HARVARD UNIVERSITY STEREO, RADFORD HD250.

Nightingale, Italian Transmission Line, KEF woofer, Peerless mid and Isophon tweeter.

 IMF speakers
 👉🏾  HOME 👈🏾  1  2  3  4  5  6  7  8  S 

Irving 'Bud' Fried attended Harvard University,^[2] meeting Professors Hunt and Pierce who, under a Western Electric research grant, conducted monumental research into high fidelity phono reproduction.^[3] 'Bud' received his undergraduate degree from Harvard University, thereafter serving as an officer in the US Navy during World War II.  Among his assignments, he'd posted as liaison officer to the Free French Air Force and after the war attended and graduated from Harvard Law School. 

 Left a TDL woofer version of the KEF B139 in the later IMF Reference Mk.VII has a paper cone.

Based on the advice of Victor Brociner, co-founder of the Philharmonic Radio Co., Bud became official importer of Lowther corner horns, creations of P.G.A.H. Voight.^[4] A year later, he'd expanded offerings and began importing the revolutionary Quad electrostatic, the ESL-57. 

 EMI 630 right, in a unique photo of a T-slot design RadioShack called a Transmission Line in their Optimus T-70 using a 30-watt REALISTIC STA-111 receiver, with two SANYO STK modules for slimline looks and before harman/kardon led the preference for discrete circuitry.  Technics used them in the A900S Reference as late as 1995, a celebrated, albeit tongue-in-cheek elite styled controller/ power amplifier set.

At the suggestion of Saul Marantz, an American musician, inventor and engineer who'd founded audio manufacturer Marantz in 1948, the IMF (Irving M Fried) trademark was registered in 1961,^[3] and later found in music reproduction: cartridges (IMF – London, IMF – Goldring), tone arms (SME, Gould, Audio and Design), amplifiers (Quad, Custom Series), and loudspeakers (Lowther, Quad, Celestion, Bowers and Wilkins, Barker, etc.) Left (photo credit Bloomberg) and right below (J.O. Hambro), Harvard University graduates.  Left, a polka dot tie, represents 'stars in the night sky', as in famed nobs of an elite glitterati.  צמצום

In 1968 a British branch of IMF opened and the combined... 

 ...Anglo-American company produced the now legendary IMF Monitor.^[4]  In 1975 the English and US divisions of IMF were split, the trademark FRIED thenceforth seen on all of Bud's items. New designs were based upon the same principles that created the IMF Monitor in addition to better know-how as it became available. FRIED benchmarks include the Model H System, Model M (1977), the SUPER Monitor, and B satellite series (1976 to 1979).  Left a Canadian, Calgary Oil State Radford Studio S90, Export T-Line.  "Bud Fried was advised by Decca to look into transmission lines and sent him to Radford who were working on them.  'Bud' intended to import them to the US but Year after year Radford postponed production.  One year Bud announced the transmission line speakers after Radford promised to deliver - they didn't so with John Wright plum decided they'd no choice but to up and produce their own.  A KEF Concerto kit was built into a transmission line with more work on drivers and x-over, that evolved into the original IMF Monitor."

Below mass-market TDL T-Line... ...speakers retain the deep gloss and weight of early, elite designs but differ from EMI in a relatively poor Frequency Response.  To get an audition of these 1989 speakers in a store, required the showing of something like a Harrods Gold card, the seller looking for creditworthiness.  Note the parquet flooring and reflected posh circular wooden foot of a long sofa.  Mass market speakers like this TDL are about a powerful leading-edge giving an exciting bite.  3D sound of 1960s EMI and similar 1970s Japanese speakers beggars belief, their very accurate Frequency Response at low input power is today favored by Bruce C. Edgar.  The powerful speakers right suited the younger buyer of their day.  A white arc is seen in both drivers due to over-excursion from beat music driven by some very capable powerhouse like a Threshold or Citation XX.  Mass market speakers have available cores where vintage don't.  Replacing EMI with similar cores would prove impossible.    

Left, a curious picture shows a QED British Shoe-box amplifier atop a 1969 year upper middle class Radford FMT3 tuner and matching amplifier from a record collector's estate sale.  The QED amplifier was one of the most tuneful of the 1980s shoe-boxes as from a 1960s speaker cable maker of famous 49 and 79-strand, so widely faked that QED took the unusual step of advising buyers they'd only ever see brown sleeved genuine QED but they'd later made a white sleeve just like the fakes, old QED speaker cable is a good online auction buy.  The photo suggests the shoe-box was preferred to the Radford amplifier set.  A look inside the QED shoe-box reveals a high standard of components.

Right, a black surround EMI 4075 version woofer of the early grey roll surround, late 1960s 2875 in the Cambridge University elite community speaker called the EMI Sirocco, of Limited Production, not known to the lower society, named after a 62mph yachting wind.  The seldom seen semi-spherical dome EMI 14A/1720 tweeter is thought to be clear plastic with the suspension visible on the rear, a hard dome in the late 1960s, nearly a decade before the upper peasantry Wharfedale Glendale XP2.  Surplus 14A/1720 was used in the Monitor Audio MA7 from 1977 with the far eastern imported Essex own brand woofer that proved disappointing compared to the long excursion, EMI 2875, elite only model from the old Cambridge-based factory.

 

Left, the 4075 woofer grey rubber on the rear betrays that EMI spray painted the cone and later roll surround and to be the Keesonic Elf Major woofer's black basket.  What of differences between the 2875 and 4075?  The mid/woofer appears to have a shorter excursion not as deep in tone and the roughened tweeter baffle that some refurbishing tinkers have mistakenly painted, accidentally destroying anti-reflective properties, has to be unvarnished again to restore its 3D sound stage effect.  Below the curious MA7 ferrous core inductors in the x-over are hard-wired but simply screwed to the cabinet with no damping foam underneath.  Capacitors are a solid  EMI  type.

>>What does the lack of damping foam under the x-over tell us about the MA7 engineers?  Well, it may be that the components used hadn't been affected by vibrations and it may mean that sound could be improved using a foam underlay but Wharfedale used a thicker, tougher foam for x-over underlay, than simply being screwed into acoustic wadding.  It was more like Hornby Model railroad track underlay.

Left, not a full range version of the EMI Sirocco woofer this cut-down 6.5 inch long excursion full range does 70Hz-15KHz and is essentially an old world squawker using a compact ceramic magnet.  A few old world squawkers once sported huge, heavy AlNiCo magnet motors as dual purpose sellers.  These could be squawkers or mid/woofers but the argument raged that they weren't ideal for either role but something of a compromise, and as a result the prices in the late 1970s had been very reasonable, today they're just never seen.  If they were to appear on an auction site, the prices commanded would be very high, based on appearances but getting these speakers to actually perform in an admirable way is a different story.  The EMI speakers of the 14A series occupy the later part of the 1960s High Fidelity Audio scene and were exclusive to the British upper class.  Some were passed to Bowers & Wilkins, B&W.

We might wonder today what all the fuss was about.  It was the future in Audio, long excursion and hard dome tweeters, ten years before mass-market designs of cheap and profitable manufacturing.  A space saving speaker capable of low frequencies using the relatively new long excursion woofer, voice coil travel optimized in the gap flux by a British Empire military research company, EMI that would deliver the goods.  The later tweeter dome baffle is rough to prevent reflections, the earlier versions left were smooth.

 

Right although the Polydax HD100D25A is very similar to the EMI 14A/1720A, and known in England as a KEF SP1068, it's an Audax and downmarket version, that is, not an elite EMI.  The reason for the asbestos resin on the rear of the EMI above as compared to the cheaper steel baffle in the Polydax, likely has a price impact on sound quality.  Odd Frequency Response in the MA7 14A/1720 tweeter is similar to the rare Rank Domus.

Above, a Fane pressed steel basket and Audax magnet assembly combine to cover a surplus elite EMI used in the IMF Compact.  Left, an Australian Richard Allan RA-82 with HP8B low-frequency speaker very similar to the IMF Compact 2.  Fane was by repute connected with Richard Allan and the similarity in build suggests a common origin although these woofer baskets look Richard Allan the Bextrene cones and surround is atypical.  Richard Allan built Transmission Line speakers with KEF units including the B139 woofer. The DT20 dome tweeter appears to be a Rank Organization, Rola-Celestion that would explain the same 1975 year Celestion 'UL series' cones of this appearance.  Richard Allan Minette was a 1960s Hi-Fi mini monitor before the mass-market LS3/5A (that had only 80Hz in low frequency as had the Rola UL6).  UL8 had 70Hz, +/- 3dB.
  


  Rogers LS3/5A near right is a lower social class speaker developed from the KEF BBC LS3/5 far right.  Although KEF made early LS3/5A woofers, most are from the Far East.  The IMF Compact 2 right above better resemble BBC LS3/5.


In Leak speakers, the cloth edge appears left and rubber edge right.  The cloth edge on the black baffle is later and the early version has different tweeter details.

Left, in the United States and Australia, it was usual to find outsourced Sandwich 300 woofer speakers that bore a seam like Quam of Chicago.  So people from the US might ask why such a feature appeared in a sandwich design that was by nature inherently stiffer.  The 300 was a much cheaper speaker and the reasoning behind the seam and black surround might suggest that it suits lower running power and that it has a lighter magnet and motor than the earlier versions.  Right the Rank Organization had bought over Leak in 1969 and the 1975 year Celestion UL8 and UL10 had these Leak magnet speakers with...
...no fixing lugs resembling the driver of the IMF Compact 2.  The origin of the cast basket on these isn't Celestion or Leak, the cones may be 'sandwich speakers' with a paper finish unlike the later plastic coned Rank Celestion UL6 and 8.  The flat edge LTP rubber surround may not have suited most mass-market amplifiers at the time.

Left, an early Lowther PM6 with a cone seam.  Lowther was an elite speaker like EMI both today known in the high end audio community.  The roll edge on the Lowther resembles EMI 350 in the Benford Horn, an elite community speaker rarer than the early Monitor Audio MA7 from the Cambridge University community.  Below, two cabinets for the elite PM6 remain after a house clearance, parquet flooring looking the worse for wear often gets renovated.

 

Victorian British gentry marble fireplace, the one below, being the modern mass-market equivalent.  An ordinary fireplace.

<<Left US only 1971 year Lafayette is a Japanese Criterion 3X mass-market alnico magnet speaker and sounds low Damping Factor for tubes or germanium power of late 1960s like the Dick Burwen LA-280 below - built to simulate tube sound as 'best bang for the buck'.  White rubber edge claimed a 'world first' for Akai in 1970, far eastern origin drivers began finding their way into British brands.  Cloth edge Leak was outsourced by Rank mindful of far eastern mass market amplifiers.  A Leak 2000 says 'Made In England' on the rear but is either Panasonic or Rotel sourced.  1990s amplifiers of 30-watt power but Damping Factor 60 didn't match Lafayette.  Digital era inputs with 60dB channel separation but poor DAC stages make vintage speakers sound poor and crossovers or speakers need run-in after standing idle.















Mitsubishi is popular in the United States, their Music Centres right styled like SONY HMK77B are mostly unknown.

Left news reached England that IMF was making this special STUDIO model for export to the United States.  Demand for something similar in the United Kingdom led to a lesser mockup model with no KEF-style external crossover and a cutout where it had been!  Down-home England's 'Export STUDIO Monitor' as seen below.  Frequency Response seems very jagged compared with 1960s EMI and so may not be a later fiber-glass cone EMI squawker albeit pictured in the lab test and seen in the IMF TLS50 down the page, it just might be a 'smooth cone' ELAC!  A split baffle STUDIO cabinet limits the bass to suit 25-60 watt Hi-Fi tube amplifiers as Output Transformers had a bass problem.  Not elite only EMI but mass-market, using a special version of an ordinary KEF bass unit - the speaker is a compact version of the IMF TLS80 with polystyrene coned B139.
IMF 8/28BR ELAC LF & MF.  MSP  IMF 6/30R

IMF was multinational and the amusing lower social classes 'Export Studio Monitor' is what lower England got.  Smooth cone ELAC right is a foam edge squawker, not the original rough coned ELAC copy (of the fiberglass doped coned EMI left) - a copy rated 'utterly astonishing' by listeners but impossible to obtain secondhand or new as elite only.  The Studio model split baffle cut low frequencies as powered at... 

...only 25 tube watts, with no F.R. peaks, unlike the above plot.  Later IMF TLS50 right below has a long baffle for Solid State amplifiers with low frequencies.
and simulated tube sound built to follow the Criterion LA-280.  Mitsubishi, Lo-D above, and SONY below are tube sound with deep bass.  The best known simulated tube sound Solid State amplifier is the British QUAD 303 in many versions aimed at reducing prices.  Later QUAD 303 help Japanese competition.  SONY V-FET TA-N7 below is unreliable needing totally rebuilt.  Hitachi's Lo-D and Mitsubishi are better but expensive and less known.  TLS50 still has the EMI squawker and doesn't use much power.  Lo-D HS-1400WA has the small baffle of the IMF Studio with alnico magnet squawker similar to Criterion 3X up page, Allied had a Lo-D relationship.  Hidden inside is a ceramic magnet woofer with grey paper pleated edge stuck on, for low Damping Factor.
Left Australian IMF TLS50 with MSP's Dutch IMF market version of the old, London based Tannoy girdacoustic cone woofer (Manufacturer's Special Products, Marconi-Telefunken, AWA) on a veneered 'long baffle'.  A British Rank Rola Celestion tweeter and British ELAC squawker.  Robert William Ludovic Lindsay OBE (18 August 1905 – 6 September 2000) English-born Australian politician.  From Norwich, England, educated at Eton College and Royal Military College, Sandhurst.  An officer of the British Grenadier Guards, fluently spoke Arabic, stationed throughout Persia from 1925–37 with the Transjordan Frontier Force, regimented nearly 2000 enlisted Nepalese Gurkha Troops.  In 1939–52, part of Whitehall Defences.  In 1954 elected to the Australian House of Representatives.  The Liberal member for Flinders, until 1966. Order of the British Empire 1971.

 Right British round version of the compact Dutch market IMF woofer above has a Bakelite printed circuit board and ELCAP solid capacitors as used by EMI.  The Dutch x-over has a blue fiberglass printed circuit board with Tosin and ALCAP brand electrolytic as well as solid capacitors.  The REALISTIC STA-450 used Tosin power smoothing caps and improves using ELNA.  The use of both solid and electrolytic caps will puzzle tricking out enthusiasts.

 Right a remarkable Australian Hi-Fi MSP woofer in a cast basket reminiscent of SONY G.  Braced for deep bass with a rectangular port dating to the 1950s.  Bitumen damping painted around the apertures isolate the baffle.  White glass fiber dates the work.  American Rola squawker and tweeter mounted in a wide dispersion is later discredited in favor of the plumb-line drivers but capable of superb 3D effects.  Wood mounted x-overs with CROSS-CAP used by EMI suggests late 1960s.  The cloth-wrap baffle right was favored in rear-mount days and no longer today due to vibration but in the 1960s there were weird, acoustical engineers who'd maintained that 'didn't matter'.  Always avoid moving any batting or changing the work of the sound engineering witnessed in these items. 

Right GEC of Singapore Genalex Mini-Mark II with Australian MSP 'girdacoustic' style cone.  RadioShack Cat No. 40-1966A.  Above the 1967 year 40-1966 REALISTIC Minimus-1, 'the mouse that roared', plywood box and cloth edge woofer with a different tweeter.  Marconi Osram, Genalex and GEC were British brands.  Elettra yacht.  Venetian Navy Museum.

 Right an AWA radiogram in New Zealand.  The set has AlNiCo speakers with germanium transistor Solid State and Frequency Response was usually 30Hz-14KHz.  The ceramic cartridge offered 40Hz-11KHz but the tube sets may only have 200Hz-4KHz based on the Mullard 3 amplifier.  They need the type of  'Class A' output, full-range speakers shown.

Left the IMF Compact II with a celebrated ELAC copy of the EMI squawker left below.  EMI were old surplus units dating to the early 1960s and the copy was elite only.  For tube amplifiers, Compact II was louder than Klipsch in the video below and the elite Peerless bass gave 35Hz from a wide dispersion driver.  It made Compact II a winner with those in smaller high rate apartments, IMF is however very expensive and certainly not mass market. Here they're restored with foams that probably aren't suitable, the originals very fast, nearer Butyl rubber.
Right OEM 35Hz Peerless foam edge woofer with its own squawker and no glass fiber plastic covering.  The strange foam edge is a flat type, not the slightly older and more sound distorting roll style.  Danes used clamps but IMF screwed through the foam.  The Peerless foam edge, squawker is also seen as the 'pistonic edge' flat foam type developed by the elite Bakers Selhurst company near London and seen in the 1950s as adopted by Gilbert Briggs of old, lower-middle-class Wharfedale.  Replacing with a 'roll' edge above probably suits less capable equipment.
Left, a re-foamed doped Peerless woofer in an IMF Studio (the short baffle reduced low frequencies that drained tube amplifier power).  EMI squawker, KEF T-15, and black- painted baffle Coles Super-Tweeter. 

Left Knight KB-55 were kitted using obsolete type British EL37 / 6L6G vacuum tubes when tricked out, sounding powerful with American lower market speakers like Klipsch with 94db SPL for 1 watt but the F.R. isn't level or in any way accurate.  Loud they are but High Fidelity they aren't.  In lower society rooms like this one, nobody was complaining.  Below V-FET was the 1960s and PowerMOSFET up page mid-1970s.

 Right, Ted Jordan preferred to call his Jupiter model right 'a Tuned Acoustic Labyrinth', the abbreviated Transmission Line Speaker 'TLS' often appears in the name.  Grey painted Polyfilla covered modules on a grey wood veneer with a Peerless tweeter and bitumen treated KEF B139B, SP1044 over an area of 1960s bare baffle, where desired.  15 watts RMS, likely aimed at QUAD II and based on some older, more expensive to make drivers from EMI and GEC, they were speakers from the tube era aimed at a lower man.  QUAD 405 below in its original 1977 form had cast metal side cheeks and grey fiberglass printed circuit boards.  QUAD 405-2 were built for the Spendor SP1, have plastic side cheeks, reduced quality, and shorter life, often noisy in transformers with buzzing sounds.  A whole guide could be written on differences in QUAD 'British shoebox' amplifiers.  Early 405 are for low power output and later 405-2 for high power use.  A 405 is good with 3D sound and partners the Jordan Jupiter right.  405-2 is at best, a lower market Solid State rectifier, simulated EL34 tube sound, preferred with Japanese compatible RCA socket QUAD 44 control amplifiers coming after the year 1992 and working with factory-built 410, two bridged 405 amplifiers powering even less efficient 1990s speakers.  410 kits will be seen as shabby, owners regretted D.I.Y. conversion. 

Left, the Crimson Elektrik slimline power amplifier made by a former DECCA engineer, Brian Powell and marketed as kits, the double mono fiberglass Toshiba output device boards resemble the original, QUAD 405 below.  Notable features are early industry round transformer, disco type smoothing can grounding rod and modular bridge rectifier.  These ... British ... 'Shoe Box' amplifiers had been a minimalist tube theory, 'simple circuitry' Solid State design intended to offer affordable Japanese sound at a time when far eastern imports were terribly expensive, they didn't sound as good as 1970s full featured imports, but were bargains.

Right, the Hafler DH-220 was built as a kit by the lower peasantry and appears in a number of curious ... home built ... inside finishes that nevertheless resemble the Crimson Elektrik or QUAD 405 only with a bigger heat-sink and is a wide-band, 6-60000Hz with 120 watts, around twice the power of the Crimson and slightly more powerful than a 405 but lacking its 'Class A' stage.  Basically without looking too deep into circuitry the Hafler has more space for a higher current power supply and many of these 1970s Hi-Fi amplifiers could have more power if more current was available in a beefier power supply.  The Hafler was popular in the US and in Britain but like some kit amplifiers it didn't flatter lower quality inputs used by lower income buyers and was more of a kit builder's area of interest.  The Hafler amplifiers had serious credibility back in their day but enjoy more of a cult following.

Above QUAD 405 high power output devices were Japanese Toshiba brand with glass fiber boards where 405-2 are US RCA with asbestos resin boards, 405 converted to 405-2 suggest otherwise.  Imported origin boards weren't as British as patriotic buyers had hoped.  405 RCA low power output stage is superior to the 405-2 RCA one.  Left IMF attempt an Altec-Lansing Flamenco sound, jagged Frequency Response liked by tone-deaf buyers.

Left B&W DM4 have an own-brand EMI styled Bextrene woofer of very low power handling but 5 watts gives 95dB.w.m.  Behind is seen in some of the original owner's decor.  A review suggests the 1972 model uses only surplus units and the woofer is of EMI origin, from a very smooth Frequency Response plot graph.
 HAMLET.
Ah, ha! — Come, some music! Come, the recorders! —
For if the king like not the comedy,
Why then, belike he likes it not...

Left, B&W DM4 plays classical Vivaldi other genre audition videos appear on YouTube.  Below a Pioneer M-77 visually similar to the earlier SPEC-4 with lower market following aimed at being powerful, loud, detailed and musical.  The particular differences between Japanese mass-market brands relate to componentry and styling.

 Below is Pioneer's SPEC-4 rendition of the Lo-D HMA-9500 tube chassis style amplifier up page.  They're 'double mono' stereo built in a symmetrical layout as idealized below.

Left,  IMF ALS40 Mk.1.  EMI squawker gives the main overall sound balance supported by specially made Peerless speakers and a standard 1972 vintage Peerless soft dome tweeter, very exciting back in their day.  Why Peerless?  Because New York had a huge following for Bang & Olufsen that engineered their superb stuff for Peerless speakers and Harvard you know, located in the neighboring state of Massachusetts had similar tastes, not to be outdone and just a stone's throw away.  The EMI squawker would've been a consignment of surplus offered at a giveaway price, just as France bought engines for their Concorde airplane from an axed British military jet, the TSR.2, similar to the US Valkyrie.

Right IMF ALS40Mk.2 with ELAC version of EMI squawker and SABA basket LTP edge woofer of unknown origin.  The tweeter is an original Audax HD 12 x 8 D25 that gives it's oft-seen square felt strip border detail to the Rogers LS3/5A, different dome finishes imply quality issues.  It's interesting the German SABA basket fits into the KEF cutout, as elite only versions might use the same cabinets.  Below Rola Celestion made British IMF Super Compact II with ELAC squawkers.  The model on the left is earlier vintage and higher in social class than that on the right.  A 'white belly' (from the doped center), KEF woofer is difficult to date without removing some are more recent. 

TC Smout, "the No.1 most snobbish university".

Left an early 1970s Celestion made British IMF Super Compact with the original fiberglass cone EMI squawker and matching tweeter.  Note how the 'white belly' KEF woofer doesn't quite fit the cutout, suggesting a SABA woofer may fit.  Below the late 1960s EMI paper squawker with speech domed 3.5-inch cone tweeter and expensive choke.  On the right side of the graph below is the very level response of the EMI tweeter in the 14A/600 and the paper speech dome tweeter below aims to approach the tweeters in the EMI 550, Club and 950 systems.

IMF International, known to Harvard alumni as the SCW Model, appears a British Rola Celestion made enclosure.  EMI fiberglass doped midrange and Peerless tweeter with unknown woofer and Transmission Line as above.  Below SCW x-over screwed to left side panel over a foam layer, similar to British Rank Wharefdale XP2.  Unspectacular asbestos resin printed circuit board with baked ceramic wire-wound resistors and barely visible air-cored coil beside a Goodmans and SONY V-FET styled iron-cored coil with a loose lamination strip.  Thickness of the baffle is seen.  These aged solid capacitors are meant to be replaced as thought to degrade as much as the electrolytic type.

It seems likely that the SCW is the Super Compact coming before the Super Compact II bringing the Bextrene unit and what IMF described as an in-line x-over network developed as a no compromise filter for the KEF bass unit, although the original SCW had bass to 25Hz and sold very well, the x-over doesn't look no compromise nor does the baffle thickness.  Peerless woofers in the original were a special design not readily available as an off-the-shelf replacement and this probably gives the SCW its appeal. Below Fried Model speakers used Series XOs, apparently no mystery but in truth, x-overs are very difficult for mere mortals.

Right, Fried Model Q from 1978, a 2-way that became a series and finished in vinyl with visible aluminum woofer rim to resemble the west coast sound of CerwinVega (of California) but was east coast toned for harman/kardon of New York, at that time still under Sidney Harman and below the hk 450 not a DC-Coupled wide-band (5Hz-70KHz) like the hk503 of 1979 year but a basic 30 watt, 20Hz-20KHz, 4-16-ohms and a compact Transmission Line based on the International IMF, but under the US Fried brand since 1975 year so three years into selling well.  Very basic city scenes, compact escapism and an awesome year for vintage Stereo, SONY V-FET and Carbocon speakers were competition.

Left, 8-ohm Fried Model A/3, 90dB SPL, 1w, 1m, Phase-Tech T631 mesh tweeter and a woofer by Dana Audio of Austin Texas, shiny black phase domes give unrivaled middle-range clarity, a few speakers of the time had them:  NAD Model 240 from Australia, Teledyne Acoustic Research AR18s, and not least, British Rank Celestion Ditton 100, long before that owned by Rola of the USA, and right back into the 1940s.  Kenwood shiny black phase domes were black polypropylene but few Americans know more about Fried than he'd made speakers of the Harvard University community.  Bottom note is 38Hz and sounds higher, 44-55Hz with a bad amplifier match, best use harman/kardon Citation 25/22 pre/power amplifier.

Right EMI 550 tweeter to obtain the level tweeter response of the 950 above and Club speaker systems.  Below the 5-inch EMI 250.  A 6-inch elite only unit is in the 1970s Cambridge based Monitor Audio factory's MA7, before the Essex move that saw far eastern drivers also used in Rogers LS3/5A and other so-called 'UK origin' speakers.  The use of a treble tone control adds distortion and affects fidelity.  The Fane tweeter for their 13 x 8 has a much larger metal foil 'presence dome' than 550, Club or 901.

 EMI 550 has a stiff edge for its twin duct air release system seen below.

Left an elite only BBC Lockwood enclosure for the EMI 550 Merciless speaker system.








n







Two plastic ducts above weren't of the usual 1980s Helmholtz resonator by DuKane in the 1960s but an elite only system operating below audibility to prevent 'closed-in' sound in amplifier mismatching.  Marketed by IMF in the United States as their Styrene Pressure Loudspeaker based on research by Lectronics and Rola Celestion,  subsequently, Rola made IMF Super Compact in England.  Although a problem with Leak and other vintage Styrene speakers is poor efficiency, the EMI 14A series didn't give better and increased amplifier power was needed.  Reduced size of speakers gave wider domestic appeal.

In an early elite version Celestion 15 speaker left aimed at the QUAD II, note a thick, bare plywood baffle and foam that the elite only EMI duct system sought to avoid.  Early Celestion 120 and later 'Ditton 15 Studio' aimed at the upper-middle class.  So many versions of Ditton 15 exist, this one serial number 4812, later versions reduce the cost of materials and improve sound with lower-cost equipment.  Black baffle Ditton 15 aims at the lower-middle-class buyer with final working-class Ditton 15 XR in a wooden veneered baffle to persuade those swayed by looks.  Made by Rank with steel basket mass-market drivers and a mesh-covered dome tweeter, they have many friends, early Ditton need pricier equipment.

The lower-middle-class Celestion UL8 below and working-class SP15.  15XR right has rare HF1001, replaced by KEF1068/ Audax HD100D25.



These polystyrene auxiliary bass radiator speakers made by Rola of the United States were all the rage in the 1970s and widely adopted by leading manufacturers like B&W and Revox.  However, they don't make a 3D sound heard from all sides.  The Home Theater system 7.1 etc places satellite speakers around the ceilings of rooms to obtain effects nearer the 3D of only two EMI speakers in stereo.  Goodmans Magnum K has a very level Frequency Response but the smaller diameter woofer is faster with a punchy quality.  Magister had a 15-inch woofer and Mezzo a ten-inch.  The larger diameter is about 'feeling the bass' even with a baffle cut-off frequency meaning we don't actually hear below it.

Left, Keesonic Ranger from Peter Keeley who'd started out in the early 1970s and like IMF, and many others, used surplus EMI drivers that when every last one had been sold followed with Dalesford, Peerless and left Norwegian SEAS of the 'SONY SOUND OF GERMANY FAME'.  Dalesford drivers weren't special but available as affordable replacements (like ALTAI) for many Keesonic and KMAL drivers, a following was something like, the US Irving 'Bud' Fried but not obviously in the same category as EMI.  Keesonic are best known for their Kub and had you know, anorak buyers following British cars like Lotus, lower middle class, Bargain Demons, a cult following from the lower independent school mold, not bought by the peasantry and lovable rogues, a humble group from free-to-parents, poor British schools.

Above the problem with this polystyrene, woofer speakers compared to EMI may be seen in their Frequency Response plots, the upmarket IMF version above.  This is why they don't have a 3D sound and helps explain the rise in popularity of the stereographic equalizers below.  In the lower-middle-class black baffle Ditton, 15 left is seen the BBC ring radiator tweeter that's very accurate but extends to only 15KHz.  Listening to, recording and playing back FM stereo broadcasts the black baffle Ditton 15 was used by the upper peasantry aimed at powerful Japanese Solid State amplifiers as were Tannoy HPD385 of that time and later made in Scotland when sensitivity increased to 94dB but had only 22Hz F.R.  Below left British BBC Atkinson TL Studio Monitor with time aligned KEF T-27 tweeter and right a lesser, mass-market equivalent doing without wide dispersion twin Rola HF 1300.  The flat KEF B139 driver originally a cheaper to make a version of EMI elliptical speakers used polystyrene and downmarket amplifiers with a 4-8 ohm load capability, dropping to 2 ohms on peaks.  Below left Ferrograph S1 and brown KEF MK.2 6171 version of B139 differs markedly from an SP1082 BD138B KEF basket in the Lentek speaker below.  Many different versions are not interchangeable as in the Model T Ford days.  Bargain demon internet reviewers write:

"...and I never heard a good Goodmans dome tweeter..."

Left a number of such dome versions, heavy Axtent 100 and lightweight, plastic-bodied clones, great with EL34, awful even with 'tube sound' Solid State like QUAD 405-2.  
Right, Lentek branded Transmission Line based on the US Fried Model R, some red stuffing appealed to Australians and not in the UK model.  Rank Celestion's take on a Coles super-tweeter and KEF designed mass-market drivers were likely shipped from a far eastern source, in the 1960s made briefly by KEF in the UK.  The matching Lentek amplifier was middle class, mass market, an average 60 watt styled after British 'shoebox' items of the 1980s -such as the NAIM below with loud hum in the speakers, a whine in its mains transformer, hum noisy mains power wires led physically around and over-sensitive input switches.  NAIM was advertised - even in the US as 'the best buy in Hi-Fi', audition of 'British shoebox' amplifiers had salespeople knowing no better, the loud hum from speakers vanished when music played but smoothing cans mounted on the rectifier module board below are the cheapest of designs.

Above Naim Nait 1 isn't recommended, restoration won't cure the mains hum issues.  Below EMI based Metrosound ST-20 separates mains wires from source switches.  Left speaker for the ST-20, described by enthusiasts as having a powerful sound was damped with fiberglass wadding and has a 3-ohm core, 13 x 8 EMI 92390EW in a ten-watt ring magnet version - not the smaller 8-watt type of the 92390EH.  To get the best sound needs expensively made low Damping Factor Solid State.  The EW version gap conductor is very long, not like edge wound Dynaudio or JBL and suits vintage amplifiers of the 1960s.

 Below the harman/kardon 730 shows the 1977 year idea of power cans on a small circuit board separate from the output board.   The reason NAIM above is thought better is due to a mismatch of speaker vintage.  730 have both channels on a single heat-sink as in the NAIM above were bolted to the metal case in British tradition rather than a pricey aluminum heat-sink.

Below more expensive than the harman/kardon 730, the 930 shows power cans clamped to the chassis for best sound quality.  Heat-sinks are separate to allow louder and better quality volume listening without the adverse effects of heating and as such the 930 is closer to a dual monoblock design where a 730 has only twin transformers.

Right when the Akai SW-180 appeared it had an American style cloth edge and not the white rubber one of an elite only, L.T.P. edge EMI it had been advertised with.  Below a bare chipboard baffle Ditton 15 aimed at valve amplifiers, makes do with mass-market Solid State instead, the sound not very good but with more expensive equipment would have a much better result.

People who are working-class or lower social classes and use mass-market amplifiers like this left are best to use the wooden baffle Ditton 15XR and wooden baffle IMF Super Compact II.  These bare baffle Ditton 15 with the Rola HF 1300 are aimed at MID-Fi valve amplifiers that reproduce to only 15KHz.  They suit cassette tape machines like the SONY TCK81 and FM tuners that go to 15KHz, QUAD FM3, and their ilk.

Above Technics 20A tube control amplifier of 1966 and right some other pieces on display.  The 1965 Technics 1 was the first branded product that Technics sold and was a small speaker believed to outperform everything in the lower-middle-class mass-market.  EMI and IMF weren't mass market and were only found in elite places.

Above the EMI 350 92390CL measured by enthusiasts and thought to suit a folded horn design.  However, as surplus units sold to the peasantry, they were fitted in small boxes with rubber foam batting where they'd given very lifelike female vocals.  Since the CL was found mostly in the US it may have suited some Beam power tubes like the 7591 in the Heathkit AA 100 left.  92390CL is in the EMI 92, 921, and 1050 (that followed the 105).  The cone has an odd, velvety grey appearance, the tweeter has no visible voice coil wiring.

Left, EMI 300 C and T had the 300 tube rectifier woofer capable of 10Hz lowest note.  The 315, 14A/780 above was the Solid State rectifier version, aimed at a special version of a color TV line scan tube known as the PL509.  The Audio version tube is out there but only bespoke dealers could have identified it.  The 315 speaker cabinet was very large with an effortless, low note very useful for beat dance music.  No Disco speaker could compete.

Left, academic built early Solid State amplifier in a 1960s germanium transistor chassis style with a single BDY55 in what might be a fast 'Class A' stage backed by a fiberglass circuit board and supported on the lower deck by TIP3056 and TIP2955 in a 'Class AB' stage with relatively small laminated mains power transformers and chassis clamped smoothing cans.

Right, two RCA phonograph plugs in driver stage cases and the black heat-sinks of the TIP transistors.  Peter J. Walker of England's QUAD created a 1977 'Class A' switching to AB design known as the 405, later the 405-2.

Left, New Jersey Semiconductor's BDY56 in a Boothroyd Stuart Meridian power amplifier below, this ... British ... company boasted its M1 Active speaker, but had power amplifiers for other brand speakers.  A fiberglass circuit board is seen and the odd, speaker output chokes later adopted by low cost British Arcam, in preference to the old 'air core' coils of Japanese imports.  British 'shoe box' amplifiers are followed in the United States and Meridian today, is a well known high-end brand but these late 1970s lower middle class models might appear strange to some modern viewers as aimed at posh buyers.  The tuner had a special front end sealed in a module, was a two radio chip design from 1979 with a round power transformer to reduce spurious noise but could it beat the later Radio Shack REALISTIC STA-2290, besides being much easier to service as a vintage high-end set?

 British high end Meridian 101 and 104 , Year 1979

 

 

 

 US Texan R E A L I S T I C STA-2290 Year 1983

 

 

צמצום  צמצום