More and more, speaker shoppers seem to want sensitive speakers that produce deep bass and don’t cost a lot. There is a rule of thumb in audio, known as
Hoffman’s Iron Law that says you can’t have a speaker in a small cabinet that produces deep bass and is very sensitive. You can pick two, but you cannot get all three. I would add that if you could actually find a speaker with all three, it might be very expensive.
I now see examples of speakers that claim to break Hoffman’s Iron Law, but most, if not all, of these designs are controversial in one way or another. Here is an example of a speaker, designed by Jim Salk and Dennis Murphy to be both sensitive and perform up to their usual high audio standards.
It clearly demonstrates what such a speaker can really do, and what it would cost.
These speakers feature the
8" Seas Exotic W8 X2-08 woofer, and the
1⅜" (35 mm) Seas Exotic T35 X3-06 dome tweeter. Both drivers have alnico magnets. The woofer has a paper cone embedded with papyrus fibers, and the tweeter has a coated fabric dome.
The cabinets are large for a stand mounted speaker, 19¼" tall × 10" wide × 13¾" deep. They weigh 37 pounds each.
These speakers are sensitive, 90 dB, and their frequency range is said to be 50Hz – 20kHz ±3db. 50 Hz isn’t all that low, but they can probably put out a wall of sound even if powered by a smaller amp.
The downside is they are expensive. Just the drivers cost nearly $3,000 for a pair of speakers. By the time all is said and done, Jim Salk estimates they should be about $6,000 per pair. It is not clear if he intends to produce them other than for special orders.
To those who insist on sensitive speakers in small cabinets that produce deep bass, these are a lesson in the reality of Hoffman’s Iron Law.
