Norsonic - Model Nor280 -Power Amplifier

• Specially designed for Building Acoustic measurements
• Lightweight and rugged construction - only 3,5 kg!
• Self contained noise generator
• 500 Wrms output power
• Emits 120 dB sound power level in the 50—5000 Hz frequency range when used with Norsonic dodecahedron loudspeakers types Nor275 or Nor276
• Wireless remote control of noise generator (optional)
• Equalization network to optimise acoustic output from speaker
• Balanced signal input for low noise and limited cross talk problems

• Sound insulation measurements
• Reverberation time measurements
• Absorption coefficient measurements

The Building Acoustics Standards place heavy demands on loudspeakers and as such many may be destroyed if traditional PA power amplifiers are used to drive them. These amplifiers are normally very powerful and designed to give a flat frequency response covering a much wider range that the speaker system can handle. Feeding these systems with broadband pink or red/white noise may destroy the speaker; the low frequency content of the noise causes the speaker cone to move with much higher amplitude than its design limits. Hence, the speaker coil or the cone itself may be destroyed. In addition a lot of energy is wasted in the low frequency area below 15Hz.

To overcome this problem, and to optimise the power where it is needed, a unique built in equalization network compensates for the falling frequency response of the speaker system in both the low and high frequency areas.

This also ensures that the 5 dB requirements between neighbour frequency bands are met when used in combination with the Nor275 or Nor276 loudspeakers. A part of the equalization network is a high pass filter that removes low frequency signals that lie below the required frequency range for building acoustic measurements and a low pass filter that removes all frequencies above 12kHz. This feature protects the speakers from distortion and concentrates power into the frequency bands where it is needed.

The class D amplifier construction ensures low weight, high power output and low heat dissipation. The amplifier delivers up to 500Wrms into a 4 ohm load and an output current of up to 35 Amp!

Both the input and output of the amplifier are short circuit protected and an automatic system will guard against overheating and too high signal voltage on the input. The built in cooling fan is normally not running. Only at high room temperatures or prolonged use of the amplifier at full power will the fan switch on. It will however, immediately switch off when the input signal goes off; this feature makes the unit well suited to reverberation measurements in areas of low background noise.

The noise generator features both Pink, White and Red/White noise excitation signals. The noise or line signal can be attenuated in 5 dB steps to –35dB . By adding option 1, wireless on/off you may switch on/off the signal remotely from another room. The balanced line input ensures minimum cross talk and induced noise when using long signal cables.

• Output: Short-circuit and over-temperature protected
• Output connector: Speakon NL4MP
• Output power:
• 500 WRMS RMS into 4ohm
• 250 WRMS RMS into 8ohm
• THD+N < 0.1%
• The built-in LP and HP filters ensure that the output power matches the Norsonic Nor275 and Nor276 series of dodecahedron loudspeakers
• Peak power: >1 kWPEAK into 4ohm
• Output current: Maximum 35 A
• Input: Balanced input to avoid ground loops and cross talk to signal cables
• Input connector: XLR
• Input sensitivity: 1.0 VRMS
• Input impedance: 10 k//220 pF
• Dimensions: (D x W x H) 275 × 110 × 246 [mm]   11 x 4,3 x 9,7 [inch]
• Weight: 3,5 kg
• Temperature: –20 to +35 °C
• Rel. Humidity: 0–90%
• Enclosure class: IP20
• Mains: 220 VAC (±10%) or 110 VAC (±10%)
• Fuse: T 3,15A (220 V), T 6A (110 V)
• EMC and Safety Standards: EN 55103-1, EN 55103-2, IEC 61340-5 part 1&2, IEC 61010, FCC part 15b part 1&2

• Accessories incl.: Mains cable, Output connector
• Optional accessories:
• Nor1494/5: Cable (5m) for connecting Nor275 or Nor276 to Power Amplifier Nor280.
• Nor1494/01: Opt. 1 : Special length; add/subtract per metre (maximumlength is 25m).