Expert: Cleggsan - 8/25/2009

Question
Hi Cleggsan, I have a Mtx thunder 7500 sub which is rated at 500watts RMS and I am powering it with a Kenwood Pst300 amp. The amp is rated at 300watts RMS. Do you think that if I got an amp that puts out the 500watts the sub can handle that I will hear any difference? If so what are some amps that you reccommend?

Answer
No. You will hear only a very small difference.  Here is why:  Increasing the power input from 300 to 500 is only about a 2db increase in power.  In terms of the human hearing mechanism 2db is a just barely perceptable increase in audio level.  In order to make a sound seem like it has doubled in loudness it takes around 9 to 10 db increases in audio power.  Thus, a big increase in power - enough to make it greatly pronounced - would take a kilowatt amplifier - which very well may destroy the speaker.

Further, the power ratings on loudspeakers pretty much falls in the fiction department.  It is a relative term mostly conjured up by the marketing and sales department.  The engineering departments don't like to rate them because there is no universally accepted method or practice use to measure power capacity.  Further, most speakers handle different amounts of power at different frequencies.

What WOULD make a big difference is if you changed out the sub for one with a big increase in sensitivity.  I don't know the sensitivity of your model (the series varies from around 88 to 91 db) but if you found one that is 92 to 94db and then increased the amplifier from 300 to 500 it would give you a system gain of 5 to 6db which would be a very audible improvement in sock power.

Good luck,
c

PS:  But, higher sensitivity may increase the resonance of the sub and cause the extreme low frequency response to be compromised.  So that is a potential downside.