Someone will probably refer you to a good book, but...Voltage is electrical potential or "pressure" provided by a source such as a battery, generator supplying your wall outlet, or an audio amplifier and is usually denoted as "E". When some load is connected across this source (e.g. light bulb, speaker) making a complete circuit from source terminal to source terminal, electrons flow in that circuit and that is current, usually denoted as "I".. Current is measured in amperes. The load offers some "resistance" to the flow of current depending in its physical characteristics, and is denoted by "R". Resistance is measured in ohms. By definition, 1 volt of potential applied across a resistive load of 1 ohm will cause 1 ampere of current to flow. The basic relationship is I=E/R or however you might want to transform it algebraically. The polarity of a battery does not change, so it is said to supply direct current (DC). The polarity of the voltage at an outlet or the output of your amp varies and is said to supply alternating current (AC), I must say at this point that there are differences between a DC source with a purely resistive load and an AC source with a load like coils (inductors) and capacitors (like in xovers) and speaker magnets. The AC scenario is much more complex. A capacitive or inductive load is said to have "Impedance" rather than resistance, although it too is measured in ohms as you know from looking at speaker spacs. However, using a DC case will show the basic relationships. The power, measured in Watts and usually denoted as "P" supplied to a load is calculated by the formula P=EI or P=I2R (2 = power, ie "sqaured). For example 10 volts across a 2 ohm load will cause 5 amperes to flow I=E/R). The power in the load is 10x5=50 Watts or 5x5x2=50 Watts. Let's look at an amp and speakers, but simplify by using DC considerations. Suppose your amp can supply a 24 volt audio signal at its output terminals. This depends on internal power supply and circuit design. Although speaker impedance varies across the frequency range, let's just consider the typical "nominal" value of 8 ohms. That means your amp could be asked to supply 24/8=3 amperes to the speaker. If it can only supply 2, because of internal power supply limitations, it will "clip" or "cut off" at 2, causing problems for your speaker. Say it can supply 4 (a rating of 4x24=96 Watts), so it is ok at 8 ohms load and the power delivered would be 24x3=72 Watts or 3x3x8=72 Watts. Now use a 4 ohm speaker. 24/4=6 amperes, 2 amperes more than your amp can supply. If you crank it, the current limitation of your amp will cause "clipping" and may well do in your tweeters. If you keep it under control, your amp can supply 72 watts to this speaker also. Now use a 16 ohm speaker. 24/16=1,5 amperes and the power delivered is only 24x1.5=36 Watts or 1.5x1.5x16=36 Watts, even though your amp is capable of more with a different load. When amp manufacturers specify power capability with different loads, you can use that to roughly calculate the current capability. Use the power specified for the lowest impedance load and P/R=I2 (squared). So, if an amp can supply 100W to a 4 ohm load (assuming 4 is the minimum specified), it can supply roughly 5 amperes (100/4=25, sqrt 25=5). Also implied is an output voltage of about 20 volts. If you used a speaker whose impedance varied considerably below that, you may run the risk of current limitation problems. Again, this is a simpistic analysis and noone should complain to a manufacturer about a design based solely on these examples as the current capability is only "implied" from such specs.Thank you. Hope this was not totally boring. :)

Difference between "Watts" & "Currunts"?

I am confused why audiophils pay attentions to "Currunts" if "Watts" is the measurement for power. And since it is important, how come amp makers don't disclose this spec and how do we find out how much "Current" a amp has? I am new to hi-end , please help me with this. Thanks for all reply.

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