some regular questions

[adio 5,000+ posts]

1.) what is displacement?

2.) how do define displacement when it comes to different size subs?? i.e. 1 10" sub hAS THE output or displacement of 2 8"subs. how does one know that and how does the scale go?

3.) besides the obvious, what makes a 12" SI sub better than a 12" crunch sub?

4.) what is the highest db that somebody hit at the lowest frequency? i.e. bunny McFunny hit 147db at 27Hz.

5.) why do some subs have bigger magnets than others?

6) what size are gaskets on subs? 1/2 inch, 1/4 inch?

7.) what is a voice coil and what does it look like?

8.) does it matter than some subs have a big surround on it and a little cone?

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[squeak9798 5,000+ posts]

1.) what is displacement?

Vd? The volume of air the subwoofer can displace.

Sd * Xmax

2.) how do define displacement when it comes to different size subs?? i.e. 1 10" sub hAS THE output or displacement of 2 8"subs. how does one know that and how does the scale go?

As above...Sd (cone area) and Xmax (linear travel).

Lets take a look at the W7 series;

8w7:

Sd - 0.0245 square meters (24500 sq.mm.)

Xmax - 19 mm (.019m)

10W7:

Sd - 0.0386 square meters (38600 sq.mm.)

Xmax - 23 mm (.023m)

For comparison purposes, you could just multiply Sd * Xmax and determine which displaces more air, and which has the potential for more output.

8w7;

245cm^2 * 1.9cm = 465.5cm^3 = 0.4655L

10w7:

386cm^2 * 2.3cm = 887.8cm^3 = 0.8878L

So, the 10w7 has about 90% more displacement than the 8w7

3.) besides the obvious, what makes a 12" SI sub better than a 12" crunch sub?

I guess it depends on what you consider "obvious".

Better build quality. More output potential. Better sound quality. Just a better overall subwoofer design.

4.) what is the highest db that somebody hit at the lowest frequency? i.e. bunny McFunny hit 147db at 27Hz.

Couldn't tell ya.

5.) why do some subs have bigger magnets than others?

Sometimes for more motor force. Sometimes they stack magnets for more rearward clearance (cheaper to stack magnets than add more steel). Sometimes it's simply for cosmetics/aesthetics.

Also depends on the type of magnets used. Neo motor structures look small because the magnet itself is much smaller while having just as much actual magnetic force.

6) what size are gaskets on subs? 1/2 inch, 1/4 inch?

What do you mean? In width?

7.) what is a voice coil and what does it look like?

A voice coil is a length of wire wrapped around a former which is then attached to the backside of the cone. The voice coil is therefore suspended in the magnetic field created by the magnet, top and bottom plates. The voice coil is the part of the speaker that the power from the amplifier is applied to, and the current flowing through the voice coil creates an electromagnetic field that reacts against the static magnetic field in the gap (created by the magnet, top plate and bottom plate)....and this reaction between the opposing magnetic fields causes the subwoofers cone to move forward and backward.

For more info on motor design; http://ldsg.snippets.org/motors.php3

Voice coils of varying sizes wrapped around the VC formers:

8.) does it matter than some subs have a big surround on it and a little cone?

Yes;

http://forums.caraudio.com/vb/showthread.php?t=133943&highlight=effective+radiating+area

http://forums.caraudio.com/vb/showthread.php?t=136784&highlight=effective+radiating+area

 

[adio 5,000+ posts]

thanks squeak, not only for a good answer but for being the ONLY FOCKING guy that answered!!!