Sharp RT-3151

Sharp RT-3388Billed rather ambitiously as ‘The First Computer that Plays Music’, the Sharp RT-3151 (called the RT-3388 in the United States and Canada) was actually a fairly standard two-head, single capstan tape deck with an undistinguished permalloy record/reply head and an average set of VU meters. True, it was nicely built and finished, but there were plenty of those by the time the deck was launched in October 1977. What really set it apart however was its sophisticated tape track location system.

In some markets, this was labelled Optonica – which was Sharp’s premium brand, rather like Aurex to the cooking Toshiba – as befitting the deck’s high end price tag, lavish finish and luxurious feature count. The standout feature was what Sharp called APLD (Automatic Program Locate Device), the ability for the deck to hunt for two second gaps in the recording (which it took to be the space between songs on a recording from an LP record) and store them in its ‘microprocessor’ brain. This could then offer the user the ability, in theory at least, to play any track on the tape in any order.

This was allied to a digital clock. In 1977, the fact that it had an LCD display was the stuff of dreams – it seemed incredibly futuristic, as only the very newest digital watches had this (most were LED). This sat proudly in the middle of the Sharp’s fascia, and formed part of the deck’s electronic control system. Bizarrely, the RT-3151 had old-fashioned mechanical piano key-style tape transport controls, just when you’d expect that this deck would have new-fangled logic control, as seen on top Sonys. To us cassette fans at the time, after we had gasped at the high tech APLD feature, we felt somewhat let down that it didn’t have logic control.

APLD actually worked surprisingly well – it would occasionally miss a track while searching, but wasn’t too unreliable. However, the one massive drawback was that while this was in operation, the tape was whizzing over the record/play head at high speed. This meant that it wore both the head and the tape, as well as depositing ferric oxide on the former, every time you used it. It wasn’t such a problem if you used APLD once in a blue moon, but using it all the time and you’d get dirty heads and ultimately head wear – because Sharp, in its penny-pinching stupidity, didn’t fit a long life head such as Sony’s F&F or Akai’s GX. In other words, this miraculous ‘Computer Controlled Cassette Deck’ was in effect a cheap, base model with a fancy clock thingie and tape search feature – rather than the high end super-deck we had initially thought.

In fairness, it managed a half-decent 30Hz to 16kHz (-3dB) with FeCr tape (13k with Ferric, 15k with Cro2), which wasn’t as good as top Sonys, Akais, Aiwas or Nakamichis, but not too scurrilous. Wow and flutter was a respectable 0.06% WRMS, which was a step up from an entry-level deck but again no match for its price rivals. Signal to noise ratio was 55dB (Dolby off), again middling and ‘could do better’. These stats confirmed that this whizz-bang electronic dream wasn’t quite as cost-no-object as its appearance suggested.

In action, the Sharp doesn’t sound bad – providing you use good tape and haven’t worn the head out. But it really is nothing to write home about, because it’s a middle-ranking product that gained its special status by virtue of its ‘computer’ and nothing else. Nowadays of course it’s crude to use, but still has loads of period charm. This deck is very much in ‘curio’ territory; find a good one and amaze your friends… of a certain age!







  1. William Fraser

    I had one of these decks for years! It served me well. Abused with tons of hours between high school and my college years, it just wore out. Grove in the head, failed lamps… No complaints, it ran well! Replaced with a Yamaha KX-1200U with DBX, another fine deck, and I still own it! Regretfuly, the Sharp went away…

  2. andyrawlins

    I bought one of these from a local ‘hifi store’ when I was a kid. It was half price – about £100 I think – as a school boy in the 70s I don’t know how I afforded it. I always thought it a thing of beauty and wonder – though always had a suspicion that actually it wasn’t that good. Eventually one channel went wonky and I replaced it with a very good Yamaha. The eventual replacement for that I still have now. And very good it is too.

  3. tuws

    Just got hold of one of these (the UK version, RT-3151) from ebay for 35 quid, seems like a bargain given the comment from andyrawlins! Sound on it is surprisingly decent and it looks awesome with the ridiculous amount of buttons and digital display. Suspect the price of these will increase (solely due to the novelty value) over the coming years (ebay sellers are generally asking £100+ for working models already) now that 70s cassette decks seem to be back in vogue!

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