Current Questions

More and more, I see the word “current” in audio reviews. The reviewers warn me that I’ll “need lots of current” for a given speaker but they don’t explain exactly what it is I need or how many “lots” is. I’ve looked at a few “Electronics For Dummies”-type sites but I’m still confused. A few questions:

—What is current?

—When someone writes, “These speakers need a lot of current,” what do they mean? Is sensitivity involved? Impedance?

—On the amplifier end, what specification measures current?

—Are there subjective considerations at work in that spec? The number of watts doesn’t tell me everything about loud an amplifier sounds. Does the number of [whatever measures current] similarly leave things unexplained?

—Everyone asks, “How many watts?” No one asks, “How much current?” Is it really so important?

paul600103-25-2022 6:22am

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jjss49 Details Discussions Posts This discussion Message User 6,612 posts 03-25-2022 at 11:52pm Copy Comment URL Report Comment Edit Delete more grist for the mill
invalid Details Discussions Posts This discussion Message User 1,269 posts 03-26-2022 at 12:16am Copy Comment URL Report Comment Edit Delete Technically speaking no amp can really double it's power when resistance is halved, the manufacturer underrates the 8 ohm power output to come up with that figure.
testpilot Details Discussions Posts This discussion Message User 985 posts 03-26-2022 at 12:22am Copy Comment URL Report Comment Edit Delete @carlsbad wrote In my first physics class I asked why C wasn't used for Current and never got a good answer. i have a physics degree from the University of Chicago. So we will keep using I for current The conventional symbol for current is I, which originates from the French phrase intensité du courant, (current intensity). Current intensity is often referred to simply as current. The I symbol was used by André-Marie Ampère, after whom the unit of electric current is named, in formulating Ampère's force law
erik_squires Details Discussions Posts This discussion Message User 16,652 posts 03-26-2022 at 12:56am Copy Comment URL Report Comment Edit Delete Technically speaking no amp can really double it's power when resistance is halved, the manufacturer underrates the 8 ohm power output to come up with that figure. That's really not what happens. Sometimes this is true, but usually manufacturers want the maximum possible 8 Ohm rating for spec and bragging rights, so they don't want to underrate it. Take a look at any of the dozens of measurements avaialble at Stereophile for SS amps, and you'll find only a ltitle bit of underrating at 8 Ohms, it at all.
holmz Details Discussions Posts This discussion Message User 2,328 posts 03-26-2022 at 01:13am Copy Comment URL Report Comment Edit Delete Yo Holmz, I appreciate the effort but you lost me in the first line. Rails? Volts? In the the equation V = I R, I assume that V is volts but what is the other stuff? V = Volts I = Amps R = Resistance Still, there may be some gold in the stream. Is current measured in amps? And since low impedance speakers are harder to drIve, does that mean that they require more current, i.e., more amps. Am I right so far? Yeah Where does volts fit into the picture? Speakers are voltage devices, and most amplifiers are. So when someone says that a particular speaker needs a lot of current, he could just as easily say that a speaker is low impedance and needs a lot of amps. Does that make sense? yeah mon. exact. But I’m left with a big question. If it’s true that current is measured in amps, what is being measured? Some kind of energy? What kind of work does this energy do in a stereo system? This is all what used to be high school physics. The speaker need to push the air to make sound waves, so it needs force ~~not energy~~. If that force need to move, and do it a lot, then that called power… Just like engine force in a car is called acceleration, and is from torque. And speed is from power. One is instantaneous and the other happens through time. The current it what is making the force in a piston speaker with a voiced coil. But some of the big flat panel speakers are doing the pushing using voltage to make the force. And other big panels use current. I think maybe the education system is not what it i once was, but a community college 101 course or a private tutor for an hour would pay off. Best might be to just ignore the physics and enjoy the music.