JBL 2370A

A 2-inch throat fiberglass horn that throws a tight, controlled 60° x 40° pattern — the workhorse of countless installed sound systems and touring rigs.

Overview

The JBL 2370A is the kind of component that rarely gets a second glance at a yard sale but quietly anchors professional sound systems for decades. It's a large-format, bi-radial constant coverage horn, built from black fiberglass, and designed to mate with JBL's 2-inch throat compression drivers. At 8.3 pounds and roughly 18 inches wide, it's a substantial piece of engineering that prioritizes controlled dispersion over sheer output — though with the right driver behind it, output is rarely a concern.

This is the "A" version of JBL's 2370 horn, part of the company's professional loudspeaker components line. The "A" suffix, according to user discussions, typically indicates an updated version or a version with a slightly different mounting arrangement — one forum contributor describes it as "the same horn with a different mounting flange." JBL's own spec sheet doesn't elaborate on the difference, so collectors and system designers treat the 2370A as the refined iteration of an already proven design.

What makes the 2370A genuinely interesting is its bi-radial flare shape. Unlike simple exponential horns that spread energy in a single pattern, the bi-radial design controls horizontal and vertical coverage angles separately through the horn mouth. The result is a 60° x 40° pattern that stays remarkably consistent across its operating range — the kind of predictability that makes system design and deployment significantly more straightforward. It's the difference between hoping your coverage works and knowing it will.

Key Features

Bi-Radial Constant Coverage Design

The 2370A's defining characteristic is its bi-radial flare shape, which JBL branded as "BI-RADIAL® Constant Coverage." The geometry allows the horizontal and vertical dispersion angles to be shaped independently, giving system designers precise control over how sound spreads through a venue. The horn delivers a 60° horizontal by 40° vertical coverage pattern, with a directivity factor (Q) of 12 and a directivity index (DI) of 10.8 dB per the JBL spec sheet. Yorkville's independent listing confirms the 60 x 40 degree coverage, and the measured angles — SC of 57.5°, VC of 42.5°, BC of 40°, and CC of 55° — show the engineering tolerances at work. This is a horn that behaves predictably, which in professional audio is worth more than any single frequency response number.

2-Inch Throat for Serious Drivers

The 2370A is built around a 2-inch throat, meaning it's designed to pair with JBL's larger compression drivers — specifically the 2445, 2446, 2447, and 2450 series. The JBL product sheet lists compatible drivers as the 2445H, 2446H, 2447J, or 2450J, while Yorkville specifies the 2445J, 2446J, 2447J, or 2450J. The slight suffix variation between sources reflects different magnet or diaphragm configurations, but the takeaway is the same: this horn is meant for serious, high-output professional drivers, not home hi-fi tweeters. With a rated impedance of 8 ohms (matching the recommended drivers) and a power capacity of 150 watts continuous program (AES), the 2370A can handle substantial signal when paired appropriately.

Fiberglass Construction with Black Finish

JBL built the 2370A from fiberglass, a material choice that balances weight, rigidity, and acoustic damping. At 8.3 pounds (3.8 kg), it's light enough for a single technician to handle during installation, yet stiff enough to resist the resonances that plague lesser horn materials. The black finish is standard across the professional line — no walnut veneer or designer grille cloth here, just functional, road-ready durability. The horn mouth area measures 208 square inches (1342 cm²), with a flare rate of 10 and a biradial flare shape. For installation work, the baffle cutout dimensions are specified at 14.25 inches in length and 6.25 inches in width, giving cabinet builders exact measurements for flush mounting.

Frequency Range and Crossover Considerations

The 2370A covers from 1 kHz to 16 kHz, with JBL recommending a crossover point of 1.2 kHz or higher. ProSoundWeb users echo this, noting the horn "goes down to about 1.2 kHz" in practical use. This makes the 2370A a mid-high horn in the classic sense — it's not trying to reproduce vocals from 500 Hz, and it doesn't need to. The recommended crossover of 1.2 kHz or higher keeps the driver operating in its comfort zone, where the horn's constant coverage characteristics hold true. Typical total harmonic distortion is rated at ≤5%, which for a large-format horn of this era is respectable, particularly given the SPLs these units are expected to produce in professional settings.

Reception & Use

Among working sound professionals, the 2370A has earned a reputation as a reliable, cost-effective solution for high-frequency reproduction in installed and touring systems. ProSoundWeb contributor Bob Leonard, who used the horns with 2445J drivers for years, describes the 2370A as "a good horn for the money" — a sentiment that reflects its position as a professional tool rather than an exotic audiophile component. Other users report they "sound fine with 2446J drivers," suggesting the horn pairs well across JBL's 2-inch driver lineup.

That said, the 2370A isn't without its critics. Some users describe "a bit of a harsh top end," and at least one forum contributor claims the horn is "not a true constant-directivity horn above 8 kHz," narrowing over 12 kHz. This contradicts JBL's published specs, which list constant 60° x 40° coverage with a DI of 10.8 dB — and manufacturer specifications take precedence over forum opinion. Still, the harshness complaint led at least one user to add a capacitor across the driver terminals to tame the top end, a DIY modification that speaks to the hands-on culture surrounding this gear. Studio Sound (June 1989, p.24) covered JBL's professional line during this period, noting additions to the Sound Power series and the company's ongoing commitment to compression driver mounting systems for horn applications — context that places the 2370A within JBL's broader professional strategy of the late 1980s.

For those considering a 2370A today, the practical realities are straightforward. The horn is designed for 2-inch throat drivers, so it won't work with the 1-inch drivers found in many home hi-fi setups. It's a professional component through and through, meant to be paired with appropriate drivers, crossovers, and amplification. The fiberglass construction has held up well over the years — these horns don't rot, rust, or warp, and the black finish hides the scuffs and scratches that come with real-world use. Whether it's anchoring a church sound system, a small venue's main cluster, or a touring rig's mid-high section, the 2370A remains a viable, well-documented choice for anyone building or maintaining professional loudspeaker systems.