Newbie's impression of building a T48

[Rick Lee]

I finished my 1st T48 last week (except for finish and casters) and should have my second one finished tomorrow (except for finish and casters). The band hasn't made up it's mind on what kind of finish to go with yet, so I wait on that....

I thought I would chime in with the problems/ideas I had as a first time builder to maybe help others looking to build a Titan. I realize none of these will be original ideas, but maybe it'll help somebody searching for ideas.

First, I'm a fairly experienced woodworker with a fairly nice workshop. I build woodstrip canoes and furniture on a fairly regular basis. However, even though others have told me I'm a craftsman I know I'm not a meticulous builder - i.e. if I can get away w/ a butt joint I'll use it. I like to build as easily as possible. I guess I'm saying this just to give a point of reference.

The most controversial thing I did was use OSB. Sorry, but I did. Yes, baltic birch is absolutely the best way to go and is wonderful to work with. However, when one descends from that stratasperic plane the choices are more mundane. I checked out the Arauco at Lowes and it obviously had voids in the ply. I've heard there are different types of Arauco and I'm sure it's good. However, $23 vs. $6.75. Advantages of OSB: no voids, a 4x8 sheet only weighs two pounds more than equivilent ply, panel resonances are about the same as plywood, cuts are consistent. Other than the baltic birch, osb and plywood have roughly equal stiffness. With osb, if it's stored right you don't have to worry as much with warping. No contest to me.
After I cut all my panels to width (29") I clamped them all together and planed the edges so the edges would be very consistent.
Instead of screws I used a brad nailer. So, instead of putting the side panels together and drilling pilot holes I took a few minutes and laid out the lines on the opposite side. That way when I put the last side on I could just nail between the lines.
The last time I used Tnuts was in Jr. High. I dislike them. However, I went ahead and used them since that was recommended and I realized the solution to my hate: Use two different drill sizes. I preassembled the baffle board and spacer, drilled 1/4" holes using the driver for spacing, flipped the baffle over and drilled the next letter size bigger where the tnuts go. This way the tnuts didn't compress and I can extract the bolts when I need to.
On the first cabinet I cut the angles as I went. However, on the second cabinet I trusted my layout lines and went ahead and cut all my angles to the lines. The second cabinet went together much quicker.
My first cab I waited until the end to put the mounting flange in and it was a little bit of a hassle. 2nd cab I put it in right after I nailed the baffle to panel one and it went much smoother. I could slide it snug up to the baffle before the glue setup. I also put a vertical strip of wood on panel 3, cut the angle and then when I joined panel 3 and 4 they trued up much easier. Also gave me more peace of mind knowing that the speaker enclosure is a little bit stronger.
I wasn't sure about attaching the braces, so after trial fitting I attached the braces before I installed the panels. The plans seem to imply that you attach the braces after you install the panels. Seems kinda hard to get them in the right place if the panels are already together. I used 1/8 plywood for the braces, fiberglassed on both sides. I had some laying around so I figured it would work fine. Don't think it saved any weight, though.
Anyway, it looks like I'm writing a dissertation here and it's getting late. I'm not trying to sound like a know-it-all, because I know I don't! It's just that when I was looking through here for tips it was taking a while to glean good info. Hopefully this will help someone that's contemplating building a cabinet for the first time. I've loved building these. They go together well, are sensible and are well designed w/ no odd dimensions.

[Tim A]

The most controversial thing I did was use OSB...the Arauco at Lowes and it obviously had voids in the ply. I've heard there are different types of Arauco and I'm sure it's good. However, $23 vs. $6.75...when I was looking through here for tips it was taking a while to glean good info.

Just so I understand, you feel that recommending the use of OSB as opposed to plywood for a savings of $16.25/sheet is 'good info'?

[Bill Fitzmaurice]

The most controversial thing I did was use OSB...the Arauco at Lowes and it obviously had voids in the ply. I've heard there are different types of Arauco and I'm sure it's good. However, $23 vs. $6.75...when I was looking through here for tips it was taking a while to glean good info.

Just so I understand, you feel that recommending the use of OSB as opposed to plywood for a savings of $16.25/sheet is 'good info'?

+100. OSB won't withstand impact damage.

[gdougherty]

Well, on the upside, the build was cheap. On the downside, if they take any abuse, they could become damaged and leak causing you to ruin that nice driver. If you don't destroy the driver, you should be able to pull it and put it into a properly built one. Yes, the Arauco has voids but they tend to be smaller. I'm a little less impressed with the most recent batch I got, but alot of that was because I got a bunch of more warped sheets from the bottom of the oldest stack (They stack them for FIFO). I didn't feel like shuffling 20 sheets off the stack to get at the fresh batch that still sat true. For final finish, having recently built and painted something out of OSB, there is no comparison. I certainly wouldn't do Duratex, only rat fur.

[Mark Coward]

I certainly wouldn't do Duratex, only rat fur.

If these cabs will be moved and gigged with, I'd go with Line-X, Rhinoliner or Scorpion coating. This would at least waterproof the OSB and add some impact strength. Rat fur will absorb moisture, bad news for OSB. I question also whether the 1/8" bracing will be sufficient. Someone reported here about some titans or tubas built for an install, using OSB, and they were vibrating themselves apart. I think he ended up putting in 2x4's for bracing or something.

[Rick Lee]

+100. OSB won't withstand impact damage.

That's true. But, it's not far behind equivilent ply in testing. What I didn't say is that I'm fiberglassing the outside since I have a ready supply and that will give it excellent impact resistance. And, I'm outlining the mouth w/ a strip of hardwood. The finish is crucial to how well they hold up for impact resistance.

I agree that BB is best, Arauco is probably second best and OSB would come in third. However, OSB can and does hold up quite well if constructed properly. Take apart some name brand cabinets and see what they're made of (and some ads have touted the superiority of their cabinets!). Except for the touring stuff you're gonna find...osb. And, I've seen quite a few that have been abused. And yes, they were all covered with rat fur.

However, I saved $100 dollars. I felt the money was better spent on a better driver because OSB, in labratory tests doesn't come in a distant second. It is about equal to regular plywood. As to osb comeing apart, I've seen plywood and mfd come apart also. These cabinets are so well braced I would be incredulous to see it come apart. All I'm trying to say is if someone is on a tight budget and they're not gonna leave them unfinished osb can be a viable option.

Again, I'm not trying to offend. I'm excited about the designs and looking forward to building many BFM's. I'll report back in in about a year (if I can remember) and give an update on how well (or badly) they've held up.

[Tim A]

However, I saved $100 dollars.

This is the part I don't get. You saved $100 on cabs you'll have for a long while, let's say 5 years. So you saved $20 a year. Big deal. It is not worth the risk.

How many times must it be said:

BY ONCE, CRY ONCE

Covering them with fiberglass will certainly improve your situation. It'll also make them heavier, but here too, unless the average DIYer is going to cover their cabs in fiberglass it is a poor choice for cabinet materials.

I agree that BB is best, Arauco is probably second best and OSB would come in third

Not even close. Any SPF in A/C would be superior to OSB. It is an inferior material for constructing cabinets. The fact that 'name brand' cabinets use it has no bearing, they do things as cheaply as possible. The whole concept of Bill's designs are vastly superior performance and construction.

[Rick Lee]

Okay ya'll, I give up! I'm not here to support the osb industry. Earlier I had inquired about weight savings using fiberglass foam core and that got shot down too. For what it's worth, I'm building a homebuilt airplane that uses a fiberglass foam core as primary structure and I certainly hope that doesn't get shot down as well

[LelandCrooks]

Yea, they were pretty hard on you. But here's the deal, you have a clue. Experience with the limitations and expectations of what your materials are and will do. Most new builders don't. OSB is not suitable for the vast majority, and we don't want inexperienced builders thinking it is.

I remember the foam core thread. I think the major shootdown was cost and time. But hell, if you can build an airplane with it, I'm guessing you could build a speaker with it.

[Mikey]

Yeah, you didn't even get a chance to duck and cover.

Bear in mind that a lot of people search and study the threads on this forum when contemplating their build. Others reading that you used OSB, then deciding they'll use it, may completely ignore the other materials and procedures which you've used in order to make the OSB somewhat viable for you. Any time someone uses a material or procedure which is questionable, people make issue of it, discuss the pros and cons, etc, if nothing else than to best ensure that a future reader is adequately informed about the situation. Please don't take it personally.

A lot of big, respected, name-brand companies use OSB in their cabs. Many people don't know or could care less, as long as their cabinet has the "right" logo badge on the front. But, using OSB with the reasoning that "the big boys do it" comes down to the same thing many of us have told our kids ... "If he jumped off of a bridge, would you?". I was floored when I opened up an SVT cab and it was OSB, and that's one of The Biggest Boys.

[Rick Lee]

Bear in mind that a lot of people search and study the threads on this forum when contemplating their build. Others reading that you used OSB, then deciding they'll use it, may completely ignore the other materials and procedures which you've used in order to make the OSB somewhat viable for you. Any time someone uses a material or procedure which is questionable, people make issue of it, discuss the pros and cons, etc, if nothing else than to best ensure that a future reader is adequately informed about the situation. Please don't take it personally.

Point well taken.

I remember the foam core thread. I think the major shootdown was cost and time. But hell, if you can build an airplane with it, I'm guessing you could build a speaker with it.

Yes, cost and time. After physically building it versus the mental exercise, yes it would take a good deal more time and would certainly be difficult for someone not used to building with it. It would shave a few pounds off but for someone that just went out and bought enough to build a couple of cabinets it would definately cost more than the Aracuo - probably about equal to BB. However, since I always have a supply I may at some point mess around with it. Maybe a pair of the DR cabs. I'd just like to see what the result would be. Hey, if it didn't work I'm sure we could take it down to the river and see if it would float...
I'm just so excited to finally find a whole DIY series of horn loaded cabinets I'm sure I'm gonna build a few. For years it's been in the back of my mind to try to find a good horn design and wow, I've hit a motherlode I've got a driver that will work in the THT, I need to try an AT in my van, I'm hyping our bass player up on a T39, I need to build 4 DRs and we definately need some wedgehorns (I could use a wedgehorn10 for my kick). Then, when we get picked by a label we'll have our own sound company, build a whole slew of cabinets and maybe we could be endorsed by BFM!

[MYork]

building a homebuilt airplane that uses a fiberglass foam core as primary structure

There's a guy on TalkBass who built a bass cabinet from fiberglassed foam core, and his post must have a kazillion responses. I'm surprised if he won't be the TalkBass write-in for President.

[Bill Fitzmaurice]

building a homebuilt airplane that uses a fiberglass foam core as primary structure

There's a guy on TalkBass who built a bass cabinet from fiberglassed foam core, and his post must have a kazillion responses. I'm surprised if he won't be the TalkBass write-in for President.

From a practical standpoint fiberglas over foam isn't....practical. If it was those companies that did try it would not have all gone out of business. The weight savings are minor, while the build costs are easily twice that of wood. Best left to aircraft and boats it is.

[Rick Lee]

From a practical standpoint fiberglas over foam isn't....practical.

Agreed. However, there have been advances in epoxy that make it less troublesome to work with than it used to be. For a DIY'r it's definately not practical. On a large scale definately more expensive and troublesome (at least seems like it would be). But on a boutique scale...? I know my brother (mid 50's, lots of money, engineer) that plays bass has spent lots of money on his hobby. He would kill for a lighter rig. I'm sure there are others out there like him. A horn, with all it's inherent rigidity, pressure contained within the cabinet, and the ease of radiusing the corners to make the path smoother (and corners stronger) looks like a perfect candidate for something like this. After reading that other thread I would argue that there would be significant weight savings. The hardest thing I'm envisioning is laying glass in the corners and joining the top. I'll radius the corners (keeping the horn path intact) and that will make the glass lay down nicely. The top I'm thinking about. There has to be continuity with the sandwich structure.
Anyway, I'm planning on building a cabinet just to try it. If it doesn't work I'll only be out a little bit of money and a weeks worth of time. If it does work...?

[Harley]

? I know my brother (mid 50's, lots of money, engineer) that plays bass has spent lots of money on his hobby. He would kill for a lighter rig. I'm sure there are others out there like him. ?

Yep, I'm one of those.

That's the reason I got into BF cabs for bass in the first place. After the hernia, the War Office stamped her feet and said "That's it, find a lighter rig or I'll sell your basses!" In other words whilst your brother would kill for a lighter rig - I risked getting killed if I didn't get one

And being something of an engineer I thought that I could use all manner of widgets, gadgets and methods of construction to improve on Bill's "basic" concepts.

Fortunately, that part of my brain that still functions OK is that of a business owner and it warned me early on in the piece to replace my word "basic" with "practical and wise"

...After reading that other thread I would argue that there would be significant weight savings......... If it does work...?

Then we're still stuck with a process that hardly any of the people who are attracted to the BF cab program can utilise themselves, which in my books is time that could be better spent in getting a better listening experience out there to the 'great unwashed' via a build system that's already simple and proven....sheeesh!