New THT Build

[Melifluonze]

I just purchased the plans on 5/5 or so, so they should be the latest, per the "update" sticky. I'm off and running, building two of these monsters at 30" wide, with the Dayton RSS390-H4 drivers. I think I hit my first bump fairly quick, just because I'm trying to be super careful.

On page 4 of the plans there's this statement that says "Parallel lines drawn 1/2 inch to the outside of these, per diagram 3, denote the joints of the major inner panels." So, I'm guessing that this means draw another line parallel to the existing ones, 1/2" towards the outside of the box for all lines, but there are no measurements in the plans themselves to really verify that this is what it means.

The thing is, the small inch measurement between the initial lines at the squeeze of the horn seems to get smaller when you add the 1/2" lines (perception). I'm worried about shrinking that little inch to 1/2" because it feels too small... So I am not sure what "outside" really means...

So, I pulled up the sketch and started taking a look by rotating it a bit...

The layout in the plans shows what looks like an extra 1/2" brace on the short part of the chamber, on the outside wall, and the sketch does not (the box goes right to the outside wall, with no extra 1/2" panel). I did notice that there seems to be an extra 1/2" of material on the access panel edge... maybe I'm just seeing that the support around the access panel is 1" wide at that edge?

Probably silly questions... Is there another piece of wood on that speaker box outer edge? Is it just the frame of the access panel hole? And what does "outside" mean when you're adding the extra lines 1/2" away from the others? Is it what I'm thinking?

Going to go measure the distance to the lines in the sketch and on the board now to see if they match the dimensions of panel #1. Maybe I can figure out the answer that way.

- Melifluonze

[asarose247]

last year I built 3 BF THTLP's from plans. I had never built anything like them before.
I know (from the hands on) that these plans are absolutely fantastic from the expert acoustical properties/performance and to the structural cleverness that makes the unit as strong and self bracing to put up with the acoustic forces.
The body of support here is unlimited and you will not fail to get a great sounding, performing sub.
As a constant refrain here, RE-read the plans, try visualizing the step by step in your head when you are unsure. measure and re-measure and keeping asking yourself does this look right wrt to the finished overall unit.
I took 2 months to build the first 24" and 2 months to do a simultaneous build on the 2 30"'s, well worth it, heat and all.
some pictures at: williamtomkiel.imgur.com

[Melifluonze]

Just to be 100% clear... I'm not busting on the plans! They are AWESOME, and Bill obviously spent significant time and effort making them comprehensive.

This is me looking way too far into the details and making sure I'm doing the right thing... measuring 1,000 times and cutting once. This is also me asking the forum questions, since I did read the plans like 8 times now, and I want to make sure I understand. Everyone thinks differently (and some may not exactly think like Bill, until they are nudged a bit)...

So I used the sketch to measure out what I was missing... The plans match the sketch. The little piece I see in the plans is a 1/2" extra around the access hole near the edge of the box.

The 1" small part of the horn IS reduced by the plywood of the speaker box, because adding 1/2" to the outside of all lines makes that go to a half inch (as shown on the plans).

- M

[Melifluonze]

I cut the access hole... heh... so I hope I interpreted correctly!

[Melifluonze]

Took the Dayton out of the box. WOW!!!

Interesting thing is, it seems to have a gasket now!? There's a continuous one on the top, and one on the bottom. The one on the top doesn't really extend past the edge of the basket much. (see the pics). I have it, and I'll probably still install it, but do I need to use Speaker Gasket, or did they change the driver design?

I read in another thread that the driver spacer was not necessary if using T-nuts, only if using wood screws (to give them more to grip)... is this correct? I am planning to use T-nuts (sealed to the driver mounting panel with epoxy) with bolts and lock washers. I'm not too keen on the wood screw mount, as there's no way to really fix those holes if they get worn out from use or change-out.

Also... what is the reasoning behind cutting out an access hole on both panels? Is it for ease of access, or is there a critical reason for it?

- M

[Melifluonze]

Oh fine... found an answer to my last question in the plans... (Jeesh, Bill... did you get a ton of feedback and incorporate it, or are you really just THAT GOOD??? )

"You don’t have to put a cover on both sides, but it’s an easier job mounting the driver if you do. Leave the second cover out if you’re putting a furniture finish on the cab and don’t want the second access cover to be seen."

Yeah, yeah... read the plans AGAIN... I DID! What's the point of the forum if everything is answered?

Would mounting the driver while the top panel is not on really be a bad thing? Is there a worry about glue dripping down or something like that?

- M

[Melifluonze]

Heh... I read about it in the forum and told myself that I'd make sure I didn't do it... then I did it myself. I cut out the driver hole in the wrong position... 9 1/2" from the 29" dimension (for 30" THTs) versus from the fixed dimension.

Does it matter to the sound if the driver is offset, if the driver clears significantly from the opposite panel? Right now it's offset more towards the start of the horn, and offset from center. PITA to change it, but if it makes a difference to the sound, then I will...

Can someone let me know?

- M

[Bryson]

Hey! I'm building my THT too, here: http://billfitzmaurice.info/forum/viewt ... 30&t=21561

Just a few steps ahead of you, but it seems we have similar questions. Good luck, hopefully it helps!

[Melifluonze]

Hey Bryson!

Thanks! There's my answer... Doesn't matter! The driver fits just fine (with about 2+" to spare). I'll follow your build thread!

I did not install the spacer on the driver baffle. I looked at the bracing and installed the driver without the spacer to check and things clear very well, and are solid.

You are doing a MUCH better (more careful and craftsman-like) job than I am. Your work is amazing!

I'm interested in the sound and not the cabinet work. My build is dirty, but solid. I imagine my second one will be a bit better, but I am gluing, clamping, air-nailing (18 ga. brads) and unclamping to go on to the next step. Seems to be working quite well so far, at least mechanically. My priority is maintaining the dimensions and the air-tightness. How beautiful it is is not important for me on this build.

And, yes, it has been in the past... (see below) But seeing as these will be inside my theater walls, I'm not caring as much...

The rest of my theater speakers consist of 5 channels of MTM Focal Aria 5 with the "old" Kevlar TC90 and 5K013L, and Focal Polyglass 10" bass acoustic suspensions. These THT's should go very well with all of that, since I'll send only the LFE below 80 Hz to them. I'm working on gathering the components for two more MTM's for 7.1, but they're hard to find now.

- M

[bossman]

Nice driver you got there. Looks like the surround protrudes quite a bit past the front gasket. You should double check to make sure that the surround will not hit any of the braces (remember at excursion it will be beyond where it is now). You may want to consider adding a spacer or notching the braces extra deep to accommodate. T nuts work good for mounting the driver. I never found the need to use any glue on them.

[Melifluonze]

Thanks, Bossman! I'm probably going to notch the braces a bit deeper. I'm probably also going to add a brace inside the cavity as well, since my driver ended up in the bottom end of the cavity (due to a whoopsie on my part).

Hey... it seems this thread is in the wrong place and I didn't realize it. Can it be moved to the DIY section?

- Melifluonze

[Bryson]

Hey Bryson!

Thanks! There's my answer... Doesn't matter! The driver fits just fine (with about 2+" to spare). I'll follow your build thread!

I did not install the spacer on the driver baffle. I looked at the bracing and installed the driver without the spacer to check and things clear very well, and are solid.

You are doing a MUCH better (more careful and craftsman-like) job than I am. Your work is amazing!

I'm interested in the sound and not the cabinet work. My build is dirty, but solid. I imagine my second one will be a bit better, but I am gluing, clamping, air-nailing (18 ga. brads) and unclamping to go on to the next step. Seems to be working quite well so far, at least mechanically. My priority is maintaining the dimensions and the air-tightness. How beautiful it is is not important for me on this build.

And, yes, it has been in the past... (see below) But seeing as these will be inside my theater walls, I'm not caring as much...

The rest of my theater speakers consist of 5 channels of MTM Focal Aria 5 with the "old" Kevlar TC90 and 5K013L, and Focal Polyglass 10" bass acoustic suspensions. These THT's should go very well with all of that, since I'll send only the LFE below 80 Hz to them. I'm working on gathering the components for two more MTM's for 7.1, but they're hard to find now.

- M

Sounds like you are on the way! I'm doing one panel or one set of braces a day, so you might pass me up soon! Good luck! Should be awesome, I can't wait to hear mine. Mine is 24.5 wide with side panels on.

[escapemcp]

T nuts work good for mounting the driver. I never found the need to use any glue on them.

Yes, but better to add epoxy and not need it than omitting it and regretting it afterwards. It only takes a few extra minutes (and some epoxy).
Melifluonze - sounds like you have the right idea with these cabs... it doesn't matter how neat they are on the inside, just as long as they are solid and airtight.

[Melifluonze]

Yeah, I figured out a cool way to cut the braces today. All the internal braces seem to be at the same angle, so I set the angle on the miter gauge and then measured out the starting width... voila!

Then I found a mistake, because the braces didn't fit in properly when I was installing panel 8! Cool... I'm on the outside panels now.

I left the driver installed, btw... and I know why that's a bad move... the magnet is heavy!!!

- M

[Bryson]

I knew you'd pass me up! I need some pictures!