Luxman MQ-88uC User manual

Owner`s Manual
VACUUM TUBE STEREO POWER AMPLIFIER
MQ-88uC

Contents
Precautions ············································································································· 1
Features of This Unit································································································ 2
Names and Functions······························································································ 4
Connections ············································································································ 6
Block Diagram········································································································· 8
Specifications ·········································································································· 9
Before Asking for Repair Service············································································ 10

VACUUM TUBE STEREO POWER AMPLIFIER MQ-88uC
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Precautions
Installation place
Install this unit in a location where good ventilation and heat
radiation are assured. Especially, installation of this unit where
direct sunlight is present, where the temperature rises exces-
sively high such as close to a heater, or where it is humid
or dusty may cause a malfunction even if heat is efficiently
released. Therefore, do not install this unit in such places.
Ventilation holes
The ventilation holes on the top and bottom boards of this
product must not be blocked because this unit is a vacuum
tube amplifier and generates considerable heat. If the ampli-
fier is installed on a rack or the like, secure ample space for
cooling and leave the door open. Do not pile up other things
on the amplifier and never put articles on it. Failure to observe
this may cause a malfunction.
Note:
For heat dispersal, do not install this equipment in a confined
space such as a book case or similar unit.
*Note
Wall
**
*
Precautions in connecting with other
components
When connecting this product to input devices such as a
control amplifier, be sure to turn off the power of this prod-
uct and all other connected devices. Otherwise, a very strong
noise may be generated and destroy the speakers. In the
worst case, this can cause equipment malfunction.
The pin-plug to be inserted in each input terminal of this unit
shall be pushed in firmly. If the grounding terminal is inade-
quately connected, noises including hum may be generated,
resulting in an adverse S/N ratio.
Cautions in connecting speakers
When making speaker system connections, be sure not to
cause short-circuiting between !and @of the speaker ter-
minals and speaker input terminals of this unit. If signals are
applied to the amplifier with its circuit left short-circuited, a
large current may be carried in the output circuit and cause
malfunctioning.
The sound is not generated shortly after
the power supply is turned on.
This product is a vacuum tube amplifier, and therefore, it can-
not deliver a sound until the vacuum tube heaters warm up.
You can enjoy music 1 minute or more after turning on the
power. We therefore advise initially setting the volume control
at a low level. After that, you may move the volume control to
your favorite sound level after the initial sound comes out of
the speakers.
Repair and adjustment
When repairs and adjustments are needed, please consult
with the dealer where you bought the unit.
Cleaning
For cleaning, use a piece of soft cloth to wipe the unit such as
cleaning cloth. When the dirt is hard to remove, use a small
amount of neutral detergent to wipe, and then wipe the unit
with dry cloth. Do not use a solvent like benzine or thinner
because such a substance can damage the exterior.
Safety caution
Caution
This unit is heavy. Be careful when unpacking, carrying, and
installation.
This unit is a vacuum tube control amplifier. In the state of the
unit in operation, the main body gets hot. Be careful not to
touch it with your bare skin. For safety, do not use this product
in a place where children or unchained animals are present.

2
Features of This Unit
Design of using vacuum tubes for all
amplification circuits
All the amplification circuits consist of vacuum tubes (ECC83S
x 2 pieces, ECC82 x 2 pieces, and KT88 x 4 pieces) that are
manufactured by JJ Electronic in Slovak Republic.
Necessary and sufficient rated output
The rated output of 25 W+25 W (at the load of 4, 8, and
16Ω) that enables necessary and sufficient sound volume in
various speaker environments.
Output tube, KT88
KT88 manufactured by JJ Electronic in Slovak Republic is
used in the push-pull structure as an output tube, which has
the reputation of powerful and thick tone quality.
Parallelized first stage
The amplifier on the first stage has been parallelized and
directly connected to the driver stage with a high S/N ratio
and low-impedance transmission.
Triode connection
The proven Mullard type circuit (for the driver stage) has been
equipped, and KT88, an output tube, has been used in a way
of triode connection.
Impedance matching
Speaker terminals dedicated for 4, 8, and 16 Ω are equipped,
which can be used according to the impedance of the speak-
ers to be used.
Old-time parts layout
This product has a parts layout inspired by the design of old-
time masterpiece, MQ60.
Monocoque chassis structure
This product features a monocoque chassis structure that is
orthodox and has been proven.
OY-15 output transformer
The OY-15 output transformer contained in an aluminum die
casting case has been revived in an original shape.
Large-capacity power transformer
An EI-type large-capacity power transformer is used to obtain
persistent tone quality.
LUXMAN’s original block capacitor
LUXMAN's original large-sized block capacitor is used to
supply stable power.
2-line input
There are two lines of inputs for input terminals; one is a
variable input capable of sound volume adjustment, and the
other is a direct input to bypass the volume.

VACUUM TUBE STEREO POWER AMPLIFIER MQ-88uC
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Bonnet for vacuum tube
A mesh type bonnet is supplied as a standard item to protect
vacuum tubes and other large-sized parts.
Custom-made parts
LUXMAN’s original custom-made parts for generating high
sound quality are plentifully equipped.
Wide pitch RCA terminals
Wide pitch RCA terminals are used to allow large-sized RCA
cables to be connected.
Highly reliable design
Prolonged life and highly reliable design have been achieved
by providing operating conditions of vacuum tubes with some
allowance.

4
Names and Functions
1. Operation indicator (OPERATION)
Turns orange when the power is turned on.
2. Operation switch (OPERATION)
Toggles the power on and off.
When wiring or connection is performed, be sure to turn off
this switch. When turning on the power switch again after
turning the unit off, wait for more than one minute.
When the power is turned off, the OPERATION indicator
will stay on for a while, but it is not a malfunction.
3. Volume control (VOLUME)
This function is effective only when a source component
such as a CD player is connected to the VARIABLE input of
this unit to adjust the input level.
When the connection is made with the direct input (DIRECT),
the signals do not go through this volume thus the sound
volume does not change.
When the DIRECT input is connected, please take extra
care for the volume of the other connected unit.
321
Front panel

VACUUM TUBE STEREO POWER AMPLIFIER MQ-88uC
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4. Direct input terminals (DIRECT)
Connects to a control amplifier or a source component.
When connected to this input terminal, the signals do not
go through the volume circuit, thus rotating the volume con-
trol on the front panel will not change the volume.
5. Variable input terminals (VARIABLE)
Connects to a source component, e.g. a CD player without
output level control.
The sound volume can be adjusted by the volume control
of the front panel.
If using a control amplifier with high output impedance in
combination with this unit, use of the connection cable as
short as possible is recommended to avoid unnecessary
treble attenuation.
6. Input selector (VARIABLE/DIRECT)
Variable or direct input can be switched.
Select the name of the terminals connected to the device to
play back by operating this switch.
When switching the input, be sure to turn off the power.
If the power is on while switching, large noise might be
generated.
7. Speaker terminals (SPEAKERS)
These terminals are output terminals to connect a speaker
system.
The right speaker terminals shall be connected to the R
side, and the left speaker terminals shall be connected to
the L side in consideration of the polarity !and @.
The speaker terminals consist of @COMMON, !4Ω,
!8Ω, and !16Ω for each channel. Connect the @termi-
nal of the speaker system to the @COMMON terminal and
!terminal of the speaker system to !4Ω, !8Ω, or !16Ω
according to the impedance of the speakers to be used.
8. AC inlet (AC IN)
Connects the accessory power cable. The power shall be
supplied from a household wall socket.
84 5 6 7
Rear panel

6
Connections
CONTROL AMPLIFER
CD PLAYER
RECORDER
CD/SACD PLAYER
ANALOG PLAYER
CD PLAYER
CD/SACD PLAYER
L R
SPEAKER SYSTEM(B)
–+ –+
(When the speaker
impedance is 8Ω)

VACUUM TUBE STEREO POWER AMPLIFIER MQ-88uC
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Before connecting
Before connecting other devices, connect the jack side of the
accessory power cable to the AC inlet of this unit.
Before connection is made, turn off the main power switch
of this unit and the power of all other connected devices to
prevent accidents due to noises generated unexpectedly.
How to connect power supply
Use the accessory power cable and insert the AC plug in the
outlet on the wall in the room where the unit is installed.
How to connect a CD player, control
amplifier
Connect the output terminal of a control amplifier to the input
terminal with 2 (R and L) pin-plug cables.
When using a source device with the volume adjusting func-
tion, such as a CD player, connect to the VARIABLE input
terminal. When using a source device with the volume con-
trol, such as a control amplifier, connect to the DIRECT input
terminal.
Select DIRECT or VARIABLE input with the input selector.
How to connect speakers
Connect the left-channel speaker to the SPEAKERS-L
terminal of this unit and the right-channel speaker to the
SPEAKERS-R terminal.
Securely connect the !terminal of the speaker system to
the red speaker terminal (!4Ω, !8Ω, or !16Ω) of this unit
according to the impedance of the speakers to be used and
the @terminal of the speaker system to the black speaker
terminal (@COMMON) of this unit.
If the !or @terminal is reversely connected to either of the
right or left of the speaker system, the signal phases repro-
duced from the right and left of the speaker system are also
reversed. In such a case, be aware that the sound level in
the low range will be reduced and the acoustic stability will
worsen, and thus the normal stereo playback is not achieved.
If the impedance of the speakers to be used is other than 4Ω,
8Ω, or 16Ω, connect the terminal with an impedance closest
to the impedance value of the speakers.
The range of the impedance of the speaker to be connected
should be within the range of 4Ω to 16Ω.

8
Block Diagram
COMMON TP-V2 TP-V1
DIRECT VARIABLE
PARALLEL
16Ω 8Ω 4Ω
KT88
CH
SW
3.6K
ECC83S ECC82 KT88
KT88 KT88 KT88
ECC82ECC83
KT88
Power Transformer
VR
TRANS OUTPUT
GND COM
BIAS BIAS
OUTPUT TUBE ADJUSTMENT
BIAS
BIAS-V4 BIAS-V3 BIAS-V2 BIAS-V1
BIAS
V2
V1
2B+3B+
+B 1 +B 2 +B 3
Operation SW
Fuse
BRIDGE DIODE
BRIDGE DIODE
+B 1

VACUUM TUBE STEREO POWER AMPLIFIER MQ-88uC
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Specifications
Rated output 25 W+25 W (4 Ω, 8 Ω, 16 Ω)
Total harmonic distortion 0.1 % (1 kHz, 1 W)
0.5 % (20 Hz to 20 kHz, 1 W)
Input sensitivity 890 mV/25 W
Input impedance 32 kΩ
S/N ratio 105 dB (A weighted, input short)
Frequency response 20 Hz to 20 kHz (+0, −0.2 dB)
10 Hz to 100 kHz (+0, −3.0 dB)
Input Line: Direct input x 1 line, variable input x 1 line
Output Speaker terminal x 1 line (4, 8, and 16 Ω independent)
Supplied functions [Front panel] Operation switch, Volume control
[Rear panel] Input terminal, Input selector, Speaker terminal, AC inlet
Circuiting system Mullard
Vacuum tube used ECC83S x 2 pieces, ECC82 x 2 pieces, and KT88 x 4 pieces
Accessories • Power cable • Terminal protection cap
• Owner’s Manual (This document) • Safety cautions
Power source 230 V 〜(50 Hz)
Power consumption 170 W
140 W (no signal)
Max. external dimensions 440 (W) x 184 (H) x 230 (D) mm
Weight 16.1 kg (main unit)
* Specifications and the appearance are subject to change without notice.

10
Before Asking for Repair Service
While in use, this unit may display phenomena which may be confused as malfunctions. Before contacting your country's official LUXMAN
distributor for repair services, please read the operating instructions and operating instructions for any connected input and through
output devices and check the troubleshooting table below. If the cause of the malfunction cannot be identified, please contact your
dealer. After LUXMAN’s representatives have accepted your request for repair services, inspection fees and transportation expenses
may be claimed, even though the unit may be found to be operating normally.
Problem Cause Solution
No power is supplied even
though the operation switch is
pressed.
• The power plug is disconnected from the
wall outlet, or it is not completely inserted.
• Insert the power plug in the wall outlet
completely.
• The power plug is disconnected from the
AC inlet, or it is not inserted completely.
• Securely insert the power plug in the AC
inlet.
No sound is generated.
(for both left and right channels)
• The volume control is set at the minimum
level.
• Rotate the volume control clockwise to
adjust the sound volume.
• The input switch is not set to the position of
the source to be played back.
• Set the input switch to the position of the
source to be played back.
• Cable connections are incomplete. • Make cable connections securely.
• The output level of the input device is set to
the minimum position.
• Adjust the output level.
No sound is generated on one
side.
• The connecting cable is not connected on
one side only.
• Make cable connections securely.
Humming sound (boon or zzz
noise) is generated.
• The ground side of the pin-plug cable has
no contact with the terminal.
• Make connections securely so that the
ground side of the pin-plug cable can be
connected.
• The connecting cables are too close to the
power cable.
• Keep the connecting cables away from the
power cable.
• Induction noise is picked up from a power
transformer of another device.
• Install it distant from other devices.

VACUUM TUBE STEREO POWER AMPLIFIER MQ-88uC
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MEMO

12
MEMO

LUXMAN CORPORATION, JAPAN
AG00987E73A
Printed in Japan
1-3-1 Shinyokohama, Kouhoku-ku, Yokohama-shi, Kanagawa 222-0033, Japan