GM's MLTL with 416-8B

[Altec Best]

Yes, when you're self employed you either have the best boss in the world or the worst boss in the world!:snickerpup:

You missed one ! I like NO BOSS !

[westend9]

Yeah, but the point is I already know what to expect with 703 and R-19, so looking to increase the knowledge base....................

GM

OK, we will push forward with the R-13.

[

Up here too ! 9-10 % In these economic times it's nice to be self-employed or own your own business !

Heh, a lot of that depends on what business you're in. I'm a residential contractor and am now competing with any of the 33% that are out of work in the construction industry.

It's the leaks around hardware and/or poor sealing factory gaskets that most folks miss and why I prefer the NEMA spec neoprene since it's self sealing when you drill through it.

GM

I will be trying to find some of that at the first opportunity.

You missed one ! I like NO BOSS !

I liked no boss so much that I fired myself.

[westend9]

I'm working on the horn sleds, presently, and wondered if there is any reason to try to adhere to the same dimensions regarding the mounting baffle as, say, the Model 19, Valencia, etc.? There shouldn't be any consideration for baffle step, correct?

My question stems from the type of and size of wood I am considering for the frame that mounts the horn. I made some 1" x 2" (nominal) pieces from spalted Maple and would like to use them for the mounting frame. Using these smallish pieces would leave little excess around the perimeter of the horn mouth, perhaps 1' or so extending beyond the horn's flange.

[voice of the theater]

It's the leaks around hardware and/or poor sealing factory gaskets that most folks miss and why I prefer the NEMA spec neoprene since it's self sealing when you drill through it.

GM

Now you guys have got me wondering if there are any leaks in my Model 19 or Model 14 cabinets. The low frequency response in all of them is amazing--so the tuning seems to be excellent--nice DEEP/clean/smooth/powerful bass. But of course I always wonder particularly with anything audio related if there is room for improvement. After all, Socrates said "the unexamined life is not worth living". So therefore, the unexamined audio system is not worth listening to! Anyways, the 19's and 14's are basically the same cabinet design (just on a different scale) as many of you out there already know. I'm thinking that where the top and bottom sections of the cabs are bolted together might be a potential leak. Is there a good test for air leaks or should I just take out the woofers and horns (to have access inside the cabs) and caulk all the seams where the top sections and bottom sections are bolted together? If so, is silicone (in a caulk tube) a good idea? I've never even checked out the bolts inside either pair of my 19's or my 14's--should I consider tightening them down more before caulking? They don't seem loose now--never seemed to be any "give" to them when moving them around (to where they're presently located). Any other place(s) particularly prone to leaks with the 14's and 19's? Or does the tuning take into account that there may be miniscule leaks--and is the fact that the bass/tuning sounds so great out of each 14 and 19 speaker that I own an indication that I should leave them the way they are? Is there a chance that if the tuning is great now that if I seal some miniscule leaks it could make the tuning sound worse in the rooms where they're located? Maybe the answers to these questions could shed light for others with their various Atlec cabs as well?

I liked no boss so much that I fired myself.

I have memories of when I first became self employed/my own boss--there were days that I decided to take off (on a whim) and thought that "I have the best boss in the world". But I also remember days where I really wanted to finish something I was working on and worked over 12 hours straight without even a lunch break and afterwards thought "I have the worst boss in the world"!

[GM]

There shouldn't be any consideration for baffle step, correct?

Depends on the XO point/slope WRT predominately baffle, horn mouth width and woofer size same as with point source drivers with the caveat that a WG or horn will have dramatically more directivity for a given desired BW than a typically much smaller point source driver, greatly reducing the need for any BSC per se, with whatever is needed usually being accomplished by the XO design and/or horn adjustable shelving filter. The M19's, 846B's XOs are good examples. For < ~500 Hz XO points, HF shelving combined with some form of CD horn EQ is usually sufficient.

In short, you can't go wrong by making a horn baffle of the same width [and height if there's room] as the cab, but in most cases there's no need for it in a HIFI/HT app beyond having a highly absorbent one to reduce mouth reflections back to the driver as much as practical. By highly absorbent, I mean more like the thick fiberglass lined early M19s, 846Bs, etc. than the mostly cosmetic sculpted ones used later on.

Unfortunately, I didn't get to do much foam testing way back when and don't know the density of the two different layers of sponge material I was fiddling with back before the lightning strike, so don't have a clue what might work for even 511/500 Hz XOs; so at this point the only foam I know of that will work is something called trail pad and then only if wrapped around the mouth at the flange to form a crude ~12" deep mouth ~90 deg included flared extension which is about as anti-WAF as anything I can think of ATM, though Pano-Mike's T-shirt? experiments might be right up [down?] there too.

GM

[GM]

Now you guys have got me wondering if there are any leaks in my Model 19 or Model 14 cabinets.

Again, at least way back when, designers either allowed for a typical amount of leaks due to manufacturing tolerances and/or intentionally designed them in such as the M19 not having any gasketing between its two cab sections and 811 mounting, so in a 'worst' case scenario, removing all leaks will lower the cab's tuning (Fb) which one may, may not prefer depending on how they sound in-room with all the variables this implies.

Personally, I would seal up any lossy cabs and then re-tune them in-room to suit if necessary since factory tunings are almost always a compromise and at the very least tends to 'sharpen up' the woofer's perceived response, but so many folks think the M19 is [near] perfect as is, so may not be worth the effort for them.

Assuming a relatively 'still' room WRT airflow, a candle, smoke or similar will find all of them worth plugging while driving the cab around/at driver Fs at some high enough SPL to see obvious cone excursion with the vent blocked off [densely stuffed with rags/whatever].

Then there's the folks that just spray a soapy liquid on all the potential leaking areas and look for bubbles except any exposed MDF could be problematic. Wonder if baby shampoo thinned with alcohol would blow bubbles without blistering MDF?

GM

[Altec Best]

Then there's the folks that just spray a soapy liquid on all the potential leaking areas and look for bubbles except any exposed MDF could be problematic. Wonder if baby shampoo thinned with alcohol would blow bubbles without blistering MDF?

GM

Or one could just caulk all the joints with silicone/adhesive etc....

[GM]

Or one could just caulk all the joints with silicone/adhesive etc....

True, but how does it answer " Is there a good test for air leaks........?" or find others that ideally shouldn't be caulked/glued?

GM

[Altec Best]

True, but how does it answer " Is there a good test for air leaks........?" or find others that ideally shouldn't be caulked/glued?

GM

It doesn't,but it shouldn't have any leaks in any of the wood joints.Driver seal leakage,door hatches/acess panels, would be another matter.

[voice of the theater]

Again, at least way back when, designers either allowed for a typical amount of leaks due to manufacturing tolerances and/or intentionally designed them in such as the M19 not having any gasketing between its two cab sections and 811 mounting, so in a 'worst' case scenario, removing all leaks will lower the cab's tuning (Fb) which one may, may not prefer depending on how they sound in-room with all the variables this implies.

Personally, I would seal up any lossy cabs and then re-tune them in-room to suit if necessary since factory tunings are almost always a compromise and at the very least tends to 'sharpen up' the woofer's perceived response, but so many folks think the M19 is [near] perfect as is, so may not be worth the effort for them.

Assuming a relatively 'still' room WRT airflow, a candle, smoke or similar will find all of them worth plugging while driving the cab around/at driver Fs at some high enough SPL to see obvious cone excursion with the vent blocked off [densely stuffed with rags/whatever].

Then there's the folks that just spray a soapy liquid on all the potential leaking areas and look for bubbles except any exposed MDF could be problematic. Wonder if baby shampoo thinned with alcohol would blow bubbles without blistering MDF?

GM

The candle test sounds like a simple, yet effective test. That way I don't have to worry about any potential damage from spraying a liquid on the cabs. Even if the leak isn't substantial enough to blow out the candle, I'm sure you'd see the flame being affected by small "gusts" of air coming out of cabinet leaks when the bass is really "thumping". Thanks GM! Should I be more careful than usual regarding how loud I play the speakers during the test--is there any potential danger to the woofer having the port blocked while testing with relatively high SPL's? I'm sure I'd want to wear ear plugs during the test--being that close to the cabs.....

Or one could just caulk all the joints with silicone/adhesive etc....

Yes, but I'd like to test just so I know if there are any actual leaks I'd be sealing in these factory cabs or am I just playing with silicone and making a mess when and/or where I don't really need to. Also, if I just caulked all the joints without doing a test first, I'd always wonder afterwards if I had actually fixed anything or not. Whereas if I test first, I'll know for sure if there were leaks that were sealed, and if so, I'd know that I may have to adjust the tuning of the factory cabs to compensate.....
P.S. Another test just occurred to me--maybe I could just put a canary inside the cabinet, temporarily seal off the port and check in a couple of days to see if he's still breathing in there (like the old coal mine test).....:doh: