4" (3.5"-5") high efficiency wanted please

[Godzilla]

I read the entire thread so far and can't wait to find out which 4" drivers will do 109db at 100hz and are hi eff!

[doug20]

Yep, I have 5 Nepro5i ribbons waiting for that driver.

[badman]

Originally Posted by sumaudioguy

Sure we get lots of "that won't work" and "you cannot do it that way" but, you know what? It can work and it does work that way every time. Ah, the difference between knowledge and theory.

What specifically did they say won't work that did? If there's some misunderstanding on my part of what a driver can (0r should) and can't (Or shouldn't) do, I'd love to be enlightened. Especially as it pertains to output, which is my problem with your system requirement.

Originally Posted by sumaudioguy

One more thing- Xmax is about the most useless driver spec there is. In no way does this single number tell anyone what amount of distortion a specific driver will make at a given SPL. Yes when Xmax values are exceeded we all know distortion will increase but in no way does Xmax provide a clear limit. Saying Xmax is automatically the limit simply shows lack of both knowledge and experience with emphasis on mathematical models and theory and not of what actually happens in the real world with real transducers.
Keep bringing those off the shelf speakers to this thread. Have seen a lot of interesting things. Thanks-

Sure, there are very different behaviors outside of Xmax. But here's the simple truth- you're limited as to how much coil you can have in the gap and how efficiently that allows the assembly to operate. You're limited by clearance tolerance, practicalities of magnet, motor, coil, and even frame design. Steel saturates, magnet width must be less than frame inside diameter for mounting practicality. The maximum sensitivity in a ceramic and steel motor is achieved with a coil the length of a saturated top plate, in the smallest gap possible. That's why we see 2mm Xmax numbers or less in the high efficiency small drivers. Exceeding Xmax by 50% is very different than exceeding it by 350-400%. You're limited by the suspension and assembly, as well as tolerance and material stiffness. The higher xmax your suspension has the more rocking modes can be introduced and the larger you have to make the gap to avoid rubbing.

So there are severe restraints there, and coil weight and diameter vs. power handling is the other issue which is just as limiting.

Originally Posted by sumaudioguy

I just do not know of any limits in particular which interfere with the driver I have in mind. As noted one manufacturer has already stated it is within their capacity. What else do you require as proof? When you say "modulation artifacts" are you speaking of IM distortion, self noise, or what? Please clarify this nebulous statement. Never have said anything about a 7mm stroke, that is your assumption. I said Fs near or below 100Hz and usable at 99dB to 200Hz or lower and able to handle 10 watts or more. My intent though that may not have been perfectly clear. By your word the 7mm stroke leads to an upper frequency limit of 12,246Hz. Is that really important for a 5" driver? No. The rest you invented so cannot really address your inventions. You must do that.

IM distortion primarily. A quarter wavelenth is an extreme case, but you're still launching small waves from a massively exurting cone.

I see your desire to run only to 2k which does reduce the IM concern quite a bit. You talk of controlled directivity, what on earth will you have above such a small driver if not a horn? I'm not aware of any tweeters that would be both omni at 2k and above, as well as being able to manage any high power/output operation. And if a horn, why wouldn't you want the 5" to taper to a closer matched beamwidth?

6.5" to 120Hz in a high output pro speaker? Which please?

The constraints above are why all high sensitivity tiny drivers are very Xmax, power handling, and highly damped in the lower frequencies. You haven't yet found a single driver that even comes close to your requirements, and you won't. The state of the technology doesn't allow it.

[badman]

Originally Posted by sumaudioguy

Am barely considering a 6" but that gets kind of big and problematic for this particular design. Satellite size needs to be pretty small.
=SUM

Originally Posted by Godzilla

I read the entire thread so far and can't wait to find out which 4" drivers will do 109db at 100hz and are hi eff!

Not just that but do it in a small box <6" wide!

I could see someone managing 109dB from a 99dB w/m driver at 150hz with a ridiculous field coil, it would sound atrocious though It would also be extremely difficult to make, every piece would have to be custom, and the small size requirement for the speaker makes a field coil out of the question. And even with mass production, if it were adopted for every studio in the world, it would be the most expensive small loudspeaker driver in the world, and quite possibly the most expensive loudspeaker period, including extreme exotica.

[doug20]

Can he not just play the 18" woofer up to 400Hz??? Assuming its located with the satellite MT design.

[Godzilla]

Maybe a 4-way is worth considering at this point?

[sumaudioguy]

Originally Posted by Godzilla

I read the entire thread so far and can't wait to find out which 4" drivers will do 109db at 100hz and are hi eff!

Well, that is asking a lot. Working on a 5" for 99dB at 200Hz. If it comes out as good as you request (suggest) will name it after you! Maybe a 6½" could do that.

Has anyone ever wondered why there are 99dB woofers and 99dB tweeters and not much in the way of a 99dB low mid? Simply put, IMO it is because no one happens to build one.

Keep on coming with other drivers for reference and possible use. Can always learn from what the other guy did, right?

Any constructive suggestions are always appreciated.

[badman]

Originally Posted by sumaudioguy

Well, that is asking a lot. Working on a 5" for 99dB at 200Hz. If it comes out as good as you request (suggest) will name it after you! Maybe a 6½" could do that.

So, you've shifted your requirement by an octave (which is still insufficient). Better but still problematic. Again, you're exceeding any reasonable driver by several times Xmax. That's unacceptable and will lead to significant distortion and eventual failure. You can't have a long throw and maximize sensitivity, and there's no "give" on maximizing sensitivity when you're talking about an undersized driver. You have to go low mms, high Qms, matched coil and gap size and as much magnet as you can get on the frame. You ALSO can't do it without a very low Qts and usually (very) high Fs, making your efficiency in the 100-200Hz range an average of 6-8dB lower than the "nominal" 99dB spec you so covet.

Originally Posted by sumaudioguy

Has anyone ever wondered why there are 99dB woofers and 99dB tweeters and not much in the way of a 99dB low mid? Simply put, IMO it is because no one happens to build one.

Uh, yeah, they do. They're either 12"s 10"s or 8"s and are available from every prosound company around. They usually have a rising response which is typical for ultra efficiency drivers.

[sumaudioguy]

Here is one I have never seen... Not so bad at all-

MONACOR INTERNATIONAL:Product detail page

[badman]

Originally Posted by sumaudioguy

Here is one I have never seen... Not so bad at all-

MONACOR INTERNATIONAL:Product detail page

Linear excursion (XMAX)
±0.7mm

And 90dB nominal efficiency at 150Hz. So just shy of 100W to reach 109dB (though if that were only peaks, power handling wouldn't be an issue), and here's the kicker-- >10x xmax to get there.

You'd be just as well going with one of the modern scan speaks who don't have as high an Fs and thus have similar sensitivity at 150, but have some real Xmax.