In Reply to: Re: Cool. posted by Adrian Mack on September 14, 2003 at 01:45:30:
Adrian, ELECTRIC impedance & ACOUSTIC impedance isn't the same! When you look at the frequency/impedance curves from drivers, you're seeing the ELECTRIC impedance - not the acoustic one...Actually, the reason why horns are working so well is that they work as impedance transformers - on the acoustic side! A driver is 'born' with a natural high acoustic impedance (speaking in popular terms, we have a rather heavy diaphragm trying to move some light air), & the air's acoustic impedance is low. So the horn offers a high acoustic impedance at the throat (for the benefit of the driver), & through the length of the horn this is converted to a low acoustic impedance, at the mouth.
Closed & reflex boxes aren't very good at this transformation, sad to say, they stink - so the efficiency for them is max ~5%. But they are MUCH easier to handle when it comes to size in the bass area. The pay (again!) - bigger amps.
Btw., the LAB 12 offers very good performance in reasonably sized boxes - too bad they are not easy to get a hold on in my country.
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