Who makes a hi-eff 15 that can do a 50 hz F3 in a sealed 3 to 5 cu ft?

here's an idea - a cheap ($90)15" in a filled 5CF 3rd order box with the magic 450uF (8 ohm) value of series cap. The first few sims are with lining rather than fill.
 

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Likely the expected efficiency goal
And Fs will play a big part.

More likely to be drivers in the
94 to even 92 dB that could do it.

Its hard to get realistic 50 Hz
with a reflex in under 4 cubic feet

Having gone through countless sims
as well with 15"

Eventually my trade off was using
reflex. But using something that works
with very very low tuning. To get rid
of the reflex transient issues that make
sealed so much more appealing.

Either way at quick glance the driver
needs very low Fs.
 
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@soulsheiksan
And is this for subwoofer, woofer or midwoofer duty?

ie. how high do you want it to play?

Eg. 30-120Hz?
To 250Hz?
800Hz?

What is Zmin do you need?
eg. 8 ohm driver? 4 ohm driver?
Twin 4 ohm drivers in parallel with Zmin of 2 ohms?

I have a few off the top of my head as a shortlist, which may be close to your needs.
 
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Why not consider the "absolute" efficiency at 50Hz? I've seen several that hit 90~93dB @ 50Hz (assuming the usual 2 pi space) in simulations, but the mid-bass tends to peak around 97-99dB, so the F3 cut-off is a bit higher.

If you need the mid-bass to be less sensitive, something like a Linkwitz transform can be implemented with op-amps.
 
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Yeah it's not clear what the OP needs.

After baffle step losses, a 15" 95dB/2.83V driver on a typical, say, 16" wide baffle is down to 90.5dB at 100Hz.

So I get his need for higher sensitivity- particularly if you're doing passive crossovers.
 
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After looking at around 30 plus drivers I only found a single eminence driver,I am sure there are some around,has the industry now only focused on br and dsp.
Anything above 95 db 1m/1w
Thanks in advance
Did you find the Eminence Lab 15?

I had a similar problem, and I chose the Lab 12. I think 89dB sensitivity.

It sounds like you are asking for a pro audio subwoofers that works well in a small-ish cabinet. That's kind of a unicorn for a couple of reasons. Pro audio subwoofers don't play as low as consumer subwoofers, because SPL matters more than sub frequencies. And to get the higher efficiency required to achieve the SPL requirements, they end up being designed for a bigger box.

If you take a pro sub driver with high power handling capability, you can do a linkwitz transform to boost low frequency. This just reduces your dynamic range. But an efficient pro audio sub should have dynamic range to spare.
 
Linkwitz's equations on his site require a bit of thinking, but it's all doable. The hardest part is probably putting it all together in a "blameless" package, which doesn't have a separate turn-on thump or noisy PSU. The actual low-pass filter could still be passive, and a modest 6dB bass boost could get some very deep bass from a 15.
 
Two related thoughts to keep in mind.

As resonance frequency goes down, so does dB's per watt (sensitivity from the driver's data sheet).

If you design a Bass Reflex speaker with WinISD or any other software the F3 frequency will be right at the driver's free air Fs taken from the data sheet.

Easy, if you want F3 at 50hZ select a driver with a data sheet Fs near 50hZ.

Thanks DT
 
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Linkwitz's equations on his site require a bit of thinking, but it's all doable. The hardest part is probably putting it all together in a "blameless" package, which doesn't have a separate turn-on thump or noisy PSU. The actual low-pass filter could still be passive, and a modest 6dB bass boost could get some very deep bass from a 15.
It'd be easier to do active crossovers for this woofer. An amp with built in DSP correction could power just this woofer, and the rest of the speaker can be passive? I prefer to go active all the way, but of course the OP hasn't stated his intentions....
 
For a given cone size, Xmax determines the maximum SPL. Why focus on efficiency when amplifier power is so easy to buy and cheap? The design process goes like this. Decide on the maximum SPL desired for the low frequency limit. So what is the maximum SPL you want to produce at 50Hz ? From that SPL and 50 Hz you can calculate the required displacement. From there using the area of a 15 inch woofer you can compute the required Xmax. You can then see what woofers have that Xmax and select the one that will have the lowest F3 in the desired box size. Lastly you compute the Linkwitz transform required to make it run flat to 50 Hz. Because you selected the proper driver, you will achieve exactly the desired max SPL at your low frequency limit without bottoming out the woofer. The efficiency can be used to determine the size of the power amplifier required, but the max power handling of the driver will often work just fine. I created a spread sheet that has the SPL and Linkwitz filter calculations. The displacement / box volume is an interesting parameter to use. It lets you sort woofers based on the required box volume. https://docs.google.com/spreadsheets/d/18BXQP-WSRRbQHTR_mXJ0OVdyYF8tixPRP3dvkLzf5m0/edit?usp=sharing After selecting a woofer go load it into WinISD . WinISD includes the Linkwitz filter modeling. in the drive signal. You can look at the frequency response and the max SPL plots to see that it works as expected. A more complex program like boxsim from Visaton can be used to include baffle step modeling and see the response in all directions. As usual a thread that asks a question that is some what ill defined, leaves a lot to the reader to interpret and is infrequently answered by the OP gets lots of response and provides a lot of entertainment as it does not resolve easily.
 

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As usual a thread that asks a question that is some what ill defined, leaves a lot to the reader to interpret and is infrequently answered by the OP gets lots of response and provides a lot of entertainment as it does not resolve easily.
Well the OP might want a <10W class-A amp with 2-way speakers. So to get extended range, a passive air cored inductor could help linearise the woofer through the mid-range. But a 1st order filter can only do so much, so an active hybrid could make it even better, and force it to be bi-amped (which is rarely done if it doesn't "have to" be done).
 
abstract: You proved my point perfectly. The OP doesn't clarify the need, so wild speculation and a very long thread follows. By the way there is no need to bi-amp a speaker to apply a Linkwitz transform. Many passive speakers have been supplied with line level bass EQ boxes including the B&W 801 and the Bose 901. It can be done with op amps, DSP, or software filters like equalizerAPO or in the DSP engine in players like JRiver Media Center.