What Determines The Amount Of "Current" In An Amp?

current is one of factor of power(watts per channel). additional current is provided during peaks that is part of discharge of filter capacitors

Per Ohm's law, Current = Voltage/Resistance (I=V/R).

The less resistance in a circuit the more current (power to do work) for a given amount of voltage.

So current is power (and I thought it was knowledge!).

There is confusion around this topic!

Power (wattage) does not exist without voltage.

If on the Voltage rule, loudspeakers are described as being 'Voltage Driven'. This is a sort of shorthand- it means that the amplifier is operating as a voltage source, which in turn means that the amplifier, if driven with a sine wave sweep from 20Hz to 20KHz, will put out the same voltage into the speaker load regardless of the impedance of the speaker.

Essentially this means the amp will be putting out twice as much power into 4 ohms as it does into 8 ohms.

But power still plays a role! and there is still the question of how much current you really need. The problem here is that the industry does not spec the current by itself and so amplifier companies are free to come up with their own expressions, which quite often have nothing to do with the power that the amp makes, and everything to do with how much current is present when your short out the power supplies in the amp!

You might want to read these two articles, which explain some of the intricacies.
http://www.atma-sphere.com/Resources/Common_Amplifier_Myths.php

and

http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php

The bottom line is how much current your amplifier will need to have will depend on the impedance of your speakers and how efficient they are, such that you will get a satisfying volume in your room.

For example if your speakers are 4 ohms and 100 watts is enough power, your amplifier will need 5 amps, which will allow it to make 100 watts (full power) into 4 ohms.

This is simplified of course, but without further information its a good place to start. If we know the speaker involved and the size of the room, a better calculation can be made.

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300 wpc amp at 8 ohms plays 4 ohms at 450 wpc

300 wpc amp at 8 ohms plays 4 ohms at 600 wpc

Does one of the above amps necessarily have more current than the other? If an amp doubles with each halving of ohms, is that an indicator of its ability to deliver more current?

Is there an identifiable specification in an amp that will tell you how much current it will be able to deliver?

The notorious Apogee Scintilla and Infinity Kappa 9 are two speakers that dip to amp-killing low ohms. What specification in and amp do you look for in its ability to drive a speaker like these. Is it current or wpc you would be looking for in a speaker like these?
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