Yea the oldschool stroker is not a point. It had short throw which increases motor force and controll(lowers Q) compared to a longer stroke.
Short stroke does not lower Qts just as high stroke does not always mean low motor force with high Qts.
Btw: Motor force is the most important, hate to break it to the people who repeat lines like: if only motor force was everything. If you have designed and built subs then you know that it's actually difficult to stay within a low enough Q. Shooting for a low Q is always the thing to have in mind. Having a weak motor will make this much more difficult and will require compromises such as less xmax, higher FS from a looser suspension and or lighter cone(Mechanical efficiency lowers the Q).
To those of you looking at the post I am quoting above, please do not look at it as everything contained in the paragraph above is false if you are looking for information on car audio subwoofers. Jim is right - motor force is
not the most important thing to look at! With small signal parameters high BL can be achieved in multiple ways. However, a very strong motor is not desired and/or wanted depending on the application. For instance, you can easily over-motor a driver to be used in sealed applications. The result will be a driver that has an F3 of 65 Hz in the target size enclosure...aka it won't play low. Will it be loud at 70 or 80 Hz? It could, but it will also have such anemic bottom end that almost 100% of customers will hate it.
And a more compliant (or "looser") suspension will result in a
lower Fs.
If I had a sub with a Qts of .28 and i wanted to lower the FS then i could add some mass to it and still stay within a low enough Q. You could also tighten the suspension for mechanical power handling. What if you wanted both? You would have to tightn the suspension and also add some mass to make sure the Fs isn't too high.
"Tighten"ing the suspension, or making it less compliant, will change the Qt more than any effects of adding mass will have on the suspension. That is, of course, unless you're talking about increasing the moving mass by 2x with a compliant suspension to begin with [note that is a LOT of mass - as in going from an Mms of 250g to 500g!]. Everything is within limits, not definite.
Now, if you have a weaker motor, to achieve an average Q like of around .4, your parts are going to be different then a sub that has a larger motor force and similar parameters. The larger motor force can have a lower Q, and or stiffer suspension and lower Fs compared to the weaker sub that had less mechanical power handling, and and or a higher Fs.
Once again this is wrong.
This is why lower line subs with smaller motors are usually geared towards sealed boxes, because to get a decently low Fs and power handling the Q will be on the high side because the motor isn't strong enough keep it low while having the mass and stiffness it does.
Loudspeaker design is all about compromises. And have you ever seen a neo motor? They are tiny in comparison yet still offer very solid motor force. The size of a motor is NOT an indicator of how well the driver will perform in every application. Know and understand what you want and go from there. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif