The Moore Horn by Chadd Moore The Moore Horn is a back-loaded tractrix horn for Lowther drivers. I use a material that is much more dense than typical builders use. This is an industrial material that is not available in lumber yards or home improvement stores. It is multiple times heavier (more dense). It has very specific criteria, whereas the "stuff" that you get at "home depot" doesn't. That type of "particle" board is made from the sawdust that is left over from everything else. –The big item here is that the mass is very important. Double thickness construction comprising two layers of 3/4" material and complete bonding of said pieces through glue covering the entire faces plus various mechanical fastening techniques is used. The end result is a 1-1/2" thick panel which is stronger, stiffer, more stable, etc. than a solid 1-1/2" piece of the same material. This is an engineering principle that is older than all of us! The front, rear, top and bottom of the cabinets are double thickness. These are the "sides" of the tractrix horn. The back chamber for the driver is also double thickness {continuation of "mass is important"}. The first section of the tractrix expansion is also built of the double thickness. This is the highest air pressure area of the entire horn which makes this the most critical area. One great benefit of this construction technique is that the cabinet is physically stable at this point. The next four sections of the horn are constructed of multiple layers of the same 3/4" material into a "solid block". This adds mass (again) as well as reinforcement to the side panels of the cabinet. Phew, this part is very labor intensive, but this is a no compromise construction, the tendency is to push it far as possible! The sides of the cabinets are not made of double thickness. Structurally it is unnecessary due to the extensive measures taken throughout the construction of the horn as described above. Also, this provides a narrower cabinet for improved imaging and aesthetics. This is good. The "perceived" size of the speaker in a room depends greatly on the baffle's width (frontal dimension). Also, experiments with a variety of baffle widths used with Lowther drivers indicated that too narrow of a baffle shrinks the "sweet spot", reduces the presentation, and makes them very fussy to placement (even to the point that they had to be leveled and shimmed to be exact mirror images of each other!) While too wide of a baffle width is just that, which takes up additional space and makes the cabinet appear larger. The width used strike a magical compromise here. After all this they are sanded, primed, and painted. A hand braided four-wire conductor is soldered to gold plated terminals in a cup which is installed (and sealed) so all that is needed is to hook two wires to your Lowther and put the four mounting screws in (a T-nut is employed for driver mounting). And last but not least four double wheeled casters if desired. Production is starting soon (by Chadd). Now that mine and Larry's are done. Email Chadd for details. by Larry Moore: I finally got my Lowthers up and running. My brother Chadd built the cabinets for me. They are a tour de force of construction on a well know backhorn configuration using the tractrix expansion. Built out of a commercial grade MDO or MDF type of material that one can’t ordinarily source. Super dense stuff. Top, bottom, front and back are double thickness, as are the panel behind driver forming the back chamber and the first section of the horn expansion. Also, if you look at the plans, you’ll see that there is this five sided thing, pretty scientific huh?, that is formed by the first expansion and four other pieces that forms the second as well as the subsequent expansions. Well, getting this thing right has always been an issue. It is tough to get it to fit exactly. Then you got to sand fill it or something. Not anymore! Solved that problem. Chadd made this out of multiple layers of the cabinet material so that it is one solid smooth block! The rest is pretty straight forward overkill construction too. They were then sanded and primed and painted. Oh yea, sound. They are awesome! I tried pretty much every thing going before arriving at these. You name it. Qwtp (TQWP), all fun, some fun, Hedlunds and a big fun in the process of arriving at the Moore Horn. Guess I should mention the three or four iterations of woofers below the TAD2001s with custom tractix horn lenses too. Well worth the effort. All three months of it. Apparently, this is the ticket for me. EMPHASIS, on “me.” Editor's note: this horn is very similar in design and dimensions to Ketil Parow's Big Fun Horn. Top