Post by: Chris Parsons on September 08, 2004, 10:17:11 PM
I have a series of questions that may have allready been asked but i'd like to know what everyone thinks TODAY
Is there any reason(s) to NOT build version 3.0?
I live in Santa Cruz, CA. Any suggestions from you bay area people as to where I can get 3/4" baltic birch?
What's the best glue (bang for the buck) and where do I get it?
How much wood should I buy? What thinkness?
What size Tee-Nuts and screws for the drivers?
Thanks for your time!
-Chris Parsons
Post by: Al Limberg on September 08, 2004, 11:02:13 PM
Welcome to the sawdust club! I'll try to answer your questions where I feel qualified and try not to BS you in areas where I'm not.
In order of appearance:
#1 Brad does absolutely gorgeous woodworking and its obvious from the pics he has posted. I'm fast approaching 16 units completed - the first 8 from Tom Danley's original plans (call it version 1) and the second batch of 8 from the updated drawings (was that Peter?). I have not attempted version 3 and probably won't simply because compound mitre joints are tougher than Chinese arithmetic to me and his plans call for at least 4 (or maybe 6) instead of the 2 per version 1 and 2 specs. I also went back and dug out the measurements Too Tall has done on my subs with Praxis and found no real sign of the 'dip' at 50hz that Brad's prediction software expected. Since extended high end response isn't necessary for my purposes (80Hz is fine for either my indoor or outdoor system low mids), I think it makes more sense for me to go with what I know.
#2 Not being from the bay area, I'd simply suggest getting on the horn and using your yellow pages and shop shop shop for your birch. Make sure you ask for discounts on quantity.
#3 For general purpose gluing, I recommend Franklin Tite-Bond Professional Carpenter's Glue. It's basically a pale yellow waterrproof variant of good ol' Elmer's!! You should be able to find it at any lumber retailer (Lowe's, Home Depot, etc. for about $13-15 a gallon - yes - buy the gallon!) For critical joints (such as the module and those joints between the module and the box, I highly recommend West System epoxy products. Too Tall will argue with me but I prefer the 'filetting' powder to mix with the 2 part epoxy to thicken it and let it act as a filler as well.
#4 You'd think a guy who had finshed 12 and had 4 in the oven would be able to quote you exactly how much wood you need, wouldn't you?? I've had the benefit of having a storage facility stocked with a bunch of 4x4 'mill-end' sheets of birch so my experience doesn't mesh well with the use of 5x5 sheets altho my supplier now has birch in 4x8 so life is better for me. If its of any help, I manage to get 8 modules and all the internal braces out of 10 5x5 sheets in my last batch. Using the 4 x 4 sheets for just the external box, 7 were required(per pair). I guess that would translate down to 4 4x8 sheets and 3 5x5 sheets with enough leftover to let you make a mistake or two without feeling like suicide was necessary (again - per a pair). I should add that frankly, I have taken a few small liberties with the original plans. As regards the end product I believe they make absolutely no difference, but they do keep my wood consumption down a little. Where i have cheated is on the internal braces that connect the modules to the side walls. The rear brace and the 'foot' brace have been downsized slightly (very slightly on the foot brace) - just enought to keep me from using an additional sheet of plywood with about 90% scrap remaining!
Oops Guess I already answered #4!
#5 I used 10-24 T-nuts to mount the speakers and the handles and jack plates and 1/4-20 for the aluminum lids and the rubber feet that I use. Obviously 10-32 would work as well as the 10-24 - it just came down to what was readily available to me. You might look for a distributor in your area - I have found the one locally that serves the hardwares here and they aren't shy at all about selling them to me (and the screws as well) at about half of the hardware price in 100 piece boxes. (That's one half of the hardware price when I buy them by the hundred there).
#6 Spend a little time making up a plan - what to do in what order. I assure you, gluing the baffle boards before installing the T-nuts could be a real bummer! If you end up building version 1 or 2, sit down and make the adjustments to the baffle board dimensions so you can dado them in to the sidewalls of the modules - life is immensely easier if you do - do the same for the braces between the module and the side walls and dado the side walls.
Best of luck and have at it!! It's worth it.
Al
Post by: Chris Parsons on September 09, 2004, 06:48:35 PM
Okay, I found what seems to be a great supplier of birch plywood. Luckly it's 5 min. away from my home!
Here are the options:
5'x5' Baltic Birch 18mm , for $39.55
4'x8' Shop Birch (from china)18mm, $34.99 (on sale from $50)!!!
I know that Baltic Birch is reccomended but the shop Birch, which looks/feels damn close to the baltic, is going for such a great price.
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Do I only need 18mm plywood?
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I'm still lost as to what verson to build. If ver. 3 takes a wood-working pro then it might not be my gig. But on the other hand, I want these to sound as great as possable. What are some things to consider?
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Thanks again for your time
-Chris Parsons
Post by: Al Limberg on September 09, 2004, 07:30:46 PM
Maybe Brad will chime in and give us his feelings on degree of difficulty,etc.
Al
Post by: Chris Parsons on September 10, 2004, 02:41:55 AM
I'm thinking to by just enough baltic birch for the modules and then use the shop birch for everything else.
Post by: Jeff Woodford on September 10, 2004, 07:34:19 AM
Post by: Too Tall (Curtis H. List) on September 10, 2004, 11:12:36 AM
| Chris Parsons wrote on Wed, 08 September 2004 22:17 |
I've decided to finally build two of these monsters. They will go under my JBL 4732's. I have a series of questions that may have allready been asked but i'd like to know what everyone thinks TODAY Is there any reason(s) to NOT build version 3.0? |
Al is a really good test case for building these because he had almost no experience in wood working before about 4 or 5 years ago. His advantages have been that he uses my wood shop, which includes significant professional tools (large 5HP tablesaw with T-Square fence system, Biscuit cutter, air nailers, Bosch plunge router, etc).
His other advantage is if he REALLY gets stuck I help him figure it out. Even then he would figure it out eventually, but it gives me an excuse to hang out.
In any case over all he his done this project by himself and made and fixed all his own mistakes. So to make a long story longer when he says version 3 is more difficult, I would add that for someone without extensive woodworking experience of this kind it is a poor risk.
For performance if the graphs are correct the version 3 is a little flatter over all before any EQ. My apologies to Al, but some of the measurements I have of LAB sub version 1 do indeed show a dip around 40 or 50Hz followed by a peak around 30Hz. To my mind not enough to make the version 3 design worth doing. A little EQ and I have the same response. In addition once EQ'd to give the same response as version 3 I believe version 1 will produce the same level output.
Version 3's true advantage is response above 80Hz. There version 1 is a dog.
| Chris Parsons wrote on Wed, 08 September 2004 22:17 |
I live in Santa Cruz, CA. Any suggestions from you bay area people as to where I can get 3/4" baltic birch? |
You said something about a shop grade Birch. My only concern would be that it has the same number of plys and that the inner plys were also solid Birch. Please keep in mind the odds are high that both of these use "interior grade" glue which means water will delaminate the plys. Check if they are interior or exterior glue. If they use interior glue make sure the entire exterior is heavily sealed and pay attention to any end grain showing. Al uses West System Epoxy to apply woven fiberglass to the outside edges which gives them strength, wear and a total seal if you didn't quite get a joint to close. Also as long as you don't splash water into the horn mouth it will make a dandy boat.
Post by: Brad Litz on September 11, 2004, 12:30:25 AM
| Al Limberg wrote on Thu, 09 September 2004 18:30 |
Maybe Brad will chime in and give us his feelings on degree of difficulty,etc. Al |
The v3.0 cabinets do have compound cuts set into dado grooves in the driver module. If you cut these wrong you will have big trouble. If you cut them accurately, they go together very easily. To help avoid mistakes, I now have drawings of the compound cut pieces posted on my web page in addition to the CAD models and viewer links:
http://www.geocities.com/hulkss/index/
I do appreciate the compliments I have received about my cabinent consruction. Just cut the pieces accurately and you will have good success. The only significant wood working I have done is my two LABsub cabinets and two Klipschorn cabinets that I built in the 70's. I bought a table saw just for the LABsub construction, maybe I'll use it again some day. I benefited greatly from all the great tips posted on this forum by those who tackled this project before I did.
Post by: Chris Parsons on September 14, 2004, 01:18:49 PM
Will I run into problems useing these plans with 18mm ply?
Thanks,
-Chris Parsons
Post by: Chris Parsons on September 14, 2004, 01:22:55 PM
Post by: Alan Searchwell on September 15, 2004, 02:02:37 AM
https://fastcad.com/n-view7.html
Once you've downloaded it you can download the ps_lab.fcw fastcad drawings. This file includes several layers among them, layouts for 18mm plywood, as a matter of fact I think all the drawings on Peter's web site were generated from this one file! The program allows you to display the dimensions in metric or imperial measure. It also allows you to zoom in and print portions of a drawing as well as calculating distances and angles between points. It really opened up a whole new world for me in terms of working with Peter's plans. Only drawback is that I had to fill out their registration form but hey, if they want to call me or send me junk mail it'll cost THEM and I really have found the software useful.
I was supposed to start making sawdust on Friday at a friends workshop but hurricane Ivan had different plans. Damage around my location wasn't very bad so the phones have been working all along and I've got water, power and cable tv back already with Internet being the last service to return to normal just this evening! I guess you could say I've been really lucky. Once we get power back at the workshop and I get the first one done I can report on the handles, wheels, T- nuts etc.
Post by: Chris Parsons on September 15, 2004, 12:53:25 PM
Post by: Chris Parsons on September 20, 2004, 06:44:38 PM
...now I just need to build the cabs
Post by: Chris Parsons on October 03, 2004, 08:32:03 PM
I've got baffles under glue right now. I'm about to get the other module peices cut but I want to double check some things.
Module peices, as well as all other internal peices are 21" wide right? That's what the notes say (V.2).
For the dados that the baffles go into: The inside of each dado should be 7" apart and centered in the module peices right?
thanks for dealing with me
-Chris Parsons
Post by: Al Limberg on October 03, 2004, 09:41:52 PM
Carry on!
Al
p.s. 21" is the magic number
Post by: Chris Parsons on October 07, 2004, 11:24:18 PM
Tonight I started to glue one of the modules together. I got everything to fit pretty exact, except for the bottom piece is only flush with the corner of one baffle, not both. The other side is about a 1/16" off. Hopefully the expanding qualities of guerrilla glue will solve this problem.
Biscuit-Joiner... used it for the first time today. Does anyone have any tips about this tool. I've got the dewalt type. When I cut slots on two pieces without moving the guide, the pieces don't line up perfectly flush. They're about an 1/8" off. Also, my biggest question is about angled pieces of wood. Should the biscuits be in straight, or at an angle? How do you guys approach this?
Thanks to all of you for helping me out here.
-Chris Parsons
Post by: Too Tall (Curtis H. List) on October 08, 2004, 10:40:56 AM
| Chris Parsons wrote on Thu, 07 October 2004 23:24 |
So yesterday I finally finished all four of my baffles. Then I realized that they were all identical! DOH! Well, at least I had enough 1/2" stock to fix the problem. Tonight I started to glue one of the modules together. I got everything to fit pretty exact, except for the bottom piece is only flush with the corner of one baffle, not both. The other side is about a 1/16" off. Hopefully the expanding qualities of guerrilla glue will solve this problem. Biscuit-Joiner... used it for the first time today. Does anyone have any tips about this tool. I've got the dewalt type. When I cut slots on two pieces without moving the guide, the pieces don't line up perfectly flush. They're about an 1/8" off. |
I have a Porter Cable so it might be slightly different, but the principle is the same.
Typically the guide is set so it is NOT dead center on 3/4" so that you can tell when you put the pieces together with the wrong face up. (This is what you did) In any case when you use the guide you press it up to a surface and then cut the slot. Whatever face you have pushed the guide against should be marked to remind you which surface was used as a reference and which face is "up".
So before picking up the biscuit cutter start by putting the two pieces together without glue the way you want them when your done.
If you are making a right angle joint start by making some "x" marks with a pencil on the edge or end grain near the joint and then on the face of the other piece right next to it.
When you make the biscuit cuts the "guide" must be placed against where these "X" marks are.
This is why you are 1/8" off. You did not pay attention which side of the piece the guide used as a reference.
For doing this kind of work I don't use the guide. I take it off.
I use the bottom of the biscuit cutter as a reference or guide. I place the piece I want to biscuit on a flat surface and place the bottom of the biscuit cutter on the same surface.
If I'm cutting into the edge I lay the piece flat.
If I'm cutting into the face I stand the piece on edge. For the piece standing on edge you must put something behind it as a backstop and to keep it at right angle to the flat surface. Al uses the table saw fence.
So in this case when you cut the biscuit you make sure the "x" marks are face down to the table you are using as a surface. And of course the bottom of the biscuit cutter faces the same table or surface so the distance the biscuit is cut above the table is always the same.
Also if you need to put a piece in the middle of another to make a "T" you can not use the guide.
| Chris Parsons wrote on Thu, 07 October 2004 23:24 |
Also, my biggest question is about angled pieces of wood. Should the biscuits be in straight, or at an angle? How do you guys approach this? Thanks to all of you for helping me out here. -Chris Parsons |
Unless it is a 45-degree angle you do not use a biscuit cutter. It is possible if you make some kind of custom "fixture" or guide for that particular angle and joint, but its not worth the trouble. Your biscuit cutter SHOULD come with a guide for 45 degrees.
Too Tall
Post by: Brad Litz on October 08, 2004, 05:28:41 PM
| Chris Parsons wrote on Thu, 07 October 2004 22:24 |
The other side is about a 1/16" off. Hopefully the expanding qualities of guerrilla glue will solve this problem. |
Gorilla glue has almost no strength when expanded to the point that it foams in a gap, however, it will provide a good air seal.
Post by: Chris Parsons on October 13, 2004, 12:54:39 AM
I installed the horizontal flare pieces on one module tonight. It was the most difficult part of the project so far. I made a mistake with their placement. I lined them up flush with the front of the module and not the side. I hope that makes sense.
Is this a big deal? What affect will it have on performance?
Thanks!
Post by: Chris Parsons on October 13, 2004, 11:50:41 AM
Post by: Chris Parsons on October 14, 2004, 12:13:12 AM
the section in bold is where the flare ended up. aye yei yei...
-Chris Parsons
Post by: Brad Litz on October 14, 2004, 12:23:54 AM
Don't worry about it as long as there are no air leaks.
Post by: Chris Parsons on October 14, 2004, 10:31:59 AM
I just picked up some west systems epoxy. I plan on going over all of the joints in the modules with it (and the fiberglass cloth) just to make sure there are no leaks...ever.
Does this modification make any change to the response? Should I build the other module with the same mistake?
-Chris Parsons
Post by: Al Limberg on October 14, 2004, 10:55:59 AM
If you don't already have the parts cut, I'd go ahead and try to do them the way they are drawn. I don't think it'll make any audible difference in the cabs but it will give you practice for your next pair.
As far as the West system goes - good plan, but I might suggest rahter than trying to fit the fibreglass cloth into the confined spaces of the module, pick up a can of the 'filleting powder'. First mix your epoxy resin base and hardener in the proper ratio then slowly add the powder to thicken the mixture till it looks like and has about the consistency as a 'brownie' mix. then you can use a trowel of some sort to apply it to the seams and joints. It will fill any gaps and strengthen the whole module.
Al
Post by: Chris Parsons on October 14, 2004, 01:38:03 PM
I'm going to remove the flares that I messed up. I guess I might need to use a sawsall to get them off. oh well... it will be worth it. I hate doing things any other way that what was planned.
-Chris Parsons
Post by: Chris Parsons on October 21, 2004, 11:48:53 AM
Aluminum time: If I can find it, can I just use aluminum for the enitre access place, not just the round discs in the middle?
I've got some metal connections here in santa cruz so I might be able to do that. Would there be any loss in rigidness?
thanks!
-Chris Parsons
Post by: Chris Parsons on October 26, 2004, 08:18:56 PM
thanks!
-Chris Parsons
Post by: Alan Searchwell on October 27, 2004, 07:35:07 AM
I wouldn't worry about loss of rigidity. Powersound of Belgium has used the largest aluminum access covers I have seen:
http://www.powersound.be/lab/01-08-03/lab_03.JPG
Tako Tomas seems to have done away with the wooden access covers and gone for one-piece circular aluminum covers:
http://www.tandartsgroep.be/shootout/ttomas/images/4b.JPG
as has N.(Nick?) Webber
http://www.geocities.com/bonitone/rothberg-4.jpg
All these pictures are from posts in the archive, that is, they are relatively old. All of these labs appear to be very well built and the finished ones are nicely finished (absolutely fabulous in the case of Tako Tomas). I assume that none of them were built just for the fun of it and that they are all being used regularly. That being said, none of these guys has posted anything about problems with access covers so, I assume they are all doing fine.
Hope that helps.
Post by: Chris Parsons on October 27, 2004, 11:55:20 AM
-Chris
Post by: Chris Parsons on October 27, 2004, 07:10:37 PM
Thanks!
-Chris Parsons
Post by: Al Limberg on October 27, 2004, 08:39:57 PM
If you are using round aluminum panels, simply measure and go for it. If you have decided to go with the square ones (which I did - 16" square actually) you can use a 'follow' router bit. I simply use a 1" chipper bit and drill a hole 'inside' the module. The 'follow' bit has a wheel on the bottom that follows the inside walls of the module and routes the appropriate hole in the 45x45 panel. Now hopefully its obvious that only 3 sides will be able to follow the module sides. I make the router cut along the back side of the module first, and then run the router about 6" up each side of the module. then I stop and, using a square placed along the back 'rout', measure out 11" from each end and connect those two points with a line. I then run the router along the sides out to that line, finishing those cuts. Now its just a matter of tacking a straight piece of wood the proper distance out from the line to use as an edge to run the router against to make the front cut that isn't against a module sidewall.
If you've followed this so far, let me make another suggestion. Again I am making the assumption that you are using over-sized square aluminum panels. I made a square template 22 1/2 x 22 1/2 which is the 16" of the panel plus 2x the offset of my router (you may need different measurements) and the bit I use to countersink the aluminum panel. I carefully temporarily tack the template in the proper location and do the countersink BEFORE I do the last cut to open the access hole. This leaves me a bigger surface to support the weight of the router as I do the countersink and makes it a bunch easier to control.
Hope this helps = of course if you're doing them round, well, nevermind! lol
Al
Post by: Chris Parsons on October 27, 2004, 08:58:17 PM
I think I got what you're talkign about. It will take a while to asorb.
You used 16" squares? Isn't that bigger than the module side itself?
Thanks!
-Chris Parsons
Post by: Al Limberg on October 27, 2004, 09:35:38 PM
Al
Post by: Chris Parsons on October 28, 2004, 02:12:54 AM
thanks for your time.
-Chris
Post by: Marjan Milosevic on October 28, 2004, 03:08:01 AM
Just remove few milimetars for the access panel to fit in to the side panel, but i still use them like they are, just painted them recently.
Post by: Chris Parsons on October 28, 2004, 12:36:17 PM
When Al said 16"x16" I thought he was also saying that the opening was that size.
-Chris
Post by: Al Limberg on October 28, 2004, 12:43:33 PM
Al
Post by: Chris Parsons on October 28, 2004, 01:57:03 PM