Gazzip
Well-known member
lindsayt said:Using this calculator: http://myhometheater.homestead.com/splcalculator.html
And feeding it with 85 db sensitivity, 150 watts, 2 speakers, away from wall, 12 feet listening distance, that gives 98.5 dbs at the listening position (that's very loud even if it's just for transient peaks)
Change it to 20 feet listening distance and it's 94 dbs. Still very loud.
What ATC says is true - for listening levels where there's peaks above 94 to 98 dbs, depending on listening distance.
Below those volumes there's no additional distortion whatsoever due to the amplifier only having 150 watts. Any sonic differences then would be down to the quality of each amplifier in normal unclipped conditions.
I think ATC are making a misleading statement as the volumes at which clipping distortion sets in with 150 watts are so high that many owners may never listen that loud. For sure a 2 watt amplifier would be unsuitable as that'd give only 80 dbs at 12 feet, but 80 to 150 watts would be fine for most people.
I can't question your maths regarding the dB level at given distances because I don't know the equation you used, but I definitely question your definition of very loud.
When expressing loudness as dB you need to factor in the "A" weighting to take account of how loud a sound is actually perceived by the human ear. dBA levels are weighted to approximate the way the human ear hears certain frequencies, and are usually much lower than dB ratings. For example a 94dBA rating is equivalent to the sound level endured inside a carriage on the London Underground.
Even if you don't take account of the "A" rating we are still only talking about a lawnmower at 94dB. Not exactly ear splitting volume levels.