adding one more sub, noticeable difference?

In "theory" doubling the power or # of speakers will give a 3db increase. So, yes..you will definatly notice a difference. But this assumes the same power is going to the speakers (which you state you are adding an amp for it..which is good) and that everything is installed/wired properly.

Now if you had 8- 12'' subs I would say adding one more would not be noticable by ear. As far as doubling power to gain 3db you would have to make sure the components could handle it.

sedate, whats up?  Ok not looking for an argument but who told you simply doubling the number of speakers yields a 6db increase? It would defy all the physics and audio theory I have come to understand.

Not to say I can't be wrong about this..just would like a little backup to substantiate that claim.

Peace.

Also I think we should discuss the terminology as well. "Doubling cone area". Does this mean adding another sub of the same size/model or increasing the physical size of one woofer to twice the area of the original? Now in either case it would still be unpredictable exactly how much gain would be realized but wouldn't a much larger speaker need a much larger motor to move that much more mass? So with the same power how could one predict the gain increase (although as far as I know it would not exceed 3db at most..simply due to physics)

There are many factors to take into consideration. In actuality the physics involved with gain predictions should be discussing the adding of one sound to another sound of the same amplitude (volume) and, adding one sound to another sound of the same amplitude and correlation.

In other words if you had a speaker playing at a certain dB and then had someone in the car yelling at the same level you would have a gain in overall dB but... where is the "cone area" in that case?

Well anyhow I didn't really want this to turn into a physics lecture but don't mind sharing tidbids I pick up. If anyone feels I am giving the wrong info I am more then open to debate.

Oh..to the point...lol

Doubling the power = 3db gain "in theory"

Doubling the # of speakers = 3db gain. "in theory"

So if you add another sub......PLUS another amp of = power..you MAY net up to a 6db gain..which is nice..remember a gain of 10db = twice as loud (hope no ones getting confused..lol)  But a 6db gain will be quite noticable by ear as well.

The reason I say "in theory" as discussed earlier there are other factors..well many factors that effect output such as car environment, accuracies of ratings, performance of products and a host of others. But this is not to say you will never gain 6db in doing this..it is possible.

Another thing..but this is important. It is not really an accurate "rule of thumb" to state that doubling of power will yield a 3db gain...why?? you might ask.

Well that would be like stating "if I dump 10 times as much fuel and air into my car engine..the HP will double"..well it might..for a second..then blow up.

Physical limitations apply. So for example if we have a sub that can handle 600w..but we were only running 300w to it...upping to a 600w amp should (or "may") give us a 3db gain. Now if we take the same 600w amp and add another sub to it..the db level would also depend on impedance. (what is the amp stable too??, what is it's output at different loads??)

If it was wired in a configuration that cut the power in half..we would (in theory) lose 3db..but..we added another speaker so in theory we would gain 3db (basically right back where we started).

But if we wired it to "double the power" but the amp was not stable (example running a 2ohm stable 600w amp to 1 ohm in an attempt to extract 1200w out of it) something would surely give in a short time as the amp can not handle the lower impedance. This factor takes into account human error, poor judgment, ignorance, whatever you want to call it.

Basically be realistic in what you expect from your equipment as well as the physics involved and you shouldn't be dissapointed.

Now either some of you are really confused...or..get the idea.

Huh.  I coulda sworn the rule of thumb was +6db for the doubling of cone area.. but maybe that rule assumed the same amount of power to each speaker.  Anywho, I just modeled it in WinISD and I was.. I was...

I was *gasp* wrong.  Adding a second woofer and running the *same* amount of power to the subwoofer system would only yield 3db.  However, running the same amount of power to the second speaker that was being run to the first would then yield the +6db.  And doubling it in the end, I think, would *then* give us +9db.

I dunno I'm sure if I wrong someone will jump on me here soon.

Nah..I think ya got it now.

In a nutshell......if he adds the other sub AND an identical amp to that sub..he gains "in theory"(sorry have to say that evey time..lol) 6dB...(3dB from doubling the speakers, 3db from doubling the power).

NOW..if he doubled the amount of power to EACH sub..he would have a 9dB gain "in theory"(3dB from doubling the # of speakers.....3dB EACH increase from doubling the power of EACH sub .....3dB + 6dB = 9dB.

Hope that helped..I know this topic can get confusing.