i'm saying that there is a threshold for when decreasing the power compromises sound quality... you can't agrue with physics in that a voice coil becomes less accurate at lower power levels becuse the speaker has resistance to the current in it changeing that must be overcome as much as possible in order to get accurate reproductions of the waveform input.
This whole statement is flat out wrong. A driver is most accurate with the least amount of movement. Period. The motor is in it's most powerful and linear region. The suspension is providing the most damping. Distortion is at its lowest. Also with only a small amount of power applied, the coils don't heat to the point that thermal power compression has a noticable effect. The only compromise made in using a small amount of power is output in dB. The sonic accuracy will be the best that the speaker can give you, but it might not be loud enough to be useable in a given application. If you were to actually look at how much power is really applied to a speaker during music playback you would find that it is MUCH lower than the rated RMS output of the amp driving it. This is because of the nature of recording and the transient nature of music in general. During normal listening you might have some transient spikes in power applied up to the power rating of the amp, but with only a few exceptions, these transients will be few and far between.
but that is beside the point...
Yes, completely.
a jl 13w7 is not purly an SQ speaker, it is commonly described as an SQL speaker because to reach the SQ it was designed for requires alot of power resulting in a VERY loud but acurate output there is a fine line to where less power means less quality and more power means less length of speaker life
Again totally wrong. The W7 series was designed as an all out SQ driver that is capable of providing reference level sub bass without compromising sound quality. This was achieved by lowering max Bl but broadening the Bl curve so the motor is linear through a longer stroke. The XBL^2 technology emeployed by the older XXX and some of the Adire subs worked on a similar concept but got there a different way. Because of the reduced strength of the motor at the center point (relative to a conventional design) the efficiency of the sub went down. To allow the sub to achieve reference levels of output with a reduced motor strength, the coil had to be made to handle increased power. This power handling is not a feature in and of itself like it would be for an all out SPL sub, it is one of the compromises of the flat BL design.
... this "magic number" for the 13 is 1000 watts, allthough most preffer to give it more than this... don't fool yourself into thinking Jl doesn't test their own products before slapping those specifications on them...
If you actuall kne whow to read JLs recommendations, they actually state that 500W is adequate for a 13W7. The minimum power recommended is based on achieving acceptable output levels and has nothing to do with accuracy of response. If you knew anything about loudspeaker physics, this would be very obvious to you.
my suggestion is if 500 watts on a 13 or a 12 is more than loud enough for you...don't be stupid you're not getting better quality with the bigger sub by underpowering it, get the 10 or 8 or a lesser series.
Once again you have no concept of what you're saying. The accuracy of a sub (or any speaker for that matter) is greatest at the center point of its stroke, its rest position. The W7 is designed such that the accuracy doesn't decrease much as you move away from the center (especially compared to a conventional design), but it still does decrease. By using less power you keep the driver closest to the center point during actual use. By doing this with a larger driver, you get back some efficiency and thus some output while keeping the driver as linear as possible. If you don't believe me on this, take a 13W7 and a 10W7 and put them in boxes of the same alignment. Apply the same power to each and tell me which has more output. Also tell me which has the lowest measured distortion.
fact is that the w7's are not ment to only be an SQ speaker, infact they require alot of output for them to reach their peak frequency responce
The highlighted portion is patently false.
if you don't believe me take a look at the W7's technowledgies on the website... you'll never find anything that mentions SQ being the focus of the design in a w7... what you WILL find alot is that they were designed to have extremely high SQ at extremely high SPL
Wow, because they don't explicitly state that "this is a pure sound quality driver" even though they do state that the sub is designed to provide the lowest distortion of any driver that they make (sounds like a no compromise SQ driver to me...) you decide that you can state that the driver is not meant for SQ but rather for the made up term SQL. The bottom line which you fail to see is that the sub is a meant to provide the most accurate sub-bass of any driver around. The key design feature behind this was a broad and flat Bl curve and a very high excursion suspension. The combination of those two things means that the sub can travel a lot befor it becomes nonlinear ot a significant degree. That doesn't mean that it was designed to play really loud in and of itself. One of the key bits of reality that you seem to be deficient on is that the W7 is a SUB woofer, not a woofer. The important thing about the difference is the frequency range for which the driver is optimized. In order to produce the same level of output one octave lower, a sub has to move four times as far. You will also get more excursion at lower frequencies with the same amount of power. Therefore if you are using the SUB as it was intended, the higher excursion is to get more output at subbass freqs rather than extra output in the range that should be covered by the mid-woofers in an SQ system. Getting a lot of output in the upper bass range takes a lot of power, if that's how you roll, good for you, but in-car you really don't need a ton of power to get awesome sub-bass in a critically damped enclosure with a high excursion sub, even one that is touted as being really inefficient.
There you are assuming again. If you look a lot of the high level SQ competition cars, they have really big subs. Why? Becuase big subs can provide usable output at really low freqs with minimal cone excursion. Why is that important? As stated above, contrary to what you think, a driver is most linear when the cone is closest to the center of the motor and suspension curve. Keep a driver from approaching its excursion limits and you get more linear output.
