In this part we will first briefly explore some of the effects experienced with different amounts of absorbent stuffing in the horn as presented in Part 1. Then I will describe the effort to add scary deep bottom end by joining it with a previous project, El Pipe-O (AudioXpress, May 2003).

Last, I will try out the larger Lowther DX4 driver, extending its top end with the TAD PT-R9 ribbon tweeter, resulting in a loudspeaker that delivers even more efficiency and dynamic range and extends from 20 Hz to as high as 100 KHz, retaining most of the essential charm of the full-range transducer.
 

33 years ago I decided to build a big horn system. Constructed in the dorm library over Christmas break, the result was dubbed The Claw, a straight exponential horn 9 feet long with a 42 Hz expansion curve and a 50 sq ft mouth. We mounted a JBL LE15A woofer in the throat and used a JBL 375 compression driver and horn for about 500 Hz on up. No matter where we pointed it, the cops showed up every time.

I've always wanted to build a stereo pair capable of even lower frequencies, and these days I am fortunate enough to have a 12,000 cubic foot listening room isolated from civilization. This summer I was also graced with the help of a twin pair of engineering students, Chris and Matt Williams, eager to build something cool. So we tackled a set of big exponential rear-loaded horns.

They are named KleinHorns as they vaguely resemble a drawing of a Klein Bottle, a 4^th dimensional container whose inside is the same as the outside. Perversely, Klein also means little in German. Horns vaguely resembling this project have been around for many years, but I believe at least the name is original.

To read more about the Kleinhorn, download the KleinHorn.pdf file (300Kb)

Unfortunately there are good reasons why such speakers are uncommon – they are very difficult to make, relying more on hard work and good taste than your average loudspeaker part. They have to be a lot more than a stiff piece of paper, plastic or metal. 

To read more about the J-Low horn, download the j-low.pdf file (300Kb)

The complete assembly document is also available for download. jlowassy.pdf (1.9Mb)

Most woofers just don’t quite do the lowest octave. You read the specs that say "usable response: 20 Hz – 20 KHz" and you know that the 20 Hz part of it is wildly optimistic. Achieving very low frequencies at reasonable power levels is not an easy job; the acoustic impedance experienced by a speaker cone declines as the inverse of the square of the frequency. As a practical matter, woofers and their enclosures need to be very large to properly reproduce the lowest octave. Even when you compensate with frequency equalization and more amplifier power, the performance suffers as you reach the excursion and power handling limitations of a small cone in a small box.

Let’s face it. Size does matter. .... more..