Infinity RS-4.5 (1980s)

Name: Infinity RS-4.5
Brand: Infinity

A floorstanding speaker system so revealing it could make you love your music more—and question everything about your amplifier.

Overview

The Infinity RS-4.5 isn’t just a speaker; it’s a statement. A towering presence at 65 inches tall, each cabinet weighs in at a hefty 150 pounds, and the system demands not only space but attention. Introduced in the 1980s as part of Infinity’s Reference Standard series, the RS-4.5 was designed to bring the brand’s high-end engineering to a broader audience—though with an MSRP of $4500 (or $2000 as a system in 1979, depending on configuration), "broader" was still a relative term. This wasn’t mass-market gear. It was for the serious listener who wanted transparency, extension, and a front-row seat to every detail in the recording, warts and all.

And it delivered—sometimes too well. Early units shipped to dealers were reportedly hard-sounding and lacking in lower midrange warmth, prompting Infinity’s chief designer, Bascom King, to personally intervene and modify the crossover network before full production. The version that ultimately reached consumers was the one Stereophile reviewed and praised as being so complete that “many audiophiles may never again feel the need for upgrading to something ‘better.’” That’s not faint praise. That’s a dare.

What sets the RS-4.5 apart isn’t just its size or weight—it’s the technology packed inside. This is an active crossover system, meaning it doesn’t rely on passive components inside the speaker. Instead, it uses a separate black box—the speaker control center—that acts as both an electronic crossover and equalizer. This external unit, measuring 10" deep by 14" wide by 2" high, is essential to the system’s operation. Without it, the RS-4.5 is silent. With it, the speaker becomes a finely tunable instrument, capable of adjusting crossover points with precision.

Specifications

Manufacturer	Infinity Systems, Inc.
Model	RS-4.5
Year Introduced	1980s
Type	Floorstanding loudspeaker system
Drivers	EMIM midrange, EMIT ribbon tweeters (4 total, one rear-facing)
Enclosure Type	Floorstanding with foam baffle
Dimensions (H×W×D)	65" × 27" × 15" (loudspeaker), 14" × 10" × 2" (equalizer)
Weight	150 lbs per speaker
Frequency Response	24 Hz – 32 kHz ±3 dB
Nominal Impedance	4 ohms
Power Handling	100Wpc minimum required
Crossover Frequencies	150 Hz, 5 kHz (lower point adjustable)

Key Features

The External Crossover/Equalizer: The Brain of the System

The Infinity RS-4.5 doesn’t play by conventional rules. It doesn’t have an internal crossover. Instead, it relies on a dedicated external control unit—a black box that splits the audio signal electronically before it reaches the amplifier. This isn’t just a crossover; it’s an equalizer too, allowing users to fine-tune response and integration between drivers. The unit offers eleven selectable crossover frequencies for the low end of the midrange drivers and the upper end of the woofers, which can be set independently. This means you can choose overlapping or separated crossovers depending on your preference or room acoustics. It’s a level of flexibility almost unheard of in consumer speakers of the era, and it speaks to Infinity’s engineering-first mindset.

EMIT and EMIM Drivers: The Heart of the Sound

The RS-4.5’s driver complement is where it truly diverges from the pack. It uses electromagnetic-induction-midrange (EMIM) units and four EMIT (Electro-Magnetic Induction Tweeter) ribbon tweeters—yes, four. One of the EMITs is rear-facing, designed to enhance spatial dispersion and create a more immersive soundstage. These drivers are not your average domes or cones. EMIT ribbons are known for their extreme speed and transparency, capable of revealing high-frequency detail with startling clarity. Some listeners have called them “harsh” or “strident,” but as one reviewer noted, that reaction may come not from the speakers themselves but from the fact that EMITs reveal flaws in recordings and electronics that other speakers politely ignore. If your source or amp is bright, the RS-4.5 will tell you.

Build and Materials: Built Like a Tank, Aging Like Vintage Leather

Each speaker stands 65 inches tall with a broad 27-inch footprint, giving it a commanding presence. The cabinets are solid and massive, built to minimize resonance. However, they are not immune to age. The foam baffle pieces degrade over time—a common issue noted across listings and forums. Grill fabric is prone to holes, loosening, and sun damage. Cabinet surfaces can develop scuffs, splits in the wood veneer, and slight bubbling in the midrange panels. Plastic feet often go missing. These aren’t dealbreakers, but they’re the reality of owning a 40-year-old floorstander. The good news? Replacement parts exist. A specific foam surround repair kit (model 2A12-12) is marketed for the RS-4.5, and both EMIT and EMIM drivers can be replaced, though sourcing them may require digging through specialist suppliers.

Historical Context

The RS-4.5 was part of Infinity’s Reference Standard series, a line intended to deliver the brand’s high-performance DNA to a wider audience. At a time when many manufacturers were chasing bass extension and cosmetic flair, Infinity focused on accuracy and transparency. The RS-4.5’s development story is telling: early production units were judged too hard-sounding and lacking in lower midrange presence. Rather than ship them as-is, Infinity’s chief designer, Bascom King, stepped in to revise the crossover network. The version that reached dealers—and the one Stereophile reviewed—was this corrected model. It wasn’t just a product launch; it was a course correction that underscored Infinity’s commitment to sonic integrity.

Collectibility & Value

The Infinity RS-4.5 is no longer in production and is considered rare. TMR Audio lists it as “no longer available,” and current listings reflect its niche status. Prices vary wildly: a pair was listed for €4,700 in Spain (Como Ficho, 2023), while another sold for PLN 15,900 in Poland (OLX, 2022). A restored pair on Audiogon had new woofer surrounds and replaced EMIT/EMIM drivers within the last five years, indicating that serious investment goes into keeping these systems alive. The external crossover unit alone has been listed for €790, underscoring its importance and scarcity.

Common failures center on age-related materials: foam baffles and surrounds degrade, grills deteriorate, and cabinet finishes suffer. But the system is serviceable. Foam surround repair kits (2A12-12) are available, and driver replacement is possible. However, given the 4-ohm impedance and 100Wpc minimum power requirement, driving these speakers demands a robust amplifier—another consideration for potential buyers.

For collectors, the RS-4.5 is less a financial investment than a labor of love. It’s not for the casual listener. It’s for the enthusiast who values engineering audacity, who doesn’t mind the quirks of vintage gear, and who wants a speaker that doesn’t just play music—it dissects it.