Larger voice coils have more surface area which aids in cooling, reducing power compression.
A larger voice coil pushes against more cone surface area, which can result in less cone flex.
6.5" seems overly large for a 12", perhaps the driver is a "smaller brother" using a voice coil designed for use in an 18" or 21", similar magnet structures and voice coils are often used with different size cones to reduce design and tooling costs.
hmm, being this big, I think it gets exceedingly diffult to make the voice coil precise and sturdy
might go againts the possible advantages
but regarding the cone, they only need to make sure the area between voice coil and surround is really tough
the rest could be just a big dust cap
but the much smaller spider will be stiffer and less 'flexible'
Here are the specs I just measured (both VC in parallel).....
* f(s)= 22.88 Hz
* R(e)= 1.05 Ohms
* Z(max)= 10.57 Ohms
* Q(ms)= 4.873
* Q(es)= 0.536
* Q(ts)= 0.483
* V(as)= 30.550 liters (1.079 cubic feet)
* L(e)= 1.07 mH
* n(0)= 0.07 %
* SPL= 80.24 1W/1m
* M(ms)= 465.20 grams
* C(ms)= 0.10 mm/N
* BL= 11.43
And at the risk of being told to just toss them in a pit and light them on fire, here is a pic.....
* f(s)= 22.88 Hz
* R(e)= 1.05 Ohms
* Z(max)= 10.57 Ohms
* Q(ms)= 4.873
* Q(es)= 0.536
* Q(ts)= 0.483
* V(as)= 30.550 liters (1.079 cubic feet)
* L(e)= 1.07 mH
* n(0)= 0.07 %
* SPL= 80.24 1W/1m
* M(ms)= 465.20 grams
* C(ms)= 0.10 mm/N
* BL= 11.43
And at the risk of being told to just toss them in a pit and light them on fire, here is a pic.....
An externally hosted image should be here but it was not working when we last tested it.
The answer is: It depends.
The number of windings, the length of the wire, the material the former is made of, the diameter of the wire etc...
My guess, since you say the driver has a cheesy reputation [cough]car audio[/cough], it's for heat dissipation / sheer size (mines bigger).
Well I let the cat out the bag, so I think you are half right at least.
They didn't market this as their highest power driver, and the higher power drivers had smaller voice coils, which made me question why they went with such a large voice coil here. Just a gimmick?
I know Kicker makes one
A 6.5" VC on a 12" sub is a bit much but if it is a car sub, the benefit by making the voice coil huge is to have the power handling of a lot of copper but without the much deeper woofer frame and thick magnet required for long stroke.
I'm assuming the sub is a "shallow mount"? Morel tends to put huge voice coils in their drivers, they have a 2" VC in a 4" speaker, a 3" VC in a 5 inch speaker and a 9 inch sub has a 5.1 inch voice coil.
Morel UW958, 9" Ultimate Subwoofer with 5.1" VC: Madisound Speaker Store
A 6.5" VC on a 12" sub is a bit much but if it is a car sub, the benefit by making the voice coil huge is to have the power handling of a lot of copper but without the much deeper woofer frame and thick magnet required for long stroke.
I'm assuming the sub is a "shallow mount"? Morel tends to put huge voice coils in their drivers, they have a 2" VC in a 4" speaker, a 3" VC in a 5 inch speaker and a 9 inch sub has a 5.1 inch voice coil.
Morel UW958, 9" Ultimate Subwoofer with 5.1" VC: Madisound Speaker Store
Ordinarily, I would say that such a large voice coil diameter, on such a small cone (relatively speaking) could translate to some desirable traits for sound reinforcement applications. Assuming that the voice coil was short and wound shallow, only 1-2 layers, and paired up with a strong magnetic field in a tight tolerance build with a light stiff cone, such a design could make for a very high efficiency, high power handling, low distortion mid-bass driver or mid-range driver for a sound reinforcement rigs.
In this case, they have taken things a different direction. (car audio approach seems to be: create drivers that create demand for larger amplification), probably making the voice coil long, and wound with 4-8 or more layers, and created a 12" driver with a moving mass that weighs almost a pound (more than many 18-24" subs). The result is a low Fs and high Pe at the expense of efficiency: ~80dB@1W = ~0.07% efficiency. I don't usually expect to see this sort of efficiency unless the driver is a full range design of less than 3" diameter.
While there is nothing necessarily "wrong" with such a design (it lends itself to small box sizes and extension to ~20-25hz), I would argue that one could achieve equal listening levels for a fraction of the amplification using different driver/s if one is willing to sacrifice some of the very bottom end where there is generally nothing musical happening anyways.
Eric
In this case, they have taken things a different direction. (car audio approach seems to be: create drivers that create demand for larger amplification), probably making the voice coil long, and wound with 4-8 or more layers, and created a 12" driver with a moving mass that weighs almost a pound (more than many 18-24" subs). The result is a low Fs and high Pe at the expense of efficiency: ~80dB@1W = ~0.07% efficiency. I don't usually expect to see this sort of efficiency unless the driver is a full range design of less than 3" diameter.
While there is nothing necessarily "wrong" with such a design (it lends itself to small box sizes and extension to ~20-25hz), I would argue that one could achieve equal listening levels for a fraction of the amplification using different driver/s if one is willing to sacrifice some of the very bottom end where there is generally nothing musical happening anyways.
Eric
Yeah their efficiency is abysmal. Good thing power is cheap these days.
I plan on putting them in 1" thick MDF boxes just large enough to hold them and then apply LT EQ. Hopefully 500W for each driver will be enough for "normal" listening levels.
Back when I still thought car audio was cool (10 years ago?), I remember seeing these drivers and thinking they were the neatest thing at the time (ignorance is fun) but could never afford their $500 price tag. I recently came across a pair for a really good price and grabbed them just out of nostalgia I guess.
I plan on putting them in 1" thick MDF boxes just large enough to hold them and then apply LT EQ. Hopefully 500W for each driver will be enough for "normal" listening levels.
Back when I still thought car audio was cool (10 years ago?), I remember seeing these drivers and thinking they were the neatest thing at the time (ignorance is fun) but could never afford their $500 price tag. I recently came across a pair for a really good price and grabbed them just out of nostalgia I guess.
I would think twice about such approach
the high Qts would cause 'uncontrolled'
high peak
on the other hand, the low VAS ought to make a relatively small closed box almost ideal
I'm wondering if that moving mass has the characteristic of causing reaction forces in the (speaker) frame to also vibrate the (car) frame as an added bonus. The total effect being .... (warning, this has gratuitous woofer shots)
Cars That Go Boom - YouTube
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