TRIO KX-7X (1981)

At 5.8kg, it sits on the shelf like a brick. This was never just another cassette deck.

Overview

The Kenwood KX 330 is more precisely the TRIO KX-7X. TRIO-KENWOOD released it in 1981 as a high-end stereo cassette deck, when Japanese manufacturers were pushing the limits of analog tape fidelity. It cost ¥64,000 and was aimed at serious audiophiles who wanted low noise, precision and advanced features. Despite the dual naming, all confirmed technical data ties back to the TRIO KX-7X, so the KX 330 may have been a regional or rebranded variant. The machine was built to get the best performance out of metal, chrome and normal bias tapes, using cutting-edge materials and digital control for its time.

The deck uses electronically controlled DC servo motors for the capstan and DC motors for the reels, aiming to deliver consistent tape speed and tension. Wow and flutter are rated at 0.04% WRMS, a figure that places it among the more stable performers of its era, though real-world results depend heavily on belt condition and head alignment. The frequency response extends to 20 kHz on metal tape, which, combined with a 57dB signal-to-noise ratio (EIAJ) and Dolby NR offering a 10 dB improvement above 5 kHz, suggests a strong high-frequency reach and effective noise reduction when properly calibrated.

Input and output levels follow pro-grade conventions. Line input is 77.5mV into 50kΩ, and output is 0.39V into 2kΩ, which keeps it compatible with contemporary preamps and recorders. The headphone output is rated at 0.35mW into 8Ω. That won't drive high-impedance cans with authority, but it's enough for monitoring. Power draw is modest at 25W, and the unit runs on 100 VAC, so it was originally intended for the Japanese market. A wired remote controller, the RC-7, was sold separately for ¥6,000.

Specifications

Manufacturer	TRIO-KENWOOD
Product type	Stereo cassette deck
Production years	Released in 1981
Original price	¥ 64,000
Track format	4-track 2-channel stereo
Recording system	AC bias system
Motor	Capstan reel motors : electronically controlled DC servo motors; Reel motors : DC motors
Heads	Recording : amorphous alloy; Erasing : double-gap ferrite
Wow and flutter	0.04%WRMS
Frequency Response (EIAJ)	Normal : 22 Hz to 18 kHz ± 3 dB; Chrome : 22 Hz ~ 19 kHz ± 3 dB; Metal : 22 Hz ~ 20 kHz ± 3 dB
S / N ratio (metal tape)	57dB(EIAJ)
Dolby NR	Dolby NR on : 10 db improvement (5 khz or more)
Overall strain rate	1% (1 kHz, 0 VU, metal tape)
Input Sensitivity / Impedance	Microphone : 0.3 mV (Compatible Impedance 600 Ω); Line : 77.5mV/50k Ω
Output Level / Impedance	Line : 0.39V/2k Ω; Headphone : 0.35mW/8 Ω
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	25W (Electrical Appliance and Material Control Law)
Maximum External Dimensions (EIAJ)	Width 440x Height 109x Depth 330 mm
Weight	5.8kg
Sold Separately	Wired Remote Controller RC-7 (¥ 6,000)

Key Features

Amorphous Alloy Recording Head

The amorphous alloy recording head was a significant technical choice. Unlike conventional crystalline materials, amorphous alloys have no regular atomic structure, which gives them higher magnetic saturation density and makes saturation less likely during high-frequency recording. The laminated ultra-thin film construction minimizes eddy current losses, and the material's high intrinsic electrical resistance helps high-frequency response. According to available documentation, this design is what lets the deck reach a 20 kHz upper limit on metal tape. That was no small feat in 1981.

Digital Program Search System (DPSS)

The KX 330 has DPSS, a microcomputer-controlled system for programmable track access and playback. It handles up to 16 tracks per side, one-track repeats, full-side repeats, and a REC/AUTOTREK mute mechanism. This level of automation was still relatively novel in consumer cassette decks at the time, and it gave users more control over their tapes without stepping into professional studio gear.

Double-Gap Ferrite Erase Head

While not unique to Kenwood, its inclusion here underscores the deck’s focus on clean, accurate recording.

AC Bias System with Tape Optimization

The AC bias system is tuned across three tape types - normal, chrome and metal - so the deck can optimize recording for each. The frequency response specs reflect this, with each tape type extending slightly further into the highs. Calibration is critical. Misalignment can easily negate the benefits of the amorphous head and bias circuitry.

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