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owolff.com ›› Acoustics news ›› Ultra slim 48x48x12mm speaker
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Ultra slim 48x48x12mm speaker

Ultra slim 48x48x12mm speaker

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As IoT speaker, for conference phones and/or alarm applications

This new powerful, low profile loudspeaker was especially developed for devices with high SPL requirements such as speech/alerts, alarms audio info systems, IoT devices, conference phones etc.

The slim profile allows the driver to be built into many low profile designs.
Maximum loudness performance will be with a sealed back cavity of 75cc, which results in a resonance frequency of 335Hz.
Under these conditions thedriver can handle up to 5W (resulting in a Sound Pressure Level of 92dBSPL/m) without any thermal challenges due to its extremely large voice coil diameter of 30.5mm with surrounding ventilation holes.
September 09 2021
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Key performance parameters

  • Very low profile (12.1mm)
  • High linear excursion (±1 mm)
  • Sensitivity: 86±2 dB (1.0W/1.0m)
  • Good bass response in small enclosures (230Hz/200cc, 335Hz/75cc, 520Hz/30cc.)
  • High power handling (Nom./Max.): 2.0W / 3.0 W (in any size of rear volumes)
  • Up to 5W Nom. power handling in a sealed rear volumes of 30-200cc resulting in 94.5 dBSPL @1m.

Ultra versatile

Install the 48mm driver in a slim enclosure for impressive performance

The slim profile allows the driver to be built into many low profile designs.

Ultra versatile



Frequency response and impedance

Free field, 1V 5cm

Frequency response and impedance

Also for fire-, burglar- and smoke alarm applications

For both 520 Hz and 3 kHz systems

• Suitable for smoke-, fire- and burglar alarms.
• 520Hz & 3 kHz alarm for hotels & residential.
• Complies with UL 217 & UL 464 standards.

The US standards UL 217 & UL 464** describes criteria to be met for hotel & Residential fire/smoke alarms. Two specific frequencies, 520Hz & 3kHz are mentioned as tones essential for maximum alert effect:

520Hz: 3 Meters distance: 85 dBA
3kHz: 3 Meters distance: 85 dBA

The 484812 loudspeaker was tailored to meet these fire/smoke alarm standards when built into a suitable enclosure (please refer to the cross sectional cut drawing below). The speaker's resonance frequency is pushed up to 520Hz and the Helmholtz resonator in front of speaker will boost the 3kHz sensitivity to its maximum.

Under these conditions, when driving the speaker system with a square wave signal, the following SPL levels are met and exceeded:

520Hz: 85dBA/3 Meters/5W.
3 kHz: 85dBA/3 Meters/5W
Also for fire-, burglar- and smoke alarm applications
Housed in a cyllindrical enclosure [Ø 53mm h: 21mm] the resonance frequency will be shifted to 520 Hz and the Helmholz resonator in the front of the driver will boost 3 kHz
With the proper enclosure, the driver can reach sound pressure levels that comply with both 520 Hz and 3 kHz alarm standards . The plot shows the SPL at 3 meters, sine wave input.

**US standards UL 217 & UL 464
While fire alarm systems and smoke alarms provide life-saving value for people when they are awake, their greatest potential benefit may be when occupants are asleep. In 2008, a compilation of a decade’s worth of research at Victoria University on the effectiveness of various alarm signals for awakening people was released. Different types of signals were tested to determine their waking effectiveness for healthy adults and high-risk groups. Of all the signals tested, the low frequency signal with a fundamental frequency of 520 Hz was most effective at waking the majority of participants. Specifically, the low frequency signal was found to be 6 to 10 times more effective at waking people than the standard alarm signal. In adults with hearing loss, it was more than 6 times as effective as the standard signal and more effective than bed and pillow shakers.

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Please use the red "Request more info" button at the top of this page if you want to learn more about the OWS-484812 driver, or contact your local Ole Wolff representative.
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