Williams AV FM 557-12 PRO – FM+ PRO System Package, 12 R37 Receivers

Product Overview

The Williams AV FM 557-12 PRO system package provides large-area assistive listening for mid-size venues, combining the FM+ T55 dual FM and Wi-Fi transmitter with 12 PPA R37N receivers and a professional installation accessory bundle. Designed for ADA compliance in churches, council chambers, theaters, and corporate meeting facilities, the system reaches listeners through dedicated body-pack FM receivers or through their own smartphones via the venue's Wi-Fi network. The PRO bundle adds the coaxial antenna, rack panel kit, charger, and rechargeable batteries that turn a component list into an installable system.

Product Description

The FM+ T55 transmitter at the center of this package succeeded the widely deployed T45, carrying forward 72 MHz-band FM transmission while adding network audio streaming over Wi-Fi — two delivery methods, one half-rack chassis, priced close to a conventional FM-only system. Program audio enters through a combination XLR/1/4-inch connector that accepts balanced or unbalanced mic or line-level signals, with phantom power selectable from the menu. The internal DSP audio processor provides compression at 1:1, 1.5:1, or 2:1 and adjustable high-pass and low-pass filters, letting the installer tailor the broadcast specifically for speech intelligibility. A bright OLED display handles local configuration, and the rear Ethernet port exposes both a hosted web page and Telnet command control for integration with room control processors — useful when the assistive listening system needs to power-manage or report status alongside the rest of the AV rack. The twelve PPA R37N receivers tune 17 wideband channels from 72.1 to 75.9 MHz, run about 32 hours on the included NiMH rechargeables (managed by the CHG 3512 12-bay charger), and include EAR 022 surround earphones; three NKL 001 neckloops support listeners with telecoil hearing aids. The ANT 005 remote coaxial antenna provides up to 1,000 feet of range, and the RPK 005 kit mounts the transmitter in a standard 19-inch rack. FCC regulations require professional installation with an approved antenna. Smaller rooms can deploy the FM 557 PRO four-receiver package; see the Williams AV collection for the complete assistive listening lineup.

Key Features

• Dual-Path Audio Delivery — One transmitter broadcasts FM to the included receivers while streaming the same feed over venue Wi-Fi to listeners' smartphones.
• Mid-Size Receiver Complement — Twelve PPA R37N receivers with surround earphones align with ADA receiver-count guidance for venues in this capacity range.
• Install-Ready Accessories — The ANT 005 antenna, RPK 005 rack panel kit, and coax cable prepare the system for a professional equipment-rack installation.
• 12-Bay Charging Station — The CHG 3512 charger and included NiMH batteries keep every receiver charged from one central location.
• Adjustable DSP Processing — Selectable compression and filter settings let installers optimize the signal for spoken-word clarity.
• OLED Display and Web Control — Local menu navigation plus a hosted web page simplify configuration, monitoring, and troubleshooting.
• Control System Integration — Telnet over Ethernet allows third-party control processors to manage the transmitter remotely.
• 17 Selectable Channels — Wideband operation between 72.1 and 75.9 MHz supports multiple simultaneous systems within one facility.
• Unlimited Listener Expansion — The FM broadcast accommodates any number of receivers, so capacity grows by adding R37N units only.

Typical Applications

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

Technical Specifications

Frequently Asked Questions

Which venues is the 12-receiver package sized for?

Mid-size assembly spaces — sanctuaries, theaters, council chambers, and corporate meeting facilities — where ADA receiver-count guidance calls for roughly a dozen units. Larger venues can step up to the 24-receiver FM 557-24 PRO, and the FM broadcast supports more receivers at any time.

Does the system include everything for installation?

Yes — the PRO bundle adds the ANT 005 remote coaxial antenna, RPK 005 rack panel kit, CHG 3512 charger, and NiMH batteries to the standard system contents. Professional installation with an FCC-compliant antenna is required by the FCC.

How does smartphone listening work?

The T55 transmitter joins the venue's existing Wi-Fi network and streams the program audio to listeners' phones. The transmitter does not create its own network, so working venue Wi-Fi is a prerequisite for the streaming feature.

Can the transmitter be monitored remotely?

Yes. It hosts a configuration web page and accepts Telnet commands over its Ethernet port, allowing facility staff or an integrated control system to monitor status and adjust settings without rack access.

Are the receivers protected against accidental retuning?

Yes. The PPA R37N supports channel lock, and the channel seek button sits inside the battery compartment, so audience members cannot inadvertently change channels mid-event.

What warranty applies?

The transmitter carries a two-year parts and labor warranty; each R37N receiver is covered by a Lifetime PLUS limited warranty, excluding earphones, headphones, and batteries.