Electrical – Connected 12V-1.0A transformer instead of 12V-1.5A


I'm using an Inspire 2.1 2400 audio set –

The set comes with a 12V-1.5A transformer, and I just connected a same-voltage-lower-ampers (12V-1.0A) transformer into it, and everything works pretty much the same..

Does it make any internal damage? What's the actual effect of lower ampers?


Choosing power supply, how to get the voltage and current ratings?

doesn't really answer my question .. I asked what happens if I plug in a lower amperage transformer.

Best Answer

Most audio systems in this class use class AB linear power amplifiers. At very low volume this type of amplifier operates in class A, drawing a small constant current. At higher volume it changes to class B, where it only draws enough current to deliver the required volume to the speaker.

The Creative Inspire 2.1 2400 uses a TDA8410J, which integrates 3 class AB power amps into a single IC. The set comes with a 12V 1.5A power adapter because the manufacturer has determined it needs that much power at maximum audio output. At lower volume it needs less power, so a smaller adapter could be used so long as you keep the volume down.

If you try to run the amp at higher power than your power supply can handle a number of things may happen:-

  1. The power supply could overheat and burn out, or shut down due to excessive current draw.

  2. Its output voltage may drop, distorting the peaks of the audio waveform.

  3. There may be increased mains frequency 'ripple' or hum which becomes audible at high volume.

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