IEC 62368-1-Annex E.2 Testing box | Audio amplifier normal operating temperature measurements box
Test conditions for equipment containing audio amplifiers
E.2
Audio amplifier normal operating conditions
Equipment containing an audio amplifier shall be operated using a sine wave audio signal source at a frequency of 1 000 Hz. In the case where an amplifier is not intended for operation at 1 000 Hz, the peak response frequency shall be used.
The equipment shall be operated in such a way as to deliver 1/8 non-clipped output power to the rated load impedance. Alternatively, a band-limited pink noise signal may be used for operation after non-clipped output power is established using a sine wave. The noise bandwidth of the pink noise test signal shall be limited by a filter of a characteristic as shown in Figure E.1.
If visible clipping cannot be established, the maximum attainable power shall be considered as the non-clipped output power.
In addition, all of the following conditions shall be considered under normal operating conditions:
– The most unfavourable rated load impedance or the actual loudspeaker, when provided,is connected to the amplifier output.
– All amplifier channels are operated simultaneously.
– Organs or similar instruments that have a tone-generator unit shall not be operated with the 1 000 Hz signal, but instead be operated with any combination of two bass pedal keys,if present, and ten manual keys depressed. All stops and tabs that can increase the output power shall be activated and the equipment shall be adjusted to deliver 1/8 of the maximum attainable output power.
– Where the intended amplifier function depends on phase difference between two channels, there shall be a phase difference of 90° between signals applied to the two channels.
–For equipment containing multi-channel amplifiers, where some channels cannot be operated independently, those channels shall be operated using the rated load impedance at the output power level that corresponds, by design, to 1/8 of the non-clipped output power of the adjustable amplifier channel(s).
–Where continuous operation is not possible, the amplifier shall be operated at the maximum output power level that allows continuous operation.
The temperature measurements shall be carried out with the equipment positioned in accordance with the instruction manual provided by the manufacturer, or, in the absence of instructions, the equipment shall be positioned 5 cm behind the front edge of an open-fronted wooden test box with 1 cm free space along the sides and top and 5 cm depth behind the equipment.
