Does a HUGE surround reduce effective cone area?

[king nothing 10+ year member]

Well? In looking at a pic of an eclipse titanium 12 it seems that the actual cone is the size of an 8 and the surround is HUGE. Does this have the effect of reducing the effective cone area or does some of the surround act as cone as well? It seems the surround is at least 1.5 inches wide

Click to read more...

 

[sundownz Pro Seller]

Part of the surround acts as radiating area. In my own testing I found no SPL difference at all from a standard half roll to a narrower high roll. I'd imagine even with the crazy big Ti surround the difference is quite minimal in reality.

 

[murph 10+ year member]

badass woofers run a pair myself.

 

[pro-rabbit 5,000+ posts]

From tests I have done it is not the surround that actually makes any huge difference. It is how most subs with those surrounds are designed that alter the over all spl(number wise).

 

[SomeGuyDude 10+ year member]

I was actually just thinking about this last night. From a strictly physical standpoint, yeah, the effective cone area is less, but my guess is that the designers have all of that factored in when they build the thing, and the size you're getting is more about the cutout needed for the box and obsessing over the diameter of the cone is something that we just need to get over.

But, yeah, if you were to extrapolate that and make a "15" that was four inches of cone and 5.5" of surround in all directions you'd have a serious drop of input, but let's throw some numbers on it. Let's say that you've got a 12" sub with about 1/2" of surround, and then another one that has a full inch:

3.14159*(12-1)^2 = 380sq

3.14159*(12-2)^2 = 314sq -> 314/380 = ~83%

An extra half inch of surround means an over 15% drop in cone area. But remember that the "rule of thumb" is that DOUBLING your cone area result in a 3dB increase in output (I don't have a source on this, just something that's been bandied about, so correct me if it's way off), meaning that ~17% of cone area you lose is gonna result in nothing substantial, PARTICULARLY if that big fat surround is there for a good reason, which I dare say is the case with Eclipse and others.

 

[bhsdriller 10+ year member]

not enough for someone to notice

 

[SPLaudio 5,000+ posts]

in general half the surrond is usable cone area...

 

[SomeGuyDude 10+ year member]

Not exactly. I mean, I know what you're saying, but the difference is that it isn't going to be moving in a linear fashion, nor is it a stiff material like the cone itself. A sub that's 14" of normal cone with an inch of surround and a sub that's one inch of cone with a gigantic foam surround are going to be VASTLY different from one another.

 

[Papermaker85 5,000+ posts]

its not a huge deal.. its probably the last varible id use when designing a woofer..