Shawn's Tuba 18 Build

[Gregory East]

You can put a tht down there and fire it right through the joists with hardly any difference to the sound. Try putting a 2x4 in front of t18, bet you can't hear it.

[shawn_g]

You can put a tht down there and fire it right through the joists with hardly any difference to the sound. Try putting a 2x4 in front of t18, bet you can't hear it.

I like the way you think.

Definitely something to consider.

[Tom Smit]

I'm going back and forth between two ideas. Can someone give me some input here on the better option?

A.) Build another T18, dual loaded to match my single loaded T18. Both placed in opposite corners of the wall.

OR

B.) Build a dual loaded TT long style and install it between the floor joists (16" spacing) in my basement, then install a large floor vent for it to fire through (in the corner of the living room). I might be able to fit it in behind my seating area instead of the basement idea, haven't decided yet. Either way, I'd need to unplug the T18.

I love my T18 and I should just be satisfied with what I have, but the extra low end extension of the TT would be nice. However, is it a larger benefit to have two T18's, or a single TT? I thought about doing the same between-the-floor joists idea with a THT LS, but the response graph make me think it wouldn't be worth it to build a minimum width THT.

The 16" is actually the centres of the joists, and that means you have to subtract 2" off of the 16" which leads to 14" space. Then, 2 x 1/2" for the sides of the cab means 13" internals.....no go. But, do you want to "renovate" just a little? Here's how.....cut out the piece of joist and nail a 4' longer piece with many nails to it's sister joist. Add the same to the other sister joist. Now you have a 25ish" opening available between the joists.

I've got two T39's and four OTop12's to build for my church before I do anything, so it might be good for me to have some time to think about it before I do anything crazy.

All I can do is think about subwoofers and speakers here lately. What has this site done to me!?!

Gasp, has the bug bitten you too?

[shawn_g]

The 16" is actually the centres of the joists, and that means you have to subtract 2" off of the 16" which leads to 14" space. Then, 2 x 1/2" for the sides of the cab means 13" internals.....no go. But, do you want to "renovate" just a little? Here's how.....cut out the piece of joist and nail a 4' longer piece with many nails to it's sister joist. Add the same to the other sister joist. Now you have a 25ish" opening available between the joists.

You're right about the the joist spacing. The one I just happened to measure when I had the bright idea, had a space of 15" (shoddy construction?). The rest seem to be around 14"-14.5" though. I like the "renovation" idea. I can always just stack the thing vertically and fire it through the joists like Gregory mentioned, but it would be nice to have it tucked up in there horizontally.

Gasp, has the bug bitten you too?

[Tom Smit]

Heh, I got to thinking later on that the "renovation" idea would only be safe/acceptable if one know exactly what one is doing. And, it also occurred to me later, that an upright cab could be placed almost right at the joists, and the one joist wouldn't even be an imposition to the bass waves. Therefore, I promote Gregrory's/my-second idea of standing it up.

[shawn_g]

Heh, I got to thinking later on that the "renovation" idea would only be safe/acceptable if one know exactly what one is doing. And, it also occurred to me later, that an upright cab could be placed almost right at the joists, and the one joist wouldn't even be an imposition to the bass waves. Therefore, I promote Gregrory's/my-second idea of standing it up.

Thanks for the concern. I most likely would have done the vertical placement either way for simplicity. It's less permanent that way too.

[shawn_g]

I've thought about this for a few days now. As much as I'd love a THT, it's just not a practical idea right now. I already have two MCM 8" drivers and I'd have to buy a different amp if I went with a THT. I'm not crazy about cutting a hole in my floor for the basement mount idea either. I've said it in another thread, but I'll build one or two THTs for my currently unfinished upstairs level when the time comes in a few years. There will be gobs of space behind the knee wall that will be perfect for the sleeper effect.

Back to the current situation: There's a spot in my entryway (connected to my living room, behind the listening area) that I thought would be a perfect spot for a Table Tuba Long Style, but it's kind of tucked away from the rest of the room.



Just to be sure it was a good spot, I put my T18 back there (corner loaded) to see how it sounded, and I'm glad I did. I kept checking to make sure it was even on because the low end just wasn't there.

To be sure, I fired up REW, put the mic at the center of the room where I usually sit, and did some measurements from the new spot as well as the usual location. Sure enough, it averaged about 4-5 dB lower through most of the range and as much as 10 dB compared to where the sub typically sits. Someone smarter than me can probably tell the exact reason, but I'd imagine it's because it's the equivalent of putting the sub in a different room.

My conclusion is that I'm going to go with my original plan to build a dual T18 (that can go in a better location) to match the one I currently have. I've been thrilled with the T18 so far. It'd be great if it went a little lower for movies, but it sounds fantastic with music, which is usually when the levels are higher for me anyway. My church OTop and Titan build plans got postponed for a few weeks, so I went to Menards last night and bought the supplies I need to get started on the T18 build.

[shawn_g]

Well, this feels like deja vu. I started on the other T18 last night and I'm making it 21" wide this time. The first panel is attached and the baffle is cut, but I have yet to make the holes for the driver. Hopefully, I'll get a chance to work on it tonight.

[shawn_g]

I got a little more work done last night. The baffle took the majority of my time, but everything went smoothly after that.




I'm already dreading the process of installing two drivers in here

[bassmonster]

Meh, it wasn't so bad attaching the two drivers on my TT. I installed the drivers before attaching the final side though. Warning, it's not in the plans to do so. I haven't had any negative effects from it except it makes it hard to paint around so you might take that into account. Also, if you were careful with installing the hurricane or t-nuts it makes it a lot easier.

[Gregory East]

Dual access covers, more work, less hassle.

[shawn_g]

Meh, it wasn't so bad attaching the two drivers on my TT. I installed the drivers before attaching the final side though. Warning, it's not in the plans to do so. I haven't had any negative effects from it except it makes it hard to paint around so you might take that into account. Also, if you were careful with installing the hurricane or t-nuts it makes it a lot easier.

That's not a bad idea. I wonder if the drying PL puts off any fumes that would be harmful to the driver.

Dual access covers, more work, less hassle.

I thought about it, but I don't think it will be too big of a deal.

--------------------

Everything is finished except for the access panel.



Installing last braces:


Last shot before it's sealed up for good:


Side on:


Check out my driver break-in rig


For what it's worth, I like the round Parts-Express speaker terminal better than the round one MCM sells. The MCM one doesn't come with a gasket (had to make one) and it's huge! I didn't have a hole saw that was that big, so I had to cut the hole out with my jig saw. Once it compressed down around the gasket, the sides were sticking up a little bit because the plastic is a little on the thin side.

I can't wait to listen to it.

[shawn_g]

Got the drivers installed today, as well as the access panel.

I took it up to my living room and temporarily disconnected the old T18 just to listen for leaks and such on the new one. My first impression was that it was a good bit louder than the single, as it should be with two drivers. It seemed like it was putting out roughly the same amount of sound at at ~12 volts that the single puts out at 20v.

The real magic happened when I hooked up the single T18 along with the new dual. The bass wraps around you now and it's nearly impossible to pinpoint the location of the subs. I popped the Transformers 2 blu-ray in and heard low frequencies that I've never heard before with the single. The two subs together seem like they're barely working now, where before it seemed like I was always pushing the single T18 to the limit.

It's hard to believe that three 8" drivers can make so much sound.





The next project is to make the table/cabinet for it to slide into to match the other one.

[bassmonster]

Nice! BTW I think the T18 would work very nicely as a small end table like you used it, where a TT would be too big the T18 fits nicely.

[shawn_g]

Nice! BTW I think the T18 would work very nicely as a small end table like you used it, where a TT would be too big the T18 fits nicely.

Thanks! I can only imagine what a pair of Table Tubas would sound like in my house.