SANSUI SP-α 1010 (circa 1990)

At 19.2kg, these bookshelf speakers are heavy for their size, and the weight is mostly cabinet damping under a walnut veneer.

Overview

The SANSUI SP-α 1010 is a plain, dense box - 270 mm wide, 450 mm tall, and 339 mm deep - and it weighs 19.2kg. Sansui sold it as a bookshelf-type bass reflex system, a 2-way, 2-speaker design built around controlling resonance and vibration. The enclosure is softwood high-density particle board with a walnut veneer finished in oil. It feels solid and damped, not hollow or reactive. The idea is for the cabinet to stay out of the way and let the drivers and crossover do the work.

The mechanical damping is the first thing to look at. Inside is a 40 mm thick X-shaped center baffle that anchors the woofer frame and magnetic circuit through an inner frame mounting system. That isolates the driver from cabinet flex and reduces coloration. The top panel is a double spruce structure covered in cowhide nubuck to minimize high-frequency resonance. The edge of the woofer cone is also reduced in surface area to suppress edge resonance, which can muddy midrange clarity.

The SP-α 1010 has EIAJ-standard magnetic shielding, which mattered when speakers sat near CRT displays. The speaker stand, the L-1010, was sold separately for ¥19,000. The speakers themselves cost ¥90,000 per unit around 1990, which put them in a premium tier.

Specifications

Manufacturer	SANSUI
Product type	2-Way, 2-Speaker, Bass Reflex System, Bookshelf Type speaker system
Original price	¥ 90,000 (per unit, circa 1990)
Playback frequency band	40 Hz to 40000 Hz
Max Input	120W
Impedance	6 Ω
Output sound pressure level	88dB/W/m
Crossover frequency	2500Hz
External dimensions	Width 270 x Height 450 x Depth 339 mm
Weight	19.2kg
Unit for low band	21 cm cone type
Unit for high-pass	2.5 cm dome type
Magnetic shielding	Magnetic Shielding Type (EIAJ)
Enclosure	softwood high density particle board with a walnut veneer on the surface and an oil finish
Sold separately	Speaker Stand L-1010 (¥ 19,000 per unit)
Stand dimensions	Width 320 x Height 430 x Depth 340 mm

Key Features

21 cm Cone Woofer with Minimized Edge Area

The 21 cm cone woofer is mounted on that massive X-shaped baffle. Its reduced edge surface area is aimed at edge resonance, a common flaw in cone drivers where the surround adds its own tonal coloration. Sansui was after cleaner midbass and a more transparent transition into the crossover region.

2.5 cm PF Carbon Diaphragm Tweeter

The high-pass unit is a 2.5 cm dome, but not a conventional one. It uses a PF carbon diaphragm, reportedly 50% lighter than standard tweeter domes of the time. The lower mass allows faster transient response and lower distortion, and helps it stay coherent with the woofer across the 2500 Hz crossover point. The light, rigid dome sits against a high-mass woofer system.

Air-Core Coils and Film Capacitors in Crossover Network

The crossover uses air-core inductors wound with OFC alloy lead wires, then potted in a special high-mass resin to prevent micro-vibrations. Mechanical stability in passive parts can affect signal integrity, especially at high drive levels. Film capacitors are used throughout. Electrolytics degrade over time, films don't.

Double Spruce Top Panel with Cowhide Nubuck

Vibration control goes beyond the drivers. The top panel is a double spruce construction, an uncommon choice in mass-market speakers, covered in cowhide nubuck. The layering adds stiffness, and the leather-like covering damps high-frequency ringing. The aim is to reduce cabinet-induced artifacts that smear detail in the upper mids and lower treble.

Internal Damping with Heavy Materials

Special heavy damping materials line the walls inside the enclosure. The page describes them only as "heavy" and "special," which suggests a constrained-layer or mass-loaded composite rather than loose acoustic wool. They are there to eliminate internal standing waves and panel resonances before they reach the drivers. The cabinet is compact and internal volume is limited, so damping matters even more for bass extension down to 40 Hz.

Magnetic Shielding for CRT Compatibility

With EIAJ-standard magnetic shielding, the SP-α 1010 was designed to sit near video monitors without distorting the picture. That was a real concern in the late 1980s and early 1990s, especially in multi-room or studio setups. Both drivers are shielded, so the entire system meets the standard.

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