THTLP Build

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ecut1
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Joined: Fri Oct 18, 2013 7:48 am

THTLP Build

#1 Post by ecut1 »

I ordered plans, sub, and plate amp today. I'll hopefully start next weekend. I've read quite a bit on here about BB plywood vs MDF. Obviously the vast majority on here prefer plywood. I built both my TT's out of MDF and have had no issues with them whatsoever. Aside from dust and weight, is there there any reason not to use 1/2 MDF for a THTLP? Advantages are cost and it doesn't warp at all. This thing will never be moved. I'll probably cut the panels outside and assemble it in the room it's going in.

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Tom Smit
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Re: THTLP Build

#2 Post by Tom Smit »

For your build, MDF will work okay, as you have found with your TTs. Outside of a situation such as yours MDF is not a desireable material because of it's fragility, inability to hold a regular screw, and infinity to absorb water (causing the material to fall apart). My preference is BB, but you already know what you will be going to be dealing with in regards to MDF.
TomS

ecut1
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Re: THTLP Build

#3 Post by ecut1 »

Well, using a friends account at the cabinet supply store I was able to get the baltic birch for about $70 more than MDF at Home Depot. I picked up one 4x8 sheet and two 5x5 sheets. I guess I get to see what all the fuss is about. :lol: As far as the width goes, how much of a difference would there be between a 24" wide (23" panels) and a 29" wide (28" panels)?
A 24" cabinet fits my plans/ideas for the riser pretty well but I have enough material to build a 29" wide cabinet. I purchased the Dayton Ultimax 15 and a Yung 300 watt plate amp. The room is 13x22 and I'm planning to try to keep both TT's and the THTLP in there. I need to get a mini dsp ordered. Sounds like I'll need some help with delay, etc.

DaveMacKay
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Re: THTLP Build

#4 Post by DaveMacKay »

Tom did a very good job of explaining why BB is preferred. I expect that you'll be pleased you went with it.

Good luck with the build.

howiez
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Joined: Sun Mar 16, 2014 5:23 pm
Location: Fox Valley, Wisconsin

Re: THTLP Build

#5 Post by howiez »

Good luck with the build! (and show pictures!)

Baltic Birch cuts like no other plywood, I'll testify to that. I built my THT, a Truck Tuba and two Titan48's out of Arauaco 5 equal ply plywood and it was fine. Then I started my DR200 project with actual Baltic Birch. I can't believe the difference. It cuts clean, almost machinable like metal. It's dense, no voids, although my Arauaco was ok with regards to voids. But it's much flatter, i.e. less warpage to deal with when gluing up. I get that MDF is cheap and subwoofer guys are used to it, but for water absoroption alone... Every MDF car sub I've had has gotten soft spots from a spilled drink or sitting on a concrete floor during summer. And if you actually think about the strength of plywood in two directions like it's meant to do. it wins hands down in the un-flexibility department for a boom box. I'd rather have oriented strands supporting each other than random particles with a buttload of glue any day!

ecut1
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Re: THTLP Build

#6 Post by ecut1 »

I'm looking forward to trying it. I've built stuff with plywood before but I've never used baltic birch. The TT plans used t-nuts to mount the woofer so there was no worry about screws failing in the MDF. On the TT's I used screws to hold things together during the build but removed them the next day and put PL in the holes. As far as width... am I likely to hear much difference between a 24" and 29" wide cabinet?

Rich4349
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Re: THTLP Build

#7 Post by Rich4349 »

You won't regret the BB- years ago I got some for my T-39, cut the pieces, then life got in the way for a couple hot, humid, summer months. Came back to the smallish cut pieces and they were ALL perfectly flat, zero warpage as if they were cut that day. Flat panels -> even easier gluing and screwing assembling.

24" vs 29" : if you have room, go for it. (You won't do much with those leftover pieces, anyway! lol) If you can get it through all of your doorways, why not? You'll never use more than 30% of it, at any width, unless you've already installed double paned glass windows on that level of your house and taken down all of the glass covered photos within 30'. If you DO think you need more bass, upgrade that amp a little bit to a 500w. It won't be the enclosure that's limiting things.
2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!

ecut1
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Re: THTLP Build

#8 Post by ecut1 »

It's going in a room which is essentially a concrete vault... viewtopic.php?f=30&t=24309
I hope to be able to run it with my dual TT's all in the same room (or at least one of them). The THTLP will sit on the concrete floor at the back of the room under a seat riser. The best size for it in riser is 18"x24" or even 18"x23" but I could try to work around getting up to 36". I have enough materials to build it 29" and I could grab another sheet to get up to 36" I'm just not sure if it's worth it. At 24" I could drop it right down in the riser between the joists and have access to pull it back out later. At anything over 24" I'd lay it the other direction and not be able to get it back out without demoing the riser. I'm basically just wondering if the advantage to go wider is likely to be noticeable enough. I'll probably just build it 24" wide.

howiez
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Location: Fox Valley, Wisconsin

Re: THTLP Build

#9 Post by howiez »

I don't have THTLP experience, buy my THT Is 24" wide with a Dayton Audio 250w DSP amp. I've pissed off the wife a bit cranking it up for demo's. She claims I've cracked drywall, I say it was shoddy work and the house is old. It's an addition put on 20 years ago, right before we moved in. It MAY have been the THT, but I honestly didn't look before I cranked so I can't say. I feel the 29" would be good to utilize your material, but if you have a 'place' for it that suits 24", i'm sure it'll still do the job. LIke Rich said, you probably won't utilize 30% of it's capability. I'm sure I'm not using mine to the fullest. We've watched a few action movies at 'reference level' if I can believe my receivers volume levels, but most of the time we're at -25 or 30dB on the volume scale/knob. I will say it is FULL at any volume, as the bass is incredible at low levels (even from adjoining rooms LOL).

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Seth
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Re: THTLP Build

#10 Post by Seth »

You wont notice a difference unless you're likely to use it at it's peak (or the amp's peak) potential.

Also, food for thought... could the TT's go under the riser and the THT be placed up front?
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

ecut1
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Re: THTLP Build

#11 Post by ecut1 »

What I have found with the TT's is 95% of the time they don't get used at their peak. Every now and then my son and I will go in there and listen to bass heavy music ridiculously loud for a half hour or so. Other than that, it's movies or video games at regular volume levels. The TT's are too wide to drop in-between joists and too tall with their legs to fit under the joists. They're also fully finished with a wood veneer and black lacquer. They could even stay in the room unplugged and just look like corner tables. Also, this room seems to like subs in the back.

ecut1
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Joined: Fri Oct 18, 2013 7:48 am

Re: THTLP Build

#12 Post by ecut1 »

PL Premium Max... is it okay to use? They were out of standard PL Premium. I can't find any info on whether or not the Max version expands like the standard version.

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Bill Fitzmaurice
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Re: THTLP Build

#13 Post by Bill Fitzmaurice »

I've never used it, so you'll have to tell us.

DaveMacKay
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Re: THTLP Build

#14 Post by DaveMacKay »

PL offers 3 different types of PL Premium (see https://www.lepage.ca/en/lepage-product ... esive.html):
  • PL Premium (also marked 3x)
  • PL Premium Fast Grab (also marked 8x)
  • PL Premium Max
It can be hard to distinguish how they differ from each other.

In the “Tips, Techniques and Supplier Links” section of the forum, there is a post (viewtopic.php?f=14&t=18487) that clarifies that PL 3x is OK, but PL 8x isn't (because it is gritty). However, no mention was made of PL Premium Max.

I used PL Premium (i.e., 3x) but have no experience with PL Premium Max. It may be perfectly fine, but maybe it'll be inferior. Were it me, given how important the adhesive is, I'd seek out the PL Premium so that I wouldn't have to be the guinea pig with PL Premium Max.

Good luck with your build, no matter how you choose to proceed.

ecut1
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Joined: Fri Oct 18, 2013 7:48 am

Re: THTLP Build

#15 Post by ecut1 »

I did a little more research, PL Premium is a polyurethane and PL Premium Max is a Silane Modified Polymer (supposedly the best of both worlds - urethane & silicone). They say it's 100% solid and won't develop voids and air pockets over time. The data sheet says you can mist it with water in the case of low humidity, so like PL Premium it cures better with humidity. I think I'll try it on panel one and see what kind of squeeze out I get. If I get none I can silicone that joint up real nice and switch to the standard PL.

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