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TC-153SD

(1975-1977)

TC-153SD, picture by Nick Jarman

The TC-153SD was one of the first battery portable cassette recorders that was capable of offering a similar level of performance to that obtainable from a full-sized domestic cassette deck. Compared to the later models (TC-D5, WM-D6C) it was very large and bulky but the size of the casework was necessary to fit everything inside. Text copyright © Walkman Central. Unauthorised reproduction prohibited.

As well as being a high quality recorder with long life ferrite heads, normal/ferrichrome/chrome tape compatibility, a servo controlled motor, full-sized illuminated VU meters and an Dolby B processor, the TC-153SD also included a built-in monitor loudspeaker (with its own volume and tone controls and a switch so that it could be automatically muted during recordings) and a mains power supply that could be used to recharge the battery if a Ni-Cd pack was fitted. Text copyright © Walkman Central. Unauthorised reproduction prohibited.

The cassette mechanism was similar to those used in many Sony machines of the period except that an automatic stop mechanism (record/playback only) of quite staggering complexity had been added. This used an epicyclic gearbox built into the reel clutch to sense when the take up spool had stopped rotating whose action then triggered another set of gears connected to the capstan that in turn released the transport keys. The electronics were also complex, the Dolby circuit in particular used discrete components only and therefore had a high component count. Text copyright © Walkman Central. Unauthorised reproduction prohibited.

Both the Dobly circuit and the servo motor required higher voltages than the four “D” cell batteries could provide so in turn a large DC-DC converter unit was needed, this stepped the 6V supply up to three separate elevated voltages, one of which was negative. Also unusual for a Sony portable machine was that AC bias and AC erasure were used (this is necessary if recordings are to be made on chrome tape) and so a powerful AC bias generator also had to be shoehorned in. Text copyright © Walkman Central. Unauthorised reproduction prohibited.

One could have used the TC-153D as a personal stereo cassette player as there was a headphone socket but because this was of a fixed volume level (the volume control was for the loudspeaker only) it was not really practical. The machine was also too large and heavy for such an application although the sound quality was excellent. It was more suitable for making outdoor recordings, where the sensitive microphone amplifier complete with a three position attenuator switch and a record level limiter were of great value. It could also be used as a home cassette deck, where it could be connected to the host equipment by either RCA (line) or DIN connectors. Text copyright © Walkman Central. Unauthorised reproduction prohibited.

In 1978 the TC-D5 could do most of what the TC-153SD could do, better in in a much smaller space. Text copyright © Walkman Central. Unauthorised reproduction prohibited.