More to report...
The designer Dave Dlugos from Planet10 added bracing to cure the resonance we got on the first try. A couple panels went into each horn, and some external slats on the outsides of each horn, perpendicular to the internal braces. A spine of bracing was also applied to the rear panels.
Altogether the speaker is greatly improved. There is still some boxyness and woodyness, and tapping the wood still has a little resonance, but it is listenable now, at least for me. I have a high tolerance for audio pain when the rest of the presentation is this good.
I plan to add stuffing to the inner chamber tonight which should further improve things by damping down the middle and upper frequencies and prevent them from being amplified by the horn. I will also paint them with a couple thick latex coats to damp the wood a little more. But of course I had to listen first, so I could learn what stuffing does - besides I just couldn't wait any longer. It feels good to check this project off the 'to do' list. It has been a long time coming.
But I do intend to build it all over again a couple more times using different materials which should require significantly less resonance control, and so they should build much faster. I have high hopes for those. The baltic birch is just not my cup of tea dispite its long history as material of choice for single driver designs.
These things have incredible tone, dynamics, clarity, detail beyond your wildest imagination. Imaging is surreal. I can't listen with my eyes closed, the imaging is too distracting. I keep feeling there is someone really there and my subconscious reflex opens my eyes to see. With further improvement in the resonance and type of wood I think it will be something very special. The drivers are the star of course, they really deserve the finest cabinet possible, and reward richly for the effort.
So yes, if you come over on May 17th you
will be able to hear them this time. Maybe even further revisions...