The WM-EX23, also known as “WM-EX 23” is a stereo cassette player Walkman manufactured by the Sony Corporation of Japan in 1993, and assembled in Malaysia. This unit has the 2× bass expansion circuitry, known as MEGA BASS. It also has an automatic volume limiter system (AVLS), anti-rolling mechanism, and comes supplied with MDR-E741 Fontopia style earphones. This unit operates on a pair of “AA” sized dry cells, to provide approximately seven hours of playback operation. It also has a two-position switch for setting the bias of the cassette, namely metal/chrome and normal.
During the early 90s, Sony released WM-EX21, WM-EX24, and WM-EX26 models, which were cosmetically identical to this unit. The WM-EX23 has a switch for enabling the Mega Bass; however, the WM-EX24 and WM-EX26 had slider controls to set the precise amount of required bass. The WM-EX26 had the additional Dolby noise reduction circuitry to decode Dolby encoded tapes.
Electronics wise, the circuit design employs the LA4582 integrated circuit (IC) by the Sanyo Corporation of Japan. This is a 3 V system in a QFP36 package, consisting of a pair of pre amplifiers and a pair of power amplifiers. The power amplifiers are capable of driving an 8-Ω load directly through pins 4, 6 and 8, without requiring an output capacitor. The result is a better sound and a lower component count.
This IC also has an integrated low frequency boost function, which translates into the Sony Mega Bass function. It also has the peak volume select system (PVSS) function, which translates to Sony’s AVLS.
The motor drive consists of a conventional DC motor controlled by the MM1038 servo IC, which was in many Walkmans in this series. It does a good job of regulating the tape speed and minimising the power consumption.
Cost / eBay
Today, the WM-EX23 would be considered an early vintage model, and I have not seen very many of these around. It was mass produced, and low-cost, and consequently many people would have disposed of it without any thought. The Fontopia style headphones that come with this unit sound rather nice, so if there is one going for around five pounds with the headphones then it is a bargain. The headphones alone are worth that much, and the rest is gravy.
This Article Continues...Sony WM-EX23
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Sony WM-EX23 inside Look
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Sony WM-EX23 Power Supply
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Sony WM-EX23 Box and Manual
Sony MDR-E741 Earphones