Williams AV FM 558-24 – FM+ Dual FM/Wi-Fi System, 24 Receivers

Product Overview

The Williams AV FM 558-24 is a large-area assistive listening system that combines the FM+ T55C dual FM and Wi-Fi transmitter with 24 PPA R38N receivers. It gives auditoriums, large lecture halls, and worship spaces an ADA-compliant hearing assistance solution that serves both dedicated FM receivers and unlimited smartphone listeners on the WaveCAST app. This is the core system package — transmitter and receivers — for venues that already have antennas, chargers, and rack hardware or prefer to specify those separately.

Product Description

The FM+ T55C transmitter broadcasts the same program audio over 17 selectable wideband FM channels (72.1–75.9 MHz) and, simultaneously, as a Wi-Fi audio stream on the facility network. DSP-based processing with selectable compression and high-pass/low-pass filtering keeps speech clear for hearing-impaired listeners, while a combination XLR/1/4-inch TRS input with selectable phantom power accepts the venue's microphone or line-level feed. The half-rack chassis fits a standard 19-inch rack (one or two units per rack space with optional RPK 005/RPK 006 kits), and a 3.12-inch OLED display plus a hosted web page handle local and remote configuration, including integration with third-party room control systems over Ethernet.

Each of the 24 PPA R38N receivers is a body-pack unit with a 1-inch OLED display, menu-driven channel selection, channel lock, and a detachable belt clip. Receivers operate up to 50 hours on two AA alkaline batteries or 32 hours on NiMH rechargeables, and their bottom charging contacts work with Williams AV CHG 3512 and CHG 3502 drop-in chargers for venues that add charging infrastructure later. Because the Wi-Fi stream carries no listener limit, total audience capacity is not capped by the receiver count — a practical advantage for overflow events.

If you want the full turnkey kit with antenna, chargers, rack panel, neckloops, and ADA signage included, see the FM 558-24 PRO package, or compare the entire Williams AV lineup at Creation Networks.

Key Features

• Dual-Transport Broadcasting — One transmitter delivers FM audio to body-pack receivers and a Wi-Fi stream to the WaveCAST smartphone app at the same time.
• 24 OLED Receivers Included — PPA R38N receivers provide menu-based tuning across 17 wideband channels with channel lock for managed venue deployments.
• DSP Audio Processing — Selectable compression ratios and filter controls optimize intelligibility for assistive listening, interpretation, or audio description feeds.
• Flexible Analog Input — The XLR/TRS combo jack accepts balanced or unbalanced mic or line signals with selectable phantom power and 1 dB gain steps.
• Unlimited Wi-Fi Listeners — App-based listening over the venue network scales audience capacity beyond the included hardware receivers.
• Rack-Mount Form Factor — The half-rack 1RU chassis installs in standard 19-inch racks with optional RPK 005 or RPK 006 mounting kits.
• Network Management — A hosted web page over RJ-45 Ethernet enables remote control, monitoring, and third-party room control integration.
• Long Receiver Runtime — Up to 50 hours on alkaline or 32 hours on NiMH batteries minimizes mid-event battery swaps.

Typical Applications

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

Technical Specifications

Frequently Asked Questions

What is the difference between the FM 558-24 and the FM 558-24 PRO?

Both include the FM+ transmitter and 24 R38 receivers. The PRO adds professional installation accessories: remote coaxial antenna, rack panel kit, 12-bay chargers with rechargeable batteries, neckloops, and an ADA wall plaque. This base package suits venues sourcing those items separately.

Do I need an antenna to operate the system?

Yes. The FCC requires this transmitter to be used with approved FCC 15.203 compliant antennas (such as the ANT 005, ANT 021, ANT 024, or ANT 025) and to be professionally installed.

Does the Wi-Fi streaming require special network equipment?

The FM+ connects to your existing Wi-Fi network through its Ethernet port; it does not create its own network. The facility network must be in place before app-based listening can be used.

Can listeners with hearing aids use this system?

Yes. Receivers output through a 3.5 mm stereo jack compatible with neckloops (such as the Williams AV NKL 001) that couple magnetically to telecoil-equipped hearing aids.

How is the transmitter integrated with room control systems?

The FM+ T55C exposes a hosted web page over Ethernet and supports management by third-party room control platforms, allowing AV staff to monitor and adjust the unit remotely.

What warranty applies?

The transmitter is covered for 2 years parts and labor; the R38N receivers carry a Lifetime PLUS Limited Warranty, with 90 days on most accessories.