MLTL Floorstanders for Alpair 7MS

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There are other drivers that would match your criteria, but you seem dead set on that Alpair.

So, you'll have to live with it, and that includes an enclosure fit for that driver.

Or you put it in the box you really want and live with a design that is not optimized or suitable for that driver.

Maybe you should let it go for a week or so, step away from it, and come back later with a clear head and a better view of what you want / need.

You seem stuck in a loop, and we are getting nowhere.
 
If I may gently point out, the entire purpose of the box GM suggested has been missed. It is not intended to have a nice, pretty straight line response with maximal extension. As was stated, it is intended for maximal power handling & you address the response within the crossover (note the caveat). It is one part of system design, not the entire system.
 
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Thanks for your thoughts and suggestions!

Will the ported design be less likely to form a smooth cohesion with my bass units?

Also, I have searched for flanged coupled speakers and only found PA style fixtures. Would you care to expand upon your suggestion here, please?

You're welcome!

More so due to its TL-like initial ~2nd order roll-off Vs a T/S max flat 4th order alignment.

Like sealed, well stuffed ones do, so experiment with stuffing if for some reason you're able to hear subtle phase differences down this low.

My thought at the time was an added massive base recessed around its perimeter so that it would snugly fit in the base's equally massive recessed, thin felt lined top panel and pinned with recessed and/or decorative screws on the sides similar to what I did one time for heavy column mounted statues.

GM
 
Yes, built a few BRs before, just checking if I'm missing something. Also I feel the volume of the box is more akin to that of a sealed cab for this driver. For a decent curve 16 litres seems to be more appropriate but we are getting back to MLTL territory with that volume and my desired length.

Quite a bit actually, along with the vast majority of folks on DIY audio forums because T/S is easy, don't need to know the underlying physics, just fill in the blanks and adjust till it's as flat as practical, especially nowadays with all the cheap/free computer software, tremendous component selections to meet virtually every conceivable app that don't break any physics laws.

Compare the two sim's diaphragm displacement and group delays to see which one will have the best overall efficiency/protection through the XO BW and least group delay, the distortion that causes some folks to only tolerate sealed and/or ~aperiodic alignments.

Consider too that once properly blended to the sub system, the response will look like the T/S alignment once it has had its mids-up BW attenuated to account for the 3-6 dB baffle step loss assuming it's not ~ up against a wall/corner, in which case some damping or EQ may be required to flatten the hump, though IME, folks don't because it takes away the more life-like/'toe tappin' quality that a prominent mid-bass adds, not to mention it enriches vocals and why its heavily boosted out to around 300 Hz in live concerts at least since the '50s.

When you have nothing better to do, please browse the speaker reviews, measurements and see how many T/S max flat responses you can find and get back to us: Reviews | Stereophile.com

GM
 
So, I have conceded that I am not ready to design my own MLTL yet, however, I have learnt A TONNE already from this thread!

Scott, my solution to my ridiculous constraints I have set myself is this!: I have folded your compact MLTL design and want to take the suggestion of GM to mount it on a weighted base. I took a long look at your Fountek Five folded MLTL and tried to replicate. As mentioned earlier it is the reverse engineering that helps accelerate learning.

I resorted to a 50mm x 110m vent as it goes deep enough to reach your specified 11cm from bottom of the line (actually it is off by 15mm, eek)

My total box volume is larger than the straight MLTL at about 13 litres. The reason for this is that I assumed that you can't simply fold the line, once must account for the path of the wavelength so I drew up a diagram to help me equate the length I should use around a corner. Based on a 12cm line depth I worked out that each 90 degree turn would result in 107mm length. The line adds up to your spec.

Am I on the right track or should I simply fold the line without adjusting the fold path lengths?

Material is 15mm.

It may seem I am floundering here but I am really enjoying this process and your help has been invaluable this far.

7MS is fine for a compact MLTL (an oxymoron in GM & my parlance, but the term will suffice)

~51Hz Fb compact MLTL. V. quick, lightly damped alignment. Internal dimensions:
L = 28.5in
W = 5in
D = 4.75in
St = 5.75in
Sv = 24.125in
Av = 3.14in^2
Lv = 4.5in
Vb (nominal) 11.1 litres [nearly].
Lag all internal walls 3/4in - 1in acoustic fiberglass, SAE-F10 felt, Ultratouch or similar & adjust to preference.
 

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Now I am getting super excited! I will be trying both MLTL and this vented design. This holistic approach is something I am only just getting used to. Scott has mentioned it before and now it is starting to sink in.

I did check the velocity and group delay and gosh dang you're right!

I hope I am not taking advantage of generosity of members here who share their wealth of knowledge. It's a slow process but I am getting there!

Quite a bit actually, along with the vast majority of folks on DIY audio forums because T/S is easy, don't need to know the underlying physics, just fill in the blanks and adjust till it's as flat as practical, especially nowadays with all the cheap/free computer software, tremendous component selections to meet virtually every conceivable app that don't break any physics laws.

Compare the two sim's diaphragm displacement and group delays to see which one will have the best overall efficiency/protection through the XO BW and least group delay, the distortion that causes some folks to only tolerate sealed and/or ~aperiodic alignments.

Consider too that once properly blended to the sub system, the response will look like the T/S alignment once it has had its mids-up BW attenuated to account for the 3-6 dB baffle step loss assuming it's not ~ up against a wall/corner, in which case some damping or EQ may be required to flatten the hump, though IME, folks don't because it takes away the more life-like/'toe tappin' quality that a prominent mid-bass adds, not to mention it enriches vocals and why its heavily boosted out to around 300 Hz in live concerts at least since the '50s.

When you have nothing better to do, please browse the speaker reviews, measurements and see how many T/S max flat responses you can find and get back to us: Reviews | Stereophile.com

GM
 
I have very little time but that was one of my three abstract queries. The other two being whether the internal vent offset is as specified since the diagram wasn't clear on that front, and noting that the driver & vent locations, notably the latter, will change from the intended positions vis-a-vis boundaries once folded up. The latter is more of an open question & depends on room acoustics & taste; with the vent higher off the floor it won't pick up as much boundary loading.

FWIW, if intending to cross at a relatively high frequency to subs then I'd simply use GM's standmount + high-mass base (with a heavy slab or pot plant added to the top too if possible) as it is better optimised to these requirements.

Note if you want a high mass base for a floorstander, clamp it to a slab of marble, granite or similar as the plinth (and then stick another or the aforementioned plant on top).
 
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