Active omnidirectional sound source Lookline active S
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Omnidirectional sound source: the dodecahedron
A dodecahedron consists of 12 loudspeakers that approximate a spherical radiation. Requirements for such loudspeakers can be found in ISO3382 and ISO140.
Typical dodecahedrons have a size (diameter) of 20 to 50 cm. In practice, one always tries to find a compromise between low weight and maximum sound level.
A sound source for room acoustic measurements does not have to weigh 15 kg!
Acoustic measurements are traditionally carried out using pink noise. This method has been state of the art since the 1950s and often requires enormous sound levels from the source. As a result, the loudspeakers are large and heavy.
By using correlation methods (from 1980), the sound levels required for acoustic measurements can be reduced considerably.
The state of the art is the chirp method. See also DIN EN ISO 18233:2006-08 (Acoustics - Application of new measurement methods in building and room acoustics)
Background information on the chirp method
With our Akulap software, you can easily carry out room acoustic measurements using the chirp method.
Acoustic source in a compact housing - Lookline active S
Twelve loudspeakers, the digital amplifier and a generator are combined in one device. This makes the dodecahedron extremely compact and suitable for mobile measurements. It is very easy and quick to set up.
To operate the omnidirectional sound source, simply supply it with mains voltage or, if available, with a battery.
Then all you have to do is switch on the power switch. You can also activate all of the sound source's functions remotely using the remote control.
Extended frequency response from 50Hz to 20kHz
All models have an equalizer that linearly extends the frequency response from 50 to 20,000 Hz.
Connection of external sources via Aux input
An AUX input (6.3mm jack) is available for playback of external signals.
remote control
The remote control's function is not limited to "Play/Stop" of the source, but enables all functions via its 16 buttons.
These include:
- Memory for 8 different types of signals
- 4 calibrated power levels with direct access
- Volume control in calibrated 2 dB steps
- Storage of the last used sound and its volume
- Long range through walls and floors
- Power supply: 2 AA alkaline batteries. Shelf life over 2 years.
noise generator
The dodecahedron can generate the following signals
- white noise
- pink noise
- Sine sweep: is a sinusoidal signal with variable frequency and exponential frequency change over time. It produces a sound level about 10 dB higher than pink noise.
- Impulse: produces a sound similar to that of a balloon bursting or a gunshot. This allows measuring the reverberation time using the impulse method.
All stored signals are available in two frequency ranges of (100 to 8,000) Hz, specifically for measurements in buildings, and (50 to 20,000) Hz for more sophisticated measurements in theaters, concert halls, etc.
The housing is custom made of composite material
Many manufacturers try to produce a dodecahedron using a 3D printer. This can easily produce a good aesthetic result. However, the mechanical properties are inadequate. There is currently no 3D printing material available with the necessary stability and acoustic damping. Housing resonances have a significant impact on the measurement.
This dodecahedron is therefore made from a composite material that combines high stability, high damping and low weight.
The housing is pressed from a mold and therefore has the ideal spherical shape, in contrast to classic dodecahedrons made of wood. This dodecahedron is therefore a spherical omnidirectional sound source. The annoying diffraction effects at the edges are eliminated.
Technical data
- Conforms to: ISO16283; ISO140/3; ISO10140; ISO 3382; DIN 52210
- Sound power LW : 119 dB ref 1pW
- Diameter: 26 cm
- Total weight: (amplifier + source) 4.9 kg
- Frequency response: 50- 20,000Hz
- Power amplifier: 150 W RMS
- remote control
- External input: Line-In jack 6.3 mm 1.1 V Rms/10 kOhm
- Power supply: AC 230 V
Conformity:
- UNI EN ISO: 140-4, 10140, 16283-1, 3382, 354;
- Directivity (D) according to: 140, 16283 and 3382.
- CE
Options (not included)
- cable
- transport bag
- tripod
