Finally got the Advent Maestro Ewaves done
It was more of a job than I thought it would be. It might have been less work if I had just started from scratch, but they sure are nice now that they are done.
There were several problems with my plan. First, the woofer placement was too far from where the QSC waveguide needed to be (near the top), so I had to make a new covering baffle for the box. To make matters worse, Advent (Jensen at the time) had covered the baffle with a layer of foam, for diffraction reduction I guess. But the foam had all turned to goo. I tried alcohol, scraping, acetone, more scraping, violent cursing, but to little avail. The stuff was really nasty to get off, and I never succeeded in completely removing it. I finally wasted a couple of coarse sander belts to knock it down enough so I could put the new baffle over it.
I thought I'd be creative for the baffle material and made an attempt at a "constrained layer damping" structure by bonding a piece of MDF to a piece of HDF with a caulk recommended by Earl Geddes. That was probably ok in itself, but I neglected to actually consider how much material would be involved after cutting the openings for the woofer and the waveguide, and after doing quarter rounds on the edges and around the woofer. Here's one of the baffles and the recessed mounting ring for the woofer:
I suspect the constrained layer does just about nothing for this, not much of it is left after machining. But it was practice for when I do make a box from scratch (next project), anyway.
Next job was to take the sawzall to the old baffle to clear space for the woofer and waveguide and get rid of the old midrange cup. Followed by the sanding mentioned above.
Then, I gave the new baffle a shot of black spray paint so it wouldn't show through the grille and put it all together. Not shown is several days of work on measurements and the crossover (in which I discovered a flaw in the way I was modeling the speaker and crossover -- I managed to work around that, but I really need to get PCD working on my computer!). Anyway, it all ended very well, the cabinets have nice proportions, feel very substantial, and sound really good. The Advent woofer is a very good performer.
Now, one of the goals for these speakers was to have them use the original Advent grilles to make my wife happier. She tolerates my raw looking speaker creations, but she'd prefer to not have to. So I went to some effort to make the new baffles fit within the old grille and its mounting posts, with the waveguide and woofer recessed. And that came out fine.
But we recently got two new kittens in the house... you know where this is going. Literally, within 30 seconds (!) of the first time I put the grilles on the finished speakers, one of the cats reached up to enjoy some cloth ripping. I stopped him before much damage happened, but we are back to having ungrilled speakers on display (fortunately neither cat has tried to rip up the woofers...yet).
Here's a quick shot of one of the speakers with it's grille. See, it's just an Advent. Or is it Ewave Incognito?
(note the enemy at bottom right, plotting his next move).
Much appreciation to Zilch, Bauhausler, Jackgiff, Wayne Parham, all the other EWavers - and of course to Earl Geddes - for all the work put into this speaker topology.
