a Power vs Volume Question

... very intersting. thank you.

just for info, the speakers in use have a sensitivity of 90db. I don't know if that says anything at all.

A lot depends on the speakers. There was a thread explaining all this about one week ago but it got nuked.

If your speakers are heavily compressing (like most do) at 200 watts then you gain very little if anything by going to 300 watts...you need the kind of speakers that can use that kind of power and actually turn it into clean sound.

Volume is often constrained by the speakers and not the amp. An extremely well built 85 db SPL sensitivity speaker may actually play louder and more cleanly than a 90 db spl sensitivity speaker with the same 200 watt amp. It doesn't seemv logical but it is true. Driver construction is crucial. Lightweight cheap northern european mass produced drivers with small motors very soon run out of gas!

Herman, why isn't 170db twice the loudness of 85db?

This is a simplified response:

Sound pressure levels are expressed in dB and the softest sound a normal person can hear is around 4dB. The threshold of pain is somewhere around 130dB, but this isn't 32.5 times the pressure level of 4dB. It is closer to 4,000,000,000,000 times the pressure level since the scale is logarithmic.

130db – 4dB = 126dB
126dB = 10 times log (pressure at 130dB divided by pressure at 4dB)
12.6 = log (pressure at 130dB divided by pressure at 4dB)
Inverse log 12.6 = about 4,000,000,000,000

This isn't exactly the same thing as loudness since it takes about 10 times the pressure level (10db) to be perceived as twice as loud and the ear's sensitivity changes with frequency and pressure level, but they are correlated.

check this out

loudness

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Pawlowski, the decibel is a logarithmic function, not a linear one. Each doubling of power increases loudness by 6 db. The ear perceives a 10 db increase in sound level as a doubling of volume.

A jet plane taking off is around 130 db. A rocket launch close hand is around 180 db.