MLTL Floorstanders for Alpair 7MS

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I am quite keen on this driver, I am big fan of the A6.2m and the new driver looks really good!!

A ported design would be easy to knock up but as I understand it would make integration with my subs less smooth?

If not an MLTL would a simple TL work? I have had even more trouble designing one of those! I've fallen in to pandoras box!

Thanks Scott for chiming in and give a much better reply than mine! :)

Graham... Are you so dead set on that Alpair driver?
It doesn't look like a good match for the MLTL design.

If you already bought that driver, then, may I suggest a simple vented design that could reach 80Hz, low enough to integrate with your subs.

You can still have the same looks as a MLTL, just make a long empty base to put the simple vented enclosure on top. Even better, fill the empty base with sand.

I am on an iPad and no access to my computer so I can't model a vented enclosure, but there might be some floating around already.
 
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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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What about the bump at 50Hz?

I remember seeing a picture from Dave where they put a miniOnken atop a column. By building the column and cabinet fron a single box, it will look seamless and similar to a long thin column. I'm sure that will easily reach 80Hz and limit the movement of the cone if pushed down to 50Hz, resulting in a cleaner sound.

Something like this on top of a column/base:

https://www.kjfaudio.com/gallery/
 
What bump at 50Hz? ;)

You get peaking at Fb if it's designed in (accident or intent) or the effective driver Q is > Butterworth.
 

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Thanks, Scott, looks very interesting and I always like your designs.

Is this what I should be looking at?

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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It doesn't look like a good match for the MLTL design.
It kinda looks like you are trying to fit a round driver into a square hole!

If you already bought that driver, then, may I suggest a simple vented design that could reach 80Hz, low enough to integrate with your subs.

You can still have the same looks as a MLTL, just make a long empty base to put the simple vented enclosure on top. Even better, fill the empty base with sand.

While I find MLTLs in general to be a great match for higher Qt drivers, the OP's various [conflicting] design goals do indeed make it a poor match IME, so to the first approximation a bookshelf + massive base seems a great solution and when super low efficiency, power handling is factored in I fall back on the pioneer's solution based on compliance and max efficiency at Fb because they had so little power to work with, which this driver's Fs is near enough ideal for the desired XO point:

Vb = [measured] Vas/1.44

Fb = [measured] Fs

Using the published specs and accounting for some damping combined with the XO's attenuation around Fb, the vent can be quite small: 2.54 cm dia x 6.2 cm long.

Fill the rest of the tower [with outrigger feet or separate wide base] with something massive such as the aforementioned sand, kitty litter, oil dry, scrap iron or similar and of course if this 'bookshelf' is actually one, then use a spiking system to couple the two if not configured to be flange coupled to it.

This combo will in theory have much more dynamic headroom due to the increased acoustic efficiency down low assuming the VC can handle [much] more music power than its 15 W [nominal] implies.

GM
 
Minionkens would be interesting but I don't think my woodworking skills are up to speed for those!

Thanks, good suggestion on the columns!

What about the bump at 50Hz?

I remember seeing a picture from Dave where they put a miniOnken atop a column. By building the column and cabinet fron a single box, it will look seamless and similar to a long thin column. I'm sure that will easily reach 80Hz and limit the movement of the cone if pushed down to 50Hz, resulting in a cleaner sound.

Something like this on top of a column/base:

https://www.kjfaudio.com/gallery/
 
Thanks for your thoughts and suggestions! This idea is getting some serious thought from me. A couple of questions if you do not mind?

Will the ported design be less likely to form a smooth cohesion with my bass units? Not knowing much about phase here but as I understood it TL variants have a response better matched? I am in no way against ported designs, I would just like to better understand the difference and whether or not they matter in my set up.

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

While I find MLTLs in general to be a great match for higher Qt drivers, the OP's various [conflicting] design goals do indeed make it a poor match IME, so to the first approximation a bookshelf + massive base seems a great solution and when super low efficiency, power handling is factored in I fall back on the pioneer's solution based on compliance and max efficiency at Fb because they had so little power to work with, which this driver's Fs is near enough ideal for the desired XO point:

Vb = [measured] Vas/1.44

Fb = [measured] Fs

Using the published specs and accounting for some damping combined with the XO's attenuation around Fb, the vent can be quite small: 2.54 cm dia x 6.2 cm long.

Fill the rest of the tower [with outrigger feet or separate wide base] with something massive such as the aforementioned sand, kitty litter, oil dry, scrap iron or similar and of course if this 'bookshelf' is actually one, then use a spiking system to couple the two if not configured to be flange coupled to it.

This combo will in theory have much more dynamic headroom due to the increased acoustic efficiency down low assuming the VC can handle [much] more music power than its 15 W [nominal] implies.

GM
 
I'm not GM, but FWIW flange-coupling the bookshelf to a massive base should ensure the latter becomes an effective energy sink. Although I'd like to stick a nice heavy pot-plant (or a slab of marble / similar) on top of it too, to mass-load the bookshelf structure into the base.

Actually, an MLTL is ported. It just happens to use quarter wave rather than Helmholtz resonance, or in the case of small / highly forced MLTLs, accounts for QW resonance in the design / tuning rather than using it at Fb per se.
 
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I understand now, thanks.

So after a long day-dreamy train journey I expanded on this BR route and got thinking about coupling.

Attached is a rough sketch of the enclosure (top) and base (bottom) with spikes of some description between the two. To achieve the mass-loading effect you mentioned Scott, I wondered if a bolt and washer through the inside bottom of the speaker enclosure going through the top of the base in to a T-nut which would sandwich the spikes and create coupling.

The base would be filled with sand and this bolt-on way of attaching the two would give me future compatibility to use the stands with other speaker projects.

To my mind this makes sense.



I'm pretty sure he meant something like:

Make a hole in the column, install flange on the "monitor" speaker and insert into hole.

I'm not GM, but FWIW flange-coupling the bookshelf to a massive base should ensure the latter becomes an effective energy sink. Although I'd like to stick a nice heavy pot-plant (or a slab of marble / similar) on top of it too, to mass-load the bookshelf structure into the base.

Actually, an MLTL is ported. It just happens to use quarter wave rather than Helmholtz resonance, or in the case of small / highly forced MLTLs, accounts for QW resonance in the design / tuning rather than using it at Fb per se.
 

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Just did a quick WinISD sim of this recommendation. 3.45l and port tuning of 74.7hz. Is this what I should be looking at?

Vb = [measured] Vas/1.44

Fb = [measured] Fs

Using the published specs and accounting for some damping combined with the XO's attenuation around Fb, the vent can be quite small: 2.54 cm dia x 6.2 cm long.
 

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