From the Golden Era of Audio Pioneer’s Fluoroscan Components were introduced in the late 70s and were Pioneer’s interpretation of the future. While they have futuristic digital displays up front these items are all analog technology behind the scenes.
Pioneer SA-608 Amplifier – 0.02% THD!!
“High power Amplifier with DC Configuration for Superlative Phase Characteristics”
The Pioneer SA Amplifier series had benefited from the final years of the Receiver Wars inheriting more power and lower distortion than the previous range. The SA-608 featured 45 Watts Per Channel at 8ohms with 20 to 20,000Hz with 0.02% THD and stunning fluoroscan output meters and function display.
To achieve this the SA-608 contains a 2-stage differential amplifier with current mirror load, all-stage direct-coupled pure complementary DC amplifier. DC Amplifiers eliminate eliminates the frequency response in the negative feedback loop and enhances the phase characteristics to a surprising degree while also greatly reducing distortion. DC Drift is dealt with by the introduction of dual transistors featuring minimal temperature drift into the first stage, and a stable negative feedback process into the differential amplifier circuit.
This amplifier also includes Phono Equalizer Circuit with Low-noise IC with a RIAA deviation of +_0.3dB and 180mV overload level, Subsonic Filter, Loudness, Tone Switch, Function Indictors, A+B Speakers and plenty of inputs with Phono, Tuner, AUX, Tape 1, Tape 2.
This amplifier produces very clean and punchy power with stunning looks and smooth analogue controls.
The speakers are 3-way with horn tweeters and 12″ inch bass driver in a sealed cabinet, all drivers are Japanese Foster brand. The cabinets themselves are heavy and real timber veneer that looks excellent after an oil. These speakers have a natural sound and still produce plenty of bass and the horn’s ensure that the high’s are not missed but not overpowering.
Specifications Power output: 45 watts per channel into 8Ω (stereo) Frequency response: 10Hz to 50kHz Total harmonic distortion: 0.02% Damping factor: 30 Input sensitivity: 2.5mV (MM), 150mV (line) Signal to noise ratio: 78dB (MM), 100dB (line) Output: 150mV (line) Speaker load impedance: 4Ω to 16Ω Semiconductors: 7 x IC, 23 x transistors, 17 x diodes Dimensions: 451 x 151 x 271mm Weight: 8.3kg Year: 1979
Pioneer TX-608 Tuner
Specifications Type: Mono/Stereo Tuner Tuning Bands: FM, MW Tuning Scale: Analogue Sensitivity: 1.9uV (FM), 300uV (MW) Signal to Noise Ratio: 74dB (FM), 50dB (MW) Distortion: 0.15% (FM) Selectivity: 60dB (FM), 35dB (MW) Frequency response: 20Hz to 15kHz (FM) Output: 650mV (FM) Semiconductors: 3 x IC, 1 x FET, 8 x transistors, 15 x diodes Dimensions: 451 x 151 x 284mm Weight: 5.3kg
Pioneer CT-600 Cassette
Specifications Type: 2-head, single compact cassette deck Track System: 4-track, 2-channel stereo Tape Speed: 4.75 cm/s Heads: 1 x record/playback, 1 x erase Motor: electronically controlled DC Tape Type: type I, FeCr, Cr02 Noise Reduction: B Frequency Response: 20Hz to 16kHz (Cr02 tape) Signal to Noise Ratio: 68dB (dolby B) Wow and Flutter: 0.05% Total Harmonic Distortion: 1.2% Input: 50mV (line), 0.3mV (mic) Output: 0.45V (line) Semiconductors: 30 x transistors, 16 x diodes, 5 x IC Dimensions: 420 x 143 x 290mm Weight: 5.7kg
Pioneer PL-514X Turntable
Specifications Type: auto-return turntable Drive method: belt drive Motor: 4-pole synchronous Speeds: 33 and 45rpm Wow and flutter: 0.055% WRMS Signal to noise ratio: 65dB Platter: 320mm aluminium alloy die-cast Tonearm: static balance type, pipe arm (s-shaped) Effective length: 221mm Overhang: 15.5mm Usable cartridge weight: 4 to 10g Dimensions: 440 x 365 x 140mm Weight: 7.5kg
This is an Extremely RARE Vintage Pioneer Cassette Receiver highly popular with cassette enthusiasts and features warm but punchy sound. Now typically all-in-one combinations items are not generally real High Fidelity or even good quality items.
But not this Bad Boy!
Why? It was built between 1976 and 1977 when Pioneer’s quality and performance were at their peak and virtually unrivaled. During this period the legendary SX-##50 series was being produced and a lot of that engineering went into this item, and some of the hardware as well. Featured on it’s front panel are 3 of the large tuner knobs used on the SX receivers of the period!! I love the VU meters on this system, combined with the big knobs I think it is a gorgeous and unique piece.
The first thing to note when opening up this one is that it is comprised of separate multiple boards and components! The Tuner, Amplifier, Cassette and Power boards have all been kept separate (Cheap ‘n Nasties tend to have everything built into a single board).
Secondly the amplifier and power supply in this unit are also very decent for it’s class. A heavy transformer is coupled to two generous 6,700uf filter caps, giving this unit plenty of headroom and dynamic power for it’s rating. In fact some highly regarded Sansui’s like the Sansui 5050 Receiver had almost identical power caps (6,800uf) to power an amplifier that was producing 33 Watts RMS per channel!
The CX-7000’s amplifier is rated at 25 Watts RMS per channel with 0.3% THD, real watts! This approximates it very closely to Pioneer’s SA-6500 component amplifier, which was only slightly up-speced to this unit. This unit enough low-end and power to comfortably host a party!
The tuner section is excellent as is most Pioneers from this era. The cassette deck section incorporates a DC servo motor and an ‘ultra-precision’ capstan and a large fly-wheel. It also features an auto-stop mechanism, Dolby Noise Reduction, chrome tape support and an illuminated cassette bay. And I have to mention once again the build quality and weight of this item, it is just so excellent!
This unit had been down at my holiday house and was effortlessly powering a pair of 100 Watt RMS Jensen’s. A friend of mine put on some of his favourite Dub-Step tracks and was gob-smacked at the sound!
Power output: 25W per channel Total harmonic distortion: no more than 0.3% Damping factor: 40 Frequency response: 30 to 15,000Hz Hum and noise: 90dB Dimensions: 430 x 220 x 357mm Weight: 13.2kg
1979 Pioneer PL-514A Turntable
This was one of Pioneer’s most popular turntable series for both newbies and audiophiles during this period. The Motor was tuned to a stable AC frequency as opposed to voltage to achieve low wow-and-flutter of only +_0.06%. It also featured a very high quality tone arm and auto-return/auto-shutoff system with anti-skate and oil-dampened cueing system.- Classic design and performance!
Technics SB-440 3-Way Speakers (1976-77)
These rare and legendary looking speakers were part of Technic’s 1976 to 1977 High Sensitivity Speaker Range and featured a 3-way bass reflex design with multi-linear horn and a cone tweeter. The horn is an extremely heavy component in its own right and made of cast iron?
Power Handling: 50 watts Impedance: 8 ohms Frequency response: 35Hz – 20kHz Sensitivity: 93dB Crossover Frequencies: 1.5kHz / 7kHz Dimensions:358 x 595 x 317 mm (Width x Height x Depth) Weight:17.4 kg Year:1976 – 1977
Superb Early 70s Sansui Components – Amplifier, Turntable, Cassette*, Analog Effects Unit, 2-Way Radiator Speakers *Cassette from 1976 Catalogue
This is an absolutely rare and gorgeous combination of vintage Sansui components from the decade when Sansui was at it’s finest. 1970s Sansui gear is highly prized and is renown for its smooth analog timbre. While virtually all the gear produced by Sansui throughout the 1970s was of very high quality, it is their early 70s items that demonstrate exceptional build quality right through their product offering.
At the heart of this setup is Sansui’s AU-555A Stereo DC amplifier. This entire series of amplifiers is a favorite with audiophiles the world over renown for their great tonal qualities. It offers bass, treble and mid-range tone controls, high-pass & low-pass filters and loudness. Among its other features it also includes other high end features such as dual turntable inputs (great for parties) and plethora of other input and recording options.
Inside is an extensive amount of shielding that in other brands would only appear in the very top models. A highly musical amplifier with enough power for most entertainment spaces and plenty of headroom. This unit is an as close to mint condition as I have ever seen for a 40+ year old amplifier and it even has some of the original protective packaging still on the fascia, what your seeing isn’t imperfections but the original protective packaging!! Stunning!
Another 555A Enthusiast on YouTube
The Sansui RA-500 Effects Unit offers an amazing acoustic experience featuring all analog technology thanks to a liquid capacitor. It’s gorgeous **Double Rainbow** display can be enjoyed whether your using the unit or not! This unit can be used to add effects to recordings. Again this unit is in superb near mint condition and is a favorite of both collectors and audio professionals in search of analog effects.
The Sansui SR-1050C is a professional 2-speed manual turntable with a 4-pole hysteresis synchronous motor, belt protection, auto/lift stop mechanism, feather touch cueing control with an induced magnet cartridge and a statically balanced tonearm and a lovely orange power indicator light. Some purists favor the pure manual movement of this model however the SR-2050C was also offered by Sansui that was identical to this one but also featured auto-return. This unit I enjoyed with it’s original cartridge and found it very musical and warm, and such a perfect match with the 555A.
Personally I think this is one of the most attractive turntables ever produced by Sansui featuring a gorgeous genuine wood veneer plinth and tinted dustcover with its metal ‘bonnet’ style stand. Condition wise there are light marks on the dustcover and the some scratches on the steel ring on the rubber platter but otherwise the unit is in superb condition.
The only component not from 1973 is the 1976 Sansui SC-2002 cassette deck. With it’s black aluminum fascia and silver knobs it is a great aesthetic match to the rest of the system. It demonstrates Sansui’s continued dedication to quality throughout the 1970s and it’s build quality is tremendous and it weighs a ton!
It featured large illuminated stereo VU meters as well as an illuminated cassette compartment usually only seen in high-end models. Other features included Dolby noise reduction, independent capstan drive, electronic servo DC motor and a responsive well-dampened VU. This unit has some signs of wear but still looks gorgeous!!
To complete this system are the stunning Sansui SP-70 2-Way speakers from the only series within Sansui’s range from the 1970s to feature metal dome tweeters! Also featured are the unique 8” inch woofer incorporating an aluminum radiator for, as Sansui puts it, “unlimited stereo pleasure!”. It’s important to note that this radiator is not just a passive dust-cover that a part of conventional woofers. If you ever come across a pair where the center dome of the woofer is depressed you can be guaranteed it will adversely effect it’s performance.
The build quality of these speakers is astounding, they are very heavy and clad in a genuine walnut veneer (not vinyl like many late 70s speakers that are now peeling) and feature the signature Sansui lattice grilles. The attention to detail is evident in all aspects of this speaker with even the rear tonal control panel that sports a heavy high quality knob featuring a spun aluminum finish. These speakers are in excellent condition.
In it’s long history Sony have produced some iconic consumer electronic designs and have introduced some truly revolutionary products like the Sony Walkman. Their HiFi components during the Golden Era were certainly unique and Sony did not ‘borrow’ their designs as so many other manufacturers did in the 1970s.
This gorgeous composite system comprises early-to-mid 70s Sony components with Realistic Nova 6 speakers.
Now I know what your thinking, what I am doing paring a gorgeous Sony Receiver with Radio Shack brand speakers? Well before you commit me to the asylum know this, the Radio Shack ‘Realistic’ brand is an absolute fave amongst vintage audiophiles, and these Nova 6 speakers demonstrate so many reasons why.
Firstly they are made of genuine walnut veneer cabinetry and feature gorgeous lattice grilles and are very heavy for their size.
Acoustically they image beautifully, are incredibly musical and just have a superb velvety timbre with an amazingly deep bass response even at low volumes – down to 30Hz.
These 2-way speakers sport an 8″ woofer and 3″ tweeter with an adjustable crossover allows you to adjust the treble response to suit.
So that said, lets talk Sony! At the heart of this setup is the Sony STR-6046A Receiver in absolutely beautiful condition. It was a 20 WPC RMS Receiver with an original 1974 RRP was $249.95USD which translates to over $1,200.00 USD in 2015.
Finished in a gorgeous real timber veneer, this unit has enough power for moderate listening levels that would suit apartments and most average size living areas. It features some luxurious options that were typically only found in high-end units such as illuminated input displays and dual mic inputs.
What strikes me most about this Sony is its tremendous quality, and this translates into what you feel when you touch this unit, it has solid knobs with a decent resistance to them, illuminated input dials and it’s timber veneer just glows. And it’s sound doesn’t disappoint either with it’s effortless silky tones with warmth and character.
The TC-134 SD cassette deck is one is one of the highly popular studio-style decks, and is in superb condition and features Ferrite & Ferrite Heads, supports normal and Cr02 tapes, Dolby NR, analog needles and fully automatic stop mechanisms, twin MIC inputs and recording volume sliders.
This was one of Sony’s high end tape decks of the day and this is evident in it’s build quality, it’s original 1973 RRP of $240USD would place it over $1200USD in 2015 money. It has more than the average number of belts (I think at least 5!) which I replaced.
The rare and beautiful Sony PS-5100 will satisfy audiophiles whilst being noob friendly
It is a 2-Speed, belt-driven turntable fitted with an S shaped tonearm and has many important features which contribute to the faithful reproduction of your records.
These include a statically balanced tonearm compatible with an induced magnet cartridge and an effective anti-skating compensator.
The platter is made of die-cast aluminum alloy, driven by a belt from a 4-pole hysteresis synchronous motor to help reduce wow and flutter.
Finally, the PS5100 is provided with an arm lifter to prevent stylus and record damage, and an auto-return and auto-reject mechanism permitting semi-automatic operation.
Sony STR-6046A Receiver Inputs: 1 x Phono MM; 2 x Tape; 1 x AUX; 1 x Mic (Stereo inputs) Inp. Sensitivity High Level: 250 mV Outputs: PRE OUT REC OUT REC/PB Equalizer Tone Controls: Bass; Treble Filters: HIGH Loudness: YES Power Amplifier Speaker Outputs: 2 x 2 Speakers A,B, A+B; Phones Continuous power 8Ω: 22 + 22 Watts Dynamic Power 8Ω: 28 + 28 Watts Frequency Response: 30-40,000 HZ Harmonic Distortion: 0.8 % at rated output Harmonic Distortion: 0.3 (Mono, 400 Hz); 0.8 (Stereo) % at rated output
Physical Characteristics Dimensions in Inches: 17 x 5.7 x 13.6 (w) x (h) x (d) Dimensions in mm: 434 x 144 x 345 (w) x (h) x (d) Weight in lbs: 19.8 lbs Weight in Kg: 9 Kg
Sony TC-134-SD Cassette Deck
Tape speed : 4,8cm/s Flutter & wow : < 0,2% ± 0,3% (DIN 45511) FF & Rew time : 120s (C60) THD : 2,5% Bias frequency : 85Khz Frequency response : 30Hz…15Khz (Type I) 30Hz…17Khz (Type II) 40Hz…11Khz (Type I, DIN 45511) 40Hz…13Khz (Type II, DIN 45511) S/N ratio : 49dB (Dolby off) Inputs : -72dB (0,2mV) (MIC) -22dB (0,06V) (RCA line) < 10kOhm (DIN line) Outputs : 0,775V (0dB) (RCA line) 50kOhm (DIN line) 8 Ohm (headphones) Power Consumption : 18W Dimensions : 41,2 x 11,5 x 22,3cm Weight :4.5kg
Sony PS-5100 Turntable
Arm Length: 295 mm (11 5/8 inches), overall 216.5 mm (18 17/32 inches), pivot to stylus Overhang: 16.5 mm (21/32 inches) Stylus force adjustment range: 0 to 3 g, 0.5 g increments Anti Skating force compensation range: 0 to 3 g, 0.5 g increments Cartridge weight range: 4 g to 12 g Shell head weight: 10.5 g Cartridge (VM-26G) Type: Stereo induced magnet (IM) Output voltage: 4 mV at 1kHz. 5 cm/sec. Load impedance: 50 k ohms Frequency response: 15 Hz to 22 kHz Channel separation: 25 dB at 1 kHz Channel balance: 1 dB at 1 kHz Optimum stylus force: 2 g Stylus: Conical 0.5 mil diamond (SONY ND-132G) Weight: 6.8 g
Realistic Nova 6 Speakers
8″ Suspension Woofer 3″ Tweeter Frequency Range: 30 Hz to 20,000 khz L-C Crossover Network 55 Watts Max Power Input @ 8 ohms 3-way cross over switch Solid Walnut Veneer Cabinetry Lattice work grille Vertical or Horizontal placement option 19 1/4″ (h) x 11 1/2″ (w) x 9 7/8″ (d)
Going against the trend throughout the late 60s and 70s Sansui produced mainly black aluminum fascias during this period. This system comprises of a 1976 Tuner and Amplifier and the 1978 components comprise the turntable and speakers.
Being an entry level level high fidelity component system provides it provides ample power suitable for apartments and average size lounge-rooms for performances at moderate volume levels. I found this quite a fun system that I enjoyed listening to a lot.
The Sansui AU 2900 is an integrated stereo amplifier with ample power (17 watts, both channels into 8 ohms, at 1000Hz) and dramatically low-distortion, clean tone characterise the most moderately-priced of the AU Series.
It’s design is also based on the true complementary OCL power circuit, with dual-transistor differential amp in the initial stage.
Dual plus/minus power supply for all major circuits gives you interference-free, stable tonal quality at all reproduction levels.
Low-noise phono equaliser Stepped tone controls Outputs for 2 sets of speaker systems Complete range of controls, high filter and loudness switches, source selectors and input/output terminals
Specifications Power output: 15 watts per channel RMS into 8Ω (stereo) Frequency response: 10Hz to 40kHz Total harmonic distortion: 0.3% Damping factor: 50 Signal to noise ratio: 90dB (line) Channel separation: 57dB (MM) Dimensions: 400 x 120 x 240mm Weight: 5.7kg Year: 1976
Tuning Range: 88 to 108 MHz
Sensitivity: 2,0 μV (IHF); 1,1 μV
Total Harmonic Distortion: less than 0,3% (Mono); 0,4% (Stereo)
Signal-to-noise Ratio: better than 70 dB
Selectivity: better than 60 dB
Capture ratio: less than 2,0 dB
Image Frequency Rejection: better than 55 dB at 98 MHz
IF Rejection: better than 80 dB at 98 MHz
Spurious Response Rejection: better tham 70 dB at 98 MHz
People Magazines: The Greatest Mustaches of the 70s
The 1970s was a decade for outrageous styles, big mustaches and big sound. It was a decade that saw major audio manufacturers competing almost solely on sound quality and power and it produced some of the finest sounding (and loudest) consumer amplifiers for a more discerning and cashed up consumer.
Today at a regular HiFi store like JB HiFi generally the higher end Receivers they stock retail for around $800.00 but in 1977 this price point was where the entry level high-fidelity gear started, like Pioneer receiver the SX-450 that retailed for over $800.00 inflation adjusted dollars. And BTW the SX-450 does sound better than then those new ones!
In order to get the equivalent sound today you need to spend big $$$ on boutique audiophile gear. And that’s why you should consider a 70s component system like this one!
This system comprises high-quality Pioneer components from their 1975-77 range. A far cry from their budget ‘Rondo’ gear designed for impoverished nations like Australia, the Pioneer componentry from this era were awesome performers and were well regarded by audiophiles and critics. This particular system comprises components from from Pioneer’s entry to mid-level of their high-fidelity range.
This combination works beautifully together and I have matched with vintage 3-Way 4-Speaker ITS Pro Speaker System featuring Japanese Foster Drivers in sealed cabinets.
With a 5 Watt RMS per channel increase in power over the previous model Pioneer’s SA-6500II DC Amplifier produces 30 Watts RMS Per Channel minimum output @8 ohms. Plenty of power to be the life of the party in the average living room space! This is a superb sounding amplifier with that still possesses a warm sound and with plenty of headroom providing dynamic bass response thanks to a large power supply coupled with twin 6,800uf capacitors for it’s class. The power indicator has been upgraded to LED to provide for long life function. This unit is in excellent functional condition with smooth controls and clean sound.
“The Pioneer SA-6500 is a low distortion, high power, stereo integrated amplifier with wide dynamic range equalizer. Combining advanced circuits with a new design concept provides no-nonsense musical performance at a pleasing price. Precision CR tone circuit, a high performance equalizer amplifier for wide dynamic range, and simple to use basic features make the popularly priced SA-6500 even more appealing as a worthwhile investment in advanced Hi-Fi electronics.”
Power output: 30 watts per channel into 8Ω (stereo)Frequency response: 10Hz to 40kHz Total harmonic distortion: 0.1% Damping factor: 30 Input sensitivity: 2.5mV (MM), 150mV (line) Signal to noise ratio: 72dB (MM), 93dB (line) Output: 150mV (line) Semiconductors: 2 x IC, 25 x transistors, 16 x diodes Dimensions: 380 x 139 x 308mm Weight: 7.6kg
Pioneer Tuner’s are well respected in the audiophile community and the Pioneer TX-5500II Stereo Tuner is a great performer and features an attractive silver backed display with a warm glow lit by incandescent bulbs. The Stereo Indicator bulb in this unit has been upgraded to LED to provide for a long life.
Type: Mono/Stereo Tuner
Tuning Bands: FM, MW Tuning Scale: Analogue Sensitivity: 1.9uV (FM), 300uV (MW) Signal to Noise Ratio: 68dB (FM), 50dB (MW) Distortion: 0.6% (FM) Selectivity: 60dB (FM), 35dB (MW) Frequency response: 20Hz to 15kHz (FM) Output: 650mV (FM), 150mV (MW) Semiconductors: 1 x FET, 3 x IC, 6 x transistors, 6 x diodes Dimensions: 380 x 124 x 269mm Weight: 3.5kg
Pioneer CT-F4040 Cassette Deck – is a quality deck from the 70s and weighs a hefty 7.2Kg unlike the cheap feather-weight decks of the 80s. It also has a unique convex sliding cassette cover which is a nice design touch!
“The Pioneer CT-F4040 is a full auto stop, stereo cassette deck with unique vertical cassette holder and oil-damped, sliding compartment door. The compartment is illuminated for easy view of the cassette at all times and features a special marker line to warn of tape end. Other features include an electronically controlled DC servomotor and electronic muting for silent mode change, hard Permalloy solid recording/playback head, Ferrite erase head, tape selector, switch for standard LH tape, Cr02 and Ferrichrome, and a Dolby indicator light.”
Type: 2-head, single compact cassette deck Track System: 4-track, 2-channel stereo
Tape Speed: 4.75 cm/s Heads: 1 x record/playback, 1 x erase
Motor: electronically controlled DC Tape Type: type I, FeCr, Cr02
Noise Reduction: B Frequency Response: 40Hz to 15kHz (Cr02 tape) Signal to Noise Ratio: 62dB (dolby B) Wow and Flutter: 0.08%
Input: 60mV (line), 0.2mV (mic) Output: 0.45V (line)
Dimensions: 380 x 150 x 316mm Weight: 7.2kg
Pioneer PL-155A Turntable – classic belt drive turntable with auto return/auto cut and wood base in silver laminate which was all the rage in the later 70s.
Motor: 4-pole synchronous
Drive method: belt Speeds: 33 and 45rpm
Platter: 300mm aluminium alloy diecast
Tonearm: static balance type, s-type arm
ITS Pro Speakers
Manufactured by Miranda HiFi, an Australian retailer from the 1970s, these speakers featured Japanese Foster drivers and sealed cabinets for a more natural sound. I love the look and sound of these speakers with their 12″ inch drivers with their mid-range and tweeter arrangement.
3-Way 4 Speaker System
Japanese Foster Drivers
Closed Speaker System to provide more natural sound
Kenwood (Trio) 1975 KA-7300 – Darlington DC Amplifier with Dual Power 2 x 65 Watt RMS at 8 ohms both channels driven from 20Hz – 20 kHz with less than 0.1 distortion.
Original 1975 RRP $400.00USD Inflation Adjusted RRP 2015 $1,769.00USD
Kenwood Corporation was the brainchild of William Kasuga a first generation Japanese American that saw an opportunity to market Trio Corporation products in America products under a new brand name. In my experience Kenwood’s 1970s gear demonstrates tremendous build quality, solid performance and stunning designs, and the KA-7300 ticks all three of these boxes.
It’s hard to believe that the features contained in this amplifier would appear in a consumer electronics product. It certainly wouldn’t happen today but in 1975 consumer audio gear was in a different league, back then it was ‘all about the sound….man’.
The KA-7300 Power Supply: Separate transformers for each channel.
Firstly lets start at the foundation of this beastie, it’s power supply. Dual Power was first introduced to the market by Harman Kardon and by the mid-70s it had really caught on, mostly in the high-end components. But different brands implemented it differently. Sansui, Marantz and Pioneer settled for a single large transformer which utilised both the negative and the positive rails to power independent amplifiers.
However in this case Kenwood had followed Harman Kardon’s example and integrated two independent transformers with their own rectifiers and filter capacitors to power each channel. Essentially this amplifier was two ‘mono-block’ amplifiers contained in the one cabinet.
Only two amplifiers from Kenwood’s range in this period featured this dual power setup, the KA-7300 and the other was their top-of-the-line ‘Model 600′. Interestingly the dual-power supply in their high-end Monster Receiver for 1977, the KR-9600, featured a dual power supply with a single transformer.
Kenwood’s dual power supply was marketed as a solution to the problem of ‘dynamic cross talk’ where the stereo stage (or image) could be disturbed by power struggles between the left and right channels – defeating the whole purpose of stereo. With each amplifier channel drawing upon a completely separate reservoir of energy this problem is overcome.
Kenwood boasted that they were the first to introduce DC amplification in an integrated amplifier, and for good reason. With DC power amplification comes incredibly low distortion even down to the ultra-low frequency range and an almost perfect frequency linear response that starts at virtually 0Hz. This results in incredibly natural sound with the amplified output signal having nearly identical waveform to that at the input terminals, or in other words the sound as it was originally captured.
Trio’s Darlington Power Pack with large heatsink.
All stages of this amplifier are Direct Coupled, from the input section to the driver and power output stages. This minimises phase distortion, the signal-to-noise ratio is improved and signal attenuation is eliminated resulting in a exceptionally high level of sound quality. The output stage consists of Kenwood’s ‘Darlington Power Modules’ that provides an improved amplification factor, wider frequency response, lower distortion and increased operating life through better heat dissipation.
The other features I would consider the icing on the cake, and these include:
Negative feed back bass and treble tone controls with turnover frequency adjustment.
Presence control for the attenuation of frequencies around 800Hz and 3 kHz
32 Position attenuator type volume control.
Attenuator to reduce output by 15 or 30 dB
Subsonic high and low filters
Dubbing facilities for 2 tape recorders.
Double protection and delay start circuits.
3 Pairs of Loudspeakers
2 Tape Deck Inputs
2 Turntable Inputs
2 Auxiliary Inputs
2 Headphone Outputs
Overall this is a superb performing and very musical amplifier that still possesses that warm timbre and with plenty of power. I can happily listen to this amplifier for many hours without fatigue.
Visually this item is stunning, as is all the Kenwood components from this product line, and is one of my personal favourites. A point to note is that these items are still very serviceable with parts still available.
Francesca DiMattio is an artist living in New York City. She and her husband share a beautiful apartment in the Chelsea neighborhood in Manhattan. Their space is filled with vintage finds, including a Sansui sound system from the ’70s and some very large wooden speakers flanking their flat screen TV.[READ MORE]
Considered by many to be the best receiver/amplifier of the 1970s (translates best-ever – period!) the Pioneer SX-1250 was the top-of-the-line model for the 1976-1977 Pioneer Receiver range.
A product of the “Receiver Wars” no expense was spared in the design and engineering of this model and this is evident in the specifications, build quality and performance.
Over the course of the 1970s Pioneer led the trends in terms of design and engineering of audio equipment with the majority of its major competitors shamelessly copying the styling of many Pioneer models. From the blue back light model Receivers of the early to mid-seventies to pressed aluminium silver tuning dials from the mid-seventies onwards.
In terms of aesthetics the SX/50 series design was a dramatic departure from all previous silver fascia receiver designs to date with its silver pressed tuning dial and warm yellow glow and was quickly duplicated by the likes of Kenwood, Sansui, Marantz and Sanyo. Few brands such as Yamaha and Sony stuck to their guns with their own distinct styling.
In Pioneers previous 1974-1975 product range the top-of-the-line receiver the blue-lit SX-1010 had made a world first by being the first 100 Watt RMS amplifier ever released and while the other manufacturers rushed to catchup with this beast Pioneer were slowly and deliberately planning a new monster. So when the SX-1250 was released in 1976 Pioneer again broke all previous power records boasting an enormous 160 Watts RMS per channel.
To achieve this unprecedented power rating Pioneer developed the now legendary power section of the SX-1250 with completely independent power supplies, including separate power supply windings, rectifiers and smoothing capacitors for each channel, the components of which include a massive 22 pound toroidal core transformer (less susceptible to power fluctuations and less likely to create noise than laminated core transformers) and four ‘Coke Can’ size 22,000uf filter capacitors.
The amplifier section was composed of a 2-stage differential amplifier and a Darlington push-pull amplifier for the final stage. All stages are direct coupled in a pure complementary OCL circuit that includes a current mirror circuit.
This combination delivered FTC regulation measurements of 160 Watts RMS per channel into 8 ohms from 20-20KHz with no more than 0.1 THD and 200 Watts RMS per channel with 0.1 THD into 4 ohms.
The preamplifier section combines exceptional flexibility with superb sound achieved through utilising field effect transistors and CR type integrated circuits. The phono input has a 4-stage preamplifier equaliser with an RIAA correction of only +_0.3dB and a overload level of 500mV meaning no magnetic cartridge can strain the pre-amp. The designs of these sections were directly borrowed from Pioneer’s separate components.
Pioneer never manufactured a unit to match these specifications ever again and this is one of the many reasons purists believe that this model is the apex of high fidelity sound. The now legendary SX-1980 from Pioneers 1978-1980 product range used essentially the same power supply to produce 270 Watts RMS per channel while the model intended to take over from the SX-1250, the SX-1280, had downgraded its capacitors to 15,000mfd even though it was rated 20 Watts RMS higher the the SX-1250!
This receiver was meant to be the finest available then and as it turns out it remains one of the finest available to this day.
“This unit is a must have if you can find one. I will never part with this monster. No other receiver has ever compared.” http://www.audioreview.com/cat/amplification/receivers/pioneer/sx-1250/prd_118733_1593crx.aspx#reviews
“NOTHING that I have ever owned or heard sounds as golden as my SX-1250 and the RT-707 reel-to-reel hooked up to it. The sound kind of reminds me of when I was a little boy and my father had purchased a monophonic tube amplifier from Radio Shack (there were only two Radio Shacks, one in Boston and one in my home town, New Haven. The SX-1250 beats that old tube amp for warmness and full-spectrum sound. It is also manufactured to outlast my life, and I am fifty! Can’t praise the sound or quality enough. Plus, it’s good looking. Beauty and brains!” http://www.audioreview.com/cat/amplification/receivers/pioneer/sx-1250/prd_118733_1593crx.aspx#reviews
“I spent a couple years in Germany in the late 70’s. All the guys were buying monster receivers from down @ Mainz (spelling?), so I’ve listened to a lot of different models and nothing tops this 1250. It’s got a “warmth” of sound difficult to describe and aesthetics beyond compare. All my wife’s friends pity her for having to put up with this yugo sitting in her house. If you come across one you can afford, don’t let it pass you by.” http://www.audioreview.com/cat/amplification/receivers/pioneer/sx-1250/prd_118733_1593crx.aspx#reviews
“This is hands down the best Pioneer receiver I have ever heard, the depth, clarity and power that the restoration has given it is something else, I can’t describe it, it’s something that must be heard to appreciate it. It will have a permanent place at the head of my rack, I don’t think I will ever sell it. ” http://mattsvintageaudiorepair.blogspot.com.au/2012/01/pioneer-sx-1250-score.html