Aiwa CS 100
At 8.4 kg, it’s a beast that demands space and attention—this is boombox engineering with serious underpinnings.
Specifications
| Manufacturer | Aiwa |
| Product type | Radio cassette (boombox) |
| AC Power | 100 VAC, 50Hz/60Hz |
| Power consumption | 20W (at AC) |
| Battery life time | Approximately 8 hours (when using EIAJ and SUM-1 dry battery) |
| Receiving frequency | FM : 76 MHz to 90 MHz AM : 525 kHz to 1,605 kHz |
| Antenna | FM : Whip Antenna AM : Ferrite Bar Antenna |
| Track system | 4-track 2-channel stereo system |
| Recording system | AC bias |
| Erasing method | AC erase |
| Tape used | C-30, C-60, C-90 (C-120) |
| Recording time | 60 minutes (C-60 round trip) |
| Frequency characteristic | 50 Hz ~ 12.5 kHz (LH Tape) 50 Hz ~ 13 kHz (CrO2 Tape) 50 Hz ~ 14 kHz (Metal Tape) |
| Signal-to-noise ratio | 54dB(Line out(JIS)) |
| Wow flutter | 0.07%(WRMS) |
| Mike | 2 built-in condenser microphones |
| Maximum practical power | Total 12W (6.0W + 6.0W, EIAJ/DC) |
| Input terminal | Mic Jack : 3.5 φ Mini Type x2 Phono/Line in jacks : 2 pin types Mixing Mic Jack : 3.5 φ Mini Type |
| Output terminal | Line out jack : 2 pin types EXT. SP Jack : 3.5 φ Mini Type x2 Phones jack : 6.3 φ standard jack |
| Speakers | For low band : 16 cm cone x2 For high pass : 2 x 5.0 cm cone type |
| Semiconductor used | IC : 9 Transistor : 67 Diode : 37 pcs LED : 8 pcs FET : 1 |
| Power | AC Power : 100 VAC, 50Hz/60Hz Battery Power Supply : 12 VDC (8 AAA batteries) Car battery (combined with car adapter) |
| External dimensions | Width 557x Height 332x Depth 170 mm |
| Weight | 8.4 kg (including battery) |
| Attachment | AC cord Erase Plug x1 |
| Sold Separately | Car Adapter DC-121 (¥ 4,000) |
Key Features
Double Capstan Transport with Dedicated Motors
The mechanism uses a double capstan system with a dedicated capstan for both forward and reverse rotations. This isn’t a single motor flipping direction—it’s a twin-engine approach that maintains consistent tape tension and speed regardless of play direction. Owners report smooth, stable operation, though the mechanical complexity means more potential wear points over decades of dormancy.
180° Rotating Record/Playback Head
To ensure identical performance in both directions, the recording and reproducing head physically rotates 180° when reversing. This eliminates the need for dual heads and guarantees symmetrical azimuth alignment. It’s an elegant mechanical solution, avoiding the cost and calibration issues of dual-head setups, though the rotating mechanism can bind if not regularly exercised.
Mechanical Logic System with Motor Shift
The transport relies on a motor shift system with a dedicated motor and mechanical logic circuitry—no microprocessors here. This all-analog control architecture uses gears, levers, and clutches to sequence operations. It’s robust in principle, but dried lubricants and worn plastic cams are common failure points in long-stored units.
Sendust (SG/SE) Head Assembly
The record/playback head uses Sendust guard (SG) material, known for high saturation magnetic flux density, improving headroom and reducing distortion on loud passages. The erase head employs a Sendust double-gap (SE) design, which enhances erasure efficiency. These were premium choices for the era, suggesting Aiwa targeted serious users, though the heads are susceptible to clogging and require careful cleaning.
BTL Amplifier with ITL-OTL Circuit
The amplifier uses a BTL (Bridge-Tied Load) configuration based on an ITL-OTL circuit, delivering a total of 12W (6W + 6W) under EIAJ/DC standards. BTL setups double effective voltage swing across the speaker, boosting output without higher supply voltages. While efficient, the design can be sensitive to speaker impedance mismatches and may stress output transistors over time.
2-Way Speaker System with Aluminum Caps
Equipped with dual 16 cm cone woofers and two 5 cm cone tweeters, the speaker array is a true 2-way system. Each high-frequency unit includes an aluminum cap—likely a phase plug or heat dissipater—intended to extend and smooth high-frequency response. The cabinets appear tuned for midrange punch rather than deep bass, typical of portable designs with physical constraints.
FM Tuner with 3-Row Variable Capacitor and PLL-IC
The front end of the FM tuner uses a 3-row variable capacitor, high-performance transistors, and an FET for stable reception. The IF stage relies on a 2-element ceramic filter for selectivity, while the MPX (stereo decoder) circuit uses a PLL-IC for accurate stereo separation. This is a serious tuner section, suggesting strong reception capabilities, though alignment drift over time can degrade stereo lock.
Collectibility & Value
A used Aiwa CS 100 listed as "junk" status was offered on an auction site with a "通電確認済" (power-on confirmed) note, indicating it powers up but may not function fully. The asking price was 1,500 JPY. No data on reliability, common failures, or spare parts availability is available. Given the lack of verified performance reports and the model’s obscurity compared to flashier contemporaries, it remains a deep-cut find for boombox collectors focused on transport mechanics rather than street cred.
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