BillFitzmaurice.info

For installing braces while they get all slippery with glue, I opted to cut dadoos with my router (very shallow, one to two mm is enough). They will not tend to drop down or slide around anymore. One setting on the router parallel jig (comes with most routers), mark where to cut on all panels and cut the dadoos all at once. It worked for me, YMMV.

The THTLP is really taking shape.

I began the day by installing panel 10. It's a small panel and installing it took hardly any time. I mounted the woofer in the new baffle (panel 6) and tested it. I wasn't sure if there was sufficient clearance, so I followed Bill's suggestion and unmounted the woofer, put chalk dust on the baffle cut out, and then re-mounted and tested the woofer again. To my relief, there was no sign of chalk dust on the woofer so that there must be adequate clearance.

I removed the woofer once again and took the baffle out to the garage to install in the THTLP. First, I installed the brace. I measured where on the baffle the brace would need to be mounted, and tested the positioning of the baffle and brace with respect to panel 2. Once I was happy with the fit, I fastened the cross brace (with PL Premium and brads) to the baffle. I was then able to attach the baffle assembly (i.e., panel 6 and the brace) without any difficulty. The temperature has dropped so that I've put a heater in the garage to help the PL Premium cure.

The next tasks are to install the last two panels (panel 9 and side B) and to cut off the overhang from panel 8. Although that doesn't sound like it should take very long, I need to allow time for the PL Premium to cure.

Although it feels like the bulk of the work is done, there's still a fair bit to do:

• adding cover flanges to the driver chamber opening

• making and installing 8 driver chamber braces

• cutting and installing the driver chamber cover and 2 cover braces

• mounting and installing the woofer

I don't expect that I'll get to that until after Christmas.

I expect to get the Dayton SPA250DSP amp (which has been out of stock for quite a while) in mid-to-late January. I'll be glad to have it so that I'll be able to see how the THTLP sounds.

Yay, haha, you did it! You got a good baffle, installed!

Today the weather warmed enough to do some more work on my THTLP project.

As usual, I started by scraping the PL Premium squeeze-out from my last glue-up and then caulking the joints.

I then cut all of the remaining pieces for the THTLP:

• 4 x cover flanges
• 8 x driver chamber braces
• 1 x chamber cover (left oversized to be trimmed when installed)
• 2 x cover braces

I was able to cut all of the parts for the THTLP (including one panel that I had to remake) from just two 4'x8' sheets of plywood. I still have about a 2'x2' piece of plywood left over.

Since I'm building the smallest-sized THTLP (only 15" wide), I have a couple of challenges to sort out:

1. if I install the driver chamber braces as indicated in the plans, it won't be possible to install the woofer. To remedy that, I plan to install half of the braces as per the plans (wide part at the baffle and narrow part at the rim), and the other half the other way round. I picked up that idea from searching on this forum.
2. I'm not sure if there'll be room for two cover braces or just one. I'll know when I get to that stage.

I also installed the last panel (panel 9). It took a little effort get get everything to line up and to straighten out some warping, but I think it turned out OK.

Here are some photos of the current state of my build: My next steps will be to install side 2 and then finish off the driver chamber and cover.

looking great! You get itchy when there's one side left to put on, and it's close to test time!

The cabinet is complete!

I spent a fair amount of time cleaning up the PL Premium squeeze-out from the day before, caulking all of the joints so that they have nice smooth fillets, and filing in holes from brads with wood filler.

With that out of the way, I attached the driver chamber rim flange to the three sides that were in place. I then fit two driver chamber braces to each side. Fortunately, I had drawn a circle around the Dayton RSS315HF-4 driver when I had temporarily installed it, so that I could use that circle as a guide, keeping the driver chamber braces clear of it. Happily, I was able to install the braces in their correct orientation by installing them 3" from the sides. It was tight, but everything fit.

Then I fit the second side to the cabinet. It took a bit of finessing to get it to fit just right. I tested with screws to see if the panels were lined up with the lines i drew at the beginning of the build. I'd check to see if I had screwed into solid material, or if I had missed the mark. Most of the lines were in the right places, which made me quite pleased. Having assured myself of the fit, I applied a large bead of PL Premium on all of the panels that would contact side 2, and put the side in place. I used a few screws to ensure alignment, but used 1 1/4" brads for most of the fastening.

With all sides of the THTLP installed, I attached the chamber rim flange to side 2, and installed the last two driver chamber braces. I checked to be sure the cabinet was square and measured the chamber opening. To my delight, it was spot-on. I then cut the chamber cover to the correct size and installed two braces. Because my THTLP is only 15" wide, the braces could only go one way. They, too, were attached with PL Premium and brads. Tomorrow, I hope to finish up the work that has to be done in my (unheated) garage:

• scraping off the PL Premium squeeze-out
• trimming panel 8 (which was purposely left too long) so that it is flush with the cabinet
• filling holes with wood filler and sanding the cabinet smooth

Then, I'll move the THTLP indoors.

Although the cabinet is complete, there is still work to do:

• mounting and wiring the driver (Dayton RSS315HF-4)
• installing a gasket on the driver chamber opening
• installing the driver chamber cover
• installing the plate amp (Dayton SPA250DSP)

The plate amp is on backorder and isn't expected to arrive for several weeks so that I'll have to practice patience while waiting to put the THTLP in action.

As can be seen in the photos, the THTLP is bare wood; I haven't put any finish on it. My plan is to veneer it in the spring (when I can comfortably work outside again).

I'd like to thank the members of the forum for their support and encouragement. I'd also like to commend Bill on how clear his build instructions were.

Wow Dave! Great job with everything... you got it all put together (for the most part) in what, a week? Build quality is darn good too.

Are you going to be able to wait for the plate amp? I wouldn't be able to myself. I'd have it powered up and shaking the house with something... maybe the amp the speaker was broken in with... a '90s era Walkman Sport... anything! LOL

I look forward to updates as the finer details come together. I've never veneered anything. It will be interesting to see it take on a new look. Is there any particular veneer you have in mind? I'd assume something that goes with existing room furnishings.

Seth wrote: ↑Wed Dec 22, 2021 1:40 am ... a '90s era Walkman Sport... anything! LOL

This

Yes, great looking build, great thread!

2022 is looking better already. Yesterday I completed my THTLP build. All I need now is the plate amplifier for it (on back-order but expected to arrive by the end of the month).

Right now the THTLP is in my basement workroom (much better than my unheated garage). I'm eager to move it up to my living room and connect it to my sound system to hear how it sounds.

The plate amplifier (a Dayton SPA250DSP) has a built-in DSP, so there'll be lots of opportunity to "tune" the THTLP.

Nice work Dave! Must be hard to wait a long time before putting it to good use. I for one would have been tempted to find some way to make it work with whatever contraptions I have available to tamper with

DaveMacKay wrote: ↑Thu Dec 16, 2021 12:31 am Also, my wife wants my tools out and her car back in the garage before the snow comes!

DaveMacKay wrote: ↑Sun Jan 02, 2022 2:02 pm 2022 is looking better already. Yesterday I completed my THTLP build.

Right now the THTLP is in my basement workroom (much better than my unheated garage). I'm eager to move it up to my living room and connect it to my sound system to hear how it sounds.

Just in time before the snow came! LOL

DaveMacKay wrote: ↑Sun Jan 02, 2022 2:02 pm Yesterday I completed my THTLP build.

Dave, that looks really good. Nice clean edges, square... sweet!

I can't wait to hear your review and opinion.

Thanks for putting up such a fantastically detailed build thread! I completely enjoyed following along.

The Dayton Audio SPA250DSP plate amp that I've been waiting for was delivered today.
I was keen to try this amp because of its DSP capability. I'm hopeful that the DSP will allow me to "tune" the THTLP to address some of the peculiarities/deficiencies of my room and my speaker placement. The amp comes with a power cord and a USB cable so that the DSP can be programmed from a PC (only a Windows version of the GUI is available).

I had purchased an enclosure for the plate amp so that I could mount it on my THTLP. Both the plate amp and the enclosure had gaskets pre-installed so that all that's needed is to measure where to put it and screw it in. I used 1/2" #8 screws to mount the enclosure to the THTLP.
The enclosure didn't provide a lot of space, but I didn't have any trouble wiring it up. I used Jago lever nut connectors https://www.amazon.ca/Lever-Nut-Connect ... B07871V4L8to mount the speaker wire to the amp.

Here's how the THTLP looks with the SPA250DSP installed: I crossed the THTLP over from my La Scalas at 100 Hz (the La Scalas stop acting as horns below 104Hz). I will have to work out how to set the DSP.

Despite believing that I'm a long way from optimal DSP settings, I'm quite pleased with how the THTLP sounds. I'm likely overdosing on bass right now, and may dial it back later, but the system sounds wonderful: it's clear, clean, and tight. Even at moderate volumes (~65 to 70 dB), the bass can be felt, not just heard.

You may recall that I'll have not just one, but two, THTLPs. @Tom Smit has agreed to build the second THTLP for me so that I won''t have to wait until spring (when my garage is warm enough to work in again). One THTLP has already surpassed what I had hoped; I can't wait to see how a pair perform!

Needless to say, I've been very pleased with the whole experience: the build was fun and just challenging enough. And the finished THTLP is a superb subwoofer. I'm a happy man.

DaveMacKay wrote: ↑Tue Jan 11, 2022 10:53 pm


I crossed the THTLP over from my La Scalas at 100 Hz (the La Scalas stop acting as horns below 104Hz). I will have to work out how to set the DSP.

Despite believing that I'm a long way from optimal DSP settings, I'm quite pleased with how the THTLP sounds. I'm likely overdosing on bass right now, and may dial it back later, but the system sounds wonderful: it's clear, clean, and tight. Even at moderate volumes (~65 to 70 dB), the bass can be felt, not just heard.
Needless to say, I've been very pleased with the whole experience: the build was fun and just challenging enough. And the finished THTLP is a superb subwoofer. I'm a happy man.

Dude! That's amazing praise!....and you're not finished yet!

This is an awesome build! It gets me even more excited for the one I just started. I'll be tuning in for your thoughts on the DSP. I think I'm going to need to add a DSP to my setup.