4XTHT With Dayton RSS390HF-4 15" @ 24" Wide

[boostick4]

This build has been a long time coming.

Back in 2011 I built my first THT with a Dayton RSS390HF-4 15" powered by a Behringer EP4000 and controlled with a Behringer DCX2496. I measured the response with a friend's OMNImic V2. I then compared the THT response to the same driver in a 7.5ft^3 sealed box and got the results in the third picture below. I was impressed with the output for a modestly priced 15" driver and was happy with it for the most part, BUT, I wanted more below 40Hz.

First THT. Laser cut steel router patterns are shown for the access door, flange, and side layout.

THT corner placement.

24" THT with Dayton RSS390HF-4 15" vs. 7.5ft^3 sealed test box with Dayton RSS390HF-4 15" at the same voltage in the same corner of the room.

So after enjoying the single THT for a little over a year, I finally got around to buying enough wood for 4 more THTs in early 2013. The gain in headroom across the passband going from 1 to 4 cabinets would allow me to be more aggressive with the EQ on the DCX, and let me achieve a flatter overall response curve without damaging drivers.

Unfortunately, in early 2013 with the intent to build 4 more THTs, life intervened and basically all time for this hobby disappeared. Flash forward to mid 2015 and more free time became available due to a new job. I built the 4 new THTs as 2 left and 2 right handed cabinets due to not wanting the access doors to be visible when in the living room. The Arauco I bought in 2013 was terrible compared to the Arauco I bought in 2011. This greatly slowed my progress due to having to fix knots and splits along the way. If I build anymore BF cabinets I will only use proper Baltic Birch with as many plies as I can find, and abandon Arauco altogether. I have realized with this last build that my time is now much more valuable than the marginal price increase for the better, flatter, defect free wood. I did not get the 4 done in time to get outdoor measurements before the snow hit this winter. However, as soon as the weather gets nice this spring I plan to haul them all outside to test the theory of adding cabinets to smooth response with real data.

Work room.

I ripped all of the 4'x8' sheets down the middle first. Then moved the fence in a hair, setup a featherboard, and ran the halves through the saw again to ensure all panels would be the exact same width.

[boostick4]

Cutting panels to size.

"Quality" of the Auruco. You can see the large splits in this board. The 2011 wood didn't have anything like this in it. The 2013 wood had many parts that I had to work around or PL like crazy.

All panels and door material for 4 THTs! Plus the clamping squares I had made. If I did it again I would have cut a series of 90DEG segments into the diagonal edge to offer more clamping locations.

Initial construction of all 4.

Clamping squares worked out very well.

[boostick4]

Clamp party.

Clamp party.

This is how I install all my hurricane nuts if possible. Press them in halfway by hand. Then PL under nut. Then drive all the way in with the arbor on my drill press. Then smear the PL squeeze out over the top of the nut making sure not to get any in the threads.

The big table really make clamping everything down easy.

You can see here all of the knots I had to PL. I PL'd all edges too to prevent any delamination down the road.

[boostick4]

Chisel and PL any knots that looked like they could rattle out.

I used laser templates for all doors and flanges to I wouldn't need to keep track of which door goes on which cab. This way they all fit all cabs. I used the Grizzley premium (purple) 1/2" flush trim bit in the router for all cuts, and its still sharp!

I got quite the workout throwing these cabs around the shop.

Production!

I wanted to get a picture with all 4 of the cabs mirrored like this but unfortunately got ahead of myself and glued 2 sides on before I remembered I wanted to get that shot. Maybe next time :)

[boostick4]

I used a floor jack (you can barely see it on top pressing against the floor joists) to press down on the cabs when I glued the sides on.

I decided late in the game to add a front door to the cabs with the intent of making them out of lexan so the driver would be visible. I still need to have these routed out, but made wood doors for now. The round hole you will see on the wood doors is a handle sealed with a 3" PVC cap PL'd into a groove.

All sanded, edges rounded, and mouths Duratex'd prior to Duratexing the outside.

Side access doors glued, gasketed, painted, and wired ready for assembly.

Outside of the side doors.

[boostick4]

Close up of exterior of the side doors. I recessed the terminal cup so the Speakon connectors wouldn't stick out beyond the side and be crushed when stacking the cabinets on their sides.

Driver break-in time!

One cab prior to driver and door assembly. Once the lexan doors are done I'd like to paint the chamber with an orange UV sensitive paint and put some 365nm LEDs on the back side of the front door flange (so you cant see them) and make the chamber glow. But we'll see.

Mouth side of the cabs, one with the front door removed.

All four assembled and in the same place the original THT was in the living room. Sorry for the crappy cellphone pictures. I'll get some better ones this spring/summer when I measure them outside.

[boostick4]

Current location of the 4 THTs. I will most likely move 2 of them to the side where the first THT is currently shown in this picture. And lay them both on their sides so they are kind of like giant end tables. We are getting all new flooring and painting soon so I haven't made wiring provisions in that corner yet. Our living room is very long (creating a somewhat unusable space where the THTs are) and open to the entire house.

Made 1 prototype lexan front door just to see what it would look like with a scrap I had laying around. I like it and will have 4 identical ones machined soon.

[boostick4]

They are currently powered by 1 EP4000 with these DCX settings. Still tweaking. I believe there is more to be had by adding a second EP4000 which I have but haven't hooked up yet. I borrowed my friend's OMNImic again but haven't had a chance to measure yet (new computer issues) and probably won't until I move the 2 to the other side of the room and the flooring is done. BUT, THEY ABSOLUTELY HAMMER!

They are currently powered by 1 EP4000 with these DCX settings. Still tweaking. I believe there is more to be had by adding a second EP4000 which I have but haven't hooked up yet. I borrowed my friend's OMNImic again but haven't had a chance to measure yet (new computer issues) and probably won't until I move the 2 to the other side of the room and the flooring is done. BUT, THEY ABSOLUTELY HAMMER!

They are currently powered by 1 EP4000 with these DCX settings. Still tweaking. I believe there is more to be had by adding a second EP4000 which I have but haven't hooked up yet. I borrowed my friend's OMNImic again but haven't had a chance to measure yet (new computer issues) and probably won't until I move the 2 to the other side of the room and the flooring is done. BUT, THEY ABSOLUTELY HAMMER!

They are currently powered by 1 EP4000 with these DCX settings. Still tweaking. I believe there is more to be had by adding a second EP4000 which I have but haven't hooked up yet. I borrowed my friend's OMNImic again but haven't had a chance to measure yet (new computer issues) and probably won't until I move the 2 to the other side of the room and the flooring is done. BUT, THEY ABSOLUTELY HAMMER!

[boostick4]

I didn't realize all of the individual picture comments don't show up in Tapatalk.... If you want to see them you have to go to Web View if you are using your mobile....

[Bill Fitzmaurice]

A few points. First, measured outdoors four will be pretty similar to one corner loaded indoors. Second, no matter how many you have the corner frequency will still be 22Hz. But with four you will be able to EQ in more output below 22Hz. Just be sure that the maximum voltage into them is no more than 28v and you won't exceed xmax at any frequency.

[shawn_g]

Amazing work on the cabs.

5 THT's in a small room like that must be brutal.