The Besta Subwoofer

[wogg]

4 days... 2 rounds of paint and sanding.

I'm done with that rattle can though, tried different spray techniques to avoid the spurts to no avail. These buggers will ensure I can never wet sand enough to get smooth without breaking into the primer.



This is what the 2nd round wet sand looked like when I found the smoothness acceptable, the first round was a whole lot more exposed primer so it feels like progress.



The new rattle can of gloss black enamel has a much better nozzle and went on much better. This time I'm going to dare 2 quick coats before letting it sit 48 hours to cure before sanding. I'm crossing my fingers that I can sand smooth without primer showing up and this will be the last paint round.

[Steve Lee]

That sounds annoying but it looks great so far - good luck.

[a4eaudio]

What rattle-can paint was splattering so much to begin with, and what was the better paint you found?

[wogg]

What rattle-can paint was splattering so much to begin with, and what was the better paint you found?

That would be helpful wouldn't it! Both are Rustoleum, the bad is an "automotive" gloss black. That has a crap nozzle. I got a can of "high performance", the tall silver can. Much better.

[Wolf]

I find Rustoleum sprayers to be less than ideal, and drip like crazy- ESPECIALLY the trigger-spray types. I went for Duplicolor/Krylon and have not complained about theirs. Sometimes, Rustoleum is the only brand that offers the colors I want, and I deal with the agony.

Later,
Wolf

[Chris Roemer]

KRYLON's nozzle will work on a Rustoleum can.

[Wolf]

Maybe they used to, but I believe that has changed.
Wolf

[wogg]

Baffle polishing all set. Not too bad for a rattle can finish, but definitely not top notch piano gloss. I don't have the patience to go further than this, likely would have needed 1 more layer of paint, more high grit sanding, and rubbing until my arm fell off.


Here's the point where I sanded as much as I was comfortable and had upped the grit to 2000 for the last round. I did a rather light full surface sand for both the 1000 and 2000 round. Prepping for rubbing and polishing now.



Rubbed and polished with cheap pads on the drill. I used a different polish than last round, that Nu Finish can separated and was tossed.



Finally, placed in the box with glue. There's 1.5" of depth in the baffle and a 1/2" rabbet for the glue joint. This should give plenty of surface for a strong hold, and I'll caulk around the whole inside to ensure the seal is good.



The Duratex is now rolled on the back panel, second coat pending and will be ready tomorrow. That's where I'll pre-fit the precision port and fine tune with DATS.

[Wolf]

Oooh, SHINY!!
Wolf

[Steve Lee]

Looks like furniture to me - you should be pleased.

[wogg]

Thanks Steve! That's the goal, blend right in the living room.

[wogg]

The organ donor process is in full swing, the old cabinet was gutted and a spare Sony powered sub put in place to keep the entertainment center running while I finish assembly.

Here's the back panel, a bit of a swing and a miss with the cut out dimensions, probably 1-2mm off so I've got some work to do to open that up slightly for the amp module to drop in.



Here's the Lab12 sitting in the recess to locate and drill the holes for the threaded inserts. That sucker is thick, the 3/4" panel is just about right for flush. The JL audio grille going over that will still leave plenty of room for the woofer to do its thing.



Here's the spot where I did some cursing... while removing the woofer it rested on the polished edge for just a second and took a chip off. This is small, but highly annoying.



Any input on how best to do that little repair would be awesome. My current plan is to spray the primer and paint into little cups and use a small brush to touch up. Once cured I'll rub it a bit to try to blend it. It won't be noticeable from a distance, only under close inspection, but I'll know it's there.

[wogg]

This amp cutout is killing me. I keep removing material with the jig saw and the hole doesn't seem to be getting any larger so the amp continues to not fit. I think I found some sort of exception to the laws of physics with this thing.

[Steve Lee]

Got a wood rasp or horse shoe file?

[wogg]

Got a wood rasp or horse shoe file?

Yeah, started with a file but there was too much to remove. Ended up taking passes at it with the jig saw from the back side. Turns out my main problem was paying attention to orientation while pulling the panel off, working it, then test fitting. I set the amp sideways then was surprised when it didn't fit the right way.... user error

It's in there now, and still has enough lip for the gasket!

I sealed it up to test tuning, got it set at 21Hz with the full length of the 4" precision port kit. The model suggested I would need a couple more inches than that, so now I have a 4" extension kit that wasn't needed. I'll post up some DATS images later, I want to compare free air to in cabinet very closely to see what blips are showing up that would indicate resonances in the IKEA cabinet skin. I'm sure I have it really solid, but the impedance will tell the tale.

[wogg]

Free air vs. in box comparison.


The free air impedance sweep looks clean, with woofer break up showing at about 650 and 900Hz.

Here's the initial tuning check sweep, confirmed 21Hz. This is without any lining in the box, and the Precision port just press fit in there to check the tuning. I expect this to be a little cleaner once I line with a bit of denim insulation and glue the port up.



The woofer break up wiggles are still there at the exact same frequency, so no relation to the box at all there as expected. I do see a slight wiggle appear at about 150Hz. That corresponds to 1/4 wavelength of my ~22" internal dimensions, so that may be a weak standing wave. I don't see any other significant wiggles that would indicate a resonance problem with the cabinet itself. I'll do another sweep once lined and ready for use to see if that 150Hz tiny lump goes away. Purely out of curiosity at this point.

[wogg]

Port glued in and denim lining complete. It's fun to stick your head in the cabinet now and hear how eerily quiet it feels.



Little better shot of the port action. The cross brace is actually glued to each other, though it's hard to tell from this angle. There's Titebond in between to ensure they don't pick up some motion and rattle inside. You can also see the edge I had to shave off the port flare to fit.



The back panel got some treatment too, around the amp.