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Right, in 1968 HACKER Radio of England was bought over by Philips of Holland and their best twin cone speaker was offered to a few elite customers. The early 1970s AMSTRAD 8000 amplifier adopted an Output Transistor from the famous Philips 22RH580 amplifier of 1968 using the germanium AD161 and AD162 for the twin cone right. AMSTRAD had used lightweight, 4 ohm Japanese ITT speakers instead (the New York based holding corporation). Back in the late 1960s, Philips had been less revered than EMI but was still considered top of the mass-market scene.
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Left, the AMSTRAD 8000 power supply is under 25 volts in its supply rail, capacity is 3000uF giving 7 watts RMS and 12w in Music Power, the amplifier typical of competition for Realistic or Sansui in the British market and such simple circuitry designs later continued as the 'British Shoebox' amplifiers running speakers like the AR8, of 74Hz minimum in lowest note. Below it's important to match the 8000 with suitable speakers as it's from the year...
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Below a tuner board is re-engineered from Sansui.
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Left, to preserve tube tuner sound quality, Heathkit had laid great store by large tuning coils, the elite Radford followed suit whereas in Radio Shack's STA-78 above, one is a little bigger than in their price competitors, today many prefer vintage AM/FM radio sounds..jpg)
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Above the STA-78 power cans are clamped to the chassis with separately fixed boards. Left, best suited mid-woofer for the STA-78 came from the very long run Nova 7B with 25Hz lowest note and a claimed 20Hz audible, the styling isn't meant to appeal as invisible to buyers. The magnet is large to deliver the low notes but the nominal power is 25 watts, some three watts above the STA-78's RMS output. Nova 7B came in a bare baffle early version, the brown baffle late version best suited to a STA-78 receiver, and has different tweeters. Best to use any speakers sold for an amplifier. Left, a 1970s Disco amplifier resembles the STA-78 in its type of aluminum heat-sink seen below. The 1960s Armstrong 521 High Fidelity amplifier has a similar and larger heat-sink located each side of its chassis and the 1980s British Arcam Alpha has its aluminum chassis as a heat-sink suited to relatively cool running devices. 
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Left Sunday In New York by Peter Nero who'd been happy to endorse the STA-78, a receiver that really is a scaled-down version of a flagship model, even with a full wrap wooden case. Right below many roughly finished 8-inch speaker horn cabinets abound based on Lowther-Voigt plans and these might be used for the REALISTIC twin cone 40-1286C of 93dB at 1 watt and 1 meter. It's a sound power equal to the Tannoy...
...Berkeley Mk II of Scottish design and manufacture. The horn cabinet uses both sides of a speaker's core and helps boost up low notes inaudible in lesser cabinets. 13 x 8 were used with EMI in the Benford left below to make the most of low power. Powerful amplifiers often sound less pleasing with sensitive speakers as aimed at cores below 91dB in 1-watt efficiency.
...Berkeley Mk II of Scottish design and manufacture. The horn cabinet uses both sides of a speaker's core and helps boost up low notes inaudible in lesser cabinets. 13 x 8 were used with EMI in the Benford left below to make the most of low power. Powerful amplifiers often sound less pleasing with sensitive speakers as aimed at cores below 91dB in 1-watt efficiency.
Right below, a SONY made 40-1286A from around 1981 year, 1286 appearing in several versions since 1972 firstly a...
...10oz ceramic
magnet and claimed F.R
of 30Hz-20KHz with a 70Hz Free Air
resonance in Air Suspension type but seen to change between 40 and 54Hz in the
various versions sold. The SONY version is listed with the same 30
watts Max as the others but the surround is a long-life rubberized type, color balance of the camera tricked by the wooden background. Early versions appear to be a higher 30 Damping Factor cloth-edge. The enthusiast range gave special results, some used for a middle-range driver.
Left a REALISTIC 93dB version 40-1286C is followed by RadioShack after the brand was dropped. This is a good picture of the small 9.8oz magnet not stressing our low power amplifiers as the 90dB 40-1341B does, taking only 2 watts more power.
Left Karlson boxes will work smaller scale or with a board cutout for a smaller core but suit some better than others as the Jabez Gough box right that in the video below is heard playing with a 1950s REALISTIC tube amplifier and 40Hz-13KHz Frequency Response EV Wolverine core. Down page the 93dB/1w/1m 40-1286C is made of Radax paper - very
lightweight...
Left Karlson boxes will work smaller scale or with a board cutout for a smaller core but suit some better than others as the Jabez Gough box right that in the video below is heard playing with a 1950s REALISTIC tube amplifier and 40Hz-13KHz Frequency Response EV Wolverine core. Down page the 93dB/1w/1m 40-1286C is made of Radax paper - very
lightweight... ...the center dome of the Whizzer cone resembles the 95dB/1w/m
Electro-Voice Michigan MC8 and the link is included. Below the redoubtable British Empire Goodmans AXIOM-80 that needs special tube equipment from the 1950s British gentry.
Below, Electro-Voice Michigan MC8 has a pleated edge and treated paper surround, the cone more controlled than a foam edge to suit its dual market role of ceiling speaker making production more cost-effective. Different amplifiers for each, best with MC8 might be lower Damping Factor than with 1286C. Frequency Response curves may not be EMI but are Lab optimized by RadioShack to give the best results. Although 95dB is louder than 93, sound quality matters too. Below Oaktron 8 from Wisconsin, heavily ribbed cone of endurance.
Below a 95dB/1w/1m EV Michigan compared to the 93db/1w, RatShack 1286C above. The speech dome is paper with an edge treatment and the voice coil appears larger for similar power. AA-3900 and 4900 for the Sansui Au-3900 are 94dB for 1 watt, 8 ohms and the crossover and Frequency Response are tailored to give an assured 35Hz-20KHz, so in effect rival speakers like the upmarket Tannoy Arden.
Below the 87db/1w/1m Shack branded 40-1271 smooth cone and 88dB 40-1272 ribbed cone were twin cone speakers puzzling viewers. Some put them to work in Hi-Fi and found the whizzer resonated at 2KHz causing shout in the upper frequencies. An old patch deployed is spreading some expanding foam 10MM round the widest outer rim of a whizzer. Seriously made and difficult to dismiss as junk, their medium efficiency suggests they dispense...
...with distortions of crossover, squawker and tweeter sets whilst forcing an ordinary amplifier to run at its ideal power level. That is it's a twin cone that doesn't need special amplifiers but will sound good with what many buyers already have at home, i.e. 70 watt Technics SU-V7. So a receiver like the REALISTIC STA-78 that's relatively low power but as high-quality suits high sensitivity speakers for 'Class B' outputs.
Left, a deep speech dome Goodmans TwinAxiom8 and below the TwinAxiom10, part of their Home Constructor Series followed by the lower-middle-class and probably independent school groups as nothing were ever shared on their use or abilities. The sound is quite good, not up to EMI but the matching amplifiers are unknown. The QUAD II tube amplifier is likely as the literature refers to a 15-watt RMS capability with 5-watt usual running power. The cabinet construction is more difficult than most and good results depend on it. QUAD II is powerful with the right speakers but used by a lot of middle-class people...
...with their own ideas. For example, some of them think the 81dB for 1-watt, meter, 15-ohm Rogers LS3/5A is a good match and in Australia, others recommend the 86dB for 1 watt, 6-ohm Wharfedale Glendale XP2. In the 1950s the QUAD II was mostly used with Goodmans and WERC, if not Acoustical's ESL57 with the same Frequency Response as the Goodmans TwinAxiom - possibly a conventional speaker equivalent for the Solid State rectifier conversion of the QUAD II giving better low frequencies. But this generation of Rupert Brooke had a quiet knowledge likened to a good brew in the cask.
...with distortions of crossover, squawker and tweeter sets whilst forcing an ordinary amplifier to run at its ideal power level. That is it's a twin cone that doesn't need special amplifiers but will sound good with what many buyers already have at home, i.e. 70 watt Technics SU-V7. So a receiver like the REALISTIC STA-78 that's relatively low power but as high-quality suits high sensitivity speakers for 'Class B' outputs.
Left, a deep speech dome Goodmans TwinAxiom8 and below the TwinAxiom10, part of their Home Constructor Series followed by the lower-middle-class and probably independent school groups as nothing were ever shared on their use or abilities. The sound is quite good, not up to EMI but the matching amplifiers are unknown. The QUAD II tube amplifier is likely as the literature refers to a 15-watt RMS capability with 5-watt usual running power. The cabinet construction is more difficult than most and good results depend on it. QUAD II is powerful with the right speakers but used by a lot of middle-class people...
...with their own ideas. For example, some of them think the 81dB for 1-watt, meter, 15-ohm Rogers LS3/5A is a good match and in Australia, others recommend the 86dB for 1 watt, 6-ohm Wharfedale Glendale XP2. In the 1950s the QUAD II was mostly used with Goodmans and WERC, if not Acoustical's ESL57 with the same Frequency Response as the Goodmans TwinAxiom - possibly a conventional speaker equivalent for the Solid State rectifier conversion of the QUAD II giving better low frequencies. But this generation of Rupert Brooke had a quiet knowledge likened to a good brew in the cask.
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Below a 1964 radio program covers the John Karlson speaker.
Below the snap-in power can capacitor and the chassis mount below right are very different in design but restorers are seen to put snap-in on a chassis and claim they've been upgraded. Well...they've been downgraded. Chassis mount is much more expensive than the truly pricey snap-in that do a fair job but these power cans have different running specifications.
Left in the REALISTIC STA-78 the tall square heat-sink in the power board is a hot rectifier commensurate on receiver power output with early STA-2000 below that was later traded for a cold type, the small black square seen in the harman/kardon 730 above left. RadioShack and many others preferred hot rectifiers for hefty current delivery but smoothing cans run hotter and may dry out quicker. Even when hot rectifiers are clamped to a chassis and so can't burn the board, they're less reliable than cold types long term. harman/kardon boasted their power supply design know how...
...and opted for cold rectifiers. Restorers need to be very careful in replacement element designs. It stands to reason that hotter running is shorter life but not all of these sets have been used up. If the dial light bulbs are blown, best buy is an example with a well-lit dial and relatively new look. Speakers for the STA-78 need to be upmarket Music System types. Below rearview REALISTIC STA-78 has 4-16 ohm speaker capability.
Left a Sanyo speaker of Tannoy HPD385 diameter with motor for 22-watt SANYO output devices in a REALISTIC STA-78, large size increases efficiency. Best Sanyo speaker for STA-78 is RadioShack Nova 7B but hasn't a lightweight mid/woofer suggesting low efficiency. 94dB/1w/1m is Tannoy Arden but Japanese 22 watt receivers are power rated by their lightest load input, so falling nearer 8 watts with Hi-Fi sources. Sansui AA-4900 is an 'easier' Arden Frequency Response fitting smaller rooms. STA-78 suit Coral 10 watt Max with 104 or 102dB for 1 watt at 1 meter. REALISTIC STA-78 is popular in Vietnam, a 1970s vintage SANYO place. Damping Factor of mid-1970s RadioShack suit 1960s speakers of 8-watt receivers like Armstrong 227, or Chapman 306, using push-pull ECL86, dubbed the poor man's KT66. Comparing power smoothing cans of a NAD 3020 with a REALISTIC STA-78, we're seeing relative output power. NAD 3020 is feeble but offered a unique and 'affordable 4-8 ohm (2 ohms minimum) speaker capability' with only 0.02% Distortion. Radio Components Specialists - RCS Minor used the BC184 transistor from Hi-End Neve studio controllers and comparing TIP31/32 circuits determine what components go where from the diagram copied below.
RCS MINOR 10 WATT at 8 ohms, 20Hz-30KHz, TIP31 and TIP32, fiberglass veroboard left, point-to-point soldered nearer tube amplifier sound, Mono above, stereo version below, click on image.
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Right, EMI loudspeakers that RCS sold for their Minor Kit included the Mini Module Hi-Fi kit comprising the EMI DECCA 5 inch bass unit with heavily doped cloth edge roll surround, the 5 inch EMI PVC surround squawker and the EMI 3.1 inch tweeter. The 13 x 8 twin tweeter was available, the Output transistor pair from the RCS Minor is particularly good with these vintage speakers. F.R. given, betters the Rogers LS3/5A and is a true mini studio monitor. Today's prices for the Goodmans Twin Axiom 8 are much higher than EMI because they work with readily available QUAD equipment.
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Above video, the British shoe-box Creek CAS 4140 a no tone controls version of the earlier CAS 4040 above photo, 1980s descendant of the Harversonic SUPER SOUND 10 + 10 aimed at the upper peasantry, although some, more uppity members of the lower peasantry also thought it worthy of praise. A modular bridge rectifier is employed, and round transformers at first suited medium sensitivity 1980s speakers but later, in cheapened amplifiers, better suited high sensitivity speakers. Left, a power supply in the British Empire engineered RT-VC Viscount III for EMI 13 x 8, names suggest people that followed Hi-Fi equipment - the nobility and gentry, to a lower priced theme the middle-class and ultimately the peasantry.
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Right, Lecson Audio HL1 Audax Polydax 12 inch x 8 inch below aimed at germanium push-pull amplifiers with a tiny, high efficiency voice coil former, similar to R&A of British Empire 1950s England. Lightweight Karad paper cone makes a mellow sound, at one time preferred but maybe colored.
Left very rare French Audax Polydax elliptical mid/bass and not so rare Polydax tweeter team up in the English Hi-Fi surplus, Marsden Hall brand. The tiny magnet suits the STA-78 above on a Hi-Fi FM radio program. Right below REALISTIC Nova 7B, rough center portion from Lafayette Criterion VI woofer, a 6-way favored by college/ high school students of the mid-1970s. Below left one of the best REALISTIC speakers of all time, the Optimus T-110 based on JBL L-150A of the time.
Right Marsden Hall MH 300 was a flagship early 1970s model with Peerless squawker and tweeter hooked to an EMI 14 x 9.
Above upper and lower low-frequency drivers were more cost-effective over elite surplus triple cone elliptical woofers.
Right, the Nova 7B center portion moves to the passive radiator speech dome. Mid/bass core is an 8/20-watt, 6 ohm of 45-5KHz and suits the STA-78 for sensitivity using a shiny-foam 'roll' surround. Right below rare close-up view of the strengthened center portion in the Lafayette Criterion VI of early 1970s American students. The rough middle range was seen in the 1960s EMI squawkers where the underlying paper was covered with fiberglass. In VI a resin bonds these grains on brown paper over the cone beneath and may be seen peeled back in some survivors.
Below the lightweight T-110 motor, 2042 mid/bass albeit labeled 'low efficiency' sounds powerful. 'Shiny foam' was a surround material used in the Canadian grey surround REALISTIC Mach One around the 1979 year. Looking like rubber it's thicker and in time, hardens, cracks appear all around before opening up into visible holes. Although better than Teledyne AR 28s foam as holding together longer, successful replacement of the surround could be difficult.
Below T-110 0756 tweeter, strong EMI influence likely Mitsubishi made. Awesome with Akai style acoustic lens increasing dispersion. Left another puzzling...
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Above changes in the gold DECCA Stereo Decola lower photo groups EL34 from the 1950s black fascia Aristocrat upper. Right large magnet on the 0756 T-110 tweeter drops to 2KHz for the complex crossover. The compact Nova 7B or Lafayette Criterion 6 was highly regarded by high school students and so presumably, performed admirably in smaller spaces.
A lesser but still as impressive speaker compared with the T-110 is the REALISTIC Optimus T-70 Tuned Labyrinth (actually T-Slot). Two-way with 8" woofer and SEAS soft dome tweeter, RadioShack Cat No. 40-2023 best has all drivers, cabinets, crossovers kept original and unmodified save for a new foam edge and run for a while. Legendary in sound, the mid/bass was custom designed by Tandy and the tweeter carefully selected from SEAS. Most examples today aren't original or have missing or blown drivers in ratty or modified cabinets. 1990s GLL IC 120 Oxford right offer T-70 sound in the braced cabinet, ported reflex - so much for polypropylene cones. The upper speaker is a special, small magnet, version squawker, and shorthorn, concentric tweeter with a separate true woofer.
GLL Imagio above brings Lowther style below to a lower market.
Right wooden dispursement cone in an elite P7M, a foam edge twin cone used in horn designs. With their own tube amplifiers, the mass market has little interest, the sound sought in lower market RadioShack 40-1272 below use not Lowther amplifiers but Technics NEW CLASS A. Note medium sensitivity or low efficiency 1272 forces an amplifier to work higher up its power output, giving quality absent at lower volume knob settings.
Sansui AA-4900 right suits the next up amplifier in the catalog. The claims that British lower social class brand speakers beat these are false but few were imported in European places with home market rivals. They were in the US and Japanese markets suited to larger rooms and not preferred there so much in the days of satellite and sub-woofer but tonally match the vintage amplifiers. Left TAMON TS-7000 are typical oriental sounding speakers of the 1970s, great for Japanese equipment. Below Technics NEW CLASS A SU-V3 are very good at stereo images.
Left 1970s Sansui SP-2000 and right similar Coral BX-1200 that are very efficient with expensive Japanese watts. In Britain, these imports were probably price inflated with tariffs as far pricier than home produced goods. But in the US they were widespread.
Right REALISTIC Optimus T-100 tailored to 'lush' Hitachi MOSFET sound. In 1980 RadioShack offered a curious receiver cobbled together from spare parts of a slow-selling HA-5700 amplifier and mid-market, FT-5000 digital readout tuner. STA-2200 had two chunky heat-sinks and just one mains transformer, vice versa in the HA-5700 but RadioShack had good engineers and many friends. In Canada matching Japanese original speakers wasn't imported. The STA-2200 tuner was poor compared to the 1970s, both in cities and rural places. Superb T-100 launch veneer right soon changed to lesser quality. Frequency Response of 55Hz-18KHz is near the bipolar transistor's ideal twin cone but makes the best of Hitachi MOSFET quality and SANYO STK chip style amplifiers in low market Marantz, Nikko, and Technics.
Left 1960s stamped steel basket Goodmans 6.5" squawker not for a Jabez Gough box.
Above Goodmans speakers of middle-class East Anglia, go out to greet the trash picker, new owners hadn't been followers of vintage High Fidelity and small cottages always need every inch of space. Right SONY SS-1005 with EMI tweeter, followed the 1000 model left below based on the elliptical EMI woofer B&W DM.1 but with the Rank DECCA super-tweeter. The 1005 EMI 20KHz tweeter works with an early B&W woven cone woofer, doped with varnish. The enclosure is by the Rank Organization and based on Leak. At this time a few competitors had 18KHz tweeters partnering an ideal amplifier, likely a linear type using the EL34 tube.
Below EMI 'Norman speaker' in Benjamin Model 55, circa the 1966 year using the EMI 'Black' cone tweeter of the 14 x 9 and 300. Bare baffles like early Celestion Ditton and Leak. Norman appears to be a 'long-excursion' type with long voice coil former.
Left EMI 'Black' tweeter in the 1966 105 models with cloth edge 14 x 9 and the EMI squawker often replaced when destroyed by the wrong amplifiers. That is ideal ones have expensive EL34 tube, 25-watt power but lots of low and high frequencies with Hi-Fi quality inputs. Below the 1968 SONY 1120 amplifier and 5000 tuner suit the B&W DM.3 or SONY 5000 version.
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Right the final Mordaunt Short MS-400 had an EMI 750 woofer and Audax dome squawker with black baffle Coles Super-Tweeter. These would be used with SONY above but the woofer isn't easy to drive and works best with some of the most powerful, effortless amplifiers of the time. The return of a 13 x 8 came after the 14 x 9
MS-400 of which there are three special core versions, early with a black surround, light grey surround, and another with shiny coned 14 x 9 of which little by way of detail might be given as to whether it's varnished or what. The EMI 750, 13 x 8 may be recommended for church organ low-frequency extension and is very loud with rock music. After the 1972 year, EMI bowed out. Below very large rave-reviewed Output Transformers for EL84.
Heathkit UA-1 and UA-2 were mass-market power amplifiers largely built as kits in place of the Williamson 0.1, which was cobbled together in the 1940s for a minority. The Heathkit tube amplifiers suffer from component tolerances so got built by technicians, rather than an amateur constructor. The Heathkit amplifiers have a good modern following when tricked out and use an EZ81 tube rectifier that has a soft low frequency suited to the EMI Dangerous Speakers, not the later Merciless range for Solid State rectifiers.
Left the second Mordaunt-Short MS-400 'Black Baffle' from the late 1960s with an early EMI 750 mid/woofer had followed the 'Brown Baffle' series with their 711 13 x 8 mid/woofers aimed at tube amplifiers. The KEF T-15 tweeter had been rejected by the BBC as too colored. At the time that meant engineers favored its efficiency for output volume and many such drivers were 'doped' with varnish to reduce these unwanted effects. In domestic use, the increased volume meant less amplifier power was needed. After this model, there were three 14 x 9 woofer versions followed by the above 13 x 8 750 mid/woofer example.
Right, first 'Black Baffle' MS-400 had a 12-inch EMI 300 'true woofer' as the KEF T-15 does 800Hz-20KHz. Followed the black tinted 'Brown Baffle' 750 woofers of the 13 x 8 'Merciless Speakers'. Bigger to make up the required minimum woofer volume as the speakers are narrow at the sides.
Left 'black tinted' 'Brown Baffle' MS-400 with 750 woofers.
Left 1971 year Danish Peerless dome tweeter and French Audax dome squawker with KEF B139 based on the EMI 13 x 8 but offering better economy and the flat diaphragm so prized in the early 1970s as the ultimate source. These seldom-seen British Ferrograph S1 speakers of the upper class deliver impressive results but their amplifier - the F307 MkII is very special in its design. Dome squawker and tweeter were thought the ideal but these were speakers of the independent schooled elite. The dome allowed the listener to sit out of the 'Sweet Spot', two listeners were possible.
Right Ferrograph F307 Mk.1 speaker was powered by germanium output transistors so relatively fragile and rare. Vintage audio enthusiasts prefer the F307 and it sells quickly, even in not working condition. The Frequency Response is only 30-15KHz but it uses steep cut controls used before Dolby reel to reel tape hiss units came into use. The older KEF B139 seen isn't easy to replace as they had various voice coil impedance matching issues and had to be factory matched to other drivers. The cone tweeter and squawker were more power efficient and had far superior imaging to the dome type above, but needed expensive amplifiers and equipment. The lower market never knew about these.
Left Classic Marantz 2252B reckoned one of their best is matched to Ferrograph S1 originally for germanium output transistors and saved using speaker-top super-tweeters to protect fragile vintage treble units, the only way to use some old speakers with digital audio. Others prefer a more authentic match.
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Left, Rega Kyte are tacky medium sensitivity upper peasantry speakers (for the Creek CAS 4040 needing round transformers) but styled after early 1970s Ferrograph F307 series of the middle-class. For EMI speakers today, the global elite uses ESS AMT by Dr. Oskar Heil but has bespoke dealers to help. It gives 92dB at 4 ohms. Unlike
a normal piston loudspeaker that excites the air by alternately pushing
and pulling a cone or dome, the Heil Air Motion Transformer linearly
squeezes and expands its diaphragm.
MS-400 of which there are three special core versions, early with a black surround, light grey surround, and another with shiny coned 14 x 9 of which little by way of detail might be given as to whether it's varnished or what. The EMI 750, 13 x 8 may be recommended for church organ low-frequency extension and is very loud with rock music. After the 1972 year, EMI bowed out. Below very large rave-reviewed Output Transformers for EL84.
Heathkit UA-1 and UA-2 were mass-market power amplifiers largely built as kits in place of the Williamson 0.1, which was cobbled together in the 1940s for a minority. The Heathkit tube amplifiers suffer from component tolerances so got built by technicians, rather than an amateur constructor. The Heathkit amplifiers have a good modern following when tricked out and use an EZ81 tube rectifier that has a soft low frequency suited to the EMI Dangerous Speakers, not the later Merciless range for Solid State rectifiers.
Left the second Mordaunt-Short MS-400 'Black Baffle' from the late 1960s with an early EMI 750 mid/woofer had followed the 'Brown Baffle' series with their 711 13 x 8 mid/woofers aimed at tube amplifiers. The KEF T-15 tweeter had been rejected by the BBC as too colored. At the time that meant engineers favored its efficiency for output volume and many such drivers were 'doped' with varnish to reduce these unwanted effects. In domestic use, the increased volume meant less amplifier power was needed. After this model, there were three 14 x 9 woofer versions followed by the above 13 x 8 750 mid/woofer example.
Right, first 'Black Baffle' MS-400 had a 12-inch EMI 300 'true woofer' as the KEF T-15 does 800Hz-20KHz. Followed the black tinted 'Brown Baffle' 750 woofers of the 13 x 8 'Merciless Speakers'. Bigger to make up the required minimum woofer volume as the speakers are narrow at the sides.
Left 'black tinted' 'Brown Baffle' MS-400 with 750 woofers.
Left 1971 year Danish Peerless dome tweeter and French Audax dome squawker with KEF B139 based on the EMI 13 x 8 but offering better economy and the flat diaphragm so prized in the early 1970s as the ultimate source. These seldom-seen British Ferrograph S1 speakers of the upper class deliver impressive results but their amplifier - the F307 MkII is very special in its design. Dome squawker and tweeter were thought the ideal but these were speakers of the independent schooled elite. The dome allowed the listener to sit out of the 'Sweet Spot', two listeners were possible.
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Below point to point soldered crossover for the AMT is complex but enthusiasts just wire the EMI speaker in where the woofer would go.
The AMT woofer appears to have a foam surround and that will match the PVC edge EMI 13 x 8 for speed and voice. The use of super-tweeters with the compact disc or digital audio is a patch measure to protect the low power tweeters. It's better to use the appropriate analog sources with the original tweeter but most prefer modern music sources.
Left Wharfedale Linton, a sought after Rank engineered unit apparently based on the Leak Stereo 70. Construction is similar to Ferrograph F307 but not so easy to tinker with. Right, a twin duct CELEF with EMI 14 x 9" that led to the Monitor Audio MA 3. The MA 1 had a KEF B139 and it was scrapped for the far superior EMI 14A/770 woofer unit. CELEF later became the elite PROAC company but started out by
cobbling together old KEF and Rola Celestion drive units. Little is known outside their circle of influence. Right Tripletone S200 speaker for Stereo 8 + 8 and DP12 amplifiers with 8-ohm capability. Most were 3 or 15 ohm and the own-brand twin cones are worth trying. Single-Ended 6BW6 beam tetrodes need 'Class A' loudspeakers made by R&A.
Left a remarkable 'Class A' Twin Cone EMI 10 x 6 with what appears to be some damping to prevent ringing in the accordion surround. Note the tiny voice coil former and the central details. Right elite only 3-ohm 92390PA 'Class B' (Biased for 'Class A') EMI 13 x 8, hybrid long-fiber pulp, and smooth cone.
Above PYE had acquired R&A Single-Ended speakers in the 1950s but on the left, it is one from the AWA company of New Zealand for the Single-Ended EL34 above connected with the Waihi PYE factory of NZ. The speaker uses MSP drivers from the Marconi-Telefunken factory in Australia.
Right the AWA speaker above with grille removed and a Single-Ended tube squawker/ tweeter by MSP denoted by a tiny, long voice coil former hooked with a Tannoy style girdacoustic ribbed Low-Frequency unit also from MSP. Although of interest to British establishment internet users, just what equipment best suits led eventually to BBC engineer Dudley Harwood creating a Rogers made LS3/5A for the affordable mass-market. LS3/5A is a very tongue-in-cheek product, deftly tooled up to resemble a similar BBC LS3/5 studio monitor. It isn't Low-Frequency reflex ported for tubes and is very austere. There's a cult following of Bargain Demons that are entitled to their opinions.
Left KMAL in mirror image stereo pairs. EMI tweeter outer and Goodmans inner, EMI-Lockwood practice of the BBC where dissimilar cone tweeters were mounted for wide-dispersion to prevent cancelation. Active powered version L.S.1/8 left below and with a Dalesford/ Keesonic replacement for the Peerless special edition 35Hz low note.
Left black baffle KMAL with Rank Leak tweeters right, and original Peerless woofer, not the Dalesford/ Keesonic replacement right. Below, EMI tweeters.
Left, an 8-ohm elite only KMAL ELF DL II sports a white foam cutout over its Dalesford-Keesonic mid/woofer, an attempt to boost middle range sounds. Rank foam-edge tweeters copy the EMI above, and around the bare baffle appears a double box. The ELF was 22 watts RMS, and therefore suited for the REALISTIC STA-78, the 1968-72 elite only QUAD II Concordant had also been 22 watts RMS.
The AMT woofer appears to have a foam surround and that will match the PVC edge EMI 13 x 8 for speed and voice. The use of super-tweeters with the compact disc or digital audio is a patch measure to protect the low power tweeters. It's better to use the appropriate analog sources with the original tweeter but most prefer modern music sources.
Left Wharfedale Linton, a sought after Rank engineered unit apparently based on the Leak Stereo 70. Construction is similar to Ferrograph F307 but not so easy to tinker with. Right, a twin duct CELEF with EMI 14 x 9" that led to the Monitor Audio MA 3. The MA 1 had a KEF B139 and it was scrapped for the far superior EMI 14A/770 woofer unit. CELEF later became the elite PROAC company but started out by
cobbling together old KEF and Rola Celestion drive units. Little is known outside their circle of influence. Right Tripletone S200 speaker for Stereo 8 + 8 and DP12 amplifiers with 8-ohm capability. Most were 3 or 15 ohm and the own-brand twin cones are worth trying. Single-Ended 6BW6 beam tetrodes need 'Class A' loudspeakers made by R&A. 
Left a remarkable 'Class A' Twin Cone EMI 10 x 6 with what appears to be some damping to prevent ringing in the accordion surround. Note the tiny voice coil former and the central details. Right elite only 3-ohm 92390PA 'Class B' (Biased for 'Class A') EMI 13 x 8, hybrid long-fiber pulp, and smooth cone.
Left black baffle KMAL with Rank Leak tweeters right, and original Peerless woofer, not the Dalesford/ Keesonic replacement right. Below, EMI tweeters.
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