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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?

paul6001

Showing 2 responses by erik_squires

erik_squires
16,589 posts
 

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.

erik_squires
16,589 posts
 

"Need lots of current" = "Hard to drive" = have low impedance and/or high phase angles (high capacitance or inductance). 

Amplifiers that are mismatched to a speaker will not be able to produce a flat frequency response, but this is typically true in the bass, where impedance tends to drop and bass gets mushy or weak.

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