Even if you are talking about magnet strength (BL), I'm not so sure that this is true, since there are so many other interrelated factors at work here. You must consider the system as a whole.
Going back to the equation F=ma (Force = mass x acceleration), we can see that the force is not the only part of the equation. If you think only of magnet strength (BL), or of moving mass (mms), then you really aren't getting a complete picture. Both must be considered together, at the same time along with all the other factors in the design of both the driver, the alignment, how is it integrated and the system as a whole.
It has been suggested in this thread that big magnets give you greater extension and tighter bass. Tighter bass is likely to come from a good sized sealed box with a good transient response and a low Q. More extension is likely to come from a vented alignment which trades a little transient response for depth, linearity and output. It's when you want deep bass and you want it tight and loud as well that things get more difficult.
Bigger magnets are irrelevant to bass quality. What matters is BL, the actual usable motor force in the voice coil. This is better achieved by good design than just sticking a bigger magnet on a driver. The higher magnetic fields are designed to increase Qts, making the driver more suitable for a smaller box.
The most important aspect is marketing. If buyers are looking for a driver and are told that a big magnet is important, (when all that matters is that you don't have an undersized one), then market pressures will lead to drivers with bigger and bigger magnets. It's only cosmetic.
The most important aspect is marketing. If buyers are looking for a driver and are told that a big magnet is important, (when all that matters is that you don't have an undersized one), then market pressures will lead to drivers with bigger and bigger magnets. It's only cosmetic.
isn't that what I was getting at in a round about way? Maybe I'm totally missing the concepts here, but I was thinking that if you have a high RMS sub then you'll have a lot of electromagnetic force in the gap thus needing a larga (i.e powerful, not physically) magnet to balance that out. Most companies aren't willing to shell out the $$$ for neodum magnets, so a larger ferrite based (isn't that the standart? remember, I'm kinda new, so call me out if I'm wrong...I won't be offended) magnet is needed, right?
I know I'm thinking in a car audio world since that's what I'm familar with, but to make a sub perform well in a small enclosure you need to increase power handeling so more 'force' is available for output, right? I know a sub in a larger sealed enclosure will have a lower power handeling than a sub in a smaller sealed enclosire, so aren't we dealing with the same concepts? I know PA speakers have lower xmax values than a car sub per dB, but those PA speakers are dealing wigh huge enclosures compared to the car audio world. I know if someone suggested a 6 cu.ft enclosure for a sealed sub most every car audo guy would shun the sub because it's impractical.
like I said....I feel we're debating the same point with differetn variables...am I right? I honestly dont' know if I"m not saying everything I "think" (not to be sarcastig...the quotes are serioous) I know or if I'm just way off base with half truths. I know the overall design (i.e. thermal capacity, v/c,, etc.) design has more to do with output than the actual magnet, but isn't the origonal author's train of though a little bit justified, at least in the small enclosre/high power car audio world I"m just finally becoming familar with?
please ream my *** if I'm way off base. like I said, I've had a few drinks and I'm speaking from almost 100% car audio experience. If I'm wrong I'd like to know why because i'm here to learn just as much (maybe more) than the next guy!
Paul
You're quite correct, my only excuse is that I posted this before breakfast!
High Qts leads to poor damping in small boxes due to the increased resonance peak. Increasing Bl is one way to improve matters, the other is to increase the depth of the magnet to allow more VC travel.
Note that these are all limited in their extent, as once the motor is saturated then increasing the magnet size will not give any more performance.
You're quite correct, my only excuse is that I posted this before breakfast!
High Qts leads to poor damping in small boxes due to the increased resonance peak. Increasing Bl is one way to improve matters, the other is to increase the depth of the magnet to allow more VC travel.
Note that these are all limited in their extent, as once the motor is saturated then increasing the magnet size will not give any more performance.
Everyone who is interested in the magnet size vs performance debate should look at this excellent article by Adire.
note: it's a pdf file, you may want to right click and "save link as ..."
It shows with both theory and measurements that:
* mms does not affect transient response but it does change frequency response
* BL does not affect it either
note: it's a pdf file, you may want to right click and "save link as ..."
It shows with both theory and measurements that:
* mms does not affect transient response but it does change frequency response
* BL does not affect it either
I found a driver for the starter of this thread...
The StarSound SSWD 6000 15".
http://www.starsound.co.za/Products/Sub_Woofers/SSWD_6000_15_/sswd_6000_15_.html
880 oz magnet, 55 lbs, enough for you? 😉
The StarSound SSWD 6000 15".
http://www.starsound.co.za/Products/Sub_Woofers/SSWD_6000_15_/sswd_6000_15_.html
880 oz magnet, 55 lbs, enough for you? 😉
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