Tritrix translam now RS150 MTM
by on Feb.23, 2010, under RS150 MTM Translam, Tritrix Translam
With all this work I’ve decided to ditch the Tritrix and upgrade to the MTM. Considering the time and money already spent, the cost difference is pretty minimal. The enclosure and baffle are identical.
Progress has been slow but steady as the weather hasn’t been great for working in the garage. Here I drilled some holes for dowels using a drill press and template.
For the bottoms, I drilled holes all the way through and used hurricane nuts so I can use these later to bolt the box to the stand.
And the next layer from the bottom is the brace, so the holes will be covered…
It’s been so cold outside I had to bring everything inside for gluing. I did two layers at a time and clamped. I tried three at a time but I couldn’t get enough clamp pressure to close everything. Two layers was just fine with about 30 minutes clamp pressure. The dowels help a lot with gluing. Despite using a drill press and template to make holes for the dowels, it still wasn’t perfectly aligned.
Here are both enclosures glued with one sanded. For sanding I started with 100 grit because it was the roughest I had on hand. After 20 minutes of little progress and an arm that was about to fall off, I ran to the store and got some 60 grit which went MUCH faster. The finished off with some 220 grit. I applied one coat of Zinsser sanding sealer (sealcoat) on the inside before applying the acoustic foam.
This is the 3/4″ Parts Express sonic barrier. Feels stiff and heavy duty, I like it!
I dumped the sawdust from the sander and mixed it with PVA glue to fill the voids.
That’s it for now!
What to do now…
by on Jan.22, 2010, under Tritrix Translam
The speakers have to fit under the projection screen, and I’m concerned this might be too low and screw up the sound stage.
Done with cuts for L/R mains
by on Jan.18, 2010, under Tritrix Translam
I’m finally done with the cuts. It’s nice and dry out, but too cold for gluing. I’m going to bring them inside and wait for a warmer day to start gluing.
Never have I dreaded so much cleaning my garage…
Tritrix Translam Underway
by on Jan.18, 2010, under Tritrix Translam
When I first saw the Magico Minis, I knew I wanted to do a translam. The Minis are crazy expensive and I’m looking for something on the other end of the price scale. This is to be a 5 speaker setup for my family room, about 80 % home theater, 20% music. After much research, I went ahead with Curt Cambell’s tritrix MTM design. It uses Dayton Classic drivers and appears to be pretty versatile, allowing the enclosure to be placed vertically for L/R mains and horizontal for the center channel, all using the same crossover. It’s a great bang for the buck from Parts Express. The mains and center are to be MTM, while the surrounds will be MT.
I ordered 4 sheets of 4×8 Baltic birch plywood (B/BB). Doing a translam, I suppose the most sane thing to do would be taking it to get CNC’d, but I had a hard time finding a local shop with a CNC willing to cut plywood. I guess I didn’t look that hard (plus I like the idea of doing it all myself).
I studied quite a few translam builds from other folks, but decided to use the same approximate proportions as the Magico Minis while using Curt’s baffle dimensions. I love the sound of sealed enclosures, and I’ll be using this setup with a sub, so sealed it is. The resulting enclosure volume is a little more than Curt’s recommended sealed enclosure, but I’m trying to leave the door open for the RS150 MTM should I choose to upgrade in the future. The baffle will be replaceable, so upgrading won’t involve rebuilding the enclosure. And with a roundover, the baffle dimensions are very close to the tritrix. This translam is going to take plenty of work so I hope the compromise doesn’t impact performance too much.
I took an overhead picture of the Magico Minis, then photoshopped it bit to get the right baffle width. Here it’s traced on a peice of 1/2″ MDF.
The toughest part was this curve. I could have cut with a jig saw and then sanded, but I felt the router would give me something more accurate. But with the changing radius of the curve, I went ahead and built a ghetto jig out of MDF. Here’s the first pass.
I couldn’t find the larger machine bolts for my router, so I used some nuts and bolts to keep the jig on…
This is after about 12 passes on the router, changing from appx 4-14 inch radius to get as close as I could to that line. I then sanded any transitions. I’m impressed with the result as I didn’t have to do much sanding.
For the front baffle cutout, I used two pieces of MDF for a straight edge and right angle. I’m going to be using a 3/4″ MDF baffle, which is a little deeper than the Magico template.
I transferred the one good side onto a new template, using the straight edge from the front baffle cutout to align the opposite side.
I didn’t follow my original template for the rear, since I want it to have the width for a port should I choose to add one later (and the enclosure needs to be shorter for the appropriate volume anyway). The rear is cutout for a 3/4″ MDF baffle also.
For bracing, I looked at the layout of the Magico braces and ghetto-rigged some paint stir sticks to have something to use with my router.
I transposed the templates (with and without braces) onto the Baltic birch plywood. The MDF is really easy to work with, but it dents too much when using flush router bit to make duplicates. I think the plywood will be more consistent.
Finally, here are all four templates.
The first enclosure took maybe 12 hours for the 30 pieces needed to make it ~21″ high. Yeah, those are burn marks from the router on the non-visible parts. When I wasn’t routing the outside curves, I got lazy with the router since I knew it wouldn’t be visible anyway. Here’s the first box dry stacked, unsanded.
I’m about half way through the second speaker. The MT surrounds are going to use the same templates, but will be only 12″ high, so I might just keep going and get them all cut while I’m setup for it. That way I can seal and finish everything at the same time. When this is all done, I’ll make a crappy MDF box for the center to be placed in the entertainment center since I don’t have room on top for a horizontal translam.
