I am currently designing an audio amplifier and am uncertain about the power supply requirements. Could somebody please give me some feedback on my supply requirement calculations/logic.
The amplifier will be 5 channels. The amplifier IC's I will be using (LM4780) can supply around 20W rms per channel into an 8 ohm load if I power it off +/-20V. So lets say I use a 15-0-15 transformer rectified to around +/-20V, how do I determine the current drawn from the transformer?
I've been working it out as follows:
5 channels at 20W each = 100W total
I = P/V = 100/15 = 6.7amps
So I believe I need a 15-0-15 transformer capable of at least 7A.
Now bearing in mind that the amplifier will be used for a home theatre setup and thus its not likely all 5 speakers will be drawing the full 20W simultaneously, do I still need to use a 7A supply or can I relax this requirement (and by how much).
Or have I gone about this incorrectly?
Thanks.
The amplifier will be 5 channels. The amplifier IC's I will be using (LM4780) can supply around 20W rms per channel into an 8 ohm load if I power it off +/-20V. So lets say I use a 15-0-15 transformer rectified to around +/-20V, how do I determine the current drawn from the transformer?
I've been working it out as follows:
5 channels at 20W each = 100W total
I = P/V = 100/15 = 6.7amps
So I believe I need a 15-0-15 transformer capable of at least 7A.
Now bearing in mind that the amplifier will be used for a home theatre setup and thus its not likely all 5 speakers will be drawing the full 20W simultaneously, do I still need to use a 7A supply or can I relax this requirement (and by how much).
Or have I gone about this incorrectly?
Thanks.
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