Same motor and soft part assembly. The difference is cone size and basket. Same amount of power is applied and the same size/tuning enclosure.

 

What I am noticing in winISD is that the two 15" are more efficient and the four 12" have a less than 3db higher output.

 

Is it fair to say that the output difference between four 12" and two 15" are negligible with same power and enclosure?

 

 

 

FYI I compared four 12" xcons and two 15" xcons in 8^3ft tubed to 32hz. I also compared four 15" xcons and two 18" xcons in 15^3ft tuned to 32hz. The 15" & 18" comparison gave the same results as mentioned above.

From what I've seen in most cases either setup would be very similar.

Same motor and soft part assembly. The difference is cone size and basket. Same amount of power is applied and the same size/tuning enclosure.

 

What I am noticing in winISD is that the two 15" are more efficient and the four 12" have a less than 3db higher output.

 

Is it fair to say that the output difference between four 12" and two 15" are negligible with same power and enclosure?

 

 

 

FYI I compared four 12" xcons and two 15" xcons in 8^3ft tubed to 32hz. I also compared four 15" xcons and two 18" xcons in 15^3ft tuned to 32hz. The 15" & 18" comparison gave the same results as mentioned above.

In an ideal, perfect world......yes.

 

One thing that isn't accounted for is the difference in power compression.  Having four drivers would allow each driver to receive half the power compared to only running a pair.  Due to this, the four drivers would experience less power compression.  How big or small of a difference this creates is going to depend on many factors.  And since no car audio manufacturer that I know of publishes power compression figures (Quentin is close with his Ethos since he's publicly stated how much power compression there is at rated power, but a lot of pro audio manufacturer's publish power compression vs power input over several ranges), it would be difficult to predict.  But it's theoretically possible for power compression to tip the balance from "negligible" to "audible".

 

Then there is the other consideration of the four drivers having less excursion, which would lead to lower distortion.  The difference is relatively minor still though in this particular comparison. 

 

On the other hand, in the case of the Xcon, it only costs an extra $20 or so to step up to the next size compared to the many hundreds of dollars it would cost to purchase 4 drivers instead of 2.  So the cost-benefit is probably not there.

Power compression will be a major variable to consider and also the most unpredictable. Although how can we even consider power compression since we can not predict it when the system is used in a "daily" scenerio?

Although how can we even consider power compression since we can not predict it when the system is used in a "daily" scenerio?

If you fly around full tilt all the time

Although how can we even consider power compression since we can not predict it when the system is used in a "daily" scenerio?

If you fly around full tilt all the time

...listening to sine waves

Two 15''s save the dough

Power compression will be a major variable to consider and also the most unpredictable. Although how can we even consider power compression since we can not predict it when the system is used in a "daily" scenerio?

You can't reliably. Hell, I didn't even mention the fact that not only is power compression not readily predictable, but the difference in power will have a different affect on the change in Re which will affect the "warm" TSP, and the difference in excursion will change the "large signal" TSP due to difference in the nonlinear behavior......both of which combine to affect the "real world" response to something other than what WinISD modeled to begin with.

So it's not just power compression busting your balls on this one. There are many factors which will change the outcome, none of which are reliably predicted without either your own Klippel machine or a hell of a lot more information from the manufacturer.

I also wonder how the impedance curve will vary between two and four subwoofers. Is it possible that the impedance curve could be shallower with one setup vs the other?

Edited December 21, 201311 yr by edouble101

Yes, as the Re changed and parameters shift the impedance curves will change