Luxman MQ-300 User Manual

VACUUM TUBE STEREO POWER AMPLIFIER

MQ-300

Owner`s Manual

Contents

Precautions ············································································································· 1

Features of This Unit ································································································ 2

Names and Functions ······························································································ 4

Connections ············································································································ 6

Block Diagram ········································································································· 8

Specifications ·········································································································· 9

Before Asking for Repair Services ·········································································· 10

VACUUM TUBE STEREO POWER AMPLIFIER MQ-300

Precautions

Installation place

Install this unit in a location where good ventilation and heat

radiation is assured.

Do not install it where the temperature is high such as in

direct sunlight, or where it is dusty or humid, as this could

result in damage to this unit despite proper heat radiation.

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 am-

plifier 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 con-

fined space such as a book case or similar unit.

* Note

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

cannot 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 con-

trol at a low level. After that, you may move the volume con-

trol 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.

*

*

*

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

inadequately connected, noises including hum may be gen-

erated, resulting in an adverse S/N ratio.

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 substances can often damage the

exterior.

Safety caution

Caution

This unit is a vacuum tube power amplifier. Be careful not to

touch this product with your bare hand because this product

becomes hot in the power-on state. For safety, do not use this

product in a place where children or unchained animals are

present.

1

Features of This Unit

Circuit configuration

Direct heated triode 300B non-feedback single stereo power

amplifier

Output tube

Highly reliable Japan-made TA-300B (manufactured by

Takatsuki Electric Industry Co., Ltd.) is used as a cathode

bias circuit. The constant voltage DC-ignition method is used

for the heaters.

Voltage amplification stage

Two-stage amplification circuit with highly reliable tubes

6SN7GTB (manufactured by Tung-Sol) in parallel connection.

Rectifying tube

Two pieces of indirectly heated tubes, 5AR4 (manufactured

by Sovtec) are used in the L and R independently, whose in-

ternal impedance is low and which have excellent regulation.

Due to a gradual rise in voltage supply to the output tubes,
their lives are expected to be prolonged.

Coupling capacitor

LUXMAN’s original high sound quality oil capacitors are used.

Power transformer

The orient core EI type is used to pursue thickness and depth

in the bass range. Optimization of magnetic flux density im-

proves electrical characteristics and achieves higher sound

quality. The L-R independent structure of the secondary

winding, rectifying tubes, block capacitors, and choke coils

eliminates unwanted coloration of the sound and achieves

expressive capability with high tranquility.

Output transformer

Orient cut core carefully chosen for 300B tubes after a lot of

consideration to its sound quality and dimensional balance.

We have improved the directivity of wire rods and winding

structure and have achieved excellence in low frequency

characteristics using LUXMAN classic OY type as a basis.

2

VACUUM TUBE STEREO POWER AMPLIFIER MQ-300

Choke coil

A choke coil of FINEMET® core is equipped in the L and R

sides independently. Regular winding in which a sheet of par-

affin paper is inserted between every winding layer can de-

crease losses and achieve elaborate and fresh sound quality

with rich content.

(FINEMET® is a registered trademark of Hitachi Metals, Ltd.)

Input terminal

This product is equipped with the copper alloy input terminal

that has high conductivity equivalent to copper and hardness

equivalent to brass.

Vibration-reducing high-rigidity chassis

High-rigidity chassis structure combining a 1.6 mm thick steel

sheet with 12 mm thick aluminum top panel.

A vibration reducing structure with heat-resistant material

support at the bottoms of output tubes and rectifying tubes

lowers microphonic noise.

Appearance

This product is designed to look as graceful as possible with

special attention to the finishing touch such as transformer

cases formed by aluminum extrusion processing, specially

processed nameplates, 12 mm thick top panel with high-

grade hairline finish, and wood panel made of natural wood

with piano finish coating in a harmonic fashion.

Highly reliable design

The sound quality and tones produced by vacuum tubes have

been refined, and at the same time, both prolonged life and

highly reliable design of vacuum tubes have been achieved

by providing operating conditions of vacuum tubes with some

allowance.

Cast-iron insulator

This unit is equipped with gradation cast-iron insulators that

cuts out unnecessary external vibration and strongly supports

the weight of this unit.

Socket floating structure

The socket floating structure that minimizes the vibration in-

fluence to structurally delicate output tubes, 300B, is used to

reduce microphonic noise.

The described company names and product names are

trademarks or registered trademarks of each company.

3