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Frequency Filter Sound Level Limiter-recorder

Frequency Logger-limiter that controls the whole sound chain with a own LCD screen and a keyboard.

  • Control by emission Sound Pressure Level or reception SPL (insulation)
  • It registers all incidents
  • It can be completely sealed
  • Adaptable to any kind of regulation
  • It does not cut out the music when using the ENOS option
  • Internal Battery
  • Data retrieval by LCD Screen, printer, serial connection with PC and modem
  • Controls noise from: discos, theme parks, exercise studios, sports stadiums, ...
  • Other applications include: noise between dwelling units, noise control for the community...

Main Features

The LRF-04 frequency filter sound level logger-limiter controls the entire sound chain in octave bands. The unit consists of an integrating-averaging frequency band (octaves) sensor and an attenuator of over 40 dB, which functions by analysing and calculating the power of the octaves in real-time, taking full advantage of the insulation of the room and achieving maximum sound pressure without either disturbing the neighbours or modifying the reproduction quality (it is not a compressor).

The room´s sound pressure, the automatic attenuation level, the date, incidents and the operation mode are permanently displayed on the screen.

The LRF-04 has a permanent memory to store the programming information and data obtained during the past 60 days, even when disconnected from the electricity supply. There is also a battery available to continue storing information for over 1 day without connection to AC power.

NOTE: This model has the option ENOS (Extraneous Noise Override System), specially designed for the local music reproduction with high ambient noise level: bars, pubs, restaurants,etc. IT DOES NOT CUT THE MUSIC. With the ENOS, the limiter controls the music so that it never exceeds the programmed limit, regardless of the noise generated by customers.

PC Software

LRF-04 Software

SFTL04 is a comprehensive software application that allows you to: display numerically and graphically data registered by LRF-04 and choose the displayed interval, generate reports of the data supplied by the software, personalize these reports by writing a maximum of 50 characters as a footnote, study in detail all the sound levels and incidences, acquire data via Modem, display, in real time, the data measured by the LRF-04, program all the parameters of the LRF-04 on just one screen and erase the LRF-04 memory.

SFTL04 shows the Time History data and the time representation of incidences, this way it is possible to study, in detail, what happens in the establishment, the sound levels produced, if the sensor has been tampered with and when.

SFTL04 provides you with a convenient, user-friendly environment for obtaining, in digital format, data acquired by the LRF-04.

Optional accessories


Giant external display of 61x32x8 cm with digits of 10x6.5 cm with cable 10m


External display with cable (10m)


RS232 connection cable for PC


MR210 Modem 


MR210 modem with AM400 power supply


Adapter via LAN


Adapter via LAN with feeder


Adapter via Wi-Fi


Adapter via Wi-Fi with feeder


Pliers for sealing


Plastic seals 9 mm diameter (100 units)


Special wire for sealing (10 m roll)


Controlling relay box with 2 relays


USB cable for the communication with a computer


Screws for sealing


Back cover for sealing connections


Feeder for communication module