (the LED will stop
flashing). Allow the preamplifier circuitry to stabilize for 1 to 2
minutes; the OUTPUT LEVEL control will then function normally.

9

Care and maintenance

To remove dust from the cabinet of the Nº28, use a feather duster. To
remove dirt and fingerprints, we recommend isopropyl alcohol and a
soft cloth.

10

Specifications

The correlation between published specifications and sonic quality is
unreliable. A list of numbers reveals virtually nothing. All technical
measurements must be subject to qualitative as well as quantitative
interpretation.

Measurements of the Nº28 yield excellent results by any standards.
However, only those specifications that apply to its actual operation
are included here.

■ Power consumption: 50W maximum, depending on options

■ Mains voltage: 100V, 120V, 200V, 220V, or 240VAC @ 50/60Hz

■ Overall dimensions: See "Dimensions"

■ Shipping weight (2 boxes): 29 lbs. (13.2kg)

■ Connector complement: 16 female RCA-type connectors

4 XLR-type female connectors

2 XLR-type male connectors

1 binding post (for turntable ground)

1 ten-pin connector

1 IEC mains connector

Phono section

Line section

■ Gain: Selectable (see "Set-up and installation")

■ Moving-magnet phono option: 38dB, 44dB

■ Moving-coil phono option: 58dB, 64dB

■ Input impedance: Selectable (see "Set-up and installation")

■ Output impedance: 10Ω

■ Maximum output (TAPE output): 6V

■ Recommended load (TAPE outputs): 10KΩ or greater

■ Gain: Selectable (see "Set-up and installation")

■ Single-ended: 6dB, 12dB, 18dB

■ Balanced: 12dB, 18dB, 24dB

■ Input impedance: 15KΩ shunted by 220pf

■ Maximum output (MAIN outputs): 6V

■ Recommended load (TAPE outputs): 600Ω or greater

For more information, see your Mark Levinson dealer, or contact:

Madrigal Audio Laboratories, Inc.

2081 South Main Street (Route 17), P.O. Box 781
Middletown, Connecticut 06457 USA

Telephone [phone]
(FAX [phone]

If purchased in North America, this Mark Levinson product’s warranty is owner-transferable.

Warranty conditions are valid only in the country where the product was originally purchased.

For warranty information and conditions on products purchased outside of North America,

contact your local dealer or regional distributor.

11

Dimensions, Nº28, top view

Dimensions

1"

(25.4)

3/4" dia.

(19.1)

17-17/64"

(438.6)

3/8"

(9.5)

1/8"
(3.2)

Dimensions, Nº28, side view

15-17/64"

(387.8)

2-9/16"

(65.1)

1-1/2"

(38.1)

17-1/2"

(444.5)

7-1/2"

(190.5)

10-7/8"

(276.3)

2-3/4"
(69.9)

12

7/16"

(11.1)

7/64"

(2.5)

Dimensions, PLS-228,

top view

8-3/16"

(208.0)

1-15/64"

(31.4)

5-3/4"

(146.1)

3/4" dia.

(19.1)

3/16"

(4.8)

3/8"

(9.5)

8-35/64"

(217.1)

Dimensions, PLS-228,

side view

2-39/64"

(66.3)

1-55/64"

(47.2)

7/16"

(11.1)

9-1/16"

(230.2)

13-1/8"
(333.4)

2-3/4"
(69.9)

5/64"

(2.0)

13

MADRIGAL AUDIO LABORATORIES

2081 South Main Street, P.O. Box 781

Middletown, Connecticut 06457 USA

Telephone: [phone]

Fax: [phone]

is a registered trademark of Madrigal Audio Laboratories, Inc.

630080-2 Printed in U.S.A.

14

©1993 Madrigal Audio Laboratories, Inc. All rights reserved.

®