How loud is loud, What DB is actually loud?

look on youtube and you will see plenty of cars hitting over 160db and 170db. you dont sit in the vehicle at these competitions! these cars use multiple alternators and batteries along with thousands of watts. plus they have bulletproof glass and heavily reinforced bracing in the vehicles. the tone bursts they play only last a few seconds, just to register on the meter.

When I remember, I am going to be taking out a sound meter at work and measuring the dB's. I have only done this once so far since getting the meter, at a rehearsal for a pops concert. In this particular case, we had an unusual set-up, and I was actually behind most of the loudest instruments, so my meter only registered a peak of 104.99 dB. I was a little surprised it wasn't higher, it was basically a big band type of set-up. I think in our normal set-up, the same concert would have registered higher levels at my chair, as the louder instruments are usually closer to me (I am a horn player). I had another opportunity at another pops show yesterday, but forgot all about it.

Doesn't adding a 2nd driver add 3db if the power stays the same? Been so long I forget. But if 100w does 100db with a single 12 then that same 100w going into a pair of 12's would equal 103db?

Driving two 100db/100W subs with two separate amplifiers, each providing 100W, would result in an spl of 103db, assuming that the subs are positioned such that their outputs are in-phase at the listening position.

Connecting two 100db/100W subs in parallel to a single amplifier, that would provide 100W into one sub, would also result in 103db, IF the amplifier is capable of providing the 200W that would be drawn by the halved impedance that the paralleled speakers would present to it. And assuming also that the amplifier has negligibly small output impedance (which is the case for most solid state amps, but not for most tube amps).

Connecting the two subs in series, btw, would not make sense as it would result in a reduction to 97db spl, with only 50W being drawn from the amplifier.

Rayray8 -- truly awesome. I'd imagine that one reason for keeping the tone bursts short is to prevent the voicecoils from melting!

Regards,
-- Al

double speaker sq area and then doubling of power would result in a 6 db gain ...

yea, I would think if you double the cone area & also double the power you would get a 6db gain vs a just increasing the power.

If each speaker is getting 50w I would think it would move more air then a single driver with 100w.

No clue with the focal stuff..... I have had really good luck with Image dynamics subs. They are excellent for SQ & do not require lots of power or a big heavy box. Great stuff........