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Bigger RadioShack Receivers




REALISTIC STA-2300 2 x 2SA908 and 2 x Sanken 2SC1585 was $100 more than the STA-2290 below with Sanken 2SC291 / 2SA1215 Silicon Epitaxial Planar output transistors rated 15 amps at 150 watts.  Build quality below was way down on earlier similar style models.  Hitachi Metals power iron as seen in 1970s NEC, double mono construction.  Tuning knob more useful than STA-2290 up/down buttons, super features overall.  The slimline AMSTRAD 2000 system down page needed the matching ACOUSTA 2500 speakers by Goodmans, but the similar 2-way Minister is more available. 


Left the SANYO (Denki) Plus Series, dry run for Technics ST-S series below, QUARTZ synthesizer tuner carried on to Bernie Appel's REALISTIC STA-2290.  Below, surplus 1974 year Bill Kasuga Trio KA-8006 NEC Output on the STA-2100 receiver.

Left, Sanken output of the REALISTIC STA-2300 receiver comprises 2 x 2SA908 and 2 x Sanken 2SC1585, as a scaled down Sansui Au 20000 that has three of each and 170 watts RMS.  Radio Shack receivers copied a best seller amplifier sometimes run at higher power output or at lower output powers giving a similar sound quality, using a custom made matching loudspeaker, the STA-2300 with the Liquid (Ferrofluid) Cooled REALISTIC Mach One speaker, only 90dB SPLw/m and an edge-wound, not the old four layer of the 1976 launch year.

Left REALISTIC STA-2290, has two versions:  '82 year 100-watt plywood edge, 12000MFD and '84 year 90-watt vinyl wood edge below 10000MFD.  Both have superb but American sound, it's an awesome sauce, a Solid State modeled on warm tube amplifiers.

Click on the image below for the full reader view.

Left video about the 6dB peak overloads iron in the STA-2290 twice the weight needed for rated output power.  The STA-2290 often looks smaller in pictures but has to be far too large for most who'd love to keep it.  A huge unit something like the later Carver MXR-130 and 150.  Enthusiast modifications give the STA-2290 more power than Carver for its better sound.

Right, 50-watt curly heat-sink of the harman/kardon PM650 amplifier, a powerhouse new suffers badly from age.  The STA-2290 is no powerhouse as stock, smaller heat-sink but modification gives increased power output.  Speakers were Liquid-Cooled Mach One with edge wound woofer similar to JBL and Dynaudio.  Harman PM650 is a better rebuild.  Curly heat-sinks were expensive know-how, putting out a lot of heat.  PM660 has two of them, one for each stereo channel.  Amplifiers for stacking sets have solid lids, below very open meaning nothing must obstruct the heat vents.  Sound quality suffers from overheating if covered on top as with this Owner Manual below or input sources.  Below, A log pot gentle-slope volume knob shows a 2 o'clock position where real kick-ass power happens in 'as new' condition.
Left, closeup on a Realistic STA-790 power supply and output stage with black curly heat-sink, wire-wound resistors of the same year STA-2290 driver board below and TOSIN brand caps, a British influence from Trident Studios in London, who'd used them with Gelec in home brew mixing consoles, the 790 with just such a slider knob equalizer. 

Left, another edge-wound coil speaker is the Scottish made Tannoy Super-Red Monitor.  Sound of Liquid-Cooled REALISTIC Mach One was preferred by enthusiasts but Frequency Response of the more compact 12-inch woofer SRM-12X is 50Hz-20KHz.  65Hz lowest note in the 15-inch edge-wound Mach One, lower notes felt by the human body but not heard.  In the Tannoy Dual-Concentric, cone center is a treble horn, the Tannoy louder for 1 watt and its 'voice', similar.  RadioShack had engineered its own brand speakers to best sell their receivers.  Tannoy SRM suit when Mach One can't be sourced easily or the Tannoy is available but has the wrong amplifier.

Edge-wound speakers are designed to run high power for hours and years but need a receiver or amplifier specially made to sound good.  The REALISTIC STA-2290 below will deliver.
 Right, left button mouse click on image for full view, early 100 watt STA-2290 with 12000MFD x 2, arrowed ALPS volume pot as in the STA-2300 above, lowered distortion in middle-class amplifiers.  Later 90 watt receiver has 10000MFD x 2.  

Left,
in the British Alchemist Axiom the ALPS volume pot is moved back to the input sockets and only appeared in the Arcam Alpha Mk.III, the first two versions with ordinary pots, the MK.II with lower noise rectifier diodes, made 0.02% THD from the original 0.5%, a crummy 30 watt amplifier.
Below, one of the first digital readout receivers, with 1977 Technics 8080 style dial in the pricey STA-240 of the 1980 year, inside is right.  Hot rectifier with small snap-in smoothing cans shares the control amplifier and tuner board.  Sansui is credited from their 1981 SUPER-COMPO T80 styling but Bill Kasuga of Kenwood know-how is likely. 
Right, internal build of the STA-2080 below, one of the most popular Shack receivers.  In the center symmetrical stereo power output modules use  NEC  transistors, of popular brands like Sansui, sought after and that were the ones to beat in-store with listening tests.  The tuner board is similar to other Radio Shack dial-tuning models.  Click on image for full size.








Left, Sondex S230, (£545 in today's money) a 1980s shoe-box with Texas Instruments TIP 41/42 Output suited to CTS of Kentucky speakers (74Hz low note) and very similar to Baron Sugar's Executive Amstrad.  13.5w peak at 4 ohm, 18.5w peak at 8 ohm, 20Hz-20KHz, single rail 60 volt supply with 6800uF smoothing can.  4 x plastic diodes as the rectifier, ceramic wire-wound resistors in the output stage.


Left, the AMSTRAD EX-330 (better than the SA-2020 below) video below has simulated tube sound using few parts and efficient loudspeakers by TAMON of Japan. Remarkable g.o. transformer, where were they sourced in the late 1970s?  Capacitor coupled sound suited to the EMI 350.  <<Click on the photo for full view.
Right,
an EMI 350 sits in an RT-VC Duo II, a surplus studio monitor and 13 x 8 found in the lower society, repair techs tinkered with these surplus cobbled-together BBC speakers.  A late issue 350 is seen with no cone wired tar points, mid/ woofer with roll edge.  EMI  350 best use a capacitor decoupled Output Stage similar to a QUAD 303 or SONY TA-1120, Baron Sugar giving the EX-330, other Executive receivers and amplifiers to match hobbyist surplus stock EMI 350, his own Japanese TAMON sourced Ex-350 named after this 1960s British EMI Merciless Speaker, from the olden days BBC Broadcast network.  The bare chipboard baffle mustn't be painted as it prevents reflections, tweeter dispersion is improved with a felt, fabric square.

 Left, REALISTIC STA-110 was downmarket of the STA-2080 above and like You Tuber Ptronix's first Pioneer SA-606 amplifier has a Speaker Off switch to avoid reducing the speaker Damping Factor with a speaker circuit protection relay.  These are cost-cutting albeit improved sound quality measures.  Add-on QED etc above left switches protect your speakers manually from switch-on or off thump. With some amplifier outputs, as in capacitor decoupling or germanium output transformers, we need a dummy load taking the switch-on (or off thump) in place of the speaker, power resistors are connected to the switch in place of one speaker pair then switched over to the speakers after a few seconds and vice versa. Right, the internal build of the REALISTIC STA-2000 below
Hitachi brand speakers below are the mid-1970s and expensive vintage, very conventional cone drivers with plastic domes and cloth edge woofer giving sensational 3D sound.  The speakers need to run for weeks to recover abilities.  Avoid any replacement but ensure gaskets are working and there's an airtight seal.  Use 1960s speaker wire.
STA-65 right, STA-120 below and STA-180 second below are Hitachi surplus receivers.  The red button is based on harman/kardon and made in their factoriesOTL or 'Output Transformerless' was developed by Electro-Voice in the USA, first by a capacitor then direct-coupled.  Main smoothing cans are very expensive.  A hundred dollars apiece for chassis-mount in a 75-watt receiver.  The 'snap-in' printed circuit board type has to balance ESR against sound quality (leakage) and may reduce the available output power.  Don't increase the can voltage, try to match the old height and get the biggest diameter.  Blown bulbs need new power supply rectifiers, a Radio tech is very pricey.
Left, in the US during the year of 1960, Essex Music International had a brochure about Tone Burst testing of their elite loudspeakers and sixteen years later Radio Shack of the US had developed their mass-market Mach One and Optimus X-100 to equal the British Empire EMI Dangerous Speaker, delivering a true spatial image where the loudspeaker is absented and the reproduced sound spread through the entire listening room like in a small hall.  

 
 
Right, the claimed Frequency Response plot of the EMI 350 pictured - only it's not but the early 1960s, roll edge BBC broadcast monitor core below, with the unique electrolytic choke. 











Why use such an old photo?  We might but hazard a guess. Right some 350 models between 1967 and 1973.  The 'roll edge' has less control then the PVC pleated edge and so needs more from an amplifier.

Left, a 319 has a slightly stiffer edge than a 350 and stronger magnets at rated power, making them louder with less input, so more sensitive.  The voice coils also differ, some cores are wound on both sides of the voice coil, where others are only on the outer part of the former.  The double coils have more force at a power, are more detailed and so louder at lower power, if it's a high-quality amplifier.  Below a 20 watt 319, needs a superb valve amplifier rated at 100 watts.  Bogen MO 100, McIntosh P153.  The 20 watts 13 x 8 were preferred in the United States.

  Right the Belgian Carad had made amplifiers for 20 watts 319 and in 1975 were acquired by Thorn to distribute Ferguson brand equipment in Europe.  Unfortunately, British industrial action had ended the venture.
Left remarkable elite only 1960 year  EMI  92390AG in a short blockboard baffle, owned by an upper-class buyer.  Many vacuum tube rectifier amplifiers had cut-off low-frequency near 60Hz.  Siemens solid-state rectifiers of the 1959 year HMV/ EMI Stereoscope 555 integrated amplifier enabled the long-baffles in the EMI speakers of Beam Echo's Junior Glyndebourne.  The 'Bookshelf' size speaker is liked for its sound, where long baffles have a much deeper effect needing a listener to sit further back.  The pleated edge allows the 13 x 8 to drive a folded horn system or be powered from 'Class A' that AlNiCo motors suit, the EMI hard PVC tweeters were fashioned after Lorenz LPH and left in twin, cluster mounting gave a wide dispersion for more than one listener in the room.
 
Right, the weird blue colored Lorenz plastic coned tweeter of which there are less zingy versions.  It was only 2.5 watts RMS but very loud and the EMI plastic cone tweeter was 10 watts and came in a number of versions between 13KHz top and 17KHz that have been identified but RCS of Croydon in England claimed one capable of 20KHz.   The British elite likely compared them on fine detail and the Lorenz was used in the British Dyna-Sonic 4T upon which Bernie Appel modeled his REALISTIC Opimux-X-200 left that hadn't been available in the USA but led to Matt Polk's SDA-1 of 1982, regional American market speakers excluded from Europe due to protectionism and a government agreed local product.  If Polk didn't make the X-200, who did?  They were for the STA-2100 receiver.  The Savard speakers in the Deep South of the United States used these piezo-electric horns left from the US Motorola company and hadn't been too popular with Hi-Fi people as having a certain tone that didn't suit all amplifiers.  A 1uF x-over bipolar capacitor at 20KHz avoids the sound but retains the 3D effects.   Offered to electronic engineers as excellent for Hi-Fi, just what amplifiers Savard suited, nobody ever shared but best seller tube amplifiers from DYNACO and DYNA seem likely.

 

 

 

 

 

 

 

 

 

Pioneer SX-6000 below was one proven Savard match. 




 Savard may suit germanium output tone.  Bill Savard used old oak hospital doors for the cabinets.


 Left, the Boulder from Crisman speakers of Colorado, a working-class city where once there were many RadioShack stores.  These speakers are rare.  Motorola created a semiconductor factory in Austin, Texas during 1974 and the Motorola horn appeared nearer 1975.  Here the squawker is a cloth-edge but unlike Pioneer works with a pleated-edge woofer coupled to a back wave cavity device, suggesting low Damping Factor tubes.  A Mototola piezoelectric tweeter doesn't need a network but has a complicated connection.  6dB per octave x-over.  harman/kardon A300 15Hz-70KHz, F.R., 12 watts from the Beam 7408 tubes is a likely match for this type of woofer surround.  Below, the Olson SP-400-A is included as a model for constructors using the superior quality, vintage Motorola variant Piezoelectric tweeters with the REALISTIC STA-2100 series.

Right, an ALTAI replacement woofer is fitted to the AKAI horn hybrid speaker, ALTAI is still around in some form, but started by Leonard H. Altaras, a shadowy figure and Director between 1957 and 1991.  ALTAI full range are both whizzer and single cone 5 inch suited to middle range driver use, besides the woofers right, a SONY-made 8 inch 8LUX full range is offered with some 38Hz lowest note, ideal for far eastern, low powered Hi-Fi amplifiers.  ALTAI was run from Wembley in England that carried some bench power supply lines of RadioShack along with studio equipment of a similar standard, and from Taiwan, not SONY's best manufacturing base but the cheapest prestige.

Right, Olson SP-400-A, Chicago region, United States.  The Ferguson 3939 below resembles the NAD 3020 in output...
...stage only, the rest based on Carad and Thorn Solid State, a better amplifier but never intended to compete in the mass market as only available in an expensive rack set.

The NAD 3020 with red arrow low current power supply capacitors.

Above these transistors seen center of the circuit were often described as those of the QUAD 303.  But the NAD and 3939 slightly differ on price with a 303.  NAD got a lot of support it hardly deserved on being 'conservatively rated at 20 watts but delivering 50 watts'.  The NAD 3020 was compared with a harman/kardon PM650 in the quality of 50 watts delivered.  Well ... as most Hi-Fi enthusiasts now know, the NAD 3020 is no powerhouse but given sensitive speakers - was as good as a Sanyo JA-222.  Both these amplifiers have a very small power supply can compare to the Ferguson 3939 but are capable of an impressive two-dimensional output.  When it comes to 3D images the Ferguson 3939 shows its Carad origins.
Left The 1971 year 40Hz-20KHz, bookshelf size Mordaunt Short MS 077 features some curious drivers -  but where had they come from?  A 1950s style cone squawker with long tarred speech dome wires.  A SABA 'greencone' below, a PVC edged cone tweeter in another MS 077 version and 1960s European Tandberg-style foam speech domed Goodmans woofer.  They probably came from Carad in Belgium.  The green resembles a Wehrmacht uniform and the tweeter is a strange Goodmans Al-Ni-Co.  One way of selling stories was 'operation paperclip' where the U.S. and British elite place German WW2 scientists in top posts.  Somebody knows if these ideas are true or false and why SABA and EMI liked Wehrmacht green.  
 


Below a DECCA London Ribbon tweeter horn in a French special with Audax Bextrene mid/bass driver.  DECCA AL1500 LF cores may well have been unavailable.  The DECCA ribbon horns later became very pricey.
Left, curiosity on internet forums about French IMF ALS 40 II 2 bass speaker with white trim:  Audax or Elac/ KEF - apparently connected at the time.  Elac were fairly independent but the basket in question is a SABA - one often branded
Audax, a SABA basket with Audax components.   In an Australian advert, England is given as a 1968 source of IMF.  In that year, IMF stopped being Anglo-American, separated into European and US markets suited for own market equipment.  In Australia Encel above used SEAS drivers from Norway and owned the Interdyn speaker brand popular in Australian coalfields.  Encel started in the late 1950s with a Philips based tube amplifier made by Sansui of Japan and worthy of speaker cores used by Bang & Olufsen below for the ECL85 output tube from 1961. Thiele/Small parameters used by loudspeaker constructors came from EMI (Australia) but not so much is known about their work as they'd played no marketing role exploited elsewhere.
Right Philips Miniwatt ECL85 in Bang & Olufsen 608 work with Peerless speakers of the early 1960s as well as 8 and 5-watt motor EMI 13 x 8.  The small size of the Output Transformer needs special, very sensitive speakers, the Dynatron LS.1018 likely better than later 1970s styles with more drivers.   Below Fane Alnico motor 8 x 5-inch elliptical takes over from an earlier EMI...
...Norman for the Rogers Cadet amplifier below and 1964 year large baffle speaker system, today using small magnet Lowther PM6A but unlikely to be better.  The PM4A has an 8-inch diameter with 200-watt magnet system for large elite room horns.

  Left a 6.5 inch Goodmans squawker that Thorn uses below in 8 inch, a foam surround in Ferguson speakers, higher than usual sensitivity.  Here a restorer used a Butyl rubber edge believing it higher quality but is slightly too fast for the tweeter, a doped cloth dome Goodmans XB, in a tower speaker and one of the best...



...ever, based on the XB 45 tower speaker with 200mm foam edge woofer but without the baffle-weakening A.B. resonator and suit the Ferguson 3939 or NAD 3020 the core below left being the original Scope Dangerous Speaker used by Carad, only with a DECCA Kelly ribbon horn.  The main advantage of the EL34 valve amplifier over the 3939 is the gradual warm-up of the Output Tubes needing no protection relay as had NAIM and Mission of the day and Ferguson...  
  ...3939 had a manual connection of speaker plug and socket before and after powering up.  A valve amplifier often sounds better than Solid State as a vintage item, but both working well and designed for similar speakers, don't favor tubes.  Vintage Solid State is brittle and difficult to repair, tubes have a lethal electrical shock risk, but the sound quality is similar.  Below 12 inch 14A/1200CA is a two tweeter version of the 14A/1000BA using a network-free bipolar as did the 37KHz top ferrous magnet Lorenz LPH65, mostly seen in the older 17KHz AlNiCo and 18KHz Ferrite.

The 14A/770 14 x 9" left has a choke seen uppermost and lacking in later models from resin board crossover designs like the LE.4.  Point to point soldered chokes are usually better over the small component resin board kind, large components are often better but quality matters.  Plastic bell EMI speakers above and below appear for sale as cores but never with their cabinets so below is an elite only...

...design by KMAL in mirror-image pairs, drivers on opposite sides. The EMI squawker is seen with a white dome tweeter made by Isophon who'd made others of KK10 grid type for KMAL.  A 12-inch woofer version might be made by audio enthusiasts.  Powered by early QUAD 303 in the United States and near New York thought the best ever heard.  Later 1970s 303 after the QUAD 405, were deliberately degraded to favor the sound of this 1977 launched 'Current-Dumping' power amplifier.  The method QUAD used isn't discussed by enthusiasts that prefer their own view that they never were inferior but maybe the opposite.  This lets them all sell as quickly, no questions asked.  The mains transformers are the likely culprit.

Left black surround 14A/1000 differ in their excursion.  Karad paper cones suggest sensitivity near...

...94dB/w/m.  Doped cone center was a practice carried on to the lower social classes Rogers LS3/5A that owners imagine being in BBC studios.  As truth is sometimes stranger than fiction.  The mysterious 14A/1000 speakers are from a hidden elite world and likely BBC Studio Monitors few know.
  
People that were superior in a time of peasants.
  Right Marsden Hall 14A/1000 has an unpainted magnet that suggests it wasn't an elite unit, sold over a counter and in a ready-made enclosure where its appearance didn't matter.  Under the plastic cup, 14A/1000BA were usually unpainted.  Other 14/1000 are smarter in appearance with painted magnets and either intended for custom builders or perhaps from elite only models. These speakers were available in the late-1960s for the QUAD 303 and are very old indeed.  Designs like the NAD 3020 and Ferguson/Carad 3939 uses an Output Stage suited to such EMI speakers as using some of the transistors responsible for the QUAD 303 sound.  Beam tubes were used to get something like the KT66 tone but the Kinkless Tetrode was best.
Below Criterion 2003A was an upmarket US speaker with Optimus X-100 squawker horn and the two tweeters of KMAL style right for wider dispersion.  The Criterion port is a slit type suggesting it makes no sound.  Crossover and power protector may limit sound quality but it's best to find a suitable vintage of matching equipment before making any changes whatsoever.

The woofer in the KMAL above looks like a Dalesford Keesonic and not the original EMI, but a replacement that works well enough.  The multi-cell middle-frequency horn of the Criterion was a 1970s 3D effect idea like the four tweeters below, giving EMI 319 effects - albeit with more distortion.  The STA-2270 receiver carried an IMX 3D effects processor later offered in stereographic equalizers.  The main advantage of the KMAL is the effects of the Criterion 2003A in a compact box, something that impressed elite buyers at one time.  KMAL wasn't ever available to the mass market and have appeared for the first time on eBay.
 
Right, Rectilinear High Boys.  In the 1960s, US loudspeakers of some brands went by the name High Boy or Low Boy depending on whether the box was high or low in height.  Tweeters were spread out on the baffle to integrate the middle and lower frequency reproducers.  The port tube increases sensitivity for tube amplifiers and boosts the perceived low frequencies, although lifting a single tone.  A bare chipboard baffle prevents sound reflections.


Above REALISTIC STA-2200 was re-engineered by RadioShack from a mid-market Lo-D/ Hitachi MOSFET amplifier with a tuner, reckoned inferior to top flight Shack receivers and seen left the tuner has a few chips, one of them a SANYO, suggesting descent from older Fort Worth tricked-out receiver know-how and using ELNA caps.  The AKAI chassis may develop hum from loose screws as did the CARVER MXR-150.
Right,
thin in cabinet depth OPTIMUS 27 of the REALISTIC STA-2200 above, was based on a 1970s British Boothroyd Stuart speaker, the now little known, Meridian M1 Active.  The receiver also suited a later edition of MACH ONE, named after the exclusive Ford car from the early 1970s, and the OPTIMUS T-100.  The 27 features a distinctive SONY acoustic lens on their dome tweeter, not appearing in hard dome until the later 1980s.  In 1995 Italian Simitel made a similar speaker called the Nightingale Concentus.  27 Woofer and Auxiliary Bass Radiator are SONY, the front panel and STA-2200 chassis by AKAI, a leading seller in New York where the STA-2200 in grey trim (as opposed to the gold up page) would've reached out to harman/kardon buyers.  Use of clamps to hold the 27 drivers is reminiscent of the European imported Peerless speakers of Bang & Olufsen.
Right, British Empire engineered RT-VC Viscount III, a double-mono stereo amplifier as the STA-2200 above but based on tube circuit theory below for EMI 13 x 8 speakers.  Pots are wired to controller, not snap-in, separate stage boards with shielded phonograph stage left.  Stud diode power supply like EMI RS.141, suits EMI 13 x 8.
Left, the early 1970s RT-VC Viscount III above based on some mid-1960s US amplifiers seen in Radio Shack stores not in the United Kingdom that had suffered a low standard of peasant life until the late 1970s.
Right, stud diodes for sound quality in the high end Soviet Корвет 048 power amplifier thought a world best for components, interesting that the much older British Empire RT-VC Viscount III for the EMI 13 x 8: 92390CR has them.  Soviet round transformer shielding ring unlike the tubes below.  Metal stud diodes cost 25x the plastic bodied equivalent but standard, asbestos resin Bakelite boards are seen. 
Left, and below, curious amplifier dated by its green LEDs and embossed metal panels that say Q 405 as if connected with Peter J. Walker of QUAD and a possible prototype.  The power amplifier uses shrouded laminated transformers and 4 x stud diodes as rectifier, as well as real chassis mount smoothing cans, connected with British disco amplifier styled solid wires.

REALISTIC STA-2100D right, was a conventional laminated transformer version of the  NEC  A-820E's round transformer STA-2100 giving the 1974 year TRIO KA-8006 sound a claimed extra fifty more watts per channel.  Dolby FM sought to cancel hiss better than SANYO LA2100 noise canceller chips becoming a failed program that Dolby Labs had abandoned before launch.
Right,
Radio Shack's mass-market take on the 1960 year EMI DLS 529 Tone Burst and Spatial Imaging know-how, the REALISTIC Mach One (named from a popular Ford model of car) used a 4-cell squawker horn instead of the secrets EMI boasted of and below is the Shack's scaled down OPTIMUS X-100.  Despite the continued popularity of these models, including EMI, they are rightly viewed as so old as to be described as 'ancient'.  EMI and Radio Shack both need careful partnering amplifiers and the EMI 319 had been used with the first Technics tube amplifiers in the late 1960s, whilst Technics amplifiers of the 70s and 80s work with Mach One speakers.


Left REALISTIC Optimus X-100 for the STA-2000 in Europe sound like EMI 319 Arthur Fiedler might have preferred.  The bigger Mach One for the STA-2100 may be seen as a downmarket rival to the EMI and Peerless based core, IMF Compact MK.1 below that it visually resembles.  Early Mach One have a 4-layer voice coil suited to the STA-2100 above with the later STA-2300 page top engineered for the LIQUID-COOLED MACH ONE, an edge wound former woofer, not 4-layer.














Below is the REALISTIC Mach Two for the STA-2500 and STA-2600 receivers that were viewed as the best on the market at up to twice their price.  Tuner Information Center says there's some competition out there.  So to look at other tuners or receivers.
 
Right, in England and European markets, the Goodmans Magnum and Mezzo speakers had been available at a low price.  The woofer had poor insulation between the magnet and steel chassis so they leaked flux and gradually lost sensitivity but had been very impressive using the ONKYO A-22 and A-33 amplifiers (rare in the US) using the Shure M75EJII phonograph cartridge.

Above uses a hot rectifier that many old REALISTIC sets don't but the early Japanese STA-2000 had.  Feature sustained high power output but burns boards.  Different circuit board versions, early STA-2500 puts out awesome current but quickly replaced by different circuit board versions of the aboveRight original 1980s REALISTIC Mach Two for the STA-2500, STA-2600 and STA-2270 available for many years, in 1991 the OPTIMUS Mach Two for the STA-2280 receiver suits a different mains transformer.  Dropped for a rare twin duct Mach Three and finally the Mach Three below.  To enjoy at their best, match up the same model year receiver and MACH TWO, substantial build revisions affect the sound.

Above STA-2500 rarely appear on eBay at the same time as STA-2600.  What is best and compare the lower power STA-2270 and STA-2280.  On eBay, there's not many lids off photos today, a decade ago a usual sight.  Visually similar on the outside, interior boards differ greatly not only in materials but one type of board won't fit another set of the same model number and outward appearance.  Right REALISTIC Mach Three is a US market version of the Mach One, probably made by Panasonic and based on the award-winning MACH TWO that was in most markets.  They all sell well.  MACH THREE suits a later version of receiver, the crossover aimed at lower running power with finer wire in the coils.  The later receivers are less powerful and 2280 use a closed transformer that may well better open ones last used in 2270.  Mach three aren't great crossovers and sound might improve with Klipsch-style large components but then why not buy a whole speaker.  Below the STA-2280 compared to the earlier STA-2270.


Above STA-2270 differ from 2280 in the IMX expander position, the dancing LED power meter is an electron digital tube or fluorescent in 2280.  Sources are lit up in 2280 as part of the dial wherein 2270 they're less clear.  Below 1973 in the US, different from in the United Kingdom.
Left, 1973 year REALISTIC QTA-750 quadrasound receiver for AlNiCo motor Optimus 1, better finished than later years, meant to last a lifetime, used a German Miracord 80 turntable, 4-channel Hitachi silicon transistor output and tidy inside layout as seen below.
Left, mid/woofer of the REALISTIC Optimus-1 below, importantly an AlNiCo magnet motor that's sounded for silicon output devices, is long excursion, high sensitivity and housed in an aluminum cast basket for low flux leakage and long service life.  Take care that many AlNiCo motors are aimed at tubes and others at Solid State.  Some are aimed at germanium, others at silicon, some suit an Output Transfomer, of Class A type, others are Class B only.  Some are 2-stage amplifier matched and others are 3-stage amplifier matched.  With Radio Shack we know what runs with what from the catalog matches.
 
Right the Optimus-1 differs from the later ring-magnet Optimus 1B, motor, each has its factory matched receiver or amplifier giving the best sound.  The double tweeters here produce solid imaging with wide-dispersion, meaning we can move around and enjoy great sound whereas single cone tweeter versions often need us to sit in single a position to appreciate 'the sweet spot'.  In both Radio Shack and AMSTRAD equipment, optimum sound quality depends on being hooked to factory matched equipment.  Of course we hook up other aftermarket speakers but we won't know how good the factory made ones were unless we try them along the way.  Note the bare chipboard baffle must not be painted absorbing reflections improving imaging.
 
   Left the EMI spherical dome tweeter, 14A/1720 used with EMI 'Club' speaker in an Expert brand tower speaker, very rare as a trade only, not named by a maker in high-end gramophones, tweeters suitable for all of the 14A series.  Below mass-market British Jaguar exploits elite Bugatti styling and seen as quintessentially British followed a lower-middle-class XK150, the XK120 combining elite only 1948 Lagonda LG6 Rapide body and later 1951 grille.


The 557 used 13 x 8 speakers like the 92390P right with single 15KHz yoke alnico tweeter and old-style, choke.  They had the double voice coil giving much higher volumes at low power, but even in those days were very expensive to make.  The Plessey cube magnet wasn't for the lower market.











Above an EMI 450, ceramic magnet version of the AlNiCo motor 92390P right.
Left, estate sale REALISTIC STA-64B, very expensive in 1979 with Snap-In circuit board mounted power cans like the Waltham below.  Seen in the gloomy backdrop, the owner's large ornamental shouldered vacuum tube, a helicopter gunship model and sailing ship in a bottle.
 
Right, internal of the surplus parts amplifier below, by the British Association of Audio Manufacturers.  Hitachi Metals transformer with hybrid output devices and Snap-In circuit mounted electrolytic Smoothing Caps, as REALISTIC  STA-790 but a discrete bridge rectifier.  Rank Organization speakers below for the LEAK 3400 receiver were sold separately as Wharfedale E30.
Above, a Waltham brand rack system by the British Association of Audio Manufacturers and Rank of England's Wharfedale 'E Series', speakers for lower power outputs.  Left a cassette deck of the British Ferguson brand.

Left, real high-end Radford MA15 Revival g.o. transformers seen in Amstrad and Solavox faux hi-End belowG.o. transformers suit only low power, high quality sound, feeding high sensitivity speakersBelow, the Executive Ex.222 sets today, need carefully upgraded elements with high sensitivity speakers, Coral, Tamon, or Goodmans Axiom.


Left a g.o. transformer in an Armstrong 521 is larger for the same 25 watts output and nevertheless the sound that Baron Sugar sought for his 222 receiver, one competing directly with high quality tube amplifiers.

Right, an economy cabinet pattern for the Goodmans 201 consists of actual timber panels, don't use block boards, plywood or chipboard instead.  These 201 panels are butt joints like Tannoy and must not be V-planked, it's a live box.  Note carefully the grey wadding pattern, brace and acoustic aperture in the lower box.  In those years vinyl wrap was used as a finish.  201 will make suitable speakers for the AMSTRAD or SOLAVOX Executive Series Ex.222 and SR2220 receivers but not the Ex.333 or SR3330 receivers.  After upgrading circuit elements, Executive receivers will need some time to run-in with your music but don't give up hope, use skill with Lasso rope.

Left, a bookshelf Axiom 201 speaker design with rectilinear port.  Note again, the use of true timber panels and butt joints like Tannoy dual concentric, for a live box. The speaker has a real wood veneer and uses yellow glass-fiber wadding in the pattern shown.  Note that the speaker below is a mass-market version of the 201 and a live box suited to the Ex.222 or SR2220 receiver.  We don't need Goodmans 201, some enthusiasts prefer vintage Goodmans and amplifiers that give them the best sound.  Few modern amplifiers will deliver with 201, they're speakers for vintage tubes and simulated tube Solid State of 1960s vintage. 

Right, speaker model for the Solavox PR.25 below, the 1940s vintage, Altec-Lansing 420 usually a Bi-Flex 420A but here the re-coned 'Y' with tweeter wired 'Network-Free' to the woofer and from the American gentry and European nobility working with tube amplifiers.




Matching speakers with the ideal electronics is important in getting a good sound and even although the A/3 used high priced harman/kardon, Alan Sugar in England had amplifiers specially built to give best with their matching speakers like those above.  A look on the inside of an Ex.222 reveals a receiver designed to sell in kit form (as MAPLIN followed with a year later) but instead ready built up and tested, due to unexpected demand and circuit designs from Sir Clive Sinclair's Audio Co., that AMSTRAD had bought out, Sinclair himself turning to his C5 car, also somewhat poorly conceived, compared to modern mobility scooters.

Left, 1980s British Nytech CA202 with 2200uF capacitor de-coupled speaker output similar to the Amstrad above. Round transformers and smoothing was 3300uF, single rail, the British shoe-box designs had a lower middle class cult following. 

Right, B.A.A.M. group's Fidelity Radio 350T tuner version of the 450TA tuner amplifier similar to HMV 4000 and 8000, manual tuning presets an upmarket feature of the day as were toggle switches, sound quality awesome despite a basic AFC tuning lock and no digital synthesis.

Right, 350 separate controller power amplifier bearing the Fidelity Radio brand of the B.A.A.M., set up to beat Japanese imports, separated pre-amplifier and power supply with power amplifier in the same box - as if to have been used as two boxes during the design stage. 
 
Left, the REALISTIC Optimus-7 had been Radio Shack's most expensive ever but matched with few receivers besides the STA-150 below with its  NEC  2SD180 silicon germanium epitaxial devices.  SiGe was accidentally discovered by IBM researcher Dr. Bernard Meyerson to become popular in the industry today.
Right, SiGe 2SD180 output devices in an old 1974 year REALISTIC STA-150, used with the Realistic Optimus-7 speakers.  Radio Shack always sold designs a good few years old, here we need speakers not for a 2-stage but a 3-stage amplifier, SiGe and OCL.  Many buyers of these didn't use the matching catalog speakers and got poor results mistakenly put down to an inferior brand.
 
Left, and below, the slimline EMI 1515 germanium amplifier from the Cambridge University community using the old EMI Sirocco loudspeaker, was later adopted by Mo Iqbal as his Monitor Audio MA7 using surplus EMI speakers.  These elite amplifiers led to mass market Amstrad sets like the germanium 8000 or hybrid 2000 and RT-VC even bought the old EMI 1515 cases for one.

Cpt. F.F. Spicer bought a Jensen F.F. the year EMI launched the 1515 left, the RT-VC Viscount IV used surplus 1515 cases, the EMI amplifier much more interesting on the inside than RT-VC. A 1970s Ferguson 3938 below.

Left, the matching 3000 Multiplex tuner is an AFC design similar to the Ferguson below and has a wood wrap to enhance sound quality, I.C. based stereo MPX.
Left, a 1971 year front end of the April issue Practical Wireless Jones lower market receiver, small tuning capacitor as the QUAD FM3.  Ferguson 3938 tuners above have small tuning caps and awesome but sibilant sound subject to station drift with center pin meters to constantly twiddle the tuning knob for best sound.  Drift wasn't always severe and better sound quality is pursued today by the Classic Audio buyer.  The circuit left was built by a genius of the peasantry that in the United States would have bought and tinkered with Radio Shack.
Below EMI 1515 germanium amplifier.

Left. the right-angle layout of HMV/ EMI 499 tube amplifiers was meant to cheat 'hum'.  Tannoy and Lowther amplifiers are less known than their speakers and may suffer from flaws like mass-market Todd transformers in Fairchild valve amplifiers, but there's never any mention of such equipment from the upper society market.

Right Amplifier 20-90 watts RMS Ariston SR90 concrete cabinet, 20Hz-25KHz, red glass-fiber batting.  Danish Peerless squawker defines the acoustic character of the whole.  Gold throat DECCA Kelly painted over in black by the owner, the baffle too.


 Clarke & Smith amplifiers below made by RAF officers for the elite EMI speakers.



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