Compression? driver

[sura]

I've heard Altec drivers called "compression drivers." I've also heard some drivers referred to as "radial phase plug." What do these terms mean? What is a "radial phase plug" and "compression driver?" Thanks.

[Old Guy]

I'll try to do a very basic explanation- here's an explanantion I clipped from the web:

"Horns require compression drivers. These transducers produce high pressure but little displacement. The diaphragm therefore moves very little, which results in less distortion than a conventional radiating driver. Horn drivers need high magnet strengths to produce the high pressure. Ordinary radiating drivers do not usually meet the requirements of a compression driver, so you cannot just horn load a normal cone speaker."

A compression driver creates a high pressure at the horn throat. The expansion of the horn ccouples this high pressure to the low pressure of the atmosphere by gradually expanding the cross section area. In other words a few square inches becomes a much larger area at the horn mouth. The result is increased efficency. Properly designed horn and driver combos are as much as 4 to 10 time as efficient as a direct radiating speaker.

A compression driver is essentially a point source. However the distance from different areas on the diaphragm to the throat will cause minor differences in the time the sound arrives (at the throat). To correct this a Phasing plug is used. It has paths, generally slits cut in the phase plug, to corecct the time (phase) differences.

A radial phase plug uses radial slits. There are other types of phase plugs of course. Obviously the Tangerine, named for it's shape. Still others too numerous to mention.

Hope this answers your question.

[sura]

Thank you very much. That makes sense.