Quad II Forty Owners manual

II–forty &

QC–twenty four

Valve Amplification System

Quad Electroacoustics Ltd, IAG House,

Sovereign Court, Ermine Business Park,

Huntingdon PE29 6XU

www.quad-hifi.co.uk

Tel [phone] Fax [phone]

Owner’s Manual

Important Safety Precautions - Please Read Carefully!

CAUTION

!

RISK OF ELECTRIC SHOCK - DO NOT OPEN!

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

!

Read Instructions: All the safety and operating instructions should be

read before the product is operated.

Retain Instructions: The safety and operating instructions should be

retained for future reference.

Heed Warnings: All warnings on the product and in the operating

instructions should be adhered to.
Follow Instructions: All operating and use instructions should be

followed.

Cleaning: Unplug this product from the wall outlet before cleaning. Do

not use liquid cleaners or aerosol cleaners. Use a damp cloth for cleaning.

Attachments: Do not use attachments not recommended by the

product manufacturer as they may cause hazards.

Water and Moisture: Do not use this product near water - for example,

near a bath tub, wash bowl, kitchen sink, or laundry tub, in a wet
basement; or near a swimming pool; and the like.

Accessories: Do not place this product on an unstable cart, stand, tripod,

bracket, or table. The product may fall, causing serious injury to a child or
adult, and serious damage to the product. Use only with a cart, stand,
tripod, bracket or table recommended by the manufacturer, or sold with the
product. Any mounting of the product should follow the manufacturer's
instructions, and should use a mounting accessory recommended by the
manufacturer.

Moving the Product: A product and cart combination should be

moved with care. Quick stops, excessive force, and uneven surfaces may
cause the product and cart to overturn.

Ventilation: Slots and openings in the cabinet are provided for

ventilation and to ensure reliable operation of the product and to protect
it from overheating, and these openings must not be blocked or covered.
The openings should never be blocked by placing the product on a bed,
sofa, rug, or other similar surface. This product should not be placed in a
built-in installation such as a bookcase or rack unless proper ventilation is
provided or the manufacturer's instructions have been adhered to.

Power Supply Cords: Power supply cords should be routed so that they

are not likely to be walked on or pinched by items placed upon or against
them, paying particular attention to cords at plugs, convenience
receptacles, and the point where they exit from the product.

Power Sources: This product should be operated only from the type of

power source indicated on the marking label. If you are not sure of the
type of power supply to your home, consult your product dealer or local
power company. For products intended to operate from battery power, or
other sources, refer to the operating instructions.

Polarisation: This product is equipped with a polarized alternating-

current line plug (a plug having one blade wider than the other). This
plug will fit into the power outlet only one way. This is a safety feature. If
you are unable to insert the plug fully into the outlet, try reversing the
plug. If the plug should still fail to fit, contact your electrician to replace
your obsolete outlet. Do not defeat the safety purpose of the polarized
plug.

Lightning: For added protection for this product during a lightning

storm, or when it is left unattended and unused for long periods of time,
unplug it from the wall outlet and disconnect the antenna or cable system.
This will prevent damage to the product due to lightning and power-line
surges.

Antenna Grounding: If an outside antenna or cable system is

connected to the product, be sure the antenna or cable system is
grounded so as to provide some protection against voltage surges and
built-up static charges. Article 810 of the National Electrical Code,
ANSI/NFPA 70, provides information with regard to proper grounding
of the mast and supporting structure, grounding of the lead-in wire to an
antenna discharge unit, size of grounding conductors, location of
antenna-discharge unit, connection to grounding electrodes, and
requirements for the grounding electrode. (Refer to diagram)

operating and maintenance (servicing) instructions in the
literature accompanying the appliance.

SAFETY INFORMATION

CAUTION: TO PREVENT ELECTRICAL SHOCK, MATCH WIDE BLADE
OF PLUG TO WIDE SLOT, FULLY INSERT.

ATTEN TIO N: POUR ÉVITER LES CHOCS ELECTRONIQUES
INTRODUIRE LA LAME LA PLUS LARGE DE LA FICHE DANS LA BORNE
CORRESPONDANTE DE LA PRISE ET POUSSER JUSQU’ A FOND.

CAUTION: FOR CONTINUED PROTECTION AGAINST RISK OF FIRE
REPLACE FUSE ONLY WITH SAME TYPE AND RATING.

ATTENTION: UTILISER UN FUSIBLE DE RECHANGE DE MEME TYPE
ET CALIBRE.

WARNING: SHOCK HAZARD - DO NOT OPEN.
AVIS: RISQUE DE CHOC ELECTRIQUE - NE PAS OUVRIR.

Example of Antenna Grounding as per

Example of Antenna Grounding as per

National Electrical Code ANSI/NFPA 70

National Electrical Code ANSI/NFPA 70

Electric service

Electric service

equipment

equipment

Power service grounding electrode system

Power service grounding electrode system

(NEC ART 250, Part H)

(NEC ART 250, Part H)

Power Lines: An outside antenna system should not be located in the

vicinity of overhead power lines or other electric light or power circuits,
or where it can fall into such power lines or circuits. When installing an
outside antenna system, extreme care should be taken to keep from
touching such power lines or circuits as contact with them might be fatal.

Overloading: Do not overload wall outlets, extension cords, or integral

convenience receptacles as this can result in a risk of fire or electric shock.

Object and Liquid Entry: Never push objects of any kind into this

product through openings as they may touch dangerous voltage points or
short-out parts that could result in a fire or electric shock.

Heat: The product should be situated away from heat sources such as

radiators, heat registers, stoves, or other products (including amplifiers)
that produce heat.

Servicing: Do not attempt to service this product yourself as opening or

removing covers may expose you to dangerous voltage or other hazards.
Refer all servicing to qualified service personnel.

Damage Requiring Service:

and refer servicing to qualified service personnel under the following
conditions:

a) When the power supply-cord or plug is damaged.
b) If liquid has been spilled, or objects have fallen into the product.
c) If the product has been exposed to rain or water.
d) If the product does not operate normally by following the operating

instructions. Adjust only those controls that are covered by the operating
instructions as an improper adjustment of other controls may result in
damage and will often require extensive work by a qualified technician to
restore the product to its normal operation.

e) If the product has been dropped or damaged in any way.
f) When the product exhibits a distinct change in performance - this

indicates a need for service.

Unplug this product from the wall outlet

Replacement Parts: When replacement parts are required, be sure the

service technician has used replacement parts specified by the
manufacturer or have the same characteristics as the original part.
Unauthorised substitutions may result in fire, electric shock, or other
hazards.

Safety Check: Upon completion of any service or repairs to this

product, ask the service technician to perform safety checks to determine
that the product is in proper operating condition.

Warning: To resist the risk of fire or electrical shock, do not expose this

product to rain or moisture. The product must not be exposed to
dripping and splashing and no object filled with liquids - such as a vase of
flowers - should be placed on the product.

No naked flame sources - such as candles - must be placed on the

product.

Service: Equipment for sevicing should be returned to the suplying

dealer, or to the appointed service agents for your territory. The addresses
of the appointed Service Agents for the UK , USA and Canada are listed
on the inside rear cover of this manual.

Ground clampsGround clamps

Antenna lead in wireAntenna lead in wire

Ground clampsGround clamps

Antenna discharge unit

Antenna discharge unit

(NEC Section 810-20)

(NEC Section 810-20)

Grounding Conductors

Grounding Conductors

(NEC Section 810-71)

(NEC Section 810-71)

Authorised QUAD Service

Centres in the U.K. and North

America

USA

IAG America, Inc.

180 Kerry Place

Norwood

MA 02062

Tel: [phone]

CANADA

Korbon Trading Ltd

6800 Kitimat Road

Units 19-20

Mississauga

Ontario

Tel: [phone]

U.K.

QUAD Electroacoustics Ltd.

IAG House, Sovereign Court,

Ermine Business Park,

Huntingdon,

Cambs PE29 6XU,

England.

Tel:[phone]

Fax:[phone]

For information on authorised service

centres worldwide contact QUAD

Electroacoustics Ltd. in the U.K.

A worldwide distributor list is

available on the QUAD website:

www.quad-hifi.co.uk

SPECIFICATIONS

Valve preamplifier

Valve complement 1x 6111 twin triode

THD @ 1V RMS < 0.2%

Frequency Response 5 Hz - 50 KHz (+0 dB/-0.5 dB)

Hum and Noise Better than - 80 dB

Line stage gain 15 dB

Recommended minimum load 50 k Ohms

Inputs 5 x Line level*

2 x Buffered tape loops

Power Consumption 15 VA maximum

* Note: Phono input is line level until optional phono stage is added

Monobloc valve power amplifier

Power output 40W RMS

THD @ 700 Hz 0.3% @ 40W

0.03% @ 1W

Residual hum and noise Better than -80 dB

Frequency response 10 Hz - 30 kHz (+0 dB/-0.5 dB)

Damping factor 20 @ 700 Hz (referred to 8 Ohms)

Power consumption 180VA maximum

Loudspeaker taps 4 and 8 Ohms

Valves 2 x 6SH7 Input

2 x KT88 Output

1 x 5U4G Rectifier

Input sensitivity 1V RMS

The QUAD II – forty power amplifier is a direct descendant of the legendary QUAD II
amplifier designed by Peter Walker, founder of QUAD and one of the guiding lights of early
Hi-Fi reproduction. Like the QUAD II, the QUAD II – forty uses the uniquely simple and
timeless circuit topology developed by Walker.

The modern listener demands a higher power output than the 15W of the original QUAD II.
The new QUAD II – forty uses larger output valves and a more robust power supply and the
input valves have been upgraded to military grade devices. Whilst the QUAD II – forty
retains the layout and styling of the QUAD II, the chassis size has been increased to take the
substantially larger components including mains and output transformers.

The QC – twenty four preamplifier uses a radically new and functionally simple audio circuit
and features relay input switching to preserve signal purity. With modern high quality
recording and reproduction equipment tone controls are now redundant and so the QC twenty
four dispenses with them. The styling of the QC – twenty four is classic QUAD and matches
the QUAD II – forty.

The QC – twenty four and QUAD II – forty are designed for the music lover. We make no
exaggerated performance claims and are content to let the results speak for themselves.

Thank you for purchasing this QUAD equipment. We can only hope that it will bring you
many years of listening pleasure, and that, like its illustrious predecessor, it will be a treasured
possession for you and for future generations of music lovers.

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ADDITIONAL INFORMATION

IMPORTANT NOTES

Running In

Valve lifetimes

Output Transformer

Most high fidelity equipment works better after it has been run in for some
time. In the case of valve amplifiers the period of running in is much more
important. Components that go into valve equipment work at voltages and
temperatures far higher than their solid-state counterparts and when new
they should spend an extended period at those working temperatures to
bed in properly. This is especially the case with the output valves and the
output transformer.

We recommend an initial running in period of at least four and preferably
twelve hours before you first use the equipment. If you decide to run in
your equipment for an extended period, make doubly sure that all the
safety conditions covered in this manual are fully met. Supervise the
equipment for the first hour or so and if you have to leave the equipment
unattended thereafter, have someone to look in every so often to make
sure all is well.

The patience and care that you devote in these initial stages will be amply
rewarded by many years of outstanding performance from your QUAD
valve equipment.

Valves contain a heating element. This heats up the valve's cathode, which
is specially coated to give off a steady stream of electrons. This coating
will eventually become exhausted and the valve's performance will
deteriorate. In the QUAD II – forty power amplifier the KT88 output
valves are most likely to deteriorate first but the 6SH7driver valves will
also eventually wear out. As the valves start to wear out the sound will
become softer and less well defined and a lack of dynamics and power
will become evident.

The KT88s should last over 6,000 hours and the 6SH7s 15,000 hours of
listening but a longer life can be expected. The 6111WA used in the QC ­twenty four is a military type with a lifetime of 60,000 to 100,000 hours so
it should not need to be replaced for a long time into the future.

When replacing valves it is essential to use the highest quality available.
Poorly manufactured KT88s will adversely affect the sound quality and
may damage the amplifier. Before the amplifiers leave the factory they
are fitted with balanced sets of valves to ensure optimum performance.

These tests are performed with sophisticated analysis equipment so, to
ensure that your amplifiers always perform as they were intended, please
return them to an authorised QUAD Service Department for servicing.

The output transformer is the most expensive component in a valve power
amplifier. It is designed to match the high voltage, low current conditions
in which output valves operate to the low voltage high current
requirements of a loudspeaker. Although robust and capable of lasting a
lifetime, an output transformer can be damaged and, in extreme cases
wrecked, by careless use.

If you operate a solid-state amplifier into a short circuit something
dramatic is likely to happen fairly quickly. If you play a valve amplifier
into a short circuit, the output transformer will soak up a lot of energy
before failing but if the short persists the transformer could be damaged
catastrophically.

Paradoxically, operating a valve amplifier at high output levels with no
loudspeaker connected can damage an output transformer. The analogy
here is to an engine racing away with no load - sooner or later it will burn
out.

European Union Directives:

QUAD equipment is designed to comply with the legal provisions of EU
Directives 89/336/EC and 72/23/EEC. The standards that have been
applied were those in force at the time of the introduction of the product.

The product bears the CE mark

Compliance cannot guarantee perfect performance. In the very rare
circumstance that you experience problems you should first try to locate
and remedy the origin of any disturbance. A further option is to relocate
the QUAD equipment in order to reduce the interference. Your dealer
should be able to provide assistance if the problem persists.

FCC Rule 15 Class B:

This equipment has been tested and complies with the limits for a Class B
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 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 mains circuit different to
that to which the receiver is attached.

Consult the dealer or an experienced Radio/TV technician for help.

Information to the user:

Alteration or modifications carried out without appropriate authorisation
may invalidate the user's warranty.

It is always good practice to switch off equipment before connecting or
disconnecting signal leads. This will prevent unpleasant and loud noises
coming from the loudspeakers and avoid the risk of damage to equipment.
It is important that any unit connected to this equipment is earthed
according to the manufacturer's instructions. This becomes more
important as the number of units that are connected together increases.

Noise Pollution:

Please be aware that very high sound pressure levels can cause permanent
damage to your hearing and also severe annoyance to neighbours.

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