QUAD

Over sixty years old ...
but still leading the way

1936: Pass Go, Collect £200!

 

Peter Walker started the Acoustical Manufacturing Company in London in 
1936. It relocated in Huntingdon after being bombed out in 1941. 

As a recognised world leader in amplifier and electrostatic speaker 
design, the company has made a significant contribution to the 
improvement of sound reproduction in the home. We are particularly proud 
to have been granted the Queen's Award for Technological Achievement in 
1979. 

Before the 1939-45 war there was no hi-fi market as such but we and a 
few manufacturers of public address equipment tried to achieve a better 
quality of reproduction than that generally regarded as economically 
feasible in the cut-throat trading conditions of those days. We also 
produced occasional monsters for use at home but there was then little 
market for such equipment. 

During the war everything stopped, and when the end of the war made it 
possible to resume "non-essential" production, it was largely with war 
surplus parts! 

New designs began to appear out of earlier elaborate and sometimes 
cumbersome equipment such as the one affectionately known in Peter 
Walker's home as the "gas stove", which was Class 'A' and DC coupled no 
less! Over the next few years amplifiers like our QA12/P (pictured 
right) -- Quality Unit Amplifier 12 watt with pre-amplifier -- designed 
for lab and studio applications began to sell for use in the home. By 
the end of the decade the hi-fi market had begun. 

The QUAD (Quality Unit Amplified - Domestic) was the next logical step 
and it was with this model in 1951 that we introduced the variable high 
frequency filter which has been a "must" ever since. We also retained 
and developed the cathode coupling of the output transformer we had 
previously used for many years in our P.A. amplifiers, which was later 
taken up in the USA in a rather retrograde form and called 
"ultra-linear". 

In 1953 we introduced the Quad II, another "first", with push buttons to 
select inputs and alternative record equalisation characteristics. 
Shortly after, we began to discontinue all our P.A. and contract work to 
enable us to concentrate on the QUAD line. 

In the 1950's we also co-operated with the late Gilbert Briggs of 
Wharfedale, the loudspeaker manufacturers, in a series of public 
concerts in London's Royal Festival Hall and other halls in Britain and 
the USA. 

In these a live performance using a variety of works and instruments was 
instantly compared with a recording of the same performance. These 
events helped considerably to promote a wide appreciation of just how 
good quality reproduction could be. 

Our Corner Ribbon loudspeaker from this period deserves a mention since 
it used a ribbon high frequency unit in conjunction with a moving coil 
bass unit, and represented a significant step in loudspeaker 
development. Many of these are still in use, but this model was 
discontinued in preparation for the full range electrostatic loudspeaker 
which we first demonstrated in London to an invited audience of leading 
audio engineers in 1956, and marketed the following year. This was the 
result of a long-standing appreciation of the basic advantages of the 
electrostatic principle and about three years of concentrated, non-stop, 
often day and night research into materials and techniques, all carried 
out in considerable secrecy at Huntingdon. 

Although electrostatics had long been recognised as providing the answer 
to most of the basic problems of loudspeaker design, the limitations in 
earlier days to materials such as animal intestines for diaphragms, and 
the problems of handling very high voltages in domestic equipment, 
rendered the whole idea impracticable. And with the introduction of the 
moving coil loudspeaker, electrostatics were largely abandoned until the 
development of suitable materials for light diaphragms made it possible 
to manufacture them. 

That this speaker remained in production virtually unchanged for 28 
years is a credit to the thought and care invested in its design and 
development. The product was truly years ahead of its time, and it 
became the standard by which all others were judged. 

Braun in Germany was the first foreign firm to manufacture the 
loudspeaker under license followed by KLH and Acoustech in the USA. The 
latter's were much larger units than the Quad, being similar to our 
pre-production model, which was then too big to sell in any quantity, 
particularly with stereo on the horizon! 

The stereo version of the control unit, the Quad 22, appeared in 1959. 
In 1964 the multiplex decoder for stereo broadcasts arrived - at a time 
when the BBC engineers were still wondering whether all the pioneer 
spadework they had done was ever likely to be used in Britain, and the 
rest of the civilised world (and some uncivilised parts) already had 
regular stereo broadcasts. 

In 1967 we introduced the first all-transistorised Quad 33/303 units. 
The "Triples" output circuit of that power amplifier, which for the 
first time successfully overcame the problems of thermal tracking in 
Class B amplifiers, was an original development carried out by the 
company and was the subject of articles in Wireless World and similar 
technical journals overseas. Such articles have also been published from 
time to time on other original Quad features such as the cathode coupled 
output transformer, the two lamp tuning indicator for the VHF/FM tuner, 
methods of testing amplifiers and, of course, the electrostatic 
loudspeaker and current dumping amplifier circuitry which had world-wide 
repercussions. 

In 1975 we presented a paper to the 50th International Convention of the 
Audio Engineering Society on the new technique for power amplifier 
design that we called "Current Dumping". In this technique the linearity 
of the main current carrying transistors (the current dumpers) has no 
bearing on the overall amplifier performance, which is determined solely 
by a low power, very high quality current controlled amplifier, using 
"feed-forward current error correction" in conjunction with overall 
voltage feedback. This makes it possible to produce an amplifier of very 
high performance without using carefully matched and selected, 
relatively fragile and expensive output transistors; without problems of 
cross-over biasing without the need of alignment or adjustment either 
initially or in the event of fitting replacement components later in the 
life of the amplifier. 

The Quad 405 current dumping amplifier proved to be outstandingly 
successful and a best seller in markets as diverse as Japan, Canada and 
France, as well as the UK. 

The Quad 44 control unit, introduced in 1979, provided complete 
flexibility of input facilities by a system of easily replaceable 
modules, using other modern techniques such as electronic switching 
instead of an electro-mechanical system, and introducing a fresh 
approach to tone controls. 

A new Quad electrostatic had been rumoured among the knowledgeable 
audiophiles for ten years or so, and finally in May 1981, we officially 
took the wraps off the Quad ESL63, known affectionately as FRED, the 
acronym for Full Range Electrostatic Doublet. 

The ESL63 is a full range electrostatic loudspeaker, using two sets of 
concentric annular electrodes fed via a sequential delay line so that 
the motion of the diaphragm produces a sound pressure pattern identical 
to that of a theoretically ideal source. 

The advantages of this approach were so clearly evident to those who 
heard the loudspeaker that the first year's production was sold within 
two months of its introduction. 

In 1982 the completely redesigned 34 and FM4 using the latest technology 
and incorporating several original features replaced the 15-years-old 
Quad 33 and its accompanying FM3 tuner. The FM4 incorporated a specially 
developed microprocessor and particular attention was paid to ergonomics 
to make it the simplest tuner to operate on the market while offering an 
audio performance limited only by the quality of the incoming signal. 

A further development of the current dumping circuit resulted in the 306 
606 power amplifiers in 1986 replacing the 303 and complementing the 
405-2. 

The Quad 66 series was a step in the direction of one-brand systems with 
an ergonomically advanced remote control system. The 66 system offered a 
combination of performance and ease of use that set it apart from the 
competition. The Quad 66 preamplifier, 606 power amplifier and Quad 67CD 
compact disc player all won awards in Britain and overseas. 

The Quad 77 continues this combination of performance and ergonomics. 
The highly original, two-way remote control provides the listener with a 
series of menus on a screen on the handset. A bus links all the units 
together and carries signal and command functions. The QUAD 77 
Integrated Amplifier won European Amplifier of the Year '95 -'96 winning 
the approval of Europe's hi-fi journalists. 

Quad products can be found in virtually all broadcasting and recording 
studios in the UK and in many overseas. Professional products make a 
significant contribution to Quad's reputation for performance and 
reliability as well as to the overall performance of the company. The 
list of QUAD owners reads like the Who's Who of the classical recording 
industry, with a number of names from the pop world too. 

Exports have always formed a significant proportion of our turnover and 
at present about 70% of our production is sold in 65 countries, our 
major markets being Europe and the Far East. 

In September 1995 QUAD was acquired by the Verity Group Plc and joins a 
stable of brands including Mission, Wharfedale and Premier Percussion. 
There are obvious advantages in being part of an active and growing 
group and there can be no doubt that QUAD will continue to be "the 
closest approach to the original sound".