Speaker test report
I attended and took part in the speaker test. Very interesting!
The main points:
1) The host and presenter, Earl Geddes, is a speaker designer and consultant. His interests are waveguide (horn) speakers, acoustics, and HT in general. He was demonstating and, in an informal setting, testing his new speaker design. He has been interested in understanding and solving the typical horn speaker coloration. His work, which he said parallels and builds upon the published work of others, is incorporated into the prototypes he showed us and tested. They're big honkers with 12" or 15" bass reflex woofers and a horn tweet of his own design. Yep, just a two-way for a speaker that size!
2) His horn design uses a specific taper and a specialized porous, open-cell foam plug that fits into the round horn rather like a large trumpet mute. He posits that much of the objectionable coloration results from "high-order modes" within a typical horn. My (imperfect) understanding of these modes is that they are the result of oblique reflections within the horn; analogous to the tangental (as opposed to axial) modes in rooms. (As a layperson I'm probably not the best reporter!)
3) He believes that uniform and tightly controlled polar response is a key to good speaker sound. In particular, he takes the somewhat contrarian view (at least as far as I understand it) that the ideal HT room should be quite "live" (where mid and high frequencies are concerned he seems to favor diffusion over absorption) and that the speakers should have a fairly narrow and well-controlled dispersion pattern (the latter sounds like THX, of course). His design aims for that. He showed us anechoic measurements taken every 7 degrees from on-axis to 90 degrees. Things of beauty. You know how you often see a dip in the off-axis response of most speakers in the crossover area? That was gone. And the high-frequency rolloffs off-axis were smooth and uniformly spaced. Pretty amazing for a two-way system with a large woofer.
4) The test: we listened blind to four speakers hidden behind an acoustically transparent black fabric. There were groups of six listeners for an hour each. For each group the speakers were shuffled so that speaker "A", for instance, would be different for each group (that way we coudn't compare notes around the bar!) Basically, the results were "all over the map" in his words with no unit (including his) the clear winners. I liked both his prototypes best. Tom Nousaine didn't think any of them sounded all that great. The other two speakers were a JBL 2-way studio monitor (big bass reflex woofer and horn tweeter) and a Gradient floorstanding speaker.
I gather that several similar tests under more controlled conditions were done and are presented in his AES paper, presented at the Novermber conference. The paper deals with his waveguide design. He has patented it. He also holds several other patents.
As you see from the picture, the listening conditions were less than ideal. No doubt, to my mind, the Gradient would have had better bass if it were near a wall as is the usual practice (I thought it had little bass and a too-bright top end, FWIW). But as one person told me, at least they were all equally handicapped. And the room was quite reflective.
And yes, he does look a bit like a cross between Capt. Picard and James Carville! The redeye from the flash makes the effect pretty scary, but he's a nice if somewhat serious, terse guy.
As a bribe to get us there, he offered free copies of his self-published book, "Premium Home Theater Design and Construction". It sells for $39. On quick perusal of my copy it's worth it. Good balance of theory and practical advice. The chapter on construction techinques is worth it alone! And he's big on value for your buck and death on BS and snake oil which his wife and biz partner, an experimental psychologist, calls "audio tarot". Here's a quote from the introduction that should endear him to the typical Audioholic:
I will limit my discussion to what I call high "value" designs and components. One can spend almost an unlimited amount of money on a HT, but that is not my interest here. My intent is to describe the most cost effective--the highest value--designs and components for the reader who has a limited budget, and I doubt that anyone reading this text would not.
Finally, about the club. The Southeast Michigan Woofer and Tweeter Marching Society (SMWTMS, affectionately called "Smootums") is heavy with engineers and audio pros. It's kind of a smaller version of the Boston Audio Society. One guy there was a former designer for the original DCM speaker company and worked on their Time Window line; another was a recording engineer who worked with Motown back in the day. But they made me, an average Joe with a liberal arts degree, feel welcome. As a new face I was asked to intro myself. When I told about my long absence from audio they asked if I had any old gear; they thought my old Dynaco gear was cool! Although one guy got a bit huffy with me during the speaker test because I rattled my response form a bit much for his liking!
Here is a link to Earl Geddes'
Website where you can read about his work, consulting biz, and buy his book. He also has a book on transducer design. Too techy for me!
Presumably his AES paper is or soon will be available from the AES Website as a preprint or journal article.
Oh, yeah, the meeting/demo was at his house and, yes, he does have a kicka$$ HT setup in his basement. He had the Talking Heads "Stop Making Sense" concert playing on a 7.1 HTPC based front projection system so we could wander in and check it out. Freakin' awesome. And very well isolated from the rest of the house. Even from just outside the doors it was a whisper. Then you opened the doors and, whoa mama!
For sound diffusion and looks, one sidewall of the room was completely done in cultured stone!
