lithium

some extra reading material. the circuit diagrams should make this easier to follow. http://hyperphysics.phy-astr.gsu.edu/hbase/electric/ohmlaw.html

no, thats not how a circuit works. look at the links i posted. each coil will see half the power, period. ugh

this is basic series and parallel circuit stuff.

how power is distributed in the circuit is easily explained http://en.wikipedia.org/wiki/Resistor#Theory_of_operation http://en.wikipedia.org/wiki/Series_and_parallel_circuits

If the sub's vc thermal rating is 500 watts thats rating for any vc combination offered. Take the SSA dcon for example, you can get a single 4 ohm or dual 4 ohm configuration. In the case of the dual coil, each coil will handle half the total rating. You dont magically gain twice the power handling by purchasing the dual coil version.

how many db's do the welds add?

Thank you yes was looking at that. MMMMMM Is that your pic? Is the volts on rca outs a big thing? The rca output voltage is NOT a big deal.

win8 tablet or carpc?

come on dude, put some effort into your post. for example, explain what you had before so we can make some suggestions.

shoe goo it and make your friend buy a recone.

Hopefully Don@sds gets back to me soon. Need to get my install moving.

2000 pages in the new hop!

jelly

If it already has one built in and set at 25hz that should be fine. Is it happening while playing low end heavy music? Are you sure its the sub and not the other speakers in the car? you should probably just back the volume down and be careful. Also, check your box for any air leaks. If the sub is actually bottoming out than a leaky box could be the cause.

a loud snap? a metal on metal sound? That's probably the coil bouncing off the backplate. What is your subsonic filter set at? it should be set a few Hz below the tuning frequency of the enclosure.

you can probably repair it. i believe shoe goo is typically recommended.

hope you don't get in an accident, that sub will rip right out of that box and kill the passenger.

The confusion stems from your use of air as a medium at different scales. here's an example: So in the first sentence you're saying that air, on a macro level (large scale), is not moving but simply transporting the energy of the speaker. Thats fine but on a micro level (smaller scale) air molecules are moving, which you understand as the means for which sound travels. So getting back to you original post: Vacuum moves air molecules and speakers move air molecules so yes air can be forced through the pores in the mdf in either case. feast your eyes on this beautiful piece of educational art.

i would read sounddeadenshowdown.com and learn how the products work yourself.

neither of which would really convey their performance in a car. what you have established is which sounds best on a display. not exactly the best way to go about it. and that's not to mention all the tricky car audio shops use to manipulate the performance of the speakers in the display.

measure each individual coil's dc resistance (which should be around 1.4 ohm) and do the math. you should get .35 ohm assuming 1.4 ohm per coil. .35 ohm dc = .5 ohm nominal. If you're getting anything different than you didn't wire something correctly, your subs are boned, or your meter is jacked.

how were they installed? if they're just plug in to a board then you're not evaluating them fairly. thats not to say that any particular set is of good value.

If put a piece of tape on the end of a bound up slinky and then let it go does the tape move?Can you move in a sine wave without any velocity? Can you do a hair trick if the air isn't moving? Does water move when you push your hand through it? Do you need me to go on? The examples you have given arent that great. A better example would be putting a piece of tape on a part of a slinky and move one hand side to side. The energy transfers throug the slinky, making the slinky move to a certain extent, but once the energy dissipates the slinky will be in the same exact resting place as it was before the energy transfer, thus the tape would also be in the same place. Or, you could see it as a rope that is held on both ends, when someone moves one side up and down quickly you will see the rope form a wave of energy that is transfered from one end to the other, the rope itself will go back to the same resting place it was previously. That is how sound waves are transfered through mediums such as air.Maybe you should stop trying to read what isn't there.If you constrain the slinky in the stretch/compress direction it is akin to holding your speaker cone completely still. Perhaps when you move your hand through the water in a lake/bathtub/pool the water doesn't move in your mind, but I bet it is moving. And btw, sound is only transferred when it moves energy. Same with any wave. They are all kinetic. Curious in your example, did your hand 'move' the slinky? Han transfer energy to it, just as with the rope example. But if a sub moved air would it not create a vacuum? If so then how would the sound wave continue to travel past the vacuum? Apparently phsyics is completely incorrect about how sound travels. http://www.physicsclassroom.com/class/sound/u11l1c.cfm

thats all fine. what you're measuring with the dmm is the resistance of the subwoofers coil (just a big spool of wire). The impedance that the amplifier will see is essentially 1 ohm. This isn't a necessary concept you really need to understand but if you want to learn more here's a link. http://en.wikipedia.org/wiki/Electrical_characteristics_of_dynamic_loudspeakers a ported box for those subs at 4-5 cu ft net will be great.