Translam Subwoofers with 18" Passive Radiators - The Jedi Mind Tricks

[Kevin K.]

I think it's a great idea for guys to show you some of the different finish effects on translam plywood. Here is a picture of my Archers before finish and after lacquer was applied. No oils, just lacquer on the translam plywood.

[KEtheredge87]

Hey Guys,

Time for another update! Again, thanks to John H, Don, Javad, and Kevin for helping me think through the finishing process. I think I may be "warming up" to the amber tones from oil based poly (forgive the obvious pun). As you guys suggested, I've decided to test some finish styles out before applying to the cabinets. I bought a quart can of General Finishes Arm-R-Seal wipe on oil based poly to try with my finishing schedules. Also, I've concluded there's no way for me to have these 100% completed in time for MWAF, so there's no reason to rush the process. Especially since subwoofers alone aren't the main competition.

I mentioned another style of finish a moment ago... I found another walnut finish from woodworkers source that caught my eye. I bought the dyes and wiping stain he used, so I'll see this in person! See the youtube video here:

Other ways I spent money recently... I bought a 17" flexible sanding block and sandpaper from Eastwood. Those arrived today, but I realized I made a mistake. The sanding block is hook and loop, but the sandpaper is PSA! (D'oh!) Apparently Eastwood carries the HL sanding block... but no HL sand paper (FAIL!) Ultimately the sandpaper is the more difficult stuff to buy in small quantities, so I just bought a different sanding block on Amazon that accepts PSA. I may try to return the HL sanding block to Eastwood. Depends on shipping cost. I can't seem to find size appropriate HL sandpaper anywhere!

As for actual work, tonight I sanded off the first layer of timbermate filler from the second cabinet. Then I used a flashlight to give another check on both cabinets. I pencil marked the locations that need a second filling, or were missed the first time. I'll fill those spots and sand them down again before getting serious about the finish sanding up to 220 grit. I also intended to drop some of those speaker grille neodymium magnets into my MDF baffles, but realized I didn't buy the 13/32" drill bit that's recommended. Yet another reason to make friends at my hardware store!

[tomzarbo]

Hey Keith, I have a question for you...

Up until this project, what's the most time you've ever spent on a speaker project? I know you've done a voxel sub, and I'm assuming a few other things before you embarked on this project.

It just seems like you're doing so many things right on such a huge project with so many elements to it's design/construction that it's hard to believe you haven't been at this for quite awhile. I guess general woodworking and handyman stuff around the house is good training as well, but still... You're doing some really nice work and making excellent choices I think. I can guarantee I'd have made twice as many faux-pas if I had tried to pull this off!

I'm thinking of the time you've put into these as well. I know for myself, it seems like the larger, more visible things we do in this hobby can take considerable time... but often the little things can eat up half a day here and there... and that stuff really adds up over a few weeks. It's good you've been putting in a few hours here, an hour there... otherwise a 6 hour Saturday could turn into a 10 hour day real fast when time isn't on your side. I know your wife has a few pictures of you around the house, but sometimes it's nice to see the actual person you're married to every once in awhile!

Good work, it's been encouraging for me to see you working so hard on these. Seeing this is helping me to get my project moving along more quickly. These things are just going to look amazing!

TomZ

[KEtheredge87]

Hey Keith, I have a question for you...

Up until this project, what's the most time you've ever spent on a speaker project? I know you've done a voxel sub, and I'm assuming a few other things before you embarked on this project.

It just seems like you're doing so many things right on such a huge project with so many elements to it's design/construction that it's hard to believe you haven't been at this for quite awhile. I guess general woodworking and handyman stuff around the house is good training as well, but still... You're doing some really nice work and making excellent choices I think. I can guarantee I'd have made twice as many faux-pas if I had tried to pull this off!

I'm thinking of the time you've put into these as well. I know for myself, it seems like the larger, more visible things we do in this hobby can take considerable time... but often the little things can eat up half a day here and there... and that stuff really adds up over a few weeks. It's good you've been putting in a few hours here, an hour there... otherwise a 6 hour Saturday could turn into a 10 hour day real fast when time isn't on your side. I know your wife has a few pictures of you around the house, but sometimes it's nice to see the actual person you're married to every once in awhile!

Good work, it's been encouraging for me to see you working so hard on these. Seeing this is helping me to get my project moving along more quickly. These things are just going to look amazing!

TomZ

Hey Tom, thanks for asking! As far as speakers go, the longest time I've spent on a project is about 9 months. That was on the Swope towers and center channel I built. It was the first speaker project I ever built, so there was lots of time learning new processes and researching. In fact, the biggest goof up I had during that project was using a belt sander! Lots of bondo to fix those issues! I will admit that a solid month or two was just using them as bare MDF while I mulled over what veneer to use and what finish style to go after. If that were 9 months of straight project work, I would probably have gone a bit crazy!

I honestly think my skills have come as far as they have due to learning from guys like you and others on the forum here. Lots of great information here to help newer guys like me! Otherwise I guess I'm just a quick YouTube study with an engineering brain. I'm always looking for techniques and suggestions online and can implement them pretty easily. The engineering in me helps with process planning and general "order of operations". On a more simple level, my wife always says I'm just not afraid to fail. I guess that's true... Im not afraid of failing, but I'm certainly afraid of screwing my projects up!

The time thing is definitely a big challenge. I admit I spend a lot of time on the little things too. A good few hours of "speaker work time" this week has just been spent ordering/buying finishing supplies. Thankfully I've got a stretch of a few solid days over the holiday where I can epoxy and sand and work on baffles! I think my wife still knows who I am, tonight was Chipotle date night, so that's always great

I'm glad that my little daily updates have been pushing your work along! Can't wait to see your latest too!

[KEtheredge87]

Hey guys - Mid-day update:

So far, we're off to a good start on the epoxy coating front! The Total Boat 5:1 epoxy seems to be doing its thing, and the pump system they supply with it is super easy to use. I've been using a foam roller to apply the stuff to the main walls, and a foam wedge brush to really push the stuff into the seams where the walls meet the ceiling and the floor. I've got one coat on the first cabinet, and half of the second cabinet. While those have been drying, I installed grill magnets in my MDF baffles using Loctite CA glue, then capped them off with some loctite 5 minute epoxy. This way I can sand the epoxy layer flush with the rest of the MDF and try not to have an obvious circle in the veneer where the magnets are buried.

On the logistics and materials front, it appears bad things come in threes!
1) Eastwood flexible sander delivered as Hook and loop (Great sander, but Eastwood doesn't sell Hook and Loop sandpaper for it!) --> fixed by ordering less awesome PSA sanding block from Amazon.

2) General Finishes oil based Arm-R-Seal order from Amazon arrived today as GF High Performance (the water based product) --> Got a refund, and a free can of HP ... but still need to re-order!

3) Guitar purfling and cabinet scraper from Luthiers Mercantile International supposedly delivered by Fedex at 10AM. I've been home doing epoxy all day, and there's NO Fedex packages! Waiting on Fedex to sort themselves out.

With any luck, I'll get a second coat of epoxy on the cabinets tonight and let them dry overnight. I'm very close to veneering and cutting driver recesses, as well as the start of finish sanding. I can almost feel the BOOM already

[Kevin K.]

What's the Vinegar and Alcohol for?

[KEtheredge87]

What's the Vinegar and Alcohol for?

Hey Kevin,

The alcohol was me doing everything I could to remove dust from the bare surface (AKA following the directions on the epoxy bottle ) The vinegar was a suggestion for cleaning my tools that I found online. Not sure I totally understand the chemistry at work, but the vinegar reportedly neutralizes the reaction and causes the uncured epoxy to lose all its tack and turn a milky white color. From there it will wipe off and clean up pretty easily. I started using it thinking I could clean out my foam rollers and reuse them instead of each one becoming rock hard. That didn't work out too well when the rollers would crumble after I tried to squeeze out all the epoxy and vinegar solution! At the very least, It kept my roller handle from getting gummed up throughout the day.

[KEtheredge87]

Last update for the evening. I have finished all the coats of epoxy that I could until I ran out of mix. Officially got through 1 full coat on each cabinet, with a second layer on one wall of each cabinet. That said, I got into my groove during the day and layed some of the wall coats on decently thick. I biased my last two coats tonight to the thirsty walls that had absorbed epoxy in places that I didn't get sufficiently thick. Overall I think this was a great bit of added insurance for the project and I really thank all the folks here on the forum who suggested it! Once the walls dry up overnight, I should be in a decent place to start finish sanding and more work on my baffles!

Cabinet 1: Cabinet 2:

Oh, I also mentioned that "less awesome" sanding block from Amazon in my post above... this is the one I bought. 17" Flexible Sanding Board by AES
While I haven't used it yet, It's certainly not quite the same level of quality as the Eastwood board. This Amazon thing feels like it was made out of an over-designed pool noodle! Very, very flexible. I imagine it will work, but I have my doubts that I won't accidentally rip the molded-in foam handles off! At least the Eastwood one had wooden handles!

[KEtheredge87]

Hi guys... time for one of those Homer Simpson "DOH!" moments. No damage has been done to anything, but I realized a major flaw in the aesthetics department.

My plan all along has been to recess mount these drivers and passive radiators. When I finally got around to sketching out my PR circles on the MDF baffles, I realized how INSANELY close my recess was coming to the edge of the MDF panel... within 1/16 of an inch! To make matters worse, I knew I also still need to add a rebate to the back side of these baffles to make them fit down into the cabinet. Now I would have a 1/16" thin section right next to another ~1/8" section. At that point, I may as well have two halves of a baffle instead of one solid piece! I guess this is what I get for doing CAD work late at night and thinking "Oh, that'll be fine later!"

The unfortunate solution is to surface mount, rather than flush mount these drivers. This will add sufficient structure back to the baffle, make the veneering job easier, and make the driver cutout work that much easier. The downside is that they'll stick out from both ends of the cabinet, which wasn't really the look I was going for!

I'm going to think on this a bit more before committing to the surface mount, but that seems like the only reasonable alternative.

[KEtheredge87]

OK... after staring at CAD for a bit, taking measurements on the passive radiator's actual mounting flange and gasket thickness, I just may be able to pull this off. However... I'm going to push this decision out for a while.

In the meantime, I can apply the walnut veneer to the surfaces of the baffles, cut the rebates required to make the baffles sit flush with the front of the cabinet. THEN I can decide whether to surface mount or flush mount. This way I won't have to guess at the final cut depth and end up with a painfully thin section.

[tomzarbo]

Keith,
Yeah, I'd agree that surface mounting is pretty much your only option. It won't make a bit of difference though, other than how it looks, and It'll still look awesome.

Like Will Smith said, "It's for the look, I don't light it...."

https://www.youtube.com/watch?v=EIfAVBvIJY8

TomZ

[jhollander]

You could cut after the baffle is mounted in the cabinet. You'll probably want to match the MDF to the cabinet before veneering.

[JavadS]

You could cut after the baffle is mounted in the cabinet. You'll probably want to match the MDF to the cabinet before veneering.

That was my suggestion too, flush mount after you glue the baffle to the enclosure, the 1/16" won't be an issue then, it's just a matter of perfectly centering things. For me, I like the flush look, it shows an extra level of effort, attention to detail and skill, but it's certainly not required. Javad

[Kevin K.]

Is the baffle already cut to size? If not, have you considered increasing the opening on the enclosures to allow for a larger baffle? In the drawing, it looks like you have close to 1/2" before you get to the radius on the corner.

[KEtheredge87]

Hi Guys, Thanks for the great responses!

To John and Javad - I like where you guys are going with this. I was intending to fit each baffle to the opening before applying the walnut veneer, making sure the bare MDF surface is just barely inset to allow the veneer some room to match up with the surface. Given the literal stack-up nature of this project, this part of the assembly is showing me all the little errors that were made along the way. Some parts of the baffle have more room to wiggle than others, so I will have to be creative when I clamp these things up so that I hold the baffles in just the right spot. I will get these baffles as close to flush with the rest of the cabinet as I humanly can, but I don't think i can expect perfection here.

To Kevin's point... I had already cut the baffles to the right size for the openings before I got to this point. If it were only a question of time and MDF, then I could see remaking those panels to a larger size and opening up the cabinet a bit more to accommodate. In addition to the "already trimmed to size part" I have applied the backer veneer, and inlayed/epoxy sealed some grill magnets for a follow-on project to protect these guys in the event of tiny humans running amok in my house!

After the problem solving efforts thus far, It seems like this is my path forward
1) Apply walnut veneer to loose baffles
2) Apply my finishing schedule and all for the walnut veneer (except final polyurethane)
3) Glue the stained baffles into place with PL Premium
4) Make my recessed baffle cuts.

Man... I hope this isn't too risky!

Also then... question: Generally accepted practice is to route chamfers for air movement behind active speakers... should we do the same for passive radiators? Gluing the baffles on and THEN making the cuts complicates any machining on the back side of the baffle, but that could be roughly done with a dremel or sanding drum on a hand drill.

Lastly, for the moment...Here's some pictures of the front baffles after some rabbeting work on the router table (Love that thing!)