Once again you are wrong. Flat out, wrong. Let me demonstrate. You said literally “Does using a shorter coil winding(less xmax) given all else is the same = more motor force, and thus a lower Qts? Yup!” Here are two FEA graphs demonstrating two coils of exactly the same winding width, or winding height:
First up we have a driver with a 20mm winding width and a 26mm tall top plate, and a BL of 12.6. Xmax is 17.8mm.
Second we have a driver with a 18mm winding width and the same 26mm tall top plate (entire gap width is the same as above). Xmax is down to 17.32mm and BL is down to 11.8. This shorter coil actually has
less Xmax and
less BL than the longer coil.
You wrote “Btw: Motor force is the most important, hate to break it to the people who repeat lines like: if only motor force was everything.” …in your previous post.
The example you just provided and the two semi-apologies contradict everything you said in your prior post. The XXX example is a good one about short coils being utilized for small boxes but not so much on low Qts being good for everything as you have previously eluded to.
Saying one thing and meaning another are difficult, if not impossible, to read into…especially on the internet. You did say Not all small motors are “weak.”
I did read the whole thing. You were on your soap box about very strong motors (ie, low Qts) being the focal point of woofer design. You said
About your testing of the BL. Use a much better example such as a coil that isn't So close to it's xmax.
Yea i will admit that I wrote things on a soap box sort of, like when i said: Motor force is the most important, hate to break it to the people who repeat lines like: if only motor force was everything.
That line was not fully serious, but it actually is. Half serious I guess. What i was getting at was how easily it is to swap out soft parts for a given motor and totally redesign a sub, changing it's specs. Well, swapping out parts is nothing but the motor actually drives it all and you having a motor with plenty of potential force is a good thing for us bass heads. The first subwoofers I have used/owned were smaller motor subs, very generic. After learning to build subwoofers, do you think I would want to add a couple of "pucks" to a walmart subwoofer for more coil clearance and throw a 2.3" WW coil or something in it for more xmax? The Q would in fact be too high in this case unless I had a pretty light moving mass, soft suspension, or similar. Power compression would also make more power handling futile.
Alright, you also highlighted how I was getting at a Low Q being the most important or the best compromise or whatever you were thinking but of coarse not. If you re-read it and think about what I said, what I was getting at was that it can actually be tough to achieve a low enough Q whenever you are designing subwoofers. I have used 9" OD motors that had the results of a high Fs(50 hz or so IIR), and had a Q in the high .5-.6s(I cannot remember the exact results). For a motor that large and the average gap I had to work with and what my goal was it wasn't good enough. It was due to the coil I used which was not very beefy in the gap.
The point was that soft parts can be changed on any motor, beefy or not, in order to get paramaters that you can work with, but the motor force itself is the true limiting factor for what you can do with the subwoofer. Like i've said, No i'd rather not have an fs of 60hz on a walmart sub in order to make sure the Q does not shoot over .6-.7 or so while redesigning one, with more motor force you would be open to lowering the FS considerably allowing more mass and excursion then then a weaker, and smaller motored sub(in the case of a smaller motored sub I am talking about a motor with say one magnet of clearance for instance, this would not include Neo as i am referring to a "lower level motor")
Example of what i'm getting at and the OT: The L7, the suspension is decently compliant, if it were not then the Q of that sub would not be where it's at. It's also rated at a power level that i don't recall, say 1krms, reguardless of power compression you have to think about how it's limited to around that power rating compared to a larger or stronger motored sub(and please don't quote and get off again about how i am claiming that a larger motor = stronger one, lol, please) which is due to the suspension not beeing very "tight". In this case, I am talking about the mechanical power limit instead of the thermal one. Yes, the box also combines as a suspension, and other things we dont need to mention, reguardless, it adds mechanical power handling, BUT, these subwoofers require large enclosures, the Qts really ain't so high, its in the .4s IIRC. The larger cone area gives a higher VAS in comparison to a smaller cone area and same suspension is why they need large boxes. If I wanted more mechanical power handling then I could "stiffen" the subwoofer up(would also lower the VAS) However as you know, the Qts would also jump up after doing this which is counter-intuitive in utilizing a smaller enclosure. Anyway, kicker obviously designed the subwoofer with the mainstream customers in mind, and the general mainstream power handling peak is like 1kw or so for the Top of the line woofers offered from these brands. So, what did kicker do? after all the R&D they figured out that the size motor that they are using works fine with the soft parts to create a subwoofer with parameters within app.
Basically, I prefer a high powered subwoofer that does fine under power, I enjoy the compromise of a subwoofer that uses power to get loud instead of efficiency. The last lines about the L7 were more towards this thread and what i thought about the OT.
Anyway, I don't like when people say things like: motor force dosn't mean anything, etc...It aint like I could use a smaller, weaker motor to achieve what a larger one can. It just seems that people believe that a smaller ferrite motor(lets point at the top plate, and say std magnets) can do anything. There really is a ceiling and the soft parts will allow you to stay within application spec after some R&D with a given motor, but you cannot expect some "special" surround, cone, spider, etc tooling, to be the end all be all. Motor force may not be everything, but it is very important. This was my original point. I just put it the wrong way, lol It happens when you have to run to work in a few minutes and you are dying to post about something.
