By 1979, Sony amplifiers had abandoned their exotic but unreliable V-FET output transistors, and were innovating in different ways – the challenge was to add an interesting twist to a conventional design. So from the middle of the new TA-F range upwards, Sony engineers placed the power transistors on the main circuit board in order to get ultra short signal paths. Normally that would result in the board melting, so rival manufacturers had never dreamed of doing it – but Sony thought otherwise. It came up with a novel ‘heat pipe’ filled with freon gas, that transferred heat away to multiple thin cooling fins, further away from the amplifier’s power transistors. It was pretty zany stuff, especially by the standards of the day.
Every high end Sony integrated amplifier had this, and it was an inspired idea. From a marketing perspective it gave the manufacturer something to talk about in the brochure – and something for the hi-fi magazines of the day to write about. In a world where “high tech” was king, a Sony dealer could say “well the Hitachi may have MOSFETs but the Sony is freon-cooled!” It also worked on two other levels though – firstly, in conjunction with a new type of power supply it meant Sony could sandwich a lot of circuitry into a relatively small space – which is why the TA-F55 is such a slimline thing. Secondly, that super-short signal path really made a difference to the sound. What little internal cabling that was needed was 99.99% pure copper, and the preamplifier stages had a FET buffer stage between them and the main amplifier section. Source selection was done by electronic switches. Inside, it was a model of compactness and elegance.
By 1979 standards, the 430x80x320mm TA-F55 was really slim, and light at just 4.6kg. Lest we forget, most Japanese amplifiers of that era were plug-ugly and fat – at least twice as tall as this. The great packaging wasn’t just down to the novel cooling system; this amplifier also ran a Pulse Power Supply – so there was no need for a bulky frame-type transformer. This rectified the line voltage, chopped it at 20kHz, inverted it and then rectified and filtered it again. The result was unusually clean DC power given the very small space it had to work in. At the same time, the power supply enabled the use of a string of high bandwidth ‘High Ft’ power transistors running in parallel; this provided excellent measured performance. Only small amounts of negative feedback were used, despite this.
So, unlike so many generic Japanese integrated amplifiers of its time, the TA-F55 was effectively designed from the inside out. It was both very slim and yet had none of the compromises that making such a small and svelte amplifier would normally entail. It was not just about shoving as much conventional technology into the case as you could; instead it was about using unconventional engineering solutions to achieve the sound quality of a full sized, premium priced amplifier. All this was clever enough, but the company thought that it ought to have a sophisticated control layout, as befitting an amplifier that cost nearly as much as a Linn Sondek turntable at the time. Reflecting the trend for new ways of doing things, and perhaps with one eye on an increasingly sophisticated Bang & Olufsen, Sony opted for an electronically controlled two-speed push-button volume control with a green illuminated linear display.
The TA-F55 delivered excellent measured performance, making a claimed 70W RMS per channel into 8 ohms – this was a lot of power for a full sized high end amplifier of that time, let alone a half-height one. Its damping factor was quoted at 50, and the THD figure was an extremely low 0.08%. The amplifier had a choice of moving coil and moving magnet phono inputs, with sensitivities of 0.25mV and 2.5mV respectively and two-step capacitance and impedance switching via small front panel selectors. There were also tuner, auxiliary and twin tape monitor circuits. Bass and treble controls were fitted, giving 10dB of boost or cut at 100Hz and 5kHz, in traditional Sony style. A -20dB muting switch was fitted too, and two sets of speaker outputs which sadly only accept relatively slim bare wire cables.
By the end of the late seventies, there was an unwritten rule of Japanese hi-fi. Most of it had all kinds of allegedly special technologies with names dreamt up by the marketing departments – often designed to solve a problem that didn’t really exist – but still it generally sounded poor. The rather conventional British A&R Cambridge (Arcam) A60 of the time, for example, vastly outperformed most integrateds from the Land of the Rising Yen. So many hardened hi-fi hacks – and indeed buyers – took all the hype with a large pinch of salt. Yet when you laid ears upon the TA-F55, you could not ignore the fact that it was actually really rather good.
In a straight A-B comparison with the aforementioned archetypal British mid-price amplifier – the A&R A60 – it was quite shocking to hear the Sony come out largely on top. There was definitely a sense that the TA-F55 was a Japanese sounding product and the A60 a British one; the latter was warmer, smoother and a little less upfront. Yet the Sony was far more refined and civilised than we had come to expect from Nipponese designs and actually had its very own version of a smooth, open and subtle sound. Harshness or haze is typical of seventies Jap amps, but this had neither. In its place was a surprisingly large and authoritative sound, with a sense of great unflappability and large reserves of power. At the same time it was very detailed and rhythmically propulsive. In short, the Sony sounded far ‘bigger’ than it looked, giving an almost high end sound despite its diminutive dimensions.
In absolute terms, there’s an ever so slightly tinselly treble and a taut and tight yet slightly light low bass, but that aside it’s hard to criticise. Indeed the upper bass is strong and very propulsive. The midband is more three dimensional that you would expect from a Japanese amplifier of this era, yet in absolute terms it’s still a little lacking in depth perspective. The other side of this is that the amplifier sends stereo images far left and far right, giving a much more commanding and all-embracing soundstage than the aforementioned A&R.
Indeed, you might characterise the TA-F55 as a kind of Japanese miniature superhero – able to do far more damage to its adversaries than they ever expected, and extremely deft in what it can do, albeit ultimately limited by its size. It has a cheeky sort of character, too – music is fun and romps along, underpinned by that solid, confident bass that never seems to run out of steam. The contrast between it and the A&R A60 is rather exasperating because if only one was just a bit more like the other’s sound, you’d have a fabulous musical performer. Match the Sony to relatively sweet, warm sources (a British belt-drive turntable of that time, for example) and you’d really hit a sweet spot.
When Sony discontinued the TA-F55 in 1982, things were changing apace. The Japanese Yen had got substantially stronger against the US Dollar and the UK Pound and all the Japanese manufacturers were beginning to cost-cut in order to be able to sell at similar price points. As a result, the next generation of Sony integrated amplifiers may have looked similar but was less interesting and didn’t match the TA-F55 and its brethren for sound quality. This was a really special little amplifier, very much of its time and one that would never be repeated. In the great scheme of classic hi-fi it’s largely unknown and so when it does turn up secondhand, prices aren’t that high – expect to pay no more than £200 for a tidy example. Although not the greatest ever amplifier, it’s very redolent of its time – which has now of course long since passed.