Williams AV FM 557-12 PRO – Turnkey Assistive Listening Kit, 12 Receivers

Product Overview

The Williams AV FM 557-12 PRO is a turnkey assistive listening kit that equips a mid-size venue with everything required for an ADA-compliant hearing assistance installation in one purchase. The FM+ T55 transmitter broadcasts simultaneously over FM and the building's Wi-Fi network, 12 PPA R37N body-pack receivers serve listeners directly, and the PRO accessory set — 12-bay charger, rechargeable batteries, remote coaxial antenna, and rack panel kit — covers the installation details that base packages leave out. It is a practical, single-SKU answer for AV integrators specifying hearing assistance in commercial meeting spaces and worship venues.

Product Description

Williams AV designed the FM+ platform to replace its long-standing FM 457 systems, keeping the dependable 72 MHz FM broadcast that body-pack receivers rely on while adding Wi-Fi streaming so attendees can also listen on their own phones — all from one half-rack transmitter at close to traditional FM system cost. The T55 transmitter takes balanced or unbalanced microphone or line-level audio through a combination XLR/1/4-inch input with selectable phantom power, applies DSP-based compression and filtering tuned for speech, and confirms levels on a 10-segment LED meter. Operators work from a 3.12-inch OLED display, while a hosted web page and Telnet-over-Ethernet commands give facility staff and control systems remote access for monitoring and adjustment. The dozen PPA R37N receivers each access 17 wideband channels between 72.1 and 75.9 MHz via a seek button inside the battery compartment, support channel lock to prevent accidental retuning, and pair with the included EAR 022 surround earphones; three NKL 001 neckloops couple audio to telecoil-equipped hearing aids. The CHG 3512 12-bay charger and 12 NiMH battery sets sustain the fleet at roughly 32 hours per charge. The ANT 005 remote antenna reaches up to 1,000 feet of transmission range, and the RPK 005 kit racks the transmitter in one EIA space. FCC rules require professional installation with a compliant antenna. Venues planning a Dante audio backbone should look at the FM 557-12 PRO D Dante variant; the full product family lives in our Williams AV collection.

Key Features

• Single-Box FM and Wi-Fi Broadcast — The T55 transmitter delivers both transmission types simultaneously, serving hardware receivers and smartphone listeners from one rack unit.
• Turnkey PRO Accessory Set — Charger, rechargeable batteries, remote antenna, and rack panel kit arrive in the box, so no separate accessory orders are needed for installation.
• Twelve R37N Receivers — Body-pack receivers with surround earphones meet mid-size venue ADA receiver requirements and carry a Lifetime PLUS limited warranty.
• Channel Lock Protection — Receivers can be locked to the house channel, preventing audience members from accidentally retuning during an event.
• Rechargeable Fleet Management — The CHG 3512 12-bay drop-in charger restores all twelve receivers overnight with no battery swapping.
• Speech-First DSP — Selectable compression ratios and high/low-pass filtering shape the broadcast for intelligibility with hearing loss.
• Remote Management — The hosted web page and Telnet control over Ethernet support off-rack monitoring and third-party control integration.
• 1,000-Foot Range — The ANT 005 remote coaxial antenna covers large floor plates and overflow spaces from a single transmitter.
• ADA Signage Included — The IDP 008 wall plaque publicly identifies the venue as equipped with assistive listening.

Typical Applications

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

Technical Specifications

Frequently Asked Questions

What makes this a turnkey kit?

Everything an installer needs ships together: transmitter, twelve receivers with earphones and neckloops, a 12-bay charger with rechargeable batteries, the remote coaxial antenna, the rack panel kit, and ADA signage. No add-on orders are required to commission the system.

How does the transmitter connect to my existing sound system?

Feed it a line-level output from your mixer or DSP via the combination XLR/1/4-inch input, or connect a microphone directly with selectable phantom power. Input gain adjusts in 1 dB steps from the menu.

Can the Wi-Fi stream and FM broadcast run different audio?

No — both carry the same program feed. The dual transmission simply gives listeners a choice between a supplied R37N receiver and their own smartphone on the venue Wi-Fi network.

How long do receivers run between charges?

About 32 hours on the included AA NiMH rechargeable batteries, or roughly 50 hours if you substitute disposable AA alkaline cells — enough for a full week of typical service schedules.

Does installation require an outside contractor?

The FCC requires professional installation with an approved FCC 15.203-compliant antenna such as the included ANT 005. Many AV integrators handle this as part of a larger sound system project.

What support and warranty come with the system?

The transmitter carries a two-year parts and labor warranty; R37N receivers are covered by a Lifetime PLUS limited warranty, with earphones, headphones, and batteries excluded.