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Benford Folded Horn (Elite only Lowther Voigt)

Likely design of the EMI 92390CL core, left in 319 form and an early 350 below both found in the US and not available to the mass-market except as the Benjamin 1020, in name only, related to 20 watt 711 woofer Dutton 102 (twice the price of a DLS 529).  Click on images for full size view.

Left screw terminals have an effect on sound quality according to the enthusiasts.  Steel is a good conductor but distorts and scientific investigation showed the tightness of the connection to be crucial.

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Upper squawker powers the horn with added sounds from the black basket, early vintage  EMI  350 left.

 

 

 

 

 

 

 

 

Below, blank backed 93870CH squawker basket on the baffle rear in an EMI Merciless cabinet.  White fiberglass acoustic wadding is stuffed around the space between the rear and front baffle mounted squawker baskets, not needing a separate squawker enclosure.  Magnet is the 92390GF, slightly less powerful than similar, earlier 711 Dangerous Speaker motors, drives the speaker higher up an amplifier's power envelope where more powerful Solid State sounded sweeter in the late 1960s and continued in amplifiers for medium sensitivity speakers.

Right, one of many  EMI  elliptical squawkers, the speech dome here with a circular hole, the surround of the roll type unlike the pleated edge in the Benford.  These are elite speakers of the British nobility and little is known of any of the designs they used.  The time of the rich man may be spent in so many ways and EMI speakers were one of the most valued elite brands.

Left, 8/EB (as opposed to smooth shiny cone 8/EC squawker above) a whizzer-coned squawker with Karad paper cone, a Merciless Speaker, white acoustic wadding rear-loaded under 93870CH squawker stamped steel baskets, worked with difficult-to-power, EMI 750 roll edge woofer with EMI x-over akin to chokes on 14A/770, 14 x 9" with two Erie electrolytic capacitors.  8/EB were speakers of the EMI kit series likely available to the British elite built by Lockwood BBC speaker cabinet makers.  Click on the image for full view.

Right and below, an EMI 319 built to enclosure specifications of the Benford Horn might be the standard issue, elite British EMI 319 cabinet with vinyl hide rear, once popular with 1960s British Hi-Fi buyers when High Fidelity was an elite thing as it stayed until the early 1970s, never commonplace nor in the mass market until the 1970s.  Wharfedale and others were a usual working-class prestige buy.  The studio EMI 319 has a rectilinear drone and plywood panels but elite EMI use a 'tuned labyrinth' and the cabinets are never broadcast on the internet, they have a deep gloss Burr Walnut finish. Many wonder if vintage tube audio collectors would reconstruct the original cabinets for the metal inner components, bought separately as they appear in auctions.  Within the British peasantry, vintage loudspeakers are rarely seen today, even although EMI was particularly suited for tube amplifiers of BBC type, QUAD II and LEAK TL.12, EMI was an elite speaker not known in the lower society as not among more popular brands of the 1960s.  Elite viewers today scoff at EMI speakers and suspect, they might found on the underside of parcel shelves in just about any car of the time, not so, EMI were rare and the best on the market, the big elliptical speakers wouldn't even fit into cars but there's extreme snobbery in High Fidelity Audio, so much scorn and contempt is witnessed.

Right EAGLE L7700 were Japanese 'oriental sound' speakers for the A7600 above, vinyl wrap, and a surprise to find on a Persian rug and in plush surroundings.  For the true working-class, amplifiers are higher in distortion, speakers with nasty power meters, and cheap knob controls.  The oriental sound had disappeared in Europe but continued in Brazil, and the US, still sought after everywhere fetching better than expected prices, loud, satisfying, and for mass-market items, harder than most to find.  The volume knob follows a lit style of Akai, found easily in the dark.  NEC probably hoped to tap the EAGLE market in the UK.  Sonics AS450.

Left the Tannoy Windsor Gold is the most prized mass-market elite speaker with the Tannoy Red cores and here uses a super-tweeter to lift the tonal balance of the connected Leak Stereo 20 amplifier that uses the EL 84 output pentode.  The  EMI  speakers still aren't available to a mass-market but from bespoke dealers selling to a minority.  Note the Persian Rug and polished wooden floors of elite rooms.

 Right, a SONY speaker made for the 1960s NEC V-FET transistor has the same squawker as the NEC S-6000 speaker below.  Sansui BA-1000 and Yamaha B-2 were V-FET outperforming the old King KT66 tube of elite amplifiers like the Williamson 0.1.  The European nobility continues to use bespoke amplifiers of the 1940s and 50s and never seen on the internet.  The US mass-market use Luxman MQ-60 based on British Mullard know-how.  In the United Kingdom, the demand is small enough that Mullard 5/20 can be had at a sobering price.






Left NEC 50CA10 is a triode output tube only found in the mass-market Luxman MQ-60.







 



NEC AU-A6000E


 Below NEC AUS-6000E speaker for the AU-A6000E above.

 Below NEC AU-A6000E build for the above S-6000 speaker, SONY V-FET squawker!

Above-right, MCS/NEC 8265 speaker system for the rack system on the left.<<

NEC Authentic Series A820E and S-637E left above.

Speaker for the NEC A-230E>>

Below Curtis Mathes, HA280, Texan NEC A-820.

 

Left, Texan speaker for the Curtis Mathes HA280 above as made by ONKYO, also of Japan and from their similar and upmarket D-7R, that likely differs tonally matching own brand amplifiers, among the most popular in the US.  Although  NEC  A-820E speakers may be styled after the D-7R, Texas secured its own, warm sounding special of ONKYO style, the NEC S-637E very 'cold' sounding, more suited to a hotter climate, Florida rated hottest year around, Louisiana and Texas coming a close second.  Buyers may wonder, how to get the best from these but after tinkering with components to refurbish the units, their sound will change, most with the quality of 'Snap-In' power smoothing can fitted to a price, always best pay top dollar.

Left, NEC A 520E (Curtis Mathes HA 250) (820E, Curtis Mathes HA280) with computer-controlled cassette deck and digital tuner, a High Speed amplifier it always had dry solder and awful sound, but new solder (very hard job) gives its true magnificence, some more new caps and component tweaks.

Above short-lived green filament bulbs blew if knocked whilst hot.  >>Speaker for the A-520E above has a ten-inch woofer to the 12-inch in S-637E above left.  An 8-ohm sensitivity of 91dB, SPL, 1w/1m, Frequency Response of 40Hz-20KHz for the 'wide-band' type amplifier, 5Hz-70KHz in the A520E and of T.H.D. less than 0.008% at 50 watts RMS output, the speaker right takes 70 watts maximum.  Phonograph is 87dB and the line-level 105dB, S/N ratio.  A520E amplifiers distort with 6-ohm or 4-ohm speakers, more with a British elite 4-8 ohm load.  It's a Three-stage Differential Amplifier but meant to have 8-ohms and Luxman MQ-60 tones don't please everyone, a simulated tube sound nearer PL509.  The treble horn lifts high frequencies as with the Tannoy Windsor.

Above, left and below, A520E symmetry stereo two transistor discrete output.  Solder needs replaced to create a super sound stage effect but as seen, gives horrible sound, severe lack of treble and detail.

 Below and left the NEC A230, none more loved by the British working class.  The circuit below shows a separate control amplifier.  Hardboard baseplate improves sound quality over metal.  Long term reliability modular cold rectifier.  Hitachi Metals mains iron.    Rubycon smoothing cans for Luxman MQ-60 sound balance.  Speakers for the 230E have wide-dispersion twin cluster cone tweeters.

 Below 25 watts, 10Hz-50KHz, 0.05% THD, 100dB Line, 8-16-ohm speakers

3-LED tuning T230 above is on Canadian T530.  Left Benjamin  EMI  S-1050 with 92390CL unlikely to best match with an NEC 50CA10 sound or NEC developed V-FET, later tried by SONY as a novelty.  The Authentic Series was the basis of the MCS 3125 receiver and 8330 speaker system.











 Right NEC S-637 valued original, very loud sound.  Black tweeter horn throat isn't OEM but from a ferrite magnet Kenwood 777.  The compression driver used by NEC is an aluminum dome and rebuilding, hinges on some trial and error, what sounds best with the rebuilt NEC amplifier.  Solder in the Authentic Series is expensive but now resistive high Lead against Tin content, circuits brighten up and become lively when it's replaced.  91dB SPL at 8-ohm, 40Hz-20KHz through ported design suited only to some rooms - either it works or it doesn't.

Yellow fiberglass batting pattern seen above is vital for air loading of the port tube that NEC covered with grille cloth.  Left MCS/NEC woofers bear a small magnet for simulated tube sound sought by Japanese engineers.  A lightweight magnet in a motor of very high quality might be perceived by the thickness of aluminum outer trim.  When properly sealed in enclosures, such woofers have astounding ability reckoned closest to mass-market Luxman tube amplifiers of which there are many to compare.  

Right, a stepped baffle Linear Phase, MCS 8320 speaker from Panasonic in the 1981 year of the  NEC A-520E.  JCPenney of New York had an MCS, (Modular Components Systems) range divided between both Panasonic and  NEC  products so we have to match the right speaker and amplifier for best sound.  The NEC A-520E was offered in Florida, was branded 'Curtis Mathes' in Texas, and widespread in Canada where there had been extra features versions.  In Australia  NEC  sourced MCS stereo components are sought after today as offering unrivaled value for money, but the Australian market was never easy for audiophiles and almost any vintage stereo is considered precious there.

The squawker in NEC Active Drive amplifier speakers is based on one right for Technics 'New Class A' outputs, the horn tweeter of wider dispersion than NEC.  A ribbed squawker long appeared in American mass-market Technics SB-G400, 500 and 600.  MCS carried downmarket versions of Technics, unfortunately, NEC Authentic Series squawkers or tweeters seem to be custom manufactured, special units not so easy to replace.

Left, compare the reproduced piano waveform with the original and find the differences but because the NEC Active Drive system has a simulated tube sound, the use of Technics Linear Phase Speaker Systems won't deliver a great sonic match, a different sonic signature needs another speaker.  The NEC Authentic Series squawker below was factory doped with varnish to improve the 3D image, often called a soundstage.

Above left a Trio-Kenwood bullet horn and above the NEC Authentic Series AUS-7300 for the A-520E.  Left the AUS-8300 for the A-820E.  These doped squawkers seem to be custom made by Technics.  The phase dome left isn't original, a squashed one has been cleverly covered by a crafty review author, albeit with no understanding of phase dome theory.  Again the black horn throat is an after-market replacement, the original silver horn tweeter very fragile as aimed at high quality, low power outputs.

Right, a Lo-D, Hitachi bullet horn.  What's important to the speaker builder, trying to match NEC pseudo 'Class A' amplifiers, is what compression driver NEC used with the surplus cast horn throats.  The flagship NEC speakers are so rare today that it won't be easy.








Left Trio-Kenwood KL-888D.  The pointed style bullet over blunt one in the Lo-D, suggests the NEC Authentic Series tweeter is of Trio Kenwood origin but the compression driver used may have been custom manufactured and not surplus.  This makes rebuilding speakers more difficult.  Below A-520E hadn't such popularity of the downmarket A230E.






UK market NEC AUR-8075 led to the later and powerful US MCS 3125.
NEC A7 amplifier and T-6 tuner.

NEC A-7 Reserve II amplifier.

NEC A-700 amplifier.

Left NEC A10 and in type, IV, 2-ohm low-load drive compatible aimed at the British elite 4-8-ohm load, peaks dropping to 2-ohms.  Critics praised the ability to conduct current according to Ohm's Law as "the ideal amplifier" and it sold well.

Left NEC A10 Type III

NEC M50 power amplifier

NEC A7 Reserve

The potted toroidal transformer in RadioShack's STA-2100 is oversubscribed, similar in the NEC A820E with its own brand speaker is very loud in huge rooms and with excellent dispersion.  The A520E power output is of double mono style and that lower power sounds best, has people tinkering.

Left NEC A10 Type IV 

Below NEC AUA-8000E, with all-black and US MCS 3865 gold/black Hitachi Metals power irons.  At least since amorphous core transformers were developed at Caltech in 1960, the optimum electrical crystalline structure of wires has been studied by metallurgy.  NEC uses Lo-D/ Hitachi power transformers and avoided the SONY smart mode power supplies as mainly reducing shipping weights.

Below NEC A-11

NEC AUA-8000E with DianGo, Rank Arena, Palladium and MCS brands.

























Black circuit boards from the DianGo/  NEC  tuner above with a triple chipset. 

 

Left, a surplus tuner board in Baron Alan Sugar's late 1970s Amstrad Executive Series Ex.222 differs from the Ex.333 where the off center air gap tuning capacitor occupies a place by itself.  Germanium and Silicon transistors appear suggesting better sound from the upmarket version tuner.  The integrated circuit to the right is an LM1303 by National Semiconductor and these sets were not cheap until COMET warehouses had sold them in the early 1980s at knockdown prices, they were built to outperform the best Japanese imports but at a lower price and had won many friends.

Left NEC A-10XX and A10XXP appear in the US market.  NEC amplifiers need specially engineered speakers.  Getting a good system has never been easy.  Below NEC A-610, opening flaps began in the Authentic Series A720.

 Above the A910 styled after NEC video recorders, then a prestige symbol.

Left Authentic Series S-319C speaker for the NEC A610 above.  Orange badge compliments the power meter.  2-way speaker, cone tweeter and Technics MCS wide-range mid-woofer.  More complex speakers are less likely to sound so good with the A610 and it might help explain why the perceived sound of NEC amplifiers so often fails to measure up to Technics.  That is different matches of equipment add up to more or less satisfactory results.  Below NEC A420E that some working-class buyers thought the best ever.  But many Japanese amplifier brands like Sansui had an early 1980s problem of needing speakers of at least 8-ohms.  Connect up anything less, even British society 4-8 ohm loads of Rola Celestion and such far eastern amplifiers won't give the best sound.  Another problem with far eastern amplifiers is the more powerful AR speakers, particularly starting with the 28LS and going upmarket.  These 4-ohm speakers need American muscle amplifiers.  The larger a Ferrite ceramic magnet is, the more amplifier power is needed to drive it.  The British rightly presupposed that all Japanese amplifiers were power rated on a resistor tone burst at 1KHz and unable to power what American designs could although rated at the same output power.  Allow Japanese RMS power figures to be a third of British ratings.

 

Left and below the NEC  A420E amplifier, a back emf tolerant design in an upmarket setting.  T-530E tuner.  P435 TT, K 450 cassette deck.

NEC AUA-5000E, Hitachi Metals transformer, separate control & power stages.

Left, the only NEC Mini-System was copied from the 1970s Ferguson/ Carad System 15 and 30 above that were awesome and the legendary SANYO M-9998, that was unbelievably loud and impressive.  NEC were revered by the working-class but like the 1982 year AMSTRAD 8090, their mini-system woofers flapped about at full output, internal power supply lacking the current rating to deliver.  NEC Palladium A-7000 below has a Hitachi/Lo-D mains iron.  

Below NEC AUA-7000E similar internally to the above German market version.

Left, the key to success with NEC 7000 above is speakers close in design to Japanese originals.  The AUS-7000E is a US market MCS-made by Korean owned National Technics, after the year 1975 and with lightweight magnet motors of the tube amplifier type but awesome.  Below an NEC Palladium, a power amplifier suggests other comparable sets exist to make a rack system.

Right the German elite speaker for the NEC amplifier above uses a down-firing RadioShack musical instrument woofer, known in its day as 'the Big One', an orange basket 15-inch and one of the earliest sub-woofers, often suffering high distortion but aimed at low-frequency impact.  Certain RadioShack speakers were popular with Germans, in particular the Optimus X-30 series.  The elite speaker has the German Isophon KK10 grid tweeter of the British Elite's KMAL, Keith Monks Audio Limited speakers that use EMI squawkers.  Horn-loaded dome squawkers right are seen today with EL34 tube amplifiers. The nine full-range cores with silver whizzers succeed for accurate Frequency Response in off-axis listening.  The crossover is seen on the horizontal brace panel below.  The thickness of the baffle used above may counteract the fixing bolt holes giving rigidity, full-range speakers...

 ...mounted behind the baffle.  The REALISTIC STA-2000 receiver has an NEC output stage and uses a similar appearance Optimus X-30 speaker to give the preferred tonal balance.  A seam in the cone of 'the Big One' left identifies with one of the world's oldest loudspeaker manufacturers, Quam of Chicago, established in the year 1930. NEC is much older.  Kunihiko Iwadare and Takeshiro Maeda established the Nippon Electric Limited Partnership on August 31, 1898, using facilities bought from Miyoshi Electrical Manufacturing Company and telephone know-how brought them to Western Electric (1869) of the United States.  Below 1977 year down-firing woofer CerwinVega 12TR .

 

Above a cone, seam identifies RadioShack's 'Big One' with 1950s Oaktron of Wisconsin and right Quam from Chicago, established in 1930.  Bernie Appel had CTS of Kentucky re-cone wore-out Heppner steel baskets for Nova 9 and it might 'seem' from this that Utah musical instrument baskets were refurbished too by Quam, the one right of AlNiCo motor style, all reckoned best for long life under stressful conditions, but can be used as squawkers. 

Right, Pioneer speaker using a 2 watt Mitsubishi woofer of 25 watts MAX.  Twin duct, note the acoustic wadding color and type doesn't wrap fully around the sides as it is a ported reflex design.  Tweeter is Al-Ni-Co, middle-range and woofer are ceramic.  A top and bottom panel brace is seen.  2 watt rich speakers are readily available and suited to Japanese amplifiers that some tonally match a ceramic motor tweeter better.  The enclosure is of the dead box type.  Rear panel seals the box with a gasket tape.  Such high efficiency speakers are recommended for low power Japanese amplifiers and receivers.

 

 













Left an early 5 watt NEC speaker likely by Mitsubishi.  A Luxman MQ-60 amplifier with NEC tubes.

Right SONY SS-G7 cabinet with short port bass reflex and damping detail useful in improving similar Japanese speakers of lower price.  The Sony SS-G were hi-End mass-market rarely seen out of the big cities. The SS-G is clearly made by the same manufacturer as NEC but the cross-hatched baffle is plywood and the pattern improves the sound.


NEC AUP-7000 turntable has most knobs, lower models look impressive too.

 

Left, early  NEC  version of REALISTIC STA-19 was the STA-12 with BTL later found on the Onkyo M-5000R-B.  The later STA-19 had a fake wood top panel and special speaker bass excavator similar to the Hitachi made STA-7, metal-cased with twin HA-1370 car audio modules. 

Right, the British and Canadian flagship turntable P735E runs with the  NEC  A-820E amplifier and these are very good, a loud stereo system of Pioneer character but a slightly chilling sound, not warm or the most seductive, not a punchy sound, not a favorite sound.

 

Left, the Hitachi made SYSTEM SEVEN, STA-7 receiver from the days Hitachi made some Radio Shack items, was followed by the  NEC  made STA-700 above and below, for the Realistic Minimus-7 micro speaker system.  The STA-700 has an all NEC tuner stage and was considered Hi-Fi sound by owners but the STA-7 remains a firm favorite with 1970s Minimus-7 speakers.

 

Left, first of three versions of the Minimus-7 the Cat No. 40-2030 for the STA-7 receiver.  2030 has a different tweeter motor and baffle with a heavier magnet woofer motor and is the flagship model, upon which the later versions, 40-2034 and 40-2039 are based.  It does appear that the lighter die-cast cabinet, that can be felt vibrating with the sound, appeared very early in the 40-2030A.  Besides the AMSTRAD LS101, a great many versions of these speakers abound, wearing different brands, the later Radio Shack versions with lighter magnets, could then be driven by the lower power STA-700 below, although not advertised as such by RS, the power iron size tells which is the most powerful.
 

Right, the Hitachi made STA-7 has a much bigger power iron, and an interesting heat-sink.  The 1989 year SUB-700 sub-woofer is recommended for Minimus-7 and sold in some American states but isn't seen in U.S. catalogs.

Left, and below, the REALISTIC SUB-700 an early sub-woofer for the STA-700 receiver, actually made by Hitachi in the days when they'd lost their former greatness of the 1970s, as stock it had 50Hz lowest note but could go deeper.

Above and right, the AMSTRAD 101 system took its name from the Merdian 101 and used the LS101 speaker resembling a Realistic Minimus-7 but with a LOUD seductive sound.

 Sanyo STK 0039 modules are still available.

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