PRODUCT HISTORY
BACKGROUND
Tannoy is famous worldwide for its innovative, unique and very accurate sounding
Dual Concentric. A Dual Concentric speaker unit is very different from the
standard speaker industry drive unit. It has the tweeter or treble unit mounted
at the center of the bass unit so that the two units operate in total harmony
with each other.
Many manufacturers such as JBL, Altec, Urei, KEF, Pioneer, Diatone, TEAC, have
recognized the benefits of the co-axial or concentric arrangement of woofer and
tweeter to cover the whole audio band from a single apparent point source. None
of them has solved the problem from an ideal acoustic engineering point of view
in the way that Tannoy has.
The construction and operation of the
Tannoy Dual Concentric (upper case 'D' and 'C'!) is unique and provides benefits
that other manufacturers cannot. The waveguide high frequency unit (so called
because of the analogy in design to microwave engineering) has a smooth acoustic
path through the center of the low frequency unit without problems due to
masking or diffraction. The low frequency unit operates without obstruction, as
the cone piston apex is well clear of the high frequency unit. Both units
operate in harmony together providing a single point source covering the whole
acoustic audio spectrum and in a way that recreates the original sound field
better than any other system.
Tannoy Dual Concentrics are by their
very nature complex to manufacture and therefore you will not find them in a low
price system. In this world you get what you pay for and therefore for the best
type of speaker system you should be prepared to spend more. The results are
demonstrably worthwhile even in the unfamiliar surroundings of an in-store
trial.
THE FORMATIVE YEARS
Tannoy was the trade name of a company formed by Mr. Guy R. Fountain in 1926.
The name originates from a solid-state rectifier invented by Guy Fountain made
from an alloy or mixture of Tantalum and Lead. This Tantalum-Lead Alloy produced
the name Tannoy. The name stuck fast to the company's products over the years
and eventually became the company name, Tannoy Ltd.
From 1926 through the recession of
the thirties and during the Second World War Tannoy produced many different
products all to do with speech and music communications. One innovative design
was a universal speaker system designed for a travelling circus.
The speaker requirement was for high quality speech and music for announcement and entertainment purposes in the largest travelling circus of Bertram Mills. The speaker had to be efficient because all the amplification was by tube amplifiers (design and built by Tannoy of course) and the power supplies were derived from not very efficient motor generators and rotary converters.
THE FIRST TANNOY DUAL CONCENTRICS
Drawing from his knowledge of high efficiency products made for the high quality
public address market, the Chief Engineer, Mr. Ronnie H Rackham combined a high
frequency compression horn drive unit concentrically with a 15" direct radiating
bass driver. His skill in designing wide band horn systems married the two
drivers together so that the flare shape of the 15" bass unit continued the
flare rate of the high frequency unit.
It was this important part of the
design process that conceived a very low coloration horn device. Because the HF
horn had a very large mouth diameter it had an inherently low cutoff frequency.
The crossover point from bass to high
frequency was selected at 1kHz; nearly a whole octave above the natural horn
frequency lower cut off point, leading to previously unheard of low levels of
coloration.
In 1947 the first Tannoy Dual
Concentric was born. It was designated the '15" Monitor Black', had a power
handling of 20 Watts RMS, a voice coil impedance of 15 Ohms and a crossover
point of 1 kHz. Magnetic gap fluxes were provided by a cast iron alloy magnet
and were very high for a speaker of the 1940s at 12,000 gauss for the low
frequency voice coil and 18,000 gauss for the HF coil. (10,000 gauss = 1 Tesla).
At 20 Watts power handling in 1947 the unit was very well received and this,
coupled with a sensitivity close to 92 dB for 1 Watt at 1 meter right up to the
highest frequencies, was a milestone for the company in providing high quality
speech and music capabilities in an efficient way.
Six years later the unit was improved
to 25 Watts power handling and the free air resonance lowered to 40 Hz to enable
the unit to be used in encloses to improve the low frequency performance. The
heavy, black crackle finish, overly engineered cast chassis was replaced by a
gravity casting with much more open area to the rear to prevent rear
reflections. The livery was changed to silver and in the autumn of 1953 the '15"
Monitor Silver' loudspeaker from Tannoy was launched in a compound horn cabinet
called the 'Autograph'.
The previous 15" Monitor Black had an integral crossover network and line-matching transformer built into a square aluminum box mounted on the side of the chassis. All components were 'potted' in wax to prevent resonance and to protect the wax paper capacitors used at the time from moisture.
THE MONITOR SILVER
When the 15" Monitor Silver was announced, the crossover network was separated
from the chassis to prevent interactions with the ferrous magnet parts. The 15"
Monitor Silver was also used in the Corner GRF loudspeaker system launched in
1955. The 15" Monitor Silver was accompanied in 1957 by a smaller unit, the 12"
Monitor Silver, which was the predecessor of the famous Tannoy Little Red
Monitor launched in 1979.
The Monitor Silver range of 2 units
continued in development with improvements to power handling, sensitivity and
free air resonance through 2 more generations before significant changes took
place.
THE MONITOR RED
In 1958 the Silver range became the famous original Monitor Red series with a
10" Dual Concentric being added in 1961. Power handling figures were improved to
50 Watts for the 15" (25 Watts for the 12") and sensitivity levels kept well up
at 94dB for 1 Watt at 1 meter to match well with tube amplifiers. The speaker
units were designated:
15" Monitor Red LSU/HF/15-L
12" Monitor Red LSU/HF/12-L
10" Monitor Red LSU/HF/111-LZ
A couple of significant things
appeared here. The designation 'L' at the end of the type number stood for Low
impedance. The 15" and 12" units had 15 ohms voice coils that most people today
would take as high impedance. The 'L' designates that the unit is of low
impedance with respect to a 100 Volt line system.
The 10" version was a different story. This unit departed from the 2" LF voice
coil used in the 15" and 12", using a 2.5" coil. The solution to the voice coil
and magnet gap design (or motor design as we call it today) was optimum only for
a low impedance coil. The resistance of the '111LZ' coil was 2.8 Ohms. The unit
was supplied with an impedance matching transformer to get the impedance up to
15 ohms to match a tube amplifier. When the early transistor amplifiers were
introduced the primary of the transformer was very bad news for the output stage
as it presented a short circuit to any DC offset condition. It is interesting
that with today's robust amplifier design the best thing would be to drive the
voice coil directly and get a very good damping factor and apparent sensitivity.
THE MONITOR GOLD
In 1967 the 'REDS' were upgraded to 'GOLDS' with the arrival of the Monitor Gold
series. Power handling was now 60 Watts RMS for the 15" Monitor Gold but with
sensitivity levels dropped back to 92 dB and, what is now considered the
conventional impedance of 8 Ohms. The sensitivity was reduced as the best
compromise in bass extension and available amplifier power. Cone weights were
increased to get a low free air resonance as the units were being used in
cabinets of either vented or infinite baffle (acoustic suspension) design. The
original compound and rear horn loaded designs such as the Autograph and Corner
GRF were cumbersome for the increasingly sophisticated domestic market.
From 1947 to 1974 the front
suspension design of the cone pistons in the Dual Concentric drivers had changed
little. The relatively conventional looking corrugated paper surround at the
circumference of the cone was a very sophisticated device. The importance in
providing an excellent and well-damped cone termination was understood even in
the sixties by the Chief Design Engineer, Ronnie Rackham. His surround design
was at the forefront of cone manufacturing technology in that the surround edge
was significantly thinner and more flexible than the cone body.
This was achieved by screening the
pulp mesh within the cone forming process so that fewer fibers were deposited in
the crucial surround area. When the cones arrived at Tannoy a lengthy process
involving glycerin and polyisobutylene with an acrylic barrier was devised in
creating the correct cone termination properties with a high strength and
compliance factor. In addition, a 'rug wool' strip mounted at the extreme
perimeter of the surround provided an acoustic barrier.
During the change from Monitor Red to
Monitor Gold the high frequency diaphragm rear throat cavity was changed from
aluminium pressing to a glass filled thermo set compression molding. This is one
of the many design change clues that can date an old Tannoy Dual Concentric very
accurately. Although the chassis color generally followed the model changes
through the years, export countries often had different combinations of design
status and finishing color.
Monitor Red units had a grey chassis and a red/pink rear magnet cover.
Monitor Gold units were grey chassis with gold covers.
These units were designated:
LSU/HF/15G
LSU/HF/12G & LSU/HF/12G/RS (rubber surround)
LSU/HF/III LZG (LSU/HF/111 LZ2GU & GH)
In 1974 a radical approach to
surround design was taken and the cone structures of the 15" and 12" completely
redesigned for the HPD Series.
'Tannoplas' surrounds were fitted to
'Girdacoustic' reinforced cone structures in a wildly enthusiastic attempt to
market the mystery of loudspeaker design to a world that was fairly ignorant of
the Dual Concentric principle.
What the world did not grasp was that most recorded music available was being produced on the Tannoy Dual Concentric using either Monitor Red's or Monitor Gold's. All the music at EMI including Abbey Road and most of the Decca Classical output was produced using Tannoy loudspeakers.
THE HPD
A major redesign of the Monitor Gold led to the 'Monitor High Performance Dual'
HPD Series. Power handling was improved considerably by using high temperature
adhesives in specially set up Tannoy coil winding and heat treatment sections.
Sensitivity was maintained at 92 dB for 1 Watt at 1 meter while moving cone
masses increased to give the correct 'Q' values for a range of 5 cabinet models.
Three different drive units were
designed and manufactured for these cabinets:
15" Monitor Dual Concentric HPD385
12" Monitor Dual Concentric HPD315
10" Monitor Dual Concentric HPD295
The numbers after HPD refer to the
nominal diameter of the unit in millimeters.
All units were 8 ohms and also
supplied with crossover and terminal panel as kits for the professional market
or home constructor. The crossover network is worthy of mention as there were
some sophisticated circuits used for controlling both the level of energy from
the HF unit and the degree of roll-off above 5 kHz. An autotransformer was used
to match the relatively high impedance of the HF voice coil (10 Ohms resistive,
approximately 18 Ohms above 1 kHz).
Many HPD's were built into large
cabinets for studio monitoring by a UK company called Lockwood. Such models as
the Lockwood Major, Lockwood Universal played a very significant part in the
development of the world's recorded music as these were bought almost entirely
by the professional studios. For example, most of the successful records made by
Mickey Most at RAK Records were produced on Lockwood Monitors with Tannoy Dual
Concentric drivers.
Trying to increase sales, especially
to export countries, Tannoy produced a range of 5 cabinets using the HPD unit
designated the 'A' variation. These were:
ARDEN using HPD385A 15" Dual Concentric
BERKELEY using HPD385A 15" Dual Concentric
CHEVIOT using HPD315A 12" Dual Concentric
DEVON using HPD315A 12" Dual Concentric
EATON using HPD295A 10" Dual Concentric
As well as being universally accepted around the world this range was exceptionally successful in Japan between 1975 and 1980 helping to establish Tannoy in the Far East as a manufacturer of very high quality loudspeakers.
ANISOTROPIC BARIUM FERRITE
From 1947 to 1978 Tannoy Dual Concentric drivers used a metal magnet made from
an alloy of nickel, aluminium, cobalt and iron. Although of great strength this
magnet material was not very efficient in power to weight ratio and difficulty
in the world supply of cobalt was generating a problem in maintaining smooth
production at the Tannoy factories in West Norwood, London and Coatbridge in
Scotland.
During the latter part of 1977 the
decision was taken by Tannoy to design a new series of Dual Concentric drive
units using Anisotropic Barium Ferrite magnets. This material is more efficient
in power to weight ratio and had a much higher coercive force leading to fewer
problems in demagnetization under high power or low storage temperatures.
New magnet charging equipment was
purchased to supply the much higher magnetizing force needed by the new
material. Magnets are supplied unmagnetized to Tannoy so that the magnet can be
magnetized with all its metal pole pieces in place for higher gap field
strength. The process of magnetization is called 'charging' the magnet and takes
place inside a heavy coil that generates an exceptionally strong magnetic field
for a faction of a second to align the magnetic domains within the material.
The first unit to emerge with the
Anisotropic Barium Ferrite magnet system was a very high power high sensitivity
midrange unit used in the Buckingham and Windsor cabinet models. This unit
subsequently went on to be used in the Buckingham Monitor and, with further
modifications in high power music concert rigs throughout Europe.
From 1978 the pace of research and
development at Tannoy increased many times over. A strong engineering team was
assembled at the Scottish factory that was by 1980 the central focus of the
company. A long-term plan was developed that sought to improve every
specification of the famous Dual Concentric units while developing specialist
units for varying applications. This was to remove the inevitable compromise of
using only 3 different units in a variety of applications.
The cornerstone of the hi-fi Dual
Concentric loudspeakers was the 10" unit with a revolutionary Polyolefin vacuum
formed cone piston. Domestic hi-fi required smaller cabinets in the eighties and
so a smaller unit was developed with very low coloration, high compliance and
power handling and wide dispersion.
Together with an Auxiliary Bass
Radiator design (ABR) a range of Hi-Fi Dual Concentric cabinets appeared:
T225 Mayfair using 2528 Dual Concentric with 2500 ABR
T185 Dorset using 2528 Dual Concentric with 2500 ABR
T165 Chester using 2528 Dual Concentric
T145 Ascot using 2528 Dual Concentric
This range was launched in 1978 as a
replacement to the Arden - Eaton range and proved successful in increasing
export penetration. However it was too much to ask of a 10" Dual Concentric even
augmented by a 10" ABR to compete with the sheer sound reproduction capability
of a 15" Dual Concentric in a big cabinet (the Arden or Berkeley). Those markets
that had a particular affinity for the 15" Dual Concentric and its fine ancestry
demanded its continuation.
This range was launched in 1978 as a replacement to the Arden - Eaton range and
proved successful in increasing export penetration. However it was too much to
ask of a 10" Dual Concentric even augmented by a 10" ABR to compete with the
sheer sound reproduction capability of a 15" Dual Concentric in a big cabinet
(the Arden or Berkeley). Those markets that had a particular affinity for the
15" Dual Concentric and its fine ancestry demanded its continuation.
STUDIO MONITORS
In parallel with the hi-fi developments during the 1977 - 1979 period a separate
team were working on Dual Concentric loudspeakers for the Professional Studio
Monitoring market. Although a survey at the time showed Tannoy to have the
largest share by far of the studio market it had never advertised its Duals for
this purpose. The Duals had been fitted to Lockwood cabinets or fitted into
similar cabinets by end users.
The engineering team were confident
that standards could be improved yet further using the Dual Concentric in a
purpose designed and matched cabinet, and in 1979 at the AES Convention in
Brussels, 3 models were unveiled specifically for the high power studio
monitoring applications for which Tannoy had been famous. The famous Tannoy
advertisement stated: "After 53 years of Research and Development, Tannoy is
proud to present its Studio Monitor range."
Two new 15" Dual Concentric units
were available. One was the 3838, a high compliance, lower free air resonance
Dual for the TV and Broadcast marketplace where bass performance is crucial but
ultimate levels of sensitivity are not required; and the other, the 3808, was a
low cone piston mass, high sensitivity version for high sound pressure level
monitoring and track laying.
A third system was also launched
using the 2548 high power midrange Dual coupled with two 12" bass drivers (type
3126) in a 300 litre cabinet. To control HF dispersion the extra degree of
freedom in having a midrange Dual Concentric in the Buckingham Monitor allowed a
sophisticated wave front shaping Waveguide to be fitted - the first acoustic
lens system ever fitted to a Dual Concentric.
In 1980 following hot on the heels of the 3 Professional Dual Concentrics were 2 smaller Professional versions for nearfield monitoring, the 3149 used in the SRM12X and Little Red Monitor, and, the 2558 used in the SRM10B. These additions completed a line of 6 Studio Monitors that cemented Tannoy Dual Concentric units onto the world map in their own right. Recorded music had been using the Tannoy Dual Concentric principle for years but had not realized it. With purpose designed cabinets and high power crossover systems the full potential of the Dual Concentric could be realized.
The 1979/1980 Studio Monitor Range:
Buckingham Monitor using 2548 Dual Concentric with 2 x 3126 Bass.
Classic Monitor using 3828 Dual Concentric.
Super Red Monitor using 3808 Dual Concentric.
SRM15X using 3808 Dual Concentric.
SRM12X using 3149 Dual Concentric.
Little Red Monitor using 3149 Dual Concentric.
SRM10B using 2558 Dual Concentric.
Following the success of the big
Duals in the domestic markets in the Far East during the 1975 to 1980 period,
Tannoy decided to maintain a high profile by developing loudspeaker systems with
cabinets large enough to make full use of the Dual's capabilities, whilst being
aware of the domestic space available for large speaker systems.
Between 1980 and 1982 three smaller footprint domestic models were introduced
using the same research and development pioneered for the professional line but
with slightly less demanding power handling specifications. Three more very
radical domestic systems were also developed as a trial in the marketplace for
something very special in appearance and performance.
The small footprint range consisted of:
Arundel using 3839 15" Dual Concentric
Balmoral using 3128 12" Dual Concentric
Caernarvon using 2558 10" Dual Concentric
THE 'RADICAL SYSTEMS'
The radical systems consisted of:
Westminster using 3839W 15" Dual Concentric
GRF Memory using 3839M 15" Dual Concentric
Edinburgh using 3149 12" Dual Concentric
Two systems are worthy of note. The
GRF Memory was based on some old drawings found in Guy R. Fountain's office when
the final removal from the West Norwood site was in progress. It is believed
that Mr. Fountain himself made the sketches in the days running up to the sale
of the business to Harman Industries in 1974. Rather than see such interesting
ides go to waste the Design team in Scotland thought it would be a good idea to
use the concepts to produce a speaker system worthy of his name. This they did
in the Guy R. Fountain Memory.
The Westminster is also worth a further look. In the early eighties the hi-fi
industry seemed to be concentrating on smaller cabinets with increasingly low
levels of efficiency. The Tannoy Engineering team was keen to demonstrate that a
large an effective compound horn loaded system could provide a level of
sophisticated reproduction that no other type of system could get close to. They
were part of only a handful of speaker engineers around the world who were
capable of designing and engineering such a system.
And so the Westminster was created-
250 pounds weight of speaker with a transient attack and low frequency
performance that many people in the world could not believe. Music lovers had to
be prised away from the demonstration seating at exhibitions, where
Westminster's were being put through their paces, to make room for the queues
outside.
The success of the Westminster, GRF and Edinburgh in the Far East spawned a smaller design named the Stirling, introduced in 1983. In a way this speaker was a return to the concept of the original 111LZ using a 10" Dual in a bookshelf size cabinet. The Stirling completed the "radical" range of speakers and the line was designated the Prestige Series.
THE WILDCATS
In 1984 the Research and Development team at Tannoy wanted to prove that the
Dual was an excellent solution to very high quality live music performance
venues. Clearly, with the sizes of magnet and levels of efficiency available it
could not compete with the outdoor rock concert systems from Altec, Meyer and
JBL but there was a niche in the cabaret and small club market where the sound
quality needed to be considerably higher than that to which people were
accustomed. Specially adapted Duals were designed that had more power handling
and greater sensitivity than had ever been produced before by Tannoy. These were
fitted to a range of very robustly made cabinets with reinforced handles and
corners suitable for mobile cabaret or fixed contractor installation work. The
line was christened the 'Wildcats' and was the start of a very successful
venture into high quality voice and music provision for sophisticated venues
such as clubs, theatres and churches.
The Dual Concentric is a unique
speaker system ideally placed for communication and intelligibility in difficult
acoustic surroundings. The dispersion character (directivity) is much more
constant throughout the audio band than with most other systems. Therefore more
direct sound reaches the listener than reflected sound and the intelligibility
of the reproduced program material is greatly enhanced. The directivity
characteristic also prevents excitation of troublesome room resonance associated
with the reverberation time of room acoustics.
Intelligibility and communication
ability in halls and theatres is measured in 'Alcons' or 'percentage alcons'.
The measurement is a quantitative analysis of the hit rate of a listener in the
hall interpreting different words that have similar vowel and consonant sounds.
A perfect acoustical environment would score 100%. The Dual Concentric system is
notoriously good at providing the highest percentage alcon figures in any
environment when compared to the competition.
The Tannoy Wildcat range consisted of the following speaker systems:
Lynx using 3169G two 12" high sensitivity Dual Concentrics in a double cabinet.
Bobcat (B50) using 3169R 12" high sensitivity Dual Concentric in a single small cabinet.
Puma (P100) using 3805 15" high sensitivity, high power Dual Concentric.
Jaguar (J200) using 3809 Puma driver in a larger cabinet for deeper bass.
Panther (P200) using 3859 15" Dual Concentric in a front sectored horn cabinet.
Cougar using 3859 15" Dual Concentric in a floor wedge monitor.
Lion (L300) using 15" bass unit in a coupled cavity bass bin.
Cheetah (C150) using 15" bass unit in a small coupled cavity bass bin.
Leopard (L200) using 15" bass unit in a direct radiating bass bin.
The original Wildcat series was split
into two ranges in 1987 to create a dedicated road proof MI cabinet series and a
specialist contractor's line for permanent installation. In 1985 Tannoy started
test marketing the high-output Dual Concentrics of the Wildcats into the more
domestic end of the market. The Impulse Series was created using similar Duals
to the Wildcats in more acceptably finished cabinets for home use. The series
was not considered a major success but out of the work in engineering, a new
high power studio monitor was developed - the FSM.
The FSM was designed to sit at the top of the studio monitor line that was being
improved and developed by Engineering for launch in autumn 1985.
Many improvements had been worked on in the period from 1980- to 1985 and the time had come to incorporate all enhancements into the new range. The range change is signaled by the move from Super Red Monitor to Super Gold Monitor. Edge would coils, higher power and thermal handling, improved levels of sound quality and a 'faster, tighter' sound quality contributed to the success of this line.
SIGNIFICANT IMPROVEMENTS
From 1985 Tannoy abandoned printed circuit boards and wafer switches in the
crossover designs. A significant amount of research had shown conclusively that
the layout and mechanical design or a high power speaker crossover was vital.
Listening tests were carried out with great precision to isolate some of the
aural effects encountered.
The Tannoy R & D department concluded
that:
Printed Circuit Boards are detrimental to sound quality.
Star earthing is of paramount importance.
Components must be held down securely to prevent microphonics.
Wiping contacts and switches downgrade sound quality significantly.
Gold plating of electrical contacts is beneficial to sound quality.
Connecting cables can have audible effects.
In 1985 the introduction of the Super
Gold Monitor series and a top end monitor called the FSM commenced, replacing
the Super Red series. Simultaneously a gradual change over in other products to
'Hard Wiring', eliminating printed circuit mounted components and, 'High Current
Switches' using gold plated screw terminals, for which many worldwide patents
were granted, was undertaken.
SEPARATE MAGNETS
In 1986 a smaller model was slotted in at the lower end of the Prestige Range
called the Greenwich using a newly developed 8" Dual Concentric, and a similar
Dual Concentric drive united for the DTM-8 (8" Dual Concentric Desk Top
Monitor).
The introduction of the new 8" Dual,
designated 2008C for the cast chassis version and 2008S for the rigid steel
version, was another milestone for Tannoy. The 2008 used a split magnet system -
separate magnets for LF and Concentric HF portions of the driver.
This gave greater manufacturing
versatility and commonality with other components making the 2008 more
economical to manufacture. Previously all Tannoy Dual Concentric drive units
used the single magnet philosophy pioneered by Ronnie Rackham in the late
forties.
With the advent of very high precision, high-pressure zinc die-casting processes during the eighties an extra degree of flexibility was beginning to appear; first in manufacture and then in design of the Tannoy Dual Concentric.
ALCOMAX 3
As explained earlier the large cast metal magnets were abandoned in 1978 in
favor of Anisotropic Barium Ferrite. However there was a considerable lobby from
traditionalists that the cast metal magnet Dual Concentric units had a certain
sound quality that was impossible to reproduce in ANY other type of speaker
design. A research project was initiated in 1988 to attempt to quantify this
feedback. The result was a recognition that the cast metal magnets were acting
as a shorted turn around the coil thereby minimizing flux modulation. For the
aficionados and traditionalists a version of the Dual Concentric was designed
and engineered with a new Alcomax 3 metal magnet
made from an alloy of cobalt, aluminium, selenium and ferrous iron. This unit
was put into a very prestigious model of the Westminster, the Westminster Royal,
and into a traditional period cabinet named the Canterbury. All the knowledge
learned so far in the Tannoy Engineering department went into these models
resulting in spectacular performance and acceptance into the market.
RHR LIMITED EDITION
Tannoy decided to honor its principal mentor and now retired Chief Engineer in
1986 by asking him to design a period cabinet with a traditional rear folded
horn. This project was completed by Ronnie and launched as the RHR Limited
Edition. Only 111 pairs were made and were actively sought around the world. In
response to overwhelming demand a further small quantity were produced with
subtle appearance design characteristics and named the RHR Special Limited
Edition. They change hands now for a premium. Although Ronnie had passed
retirement age he was keen to maintain a place in the Tannoy Design Team. He
regarded it as a special honor to be able to play a leading role in the cabinet
design of the Canterbury 15 and Canterbury 12.
Ronnie passed away peacefully in
December 1990 after an illness in which he showed the same practical fortitude
and great strength of character that he had brought to the whole Tannoy team
over more than 40 years service with the Company.
In 1989 the pace of Dual Concentric
innovation increased considerably. The two magnet system approach pioneered in
the 2008 was carried a stage further with the introduction of Waveguide
principles.
SERIES 90
A new 8" Dual Concentric was conceived, the 2025, used in 3 domestic hi-fi
cabinets:
DC1000 using 2025 Dual Concentric in 25 litre cabinet.
DC2000 using 2025 Dual Concentric with 2026 bass in 35 litre cabinet.
DC3000 using 2025 Dual Concentric with 2026 bass in 50 litre cabinet.
DIFFERENTIAL MATERIAL TECHNOLOGY
A separate research project had shown amazing results in Differential Material
Technology, the science of combining different materials to achieve the required
acoustic properties at strategic places in a speaker design.
DMT coupled with the new 2025 design put Tannoy firmly on the worldwide map for
the Dual Concentric system performing in small footprint domestic cabinet
systems. At last the population could listen to recorded material and be assured
that they would hear everything that the artist intended.
WAVEGUIDE THEORY
The Waveguide theory and research started in 1989 for the 2025 was developed in
an increasingly sophisticated way using Computer Aided Design and draughting
techniques coupled with mathematical modeling of Waveguide principles. Much
progress was made during 1989 and 1990 resulting in a very special and totally
different approach to the HF section of the Dual Concentric.
The 2025 Dual Concentric provided the
clues to Tannoy's direction but when the new 12" and 15" Dual Concentric drive
units appeared in the Monitor Series System 12 and System 15, people realized
that Dual Concentric design would never be a traditional approach again. A new
range of professional monitoring systems was introduced in 1990 based on
Waveguide principles:
System 215 using 3833GG 15" Waveguide Dual Concentric with separate 3834 15"
bass (Soffit mount monitor).
System 15 using 3833GG 15" Waveguide Dual Concentric (mid field monitor).
System 12 using 3133GG 12" Waveguide Dual Concentric (mid field monitor).
System 10 using 2525GGG 10" Waveguide Dual Concentric (near field monitor).
System 8 using 2025GGG 8" Waveguide Dual Concentric (desktop near field
monitor).
System 2 using 0259 tweeter and a 1668GG bass/mid 2 way discrete system (desktop
near field monitor).
All the system series cabinets had a revolutionary design appearance and had all the latest thinking in DMT cabinet design.
CONTRACTOR SERIES
Also in 1990 a new range of Wildcat replacements were introduced using more
robust versions of the Duals developed for the System series. These cabinets
were designed specifically for the sound and video contracting market providing
very high sound quality with unequalled robustness.
An innovative cabinet was designed
with a trapezoidal shape incorporating an aluminium extrusion housing integral
flying points to suspend the cabinets safely above an audience. The whole
suspension system was rigorously safety tested and has a national certification
of safety. The Contractor Series was given the code system in engineering of CPA
and this has stuck with the development right out into the marketplace.
The range consists of:
CPA 15 using 3836 15" high output waveguide Dual Concentric in a trapezoidal
cabinet.
CPA 15FM using 3860 15" high output Waveguide Dual Concentric in a compact
cabinet.
CPA 15.2 using 3861 two very high power 15" bass units in a rectangular bass
bin.
CPA 12 using 3134 12" high output waveguide Dual Concentric in a very compact
trapezoidal cabinet.
CPA 5 using 1501 5" ICT Point source drive unit in an exceptionally compact
easily mounted molded cabinet.
Of the range the CPA 5, the last one
to be introduced in May 1991 at the NSCA Show is worth further investigation.
The HF unit of this tiny driver operates on entirely different principles to all
the other Tannoy drive units. The HF driving diaphragm has no coil, but a
'skirt' projects from the bottom of the diaphragm. The skirt is immersed in the
same magnetic field as the LF unit coil and energy is induced into it from the
LF coil. The crossover point can be set by the LF coil parameters and the
diaphragm diameter. Eddy currents in the skirt which acts as a shortened turn
similar to transformer theory effectively drive the HF diaphragm. The unit is
therefore exceptionally robust with no possibility of HF burnout, a common
problem with systems of this size and use.
WESTMINSTER ROYAL
The potential in the design of the Westminster Royal for a superb performance
loudspeaker was well demonstrated with the incorporation of the
Alcomax 3 cast alloy magnet system. The longer
HF horn resulting from the increased magnetic length of the magnet gave an even
better match to the acoustical front loading of this very complex and special
cabinet.
To take full advantage of the Dual
Concentric drive unit the cabinet was specified as birch plywood throughout and
to compensate for thicker internal partitions the whole cabinet and low
frequency horn mouth area was increased accordingly.
In addition to the increased height
of the cabinet distinguishing the Westminster Royal from the Westminster HW the
solid walnut top and bottom moldings were sharpened in profile and subtle inlays
of burr walnut were added to the front baffle. Increasing awareness of the
effects of the purity of the copper interconnecting wires during associated
research projects pointed the way for all the internal wiring in the Westminster
Royal to be specified as Van Den Hul cable. Careful listening tests determined
the gauges of cable in various areas; even the connecting wire integral with the
drive unit HF section was re-specified.
The result was another landmark in loudspeaker design and performance and is recognized throughout the world as one of the finest loudspeaker systems ever to have been produced.
THE SIXES
The SIXES were introduced at the Consumer Electronics Show in Chicago in June
1991. This range of seven models comprised three discrete 2-way speakers and
four Dual Concentric models. Of particular note was the introduction of a 6.5"
Dual, the smallest that Tannoy had ever designed.
The range was to replace Series 90,
but with the incredible pace of development on Dual Concentric drivers most of
the range used either the 8" or the 6.5" Duals, the two top models having both
driven bass units and Mass Tuned Passive Cones to produce very low frequencies.
Much research had gone into this method of getting a much lower fundamental
tuning of the cabinet and new techniques and materials were becoming available.
Of particular note in the Sixes Dual
Concentric drivers was the use of injection-molded cones. Most manufacturers
were content with vacuum forming cones because of the economy of the tooling.
Tannoy realized that the vacuum forming process could not obtain the optimum
profiles required to make the next quantum leap for the Dual. Very expensive
injection molding tooling was developed and both the 8" and 6.5" cones used this
new technique.
Yet another first for Tannoy was seen
in the surrounds of the SIXES bass units and Duals. A very special and secret
technique for making the roll surround an integral part of the cone profile
resulted in both excellent acoustic matching of energy in the cone and surround
and gave a much smoother transition for the HF wave front as it propagated down
the profile.
The HF unit at the heart of the Dual
Concentric drive unit is broadly similar in diaphragm and coil design to a
direct radiating unit. However the energy from the diaphragm is matched to the
air load by creating a spherically expanding wave front. This ensures that the
directivity is even more constant and symmetrical and the whole system produces
an incredible stereo image.
The perfectly spherical wave front is
generated by the Waveguide at the throat of the LF unit so that the energy then
propagates down the carefully arranged flare of the injection molded LF cone,
which itself is optimized to ensure a smooth and extended response well
integrated with the bass/midrange energy from the LF unit.
The SIXES Dual Concentric
loudspeakers consist of:
6o9 using 2033l 8" Dual Concentric
611 using 2033 8" Dual Concentric, 2035 8" bass
613 using 1662 6.5" Dual Concentric, 1663 6.5" bass, 1664 6.5" MTPC
615 using 2033 8" Dual Concentric, 2034 8" bass, 2037 8" MTP
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