# 212 + 410 = 710?

Discussion in 'Amps and Cabs [BG]' started by HeavyFingers, Aug 21, 2007.

1. ### HeavyFingers

Mar 18, 2006
NOVA
As the title suggests I was wondering what a 212+410 stack would be equivalent to in all 10's.

2. ### D.A.R.K.Supporting Member

Aug 20, 2003
Virginia
one way to look at it:
4x10=40 inches of coverage
2x12=24 inches of coverage
total=64 inches of coverage

6x10=60 inches of coverage

although that has nothing to do with sound etc.
you must be as bored as me right now...
i think i'll go practice lol...

3. ### Want a 9

Nov 27, 2004
Abingdon, Virginia
D.A.R.K.,

You are looking at the coverage number incorrectly.

Speakers are cone shaped not straight lines. You need to look at the surface area of the speakers. this can be approximated by using the formula for the surface area of a circle - Pi x radius squared. So One 10 inch speaker would have approximately (3.14 x (5 x 5)) = 78.5 square inches.

Thus a 6x10 would have about 471 square inches of surface area.

A 4x10 plus a 2x12 would have about (314 + 226) = 540 square inches of surface area. The more speaker surface area the more air you can move.

7x10 = 550 square inches so yes a 4x10 + 2x12 is very close to 7x10's.

Somebody may chime in with more exact numbers than mine, but you get the idea.

It is also important to note the the efficiency of a speaker cabinet can effect the overall volume also, so the amount of speaker surface area is not the only thing to consider.

4. ### D.A.R.K.Supporting Member

Aug 20, 2003
Virginia
as i said....
(i know it had nothing to do with exact coverage. you would also have to allow for specific voicecoil dustcover
size and radius for an exact measurement)
and yeah, i got more than a couple of hours practice in!...

5. ### Crockettnj

Sep 2, 2005
North NJ

Ifyou are talking the amount of air moved, then I am pretty sure the xmax comes into play. for instance, a small "long throw" 8" driver can move a lot more air than a 12" driver with a tiny xmax.

I think.

6. ### HeavyFingers

Mar 18, 2006
NOVA
well....just for argument sake, lets say an avatar 212+410 (both have the extended x-max) vs. an ampeg 810.