Williams AV FM 558-24 PRO – FM+ Assistive Listening System, 24 Receivers

Product Overview

The Williams AV FM 558-24 PRO is a large-venue assistive listening system built around the FM+ T55C transmitter, which broadcasts program audio over FM and Wi-Fi at the same time. The package supplies 24 PPA R38N body-pack receivers plus professional installation accessories — remote coaxial antenna, rack panel kit, 12-bay chargers, and ADA signage — so AV integrators can deliver ADA-compliant hearing assistance in auditoriums, houses of worship, and government facilities from a single SKU. Listeners without a receiver can stream the same audio to their own phones through the WaveCAST app over the venue's Wi-Fi network.

Product Description

The FM+ T55C transmitter occupies half of a 1RU rack space and is mounted with the included RPK 005 rack panel kit in any standard 19-inch equipment rack. Audio enters through a combination 3-pin XLR / 1/4-inch TRS jack that accepts balanced or unbalanced microphone or line-level signals, with selectable phantom power for condenser microphones. Onboard DSP provides selectable compression (1:1, 1.5:1, or 2:1) and adjustable high-pass and low-pass filtering, shaping the signal for maximum speech intelligibility. Configuration is handled on the 3.12-inch OLED front-panel display or remotely through the transmitter's hosted web page, and the unit can be managed by third-party room control systems over its RJ-45 Ethernet connection.

On the listening side, each of the 24 PPA R38N receivers offers a 1-inch OLED display, menu-based selection across 17 wideband FM channels (72.1–75.9 MHz), and channel lock to prevent accidental retuning. Receivers run up to 50 hours on AA alkaline cells or 32 hours on the included NiMH rechargeable batteries, which charge in the two CHG 3512 12-bay drop-in chargers supplied with the system. Twenty-four EAR 022 surround earphones and six NKL 001 neckloops accommodate listeners with and without telecoil hearing aids, while the ANT 005 remote coaxial antenna extends FM coverage up to 1,000 feet. The IDP 008 ADA wall plaque completes the compliance picture at the venue entrance.

If your audio infrastructure runs on Dante, step up to the FM 558-24 PRO D with Dante input. Explore more options in the Williams AV collection at Creation Networks.

Key Features

• Simultaneous FM and Wi-Fi Broadcast — A single FM+ T55C transmitter serves dedicated FM receivers and unlimited smartphone listeners on the WaveCAST app at the same time.
• 24-Receiver Fleet — The package includes 24 PPA R38N OLED receivers with 17 selectable wideband channels and channel lock for managed deployments.
• 12-Bay Drop-In Charging — Two CHG 3512 chargers and 24 sets of NiMH rechargeable batteries keep the full receiver fleet charged between services or sessions.
• Professional Install Accessories — The ANT 005 remote coaxial antenna, RPK 005 rack panel kit, and IDP 008 ADA wall plaque are included for a complete commercial installation.
• DSP Speech Processing — Selectable compression and filter settings tailor the audio for hearing-impaired listeners in speech or music applications.
• Telecoil Support — Six NKL 001 neckloops couple receiver audio magnetically to telecoil-equipped hearing aids and cochlear implants.
• Network Remote Control — The hosted web interface over RJ-45 Ethernet enables remote monitoring, configuration, and integration with room control systems.
• Long FM Range — FM coverage extends up to 1,000 feet with the included antenna, covering large seating areas without repeaters.

Typical Applications

• Auditorium
• House of worship
• Government space
• Multi-purpose room
• All-hands room
• Commercial meeting space
• Training room

Technical Specifications

Frequently Asked Questions

What audio sources can feed the transmitter?

The FM+ T55C accepts a balanced or unbalanced microphone or line-level signal through its XLR/TRS combo input, with selectable phantom power. Typical sources include a DSP output, mixer bus, or paging system line out.

How many people can use this system at once?

All 24 included R38N receivers can operate simultaneously, and the Wi-Fi stream supports an unlimited number of additional listeners using the WaveCAST app on their own devices.

Is professional installation required?

Yes. The FCC requires the transmitter to be professionally installed and used with approved FCC 15.203 compliant antennas, such as the included ANT 005 remote coaxial antenna.

Does the Wi-Fi side need its own network hardware?

The FM+ connects to your existing facility Wi-Fi network via Ethernet; it does not generate a wireless network on its own. Coordinate with IT to confirm network capacity for streaming listeners.

Can this system support more receivers later?

Yes. Additional PPA R38N receivers can be added at any time, and the system supports any number of FM listeners on the selected channel.

What does the warranty cover?

The transmitter carries a 2-year parts and labor warranty; the R38N receivers carry Williams AV's Lifetime PLUS Limited Warranty, with 90 days of coverage on most accessories.