I originally planned to finish the horns with shelac--my finish of choice for just about any wood project. I tested shelac, and I just didn't like the results. It darkened the wood to an amber color. I also tried using wax, and again, I wasn't happy with the darkened wood. So, I sanded it all back down to 60 and stepped back through the grits to remove all of finish. Next time, I like to think that I'll test on a scrap piece. The picture shows my first completed 320 tractrix horn being tested. To the left of the horn is an Electro-Voice Aristocrat speaker that I built from baltic birch and wenge.
I love the look of the look of the 190 layers of baltic birch, and I now knew that I didn't want to darken the wood, so I decided to try my first ever water-based finish. I bought a quart and went to work applying three coats with a brush while hand-turning the lathe. No smell, easy water clean-up, and it turned out great. I can't say that I'd use the finish on hardwood, but I think it looks spectacular on stacked baltic birch.
You can see how the driver mounts to the layer of baltic birch (closest to the throat) that was not glued to the rest of the stack. I recessed large washers and added lock nuts to mount the compression driver. Then I mounted the wood mount back onto the horn.
I didn't have a crossover to use, so to test my results I just hooked up my spades up to the terminals on the compression driver. I just played some higher-register music (solo violin) so I wouldn't damage the driver. It sounded incredible--more detail than anything I've ever heard. I could even hear Isaac Stern breathing and the sound of his bow rubbing the strings of his Guarnerius. I can't wait to finish the mid-bass horns and subwoofer and really test this horn out.