big motors and loose suspension

[Beatin' 10+ year member]

What kind of subs out there have HUGE magnets for some serious QES but very loose mechanical suspensions?

I don't understand why high QTS subs typically have small magnets and very loose suspension, but low QTS subs have huge magnets with super stiff suspensions.

Wouldn't it make sense to have strong motors and loose suspensions together?

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[winkychevelle 10+ year member]

If you understand why they are built like that why would you want high motor force and no control you would have sloppy inaccurate bass. Not bass that would be more intense cuz the suspension wouldnt hold it back.

 

[Beatin' 10+ year member]

If you understand why they are built like that why would you want high motor force and no control you would have sloppy inaccurate bass. Not bass that would be more intense cuz the suspension wouldnt hold it back.

from what I've read, high qts subs will have better low end ouput because of loose suspension mated with a smaller magnet giving it weak and sloppy electrical damping (qes). That sloppy electrical damping mated with high xmax and loose suspension is what gives high qts subs great low frequency output. Those low qts subs with stiff mechanical suspensions with huge motors will have excellent cone control on higher notes but low end will suffer because of possible over damping, not giving the cone enough throw to play low notes loudly, which is the reason why low qts subs are recommended for ported boxes.

So why not have huge motors mated with very loose mechanical suspensions?

 

[terra 5,000+ posts]

Because we don't like it loose.

 

[winkychevelle 10+ year member]

from what I've read' date=' high qts subs will have better low end ouput because of loose suspension mated with a smaller magnet giving it weak and sloppy electrical damping (qes). That sloppy electrical damping mated with high xmax and loose suspension is what gives high qts subs great low frequency output. Those low qts subs with stiff mechanical suspensions with huge motors will have excellent cone control on higher notes but low end will suffer because of possible over damping, not giving the cone enough throw to play low notes loudly, which is the reason why low qts subs are recommended for ported boxes.
So why not have huge motors mated with very loose mechanical suspensions?[/quote']

Because if you have high motor force but nothing to control it you will rip surrounds/spiders, jump gaps, bottom out the sub, have coil ru. as well as having a sloppy sounding sub due to the voice coil moving in a none linear motion. Magnets are 100% balanced in power 360° around the voice coil. This would push the coil in many directions that if the spider isn't stiff enough it will move the cone in a none linear motion and will sound like crap

 

[*Ace* 10+ year member]

If you understand why they are built like that why would you want high motor force and no control you would have sloppy inaccurate bass. Not bass that would be more intense cuz the suspension wouldnt hold it back.

This really isn't accurate. A sub with a high BL and loose suspension could potentially give me a more efficient driver with better low end at the cost of needing a bigger enclosure without thinking of all the other variables involved. The enclosure is what is going to determine if I have "sloppy inaccurate bass", not necessarily the sub. The only thing that the T/S parameters of a sub will tell you is what kind of enclosure you will need to produce a given frequency response, or "sound". Having a loose suspension with a high BL would only be a bad thing if the enclosure required to give you the sound you want does not fit your specifications.

 

[Buck 5,000+ posts]

Higher Qts = more control of the cone at Fs (Fs kind of becomes less irrelevenant the lower the Qts), tighter suspension and stronger magnet

Low Qts = less control of the cone at Fs, loose suspension and week magnet.

I don't know this 100%, but I think people forget about progessive spiders vs. stiff spiders. Think about it, a progressive spider can seem relatively loose on a high power sub with a medium sized magnet (like my Fi BL, goes in 5-8 cubes). But the woofer has an overall lower Qts, which translates in the sub being able to handle itself better than one with a higher qms. So it'll work in big boxes because the spider is stiff enough at a point to keep the woofer under control along with the medium sized magnet, but work in small boxes because the suspension is loose enough to move a good amount. Now my DC XL M1 has a huge magnet, and a progressive suspension. But because of the kind of oversized magnet for the power handling, it works optimally in small to medium sized boxes on higher power levels (5-6.5 cubes). It has a little bit higher qms. So kind of like this: same suspension (progressive) for both. But the magnet determines box size (in this case) because of how much more it impacts the travel of the cone. Big magnet, more moving of cone, smaller box. Slightly smaller magnet (and power handling, but not too much), a little bigger box.

With that being said, there are waayyyy more factors than that, it's just a way to think about it. Put a bunch of these style thoughts together and you can figure a lot out.