Film-Tech Forum ARCHIVE: Horn loaded speakers (re: the QSC powerpoint)

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Posted by Lyle Romer (Member # 1266) on 07-15-2005, 10:05 AM:

While reading the QSC powerpoint presentation section about horn-loaded speaker systems and their efficiency I came across a question. Since the only issue with them seems to be below 200Hz, why has nobody designed a speaker system which is horn-loaded down to 200Hz and then crossed over to a direct radiator for 20-200Hz? Wouldn't this give most of the benefits of the efficiency of horns while eliminating the down side?

Posted by Steve Guttag (Member # 268) on 07-15-2005, 12:26 PM:

Lyle,

They have...look at most of the 3-way systems out there for cinemas. Most of them are Horn loaded down to 250-350 Hz (depending on model) and then direct radiator below that.

The Altec Voice of the theatre speakers were also essentially that as well (hence the cabinets were ported). The A-5 was horn loaded to about 125Hz, the A-4 was horn loaded to about 80Hz. They were only 2-ways systems though. Take the bass-wings off of an A-4 (or don't sink an A-5 into a baffle wall) and you can tell pretty quickly where the horn operation starts/stops.

There are other issues associated with horns though...they are certainly the most efficient but often are not the most flat and more often than not have a "characteristic sound" associated with the horn design (this is often called "colored").

Horn designs have evolved a bit too for all of the frequency ranges.

Posted by Samuel Hynds (Member # 2610) on 07-15-2005, 01:04 PM:

The mid frequency device of the MH-1063/1075 (from QSC Audio) has a frequency response from 250Hz to 1.8kHz. The horn is a loading type (10 inch driver with a 6 inch opening) with a phase plug inside the throat of the horn (to help the high frequency response).