Mark Levinson N28 User Manual

Operating Manual  
Mark Levinson®  
Nº28  
Preamplifier  
Madrigal Audio Laboratories, Inc.  
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.  
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.  
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  
5
CD  
PHONO/  
AUX 1  
TUNER  
TAPE 1  
4
6
MADRIGAL AUDIO LABORATORIES  
AUX 2  
3
7
TAPE 1  
INPUT  
MONITOR  
AUX 3  
TAPE 2  
Nº 28  
TAPE 2  
DEFEAT  
8
2
PREAMPLIFIER  
9
1
10  
OFF  
INPUT SELECTOR  
MONITOR SELECTOR  
RECORD SELECTOR  
OUTPUT LEVEL  
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.  
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
4
MONITOR SELECTOR  
When the RECORD SELECTOR is in the MONITOR position, this selects  
between the TAPE 1 and TAPE 2 inputs.  
OUTPUT LEVEL  
Adjusts volume at the main outputs.  
The OUTPUT LEVEL control doesn't affect the tape outputs.  
1
OUTPUTS  
INPUTS  
BALANCED MAIN  
RIGHT LEFT  
CD  
AUX 2  
POWER  
SUPPLY  
INPUT  
RIGHT  
PUSH  
LEFT  
PUSH  
RIGHT  
PUSH  
LEFT  
LEFT  
PUSH  
GND  
RIGHT  
7
4
2
8
6
5
3
1
Rear panel  
PRECAUTION  
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
3
4
TUNER  
Accepts right-channel and left-channel signal leads from a tuner  
or other line-level source equipment.  
AUX 3  
Accepts right-channel and left-channel signal leads from line-level  
source equipment.  
TAPE 1, TAPE 2 (INPUTS)  
Accept right-channel and left-channel signal leads from the tape-  
output 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  
Pin 1: Signal ground  
Pin 2: Signal + (non-inverting)  
Pin 3: Signal (inverting)  
2
1
3
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:  
1
Male RCA  
Male XLR  
(connect to  
Nº28)  
(connect to  
source)  
2
3
22-guage  
buss wire  
6
7
8
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.  
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.  
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  
Pin 2: Signal + (non-inverting)  
Pin 3: Signal (inverting)  
1
2
3
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  
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.  
Ventilation 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").  
PRECAUTION  
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 POWER SUPPLY  
PLS-228 bottom-panel  
label  
AC INPUT  
WARNING: BEFORE ATTEMPTING TO  
OPERATE THIS DEVICE, REFER TO  
OWNER'S MANUAL FOR PROPER  
OPERATING INSTRUCTIONS AND SAFETY  
PRECAUTIONS. HAZARDOUS VOLTAGE  
Voltage  
AVAILABLE INSIDE; DISCONNECT AC~  
MAINS CABLE BEFORE REMOVING COVER.  
indication  
OPERATING VOLTAGE:  
90 – 110VAC~  
105 125VAC~  
180 220VAC~  
210 240VAC~  
230 250VAC~  
~50 60HZ  
100 120VAC~  
2A SLOBLO 250VAC 3AB  
200 240VAC~  
MAINS  
FUSES:  
1A SLOBLO 250VAC 3AB  
SERIAL NO.  
DESIGNED AND MANUFACTURED IN U.S.A. BY  
MADRIGAL AUDIO LABORATORIES INC.  
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  
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 RCA-  
type 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.  
Internal adjustments: The Nº28 offers internal gain adjustment of the line amplifiers, in 6dB  
line gain 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  
Switch  
Gain  
#1  
#2  
Single-Ended Output  
Balanced Output  
Off  
Off  
On  
On  
Off  
On  
Off  
On  
18dB  
12dB  
6dB  
24dB  
18dB  
12dB  
6dB  
0dB  
Internal adjustments:  
phono gain  
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 high-  
gain 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.  
Phono gain settings  
(high-gain option)  
Switch  
#1  
#2  
Off  
On  
Gain  
58dB  
64dB  
Nominal Cartridge Output (3.54 cm/sec)  
.2mV - .6mV  
On  
Off  
.2mV and Lower  
Phono gain settings  
(low-gain option)  
Switch  
#1  
#2  
Off  
On  
Gain  
38dB  
44dB  
Nominal Cartridge Output (3.54 cm/sec)  
Greater than 2.0mV  
On  
Off  
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 825and 47K, 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)  
Switch  
#1  
#2  
#3  
#4  
30  
On  
Off  
Off  
Off  
100Ω  
Off  
On  
Off  
Off  
825Ω  
Off  
Off  
On  
Off  
10KΩ  
Off  
Off  
Off  
Off  
Optional  
Off  
Off  
Off  
On  
Cartridge loading settings  
(low-gain option)  
Switch  
#1  
825Ω  
On  
10KΩ  
Off  
22KΩ  
Off  
47KΩ  
Off  
Optional  
Off  
#2  
#3  
Off  
Off  
On  
Off  
Off  
On  
Off  
Off  
Off  
Off  
#4  
Off  
Off  
Off  
Off  
On  
Internal adjustments:  
optional load terminals  
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  
component  
Solder  
Solder  
Terminating the  
optional load  
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.  
C = CR - CT - CP  
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.  
Making the internal  
adjustments  
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 socket-  
cap screws securing the Nº28's top cover. Carefully lift the top  
cover and remove it.  
Nº28, internal adjustments  
1
2
3
4
Cartridge loading  
(right channel)  
Phono gain  
(right channel)  
OFF  
1
2
O
N
Optional load pins  
O
F
F
Cartridge loading  
(left channel)  
Phono gain  
(left channel)  
Optional load pins  
Line gain  
3. Adjust the gain switches (using a ballpoint pen or similar  
instrument) and install optional loads as desired.  
4. Reassemble the Nº28.  
8
Power connection and  
system activation  
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  
AC power cord polarity  
1 = Line (hot)  
1
2
1
2
2 = Neutral  
3 = Earth ground  
3
3
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:  
Mains voltage:  
50W maximum, depending on options  
100V, 120V, 200V, 220V, or 240VAC @ 50/60Hz  
See "Dimensions"  
Overall dimensions:  
Shipping weight (2 boxes):  
Connector complement:  
29 lbs. (13.2kg)  
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 Gain:  
Selectable (see "Set-up and installation")  
Moving-magnet phono option:  
38dB, 44dB  
58dB, 64dB  
Moving-coil phono option:  
Input impedance:  
Output impedance:  
Maximum output (TAPE output):  
Recommended load (TAPE outputs):  
Selectable (see "Set-up and installation")  
10Ω  
6V  
10Kor greater  
Line section  
Gain:  
Selectable (see "Set-up and installation")  
6dB, 12dB, 18dB  
Single-ended:  
Balanced:  
Input impedance:  
Maximum output (MAIN outputs):  
Recommended load (TAPE outputs):  
12dB, 18dB, 24dB  
15Kshunted by 220pf  
6V  
600or 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 (203) 346-0896  
(FAX (203) 346-1540  
If purchased in North America, this Mark Levinson products 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  
3/8"  
(9.5)  
1/8"  
(3.2)  
Dimensions, Nº28, top view  
1"  
(25.4)  
3/4" dia.  
(19.1)  
17-17/64"  
(438.6)  
15-17/64"  
(387.8)  
17-1/2"  
(444.5)  
1-1/2"  
(38.1)  
7-1/2"  
(190.5)  
10-7/8"  
(276.3)  
Dimensions, Nº28, side view  
2-9/16"  
(65.1)  
2-3/4"  
(69.9)  
7/16"  
(11.1)  
7/64"  
(2.5)  
12  
3/8"  
(9.5)  
3/16"  
(4.8)  
Dimensions, PLS-228,  
top view  
1-15/64"  
(31.4)  
3/4" dia.  
(19.1)  
8-3/16"  
(208.0)  
8-35/64"  
(217.1)  
5-3/4"  
(146.1)  
1-55/64"  
(47.2)  
9-1/16"  
(230.2)  
13-1/8"  
(333.4)  
Dimensions, PLS-228,  
side view  
2-39/64"  
(66.3)  
2-3/4"  
(69.9)  
7/16"  
(11.1)  
5/64"  
(2.0)  
13  
MADRIGAL AUDIO LABORATORIES  
2081 South Main Street, P.O. Box 781  
Middletown, Connecticut 06457 USA  
Telephone: (203) 346-0896  
Fax: (203) 346-1540  
®
is a registered trademark of Madrigal Audio Laboratories, Inc.  
©1993 Madrigal Audio Laboratories, Inc. All rights reserved.  
630080-2  
Printed in U.S.A.  

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