Inspiration is key, or: the rotated 17 AL
Since I have been listening to more music recently while studying for my exams, and abusing my ears with low-quality PC speakers, I thought it would be nice to listen to music on a decent system again. My last speakers were put out to pasture due to some broken surround material, so I started looking online for reasonably priced free-standing boxes. After a series of detours, I finally ended up here on Udo’s page and clicked my way through the shop and the construction reports. After taking a good hard look at my room (12m²) and my wallet, I dialed down my standards. Given my preferred musical genres (rock, metal) and encouraged by the readers’ comments, I chose the Dayton AL 17.
A simple square cabinet was out of the question for me; inspired by Albrecht Dayton’s inlay, I drew a few sketches that turned the body of the loudspeaker 90°. That would change the cross-section so that when you look straight at the box it simply looks square, while the edge runs across the front in a cosine. The only way to do that, I decided, was to glue the entire loudspeaker cabinet together from many individual layers, each consisting of 4 small slats. In Excel, I created a table with all of the possible angles and lengths; then I was eventually able to calculate the volume by entering the wall thickness, layer thickness, height and edge length. Unfortunately I didn’t think about it long enough and I forgot to calculate one angle, so the curved edge is not cosine-shaped and the wall thickness is not constant as it turns
I chose cherry for the wood, since I still had plenty of sections and rough-edged pieces for cutting out the slats. I started by planning several meters’ worth of slats for the straight pieces of the box (top and bottom), measuring 25x25mm. The slats needed to be a little wider for the curved section.
After cutting the wood to length, I started to build the cabinet out of the many individual slats, layer by layer. I glued 4 slats together into a square, using a jig. The previous layers were then glued onto this frame. I cut the slats for the rotated layers on a band saw, with angles corresponding to the rotation. Constantly referring to my Excel table, I “grew” the rotated section one layer at a time. Once all of the slats were used up, I was finally able to put together the two loudspeaker cabinets, each made from four individual segments. I evened out the insides of the rotated sections using a chisel and a plane, so the cabinets are smooth inside too.
On the outside I first sawed off the projecting corners so that I could trace the curved line of the edge on this curved surface. Using an angle grinder, a circular hand saw, a trim saw and various rasps, files and grinders, I leveled out the many steps and edges and smoothed the cabinet until the even surfaces at the top and bottom flowed into a beautifully curved surface in the middle.
For the floor, I glued in a multiplex board; for the lid, I glued in the same 25x25mm slats, but this time with a mitered edge. After the fine sanding, I treated the cabinet with oil wax. Before applying the last coat, I sanded everything one more time by hand and cut the openings for the speakers and the terminal.
Assembling the crossover and installing all of the components in the cabinet was relatively unproblematic – it was time for a first listen.
When it was connected to a 40-year-old department-store amplifier, I had the feeling – the first time I had ever experienced this with a system – that I needed to turn down the basses (but that was caused by the amplifier). Then we took the speakers to a friend’s house to run them through a high-quality amplifier, and also compared them to some boxes from well-known manufacturers. The sound is just mind-blowing – the high notes are beautifully clean and airy, and the basses offer “pressure” even at low volumes without seeming intrusive or booming. In any case, the sound from this relatively cheap assembly kit made me curious about how good the high-quality Wohlgemuth developed speakers must sound. The speakers have now been set up in my room for several months now, and I’m constantly amazed by the sound – even though they’re still waiting for the right amplifier.
Finally, I want to thank for the unusually fast delivery and for equally fast, friendly help with my questions. These boxes will definitely not be the last ones I build.
At the request of a reader, Moritz also sent us two pictures of the decorations in the middle of the boxes:
The Dayton 17 AL can be ordered from Intertechnik