Originally Posted by penngray
I guess I should ask what is the max SPL, max Watts for one F-20 at 30Hz?
You're thermally limited. The coil will probably fry before excursion becomes an issue.
Max watts for music, movies, or for sine waves so you can post plots on the interwebz? Long term thermal limit is 225 watts, and I am sure that this is conservative. I just don't know how conservative.
Top sweep was +25 dB from 2.00 volts (1 watt into 4 ohms), so I ran out of amp at 75 watts over the "rated" thermal limit of the driver. There was no complaining, even with a 10 Hz sine wave. The model suggests that there might be a driver complaint at around 19 Hz, but we did not hear anything. The compression in the plot could have been due to a lot of things, I did not let the driver rest between sweeps other than to reset the level and go. There was probably less than a minute between sweeps, so I am sure the coil was warming up. I know I was out of amp, 25 dB of gain is ~316 watts by my math. I'm sure the amp was near its limits if not entirely past them at this point, it is only a 300 watt amp. Also - BL drops precipitously once the coil leaves the gap, so SPL drops too. I'm sure that this was part of what we saw.
I've heard that people have used 500 watt amps with these drivers, but I have not tried that. I have no doubt I'd fry the coil running sine wave tests at high levels though, cause I have in the past. Double the thermal limit is simply that, and if all that power is applied at an excursion minima, the coil gets hot plenty quickly and can't cool itself off.
Music is one thing. Movies are more extreme, but sine wave testing is simply brutal.