Launched in 1976 at a non-inconsiderable £220, for a while this was Sony’s top portable stereo cassette recorder. It was intended for professional audio applications, but lent more towards the domestic home recordist than rival machines from the likes of Uher. It’s an essay in good design, having an attractive but functional appearance, superb ergonomics and excellent engineering. Even today, a well preserved example works as a very capable sound recording machine, despite being four decades old.
Measuring 350x100x240mm, it is huge by modern standards but considerably smaller and lighter (4.76kg) than the Nakamichi 550 which it was designed to challenge. It has a 100mm loudspeaker drive unit and simple two-transistor push-pull 700mW amplifier built in for mono monitoring, but is of course a full stereo design with stereo RCA line inputs and outputs. Every other feature is useful but not gimmicky; there’s tape selection for Sony’s ferric, chrome and ferrichrome, and a handy limiter to prevent tape saturating. The large illuminated VU meters are excellent; the same as those fitted to the company’s top home decks, they offer fast ballistics yet are very easily readable.
The key to the quality is the high quality single capstan transport, and the virtually indestructible F&F (ferrite) record and playback head; compared to the permalloy examples that many rivals used, it offered excellent extended frequency response and a wear-resistance that makes it just about the last part of the deck that will expire. Inside, the deck is very old school with just a single (IC 601) integrated circuit on the motor servo amp board, and all discrete circuitry elsewhere. Even the Dolby circuitry is done discretely, with a small number of transistors. It runs at 15V inside, using a DC-DC converter for the power supply.
Properly set up and calibrated, the Sony sounds surprisingly good in its way – with a big, musical and confident sound, one that is way better than you’d expect for its day. Treble is a little diffuse but excellent by 1976 standards all the same. Sony quoted a frequency response of 30Hz-12kHz (-3dB) with ferric tape and 30Hz-15kHz (-3dB) via ferrichrome. Thanks to its largish flywheel and servo controlled DC motor, speed is pretty stable (Sony’s wow and flutter figure was 0.2% WRMS), and there’s a decent dynamic range (signal-to-noise, A weighted, was said to be 57dB with Dolby out via FeCr tape).
These days, the TC-158SD is becoming something of a cult machine amongst retro tape recordists, and prices are firming. It’s pot luck really; a car boot sale might bring you one for £20, whereas ambitious eBay sellers are asking £300 or more. Unsurprisingly, these listings tend to stay up because the decks don’t sell. A realistic price is £100, if the deck is in decent working condition. Prospective purchasers should pay close attention to the cassette loading lid, which is a little more flimsy than the rest of the deck’s pretty robust plastic casework; its hinges are prone to cracking and breaking.