Westend9, Good Luck with your project. I see your in good hands with GM !!
I finally got my woofers back from GPA after 2 months, so I'm back working on my cabs again.
Cool! I sent you a PM the other day, but hadn't heard back. I still haven't installed the HF phragms yet, the XO caps were trashed in the strike too. It even oxidized all the wiring from the amp. Thankfully, the electronics except for one tube in the pre-amp and woofers seem OK..............Originally Posted by Altec Best
I finally got my woofers back from GPA after 2 months, so I'm back working on my cabs again.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Darn I didn't see it.I'm sorry GM, I had a look at it.You replied to an email I sent February 3,No wonder I had trouble remembering what it was about that was 7 weeks ago !
. Just Kidding you explained the last month were more health oriented. How are you feeling now ? I Hope Well ! It is always nice to see you on the boards.When I don't see you for a while I know your not feeling well.And that is Beat ! I'm glad to see up and around ! :lollipop:
I hope you get a chance to check those Frams out soon ! As I'm really curious as to how they sound.You don't hear much about those models too much.
Took some time, today, between errands and moving snow, to finish the cuts of all the panels except the interior braces. Looking at this stack of goods and imagining the final aspect of the boxes, if this speaker thing doesn't work out, I might drill some holes and ship myself South.
I will do some light trimming on the table saw and then proceed to vent and driver cutout. The original description of this MLTL design was to use a vent the same size as the original Model 19 and that would be positioned close to the bottom of the cab on the front baffle and centered, I would presume. I have the woofer cutout marked at 3" below the top edge. That will allow me to get a bolt into the frame of the woofer underneath the doubled top panels without too much trouble. I have established the diameter as 14 1/8" as per Altec's spec sheet.
One thing that is nagging at me is what I'm going to do for access to the interior and to provide for future vent modification. The latter isn't that critical as I am thinking of more than a few workarounds should that be necessary. I know GM advocated cutting the front baffle and that would certainly allow provision for access and vent mods but I am very reluctant to do that, mostly for cosmetic reasons. Would it be possible to use the bottom as an access port if I went to somewhat extraordinary measures to insure there is a tight seal at that point? I'm thinking of a neoprene or butyl high tech gasket material and through bolt the bottom panel into cleats or window pane of one the doubled bottom panels to accept the exterior bottom panel. Would I be better off, functionally, by using a purpose built access port in the back panel?
I presume also since I don't remember which of the many m19 variations I've done is the one you're referring to.
Yeah, a removable bottom is probably the best alternate since the sheer weight of the cab bearing down on the gasketing ensures a great seal. FYI, my gasket of choice is either NEMA 5/12 (dust/rain tight) or 3R (rain proof) Neoprene since one can drill through it and will self seal around bolt/screw threads. Not particularly cheap, but I've rotated the 515's individual baffles many times over the decades and still no air leaks as best I can tell, and this is with just large wood screws that are obviously not as hard to remove/replace as they once were.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Whoops, your design for this iteration is discussed here.
In post #13 the sizes of the cabinet are discussed and the simulated responses of the stock 19 and two sizes of variants are in post #15. I am building the MLTL 19.long, the 16 cu. ft. model (we should, at some point, maybe give this a name ).
I will follow your experienced advice on the gasket material, I have access to just about everything. There will be some minor engineering and machining on the seal area. I plan to break out the router and table to cut dados and ease edges and so forth so cutting a dado to accept a gasket will only mean a bit and fence change.
Right now, I am squaring up the panels on the table saw. I still have the interior panels to cut, including the vertical window pane brace. For the support for the woofer's magnet, I was planning to cut the brace to fit around the magnet, recessed from the magnet > 1/8" to accept a strip of felt and to allow for shimming. Is this the usual way? I had planned to make two more window paned vertical braces to tie to the side panels. I think I can get away with this if I substantially reduce their area, i.e. mostly cut out.
An alternative would be to add hardwood cross braces from the center brace to the side panels. These cross braces could tie into other vertical bracing on the side panels. The vertical braces on the side panels could be dado'd to accept these cross braces and that would make for a good, secure joint. It is also a lot of time to do it this way. Another thing I've seen with panel bracing, mostly in older designs, is to position the braces on an angle across the panels.
Back to the saw!
OK found the sim and since no one has built one yet I've changed its name to 'Westend'.
Yes, though I use scrap Neoprene.
Yes triangulating panel areas really stiffen them up, just try to bend a triangle, but not a good plan for stiffening up TLs as we don't want the turbulence they would create.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
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