Sony SS-7110 ULM11 (circa 1973)

At 13kg and nearly 55cm tall, these bookshelf speakers are heavy for their class.

Overview

The Sony SS-7110 ULM11 isn't built for delicacy. It comes from Sony's early 1970s engineering push: a 2-way, bass-reflex bookshelf speaker built around magnetic linearity and mechanical integrity. It was marketed around 1973 at ¥19,000 per unit, as a serious high-fidelity option while Japanese audio firms were busy refining their technical credentials. The "bookshelf" label is generous. At 326 mm wide, 550 mm high and 290 mm deep, it leans toward compact floor-standing proportions and needs space and a stable spot. The finish is walnut grain. The real story is inside: a 20 cm cone woofer and a 2.5 cm dome tweeter, with Sony's Ultra Linear Magnetic Path (ULM) technology meant to cut distortion at the magnetic core.

Owners report that the ULM system is more than marketing. Sony cut a notch in the center pole of the magnet and capped it with thick copper plating to tackle nonlinear magnetic distortion, a subtle flaw in many drivers of the era. Together with a metal bobbin in the woofer voice coil, it was intended to improve power handling and thermal stability. The 50W maximum input (measured with weighted pink noise) wasn't class-leading, but it points to a design aimed at clean headroom rather than brute force. The 87dB/W/m sensitivity is modest, so these speakers do better with a strong amplifier, especially at 6 Ω impedance, which calls for a current-capable output stage.

The crossover sits at 3.5kHz, a relatively high point that puts real demands on the 2.5 cm dome tweeter. Sony gave it a continuously variable level control so users could tailor the high-frequency balance, which was unusual for the time. The network uses an air-core inductor with low DC resistance, which avoids the saturation of iron-core coils under high signal loads. Mylar capacitors are specified in the crossover, likely giving a clean, low-hysteresis signal path. The cabinet is 20 mm thick hard particle board, reportedly with a double-layer structure, and aims to suppress panel resonance. No internal bracing details are documented.

One of the more interesting mechanical touches is the woofer's edge. It is a cloth surround treated with a special thin rubber and an airtight sealing process, designed to eliminate a common 400 Hz response dip. Sony was clearly addressing a known weakness in cone drivers of the period. The dust cap does more than protect: it's said to contribute to sound insulation and prevent unwanted resonance from the voice coil cavity. Even the lead wires use high-purity copper foil treated with resin for durability, a detail often overlooked but important for long-term reliability in high-excursion drivers.

Specifications

Manufacturer	Sony
Model	SS-7110 ULM11
Product type	2-Way, 2-Speaker, Bass Reflex System, Bookshelf Type speaker system
Production years	around 1973
Original price	¥ 19,000 (1 unit, around 1973)
Woofer	20 cm cone type
Tweeter	2.5 cm dome type
Playback frequency band	45 Hz ~ 25000 Hz
Output sound pressure level	87dB/W/m (New JIS)
Impedance	6 Ω
Maximum allowable input	50W (weighted pink noise)
Crossover frequency	3.5kHz
External dimensions	Width 326 x Height 550 x Depth 290 mm
Weight	13kg
Enclosure structure	Bass-reflex
Enclosure material	20 mm thick hard particle board
Finish	Walnut grain

Key Features

Ultra Linear Magnetic Path (ULM) Magnetic Circuit

The SS-7110 ULM11 uses Sony's ULM technology to combat magnetic distortion. A notch is machined into the center pole of the woofer's magnet structure, then filled with a thick copper cap. The copper acts as a shorting ring, damping flux modulation and reducing harmonic distortion from magnetic nonlinearity, especially at low frequencies and high excursions. This was a sophisticated fix for 1973, and it put the engineering into the driver rather than just the cabinet or crossover.

Metal Bobbin Woofer Voice Coil

Unlike the paper or Kapton bobbins common in the era, the SS-7110's woofer uses a metal bobbin. It carries heat away from the voice coil better, so the driver can handle higher continuous power without thermal compression or failure. It also adds mechanical rigidity and reduces deformation under high drive levels. Metal bobbins can add a little moving mass, but here the trade-off clearly favored durability and thermal performance.

Scandinavian Pulp Woofer Cone

Sony specified carefully selected Scandinavian pulp for the woofer cone, processed with proprietary paper manufacturing techniques. The aim was consistent fiber structure and damping, with a balance between stiffness and internal loss. Such materials were believed to reduce breakup modes and give a more natural midbass response, though the exact sound depends heavily on the cone's profile and treatment.

Airtight Rubber-Edge Surround

The woofer's surround uses a cloth base impregnated with a special thin rubber and sealed for airtightness. It targets a known problem: a response dip near 400 Hz caused by air leakage or flexing at the cone's perimeter. By eliminating this "valley," Sony aimed for a smoother lower-midrange transition and better cone control during excursion.

Continuously Variable Tweeter Level Control

Mounted on the crossover network, this control allows real-time adjustment of the tweeter's output level. The 3.5kHz crossover point is high for a 20 cm woofer, so the control lets users compensate for room acoustics or personal preference, softening brightness or boosting presence. It's a rare inclusion in a bookshelf speaker of this vintage.

Air-Core Crossover Inductor with Low DC Resistance

The crossover uses a large air-core coil, which avoids the magnetic saturation and hysteresis losses of iron-core inductors. The inductor stays linear even at high signal levels, preserving transient detail and reducing distortion. Combined with mylar capacitors, the network is built for signal integrity as well as frequency division.

Dust Cap with Sound Insulation Function

The dust cap is engineered to provide acoustic insulation as well as protect the voice coil, minimizing rearward sound radiation from the motor structure. This reduces interference with the main cone output and helps prevent coloration from cavity resonance behind the driver.

Similar items on eBay

No exact Sony ss-7110 listings are live right now — these searches show current Sony and similar vintage audio gear on eBay:

Search Sony ss-7110 on eBay Browse Sony audio gear on eBay

As an eBay Partner, we earn from qualifying purchases. This helps support our independent vintage technology research.