Understanding loudspeaker efficiency

February 13, 2018
 by Paul McGowan

3 comments on “Understanding loudspeaker efficiency”

  1. I am a stereophonic dinosaur when it comes to most of my equipment, as well as a mix and match specialist. I have never owned a complete system with all the same brand of components. But I have kept my now ancient Altec Lansing Voice of the Theater A7-500's since 1971. And these speakers, with all their flaws, most noticeably the "honk" of the horns, are still some of the most efficient speaker designs ever made. You can drive them with a few watts to very nice listening level, but even though they are rated at 50watts RMS , I have chosen to use a pair of bridged Crown DC300-a's which produce over 300 watts RMS with quite a lot of headroom. Why? Because that part of realism that requires dynamics, even subtle musical features, can actually be produced by high efficiency speakers and high power. It's really difficult to do that when each 3 db increase requires doubling the power. So, while frequency response, flatness as well as width, is really important, efficiency is also important to get the dynamic realism. Otherwise you will need thousand of watts of power and tons more money to get there. I have 4 A7-500's one stacked on top of the other for front speakers, but due to the tiny room they are in , I use just one horn per side. I have a home brew pair of Altec style cabinets on the rear with 811 B horns. So when I switch over to surround modes, the actual sound produced per watt is enormous with these high efficiency speakers. Small tube amps actually do a good job with very smooth sound, but I love the power of the bridged Crown's. And even with 6 15" woofers, I still have an 18" sub, powered by a Carver 1.5T. Can't do without that ultra low kick when the music demands it. Thanks again Paul for the vids and text material. Of course I am going to tear most of my system apart when I get the time and follow a few of the new rules I have learned from you.

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