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Chief narrator: Pete Riggle

An introduction by Pete Riggle: Those who have followed previous 6moons articles chronicling our loony pursuits here at the Institute of Hornographic Research (headquartered in the somewhat high and mostly dry desert of Eastern Washington State) may find continuing amusement—like the antics of Curly, Larry and Moe—in this article.

Chapter 1: Many moons ago Stephæn and Pete heard a pair of Cogent True-to-Life all horn loudspeakers at RMAF. This was a seminal listening experience. Indeed certain fluids may have been involved. We didn’t look.

Chapter 2: A year later on an airplane to Denver and RMAF, Pete startled Stephæn with the cockamamie notion that it would be not too tough (easy is the word of which Pete is most fond) to build a poor boys’ version of horns inspired by the Cogent experience. Stephæn was his usual dubious self; he’s heard the word "easy" issue forth from Pete’s mouth on way too many occasions. Unable to restrain himself, Pete then mentioned the notion to our mutual friend Jay Fisher, who led him to Jonathan Weiss who led him to Steve Schell. Steve and his partner Rich Drysdale are the moving forces behind Cogent True To Life Loudspeakers. Jonathan also showed us an RCA 9584A midrange compression driver. Steve was enthusiastically supportive. So that is how Stephæn and Pete came to spend the next year hewing and gluing to produce the Po’ Boy horns (see Hornographic Pursuits: Part One). Each channel was a rather large assemblage including :
  • a big J-shaped pure exponential horn for bass between 60 and 400Hz
  • a conical midrange horn (inspired by the work of Bill Woods at Acoustic Horn) covering 400 to 7000Hz, and
  • a smaller tractrix-style tweeter horn for the top octave.

Chapter 3:
After the Po’ Boys came a 29-foot long sub-horn dubbed Das Alpenhorn (see Hornographic Pursuits: Part Two). With a 6 foot high and 9 foot wide mouth it was built into the loft of the BBBA clubhouse listening room we call "The Garden of Earthly Delights" (with apologies to Hieronymus Bosch). Das Alpenhorn is a pure exponential horn with a design flare frequency of 15Hz, which gives a theoretical cutoff frequency of 20Hz. We were planning on a cutoff frequency of 30Hz but Steve Schell whispered in our ear that the 20Hz cutoff would be better. Das Alpenhorn did not take a year. The design took a month or two. The assembly took place like a barn-raising. The horn-raising was performed by members of our informal audio society, which we call the "Bad Boys Benevolent Association." The Bad BoyZ and GirlZ started work at 10 in the morning. We had the sub-horn playing by 8 in the evening followed by a big steak dinner.

Chapter 4: Later in the year of Das Alpenhorn, Stephæn secured a pair of the now almost unobtainium RCA midrange drivers discussed earlier and we began planning a pair of horn loudspeakers for his listening room. The basic idea was that we would try to make the J horns smaller. The J horn is the 60Hz horn. We listened to the Po’ Boys with only one half of each J-horn playing and decided that there was not much tonal difference between the half area horn and the full area horn. This led us to design a J-horn with half the area (at any point in the expansion) of the Po’ Boys. Because these horns would have a smaller visual impression—and after a lot of rather inappropriate alternative monikers—we ended up calling these the Po’ Lil’ Things. This is only a relative pronouncement because the average audiophile spouse would have a brain aneurism over the size of these babies. On the other hand Stephæn has the beautiful and wonderful Marcia who loves the aesthetics of the Things. Basically these are quite beautiful in mahogany plywood and rosewood trim. Essentially statuary. Well, the Lil’ Things turned out to be lot of work. Le travail de l'amour of course but labor nonetheless. Pete had come up with the idea that one can build exponential horns by using straight exterior sides relegating the curves to internally installed hot-wired polystyrene foam. This could have reduced labor somewhat but certainly not zero. But Stephæn said "No!"...

Stephæn wanted external curves. He is a really good friend so he gets what he wants. We got the external curves by a multitude (putting it mildly) of internal kerfs. It is hard to remember how long the woodwork took on the Po’ Lil’ Things. It seems we started woodwork about May of 2009 and we were playing the horns in April of 2010. Most Saturdays were consumed in the process. As were many evenings. Whenever we faced exhaustion we countered attacked with ethyl alcohol and other inappropriate interventions.

Chapter 5: Now here is a summary of the Po’ Boys, Das Alpenhorn and the Po’ Lil’ Things. The Po’ Boys have always sounded pretty good. However the midrange horn needs to be tamed with a notch filter characterized by an 8dB cut at 3kHz, tailing out to 1dB cuts at 1kHz and 9kHz. We have done this for digital programs with a fair amount of success using octave equalizers. It would take only a day of fiddling around and fine-tuning the results with an analog notch filter (capacitor, inductor and resistor all in parallel, that parallel set in series with the midrange driver). We have the parts. The problem is that there are so many things to fiddle with and so little time. In the past year for example, on top of all our other joint projects Pete developed a new tone arm product—the Woody™—which has been a labor-intensive effort. So we will get around to the notch filter sometime and it will be worth it when it happens.

Das Alpenhorn aka The Monster in the Attic has greatly improved the pleasure provided by the Po’ Boys. We initially planned to use the Alpenhorn to augment only the bass from 60Hz to 20Hz. But a strange thing happened. We found that when we moved the high-end roll-off of The Monster to 160Hz (the upper limit of the plate amp which drives it), the musicality of the system particularly in the bass improved greatly. We think what may be going on is that with the significant time delay associated with the 29-foot length of the Monster, it is better to let some of the harmonics of the deep bass get through to be properly timed with the fundamental tones. 

While we are discussing that beast it might be a good time to mention that a pair of Beveridge Model 2SW lens-loaded electrostatic loudspeakers moved into the Garden of Earthly Delights. Das Alpenhorn does a great job working to replace the Beveridge woofers. The Beveridges and The Beast have been providing a good deal of Earthly Delight particularly when fed a signal from a good pre-recorded tape through the spectacularly good Model 222 Tape Playback Preamplifier we purchased from Kara Chaffee of DeHavilland Electric Amplifier Company. We managed to cajole Ms. Kara into adding a phono EQ circuit to the 222 and have not looked back. 

As stated this preamplifier is spectacularly good for tape and for phono. With the Woody tone arm and the Chaffee Engineering 222 we have been getting a lot of joy from vinyl LP records, many of which have been pulled from storage and are now—thanks to another day of hard labor— gracing the rear wall of the Garden of Earthly Delights. What we are finding is that an average vinyl LP is better than an average pre-recorded tape (many pre-recorded tapes have speed errors) but that the best pre-recorded tapes are better than the best LPs.