Quote:
Originally posted by usc goose
ok, i think i got it now. so music is an AC current that oscillates in the frequency of the music being produced? |
Yep, pretty much. The way I think of it is that the position of the driver is controlled by the voltage (not quite accurate- more later) - the higher the voltage difference across the driver, the farther away from the magnet the voice coil is [or if the voltage is negative, the closer the coil is]. So by oscillating the voltage, you oscillate the driver back and forth at that frequency, causing an acoustic wave at that frequency... Quote:
and i guess voltage determines spl because the resistance of the speakers determines amperage from which you can figure out the wattage which is what sensitivity is measured in? |
Ehhh, almost. Voltage is always measured as a difference; as in, the electrical difference in potential between the power rail and ground is +15V (that is, the power rail is 15V higher than ground). In order to create a given voltage difference across a driver, you have to supply enough current that Ohm's Law causes enough of a voltage drop across said driver (voltage drop = current * resistance in ohms). But a driver operates magnetically, so not only does voltage affect how the coil moves, but current does too - more current will also move the driver more. So a power amp might be putting 10V into Speaker A and 20V into speaker B, yet they'll both be putting out the same volume because Speaker A is drawing twice as much current.
However, this assumes that they have the same sensitivity, which is measured in X dB/1W. That is to say, if you put in a 1W signal (1 volt difference across a 1 ohm load, which will draw 1 amp) the speaker will emit an X dB sound (hopefully at the frequency you put into it!). However, a 100dB/1W will get louder with less power than a 75dB/1W speaker will...
Or at least that's as far as I know! I'm sure there's some errors in there somewhere...