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[Peter Morris]

2x Air displacement = +6dBSPL.

Bigger cone = heavier cone = less efficient, but it is also moving more air, so the results are difficult to predict, and will likely vary on a case-by-case basis. FWIW, Faital Pro seems to use the same motor in their 1xFH520 (10FH520, 12FH520, etc) range, so you could compare there if you're interested.

Chris

Yes but a bigger cone also means a better impendence match between the driver and the air ... which equals more efficiency

Compare these two and their specs; same Xmax and BL product 15" Vs 18"

https://faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=201070140#Curves
https://faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=201060150#Curves

[Ivan Beaver]

Kind of, but like Ivan says, "in some areas you gain, but in others you lose."

Here's a classic example, an EV 10" and 15", both use the same magnet and nearly the same voice coil, IIRC:

Back in the day, EV used the same magnet assembly, same voice coil, same spider for the 10,12,15 and 18" models.

Obviously the cones were different. so all things were not equal

[Ivan Beaver]

Wait, what? Like Bob Stone, I've always understood that, with other driver parameters being equal, and the same power applied, doubling the cone area resulted in twice the volume of air being displaced, which in turn resulted in a 3dB gain in SPL. And sensitivity specs seemed to more or less bear this out, you would usually see a 1 or 2dB increase as you went up in size from 10" to 12", and again from 12" to 15" in a given line of speakers. Is that not at least theoretically correct?

When you double the cone area, if you keep the MMS (moving mass) the same, then the cone construction must also change.

Sensitivity is a touchy subject.  If you are talking about sensitivity at a particular freq that is one thing, but if you are talking about sensitivity based on a SPL meter, that can be very different.

Let's say you have a perfectly flat loudspeaker (for the sake of argument)  You can do this yourself to test.

Now you band pass it to a very narrow range, you get a certain SPL at those freq, as read on a SPL meter.  Let's say 100dB.

Now just widen the freq response by changing the high and low pass filters.  The TOTAL SPL will increase, but yet the SPL at the freq in step 1 are no louder.

So did the SPL go up when you changed the freq response?  It depends on how it is measured.  Just like using a bigger one, what SPL went up?  The overall or at a particular freq?

When you start to dig, it gets more complicated.

[Chris Hindle]

When you start to dig, it gets more complicated.

When you start to dig, you realize how much you don't actually know about a particular "system"
This applies to everything life, not just speaker design.
Kudos to all the designers and engineers out there that mostly get it right for us "users" to enjoy.
Chris.

[John Roberts {JR}]

loudspeaker design is the poster boy for multivariate equations... almost everything is some kind of compromise or tradeoff.

JR

[Peter Morris]

loudspeaker design is the poster boy for multivariate equations... almost everything is some kind of compromise or tradeoff.

JR

love that description JR    and if you can, its just a matter of adjusting the variables in those equations to find the best compromise for your application 

[Ivan Beaver]

loudspeaker design is the poster boy for multivariate equations... almost everything is some kind of compromise or tradeoff.

JR

I always say that loudspeakers are a matter of compromise.  You MUST give up something for something else.

That may not be bad.

But understanding the compromise is important, ESPECIALLY when trying to compare products.

You cannot say you want "loudest and lowest" at the same time.  One of them must be fixed (or set as a minimum) in order to compare.

For example, all other things be equal (which they are not), as a "general rule" you give up 9dB SPL output per octave when going lower.  So how important is going lower vs SPL output?  Hard to say.

And it goes on and on and on.

And then you get into the whole "how is it measured" thing and it gets real messy real quick.

[Ivan Beaver]

love that description JR    and if you can, its just a matter of adjusting the variables in those equations to find the best compromise for your application 

Yeah, and "Your" application may be very different than somebody else, for the same type product.

Just like with automobiles, what is best?  The best 0-60 time?  The greatest hauling capacity?  The greatest gas mileage?  The greatest person capacity, the greatest ground clearance, the greatest mileage between fillups etc.

[ProSoundWeb Community]