1825PM Duet Plus Loud Ringer

Analog Loud Ringer & Paging Amplifier

The Algo 1825PM Duet Plus is a high performance low-frequency loud ringer for high noise / wide area environments where telephone ringing is difficult to hear (e.g. factory, machine shop, warehouse, lunch room). The Duet Plus can also help to avoid missed calls due to a hearing impairment. The device interfaces to a CO line or with any telephone system via an analog FXS port, ATA or contact closure such as a night bell.


Loud ringing can be activated by a relay or switch closure (dry contacts), low voltage detection, 90V analog telephone ringing, or the headset jack on selected Nortel Norstar and BCM digital business telephones.

Non-Irritating Tone Output

The 1825PM Duet Plus can be wall mounted in office or quiet warehouse applications utilizing its built in speaker to generate up to 93 dBA (at 1m) warble tones. An optional 1186 Horn Speaker is available for very loud or outdoor requirements (112 dBA at 1m). The combination of lower frequency warble and high sound pressure level creates an extremely effective and pleasant telephone alert for large or noisy locations.

Amplified Voice Paging

An additional feature of the 1825PM Duet Plus is its capability to provide amplified voice paging as a separate application or in combination with loud ringing utilizing the same speaker. The Duet Plus is a cost effective solution for small warehouse, storage yard, or machine shop applications where single speaker coverage is adequate. Separate volume control is provided for voice page and loud ring levels.

Other useful features include adjustable warble frequency, adjustable volume, and integrated test button.

Key Features

  • Convenient 90 volt ring detection via an RJ11 modular jack
  • Avaya IPO connectivity directly to an FXS port for “wet” paging
  • Auxiliary speaker output for connection to existing amplifier/paging systems
  • Dry contact activation from push-button, Algo doorphone controllers, or PBX Night Bell/Auxiliary Ring contacts
  • Operational from the headset jack of Nortel Norstar and selected Meridian 1 station sets
  • Easy connectivity to BCM Media Services Card using optional 2503 BCM Connector Kit
  • Visual Ring indication with optional 1128 Analog LED Strobe Light or 1127 Visual Alerter
  • Low frequency tone output provides effective non-irritating notification of telephone and paging signals
  • Interfaces easily with optional Algo 1186 Horn Speaker to provide increased loud ringing or voice paging volume
  • Adjustable volume and frequency controls to suit user preferences
  • Designed for easy wall mounting


Typical 1825 Duet Plus Application in a Warehouse

  • Machine shops
  • Small Warehouses
  • Outdoor work yards
  • Farms
  • Lunch rooms
  • Hearing impaired

Audio Sample from 1825 Duet Plus

Click the play button below for a short audio sample of the Duet's low frequency warble tone.

Ordering Guide

Description Product Code
Duet Plus with 24V Power Supply (North America) - 117V 60 Hz adapter and 2501 Modular Cord 1825PM
Horn Speaker (weatherproof) 1186

1825 Duet Plus Loud Ringer


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