My next system is going to have two 15" subs. I want deep bass extention
and output, but i want my trunk. I love the sound of 15's, so i've been looking into aperiodic set ups. I've never used or built one. What can i expect in terms of deep bass extention and output compared to a vented box of optimum size and tuning? I've spoken to eric holdaway and he says he can tune the mats accordingly based on the sub's t/s parameters.

 

Extension is good, output will be much lower. Tuned vented box will be much larger in size, but likely have better output by far. There is definately a trade off for AP.

 

I've read that the efficiency is much lower, but i thought that if i used a pair of high powered subs (1000 watts rms or more) then i'll just give them the juice they need to overcome the efficiency issue. By the way, can any sub be used or is the alignment more agreeable to one type (ported or sealed) of sub than the other?

 

Ap generally, not as a rule of thumb however, lends it's self better to subwoofers designed for vented enclosures. It's not a matter of high powered subs. It's more of a box and sub relationship that causes the lower output simply because you are dealing with an impedance curve correction with AP at the cost of output where as a tuned or acoustically suspended enclosure box will afford you better output. With AP, you will be relying much more heavily on driver suspension and electric control from the amplifier with less help from the enclosure as far a suspension is concerned.

 

So is there an advantage to going ap as compared to using a sealed box set up? These days many sealed box applications allow for even 15" subs to be placed inside 1.5cubes. I estimate that the physical dimensions alone of the drivers will require an ap box of similar size.
Are you saying that I'll get more output using a sealed box than with ap? If that's the case, then there's really no advantage to going that route. I thought that with ap, I'd get at least similar output to a large sealed box with the bass extension and low octave boost of a vented alignment.

 

Doesn't the resistive nature of the mat make up for the lack of enclosure, per se?

OP: In addition to what was posted above by Sawnixs. Ideally the rule of thumb is to look for drivers with Qts value(s) of between 0.25 and 0.5.

Lower than 0.25 and the effect of the membrane becomes negligible minimal as the mat is very light and has minimal density.
As the driver Qts increases the mat becomes progressively denser and the efficiency is further and further reduced.

Thing to remember is that the A/P systems were more prominent when the drivers that were being used were very high efficiency drivers that required massive enclosures for peak performance.

Not trying to discourage you BTW, just offering some food for thought, as there may be easier and less costly ways to get what you are looking for.
Why not look at a 15 that does very well in an infinite baffle set up? The JBL GTi comes to mind... just my opinion though.

Hope this helps.

Cheers!

 

oh don't worry about discouraging me...I'm trying to figure out the best way to go about this. Any reasonable, educated, or experienced input is welcomed. I've also considered IB set ups, but was unsure of which drivers were applicable as nobody seems to make them anymore...at least they don't specify if they're IB capable. Good to know the JBL GTI is though, as that's one of the subs I'm thinking of using.

 

Hopefully you can get some other suggestions for suitable I/B drivers using the search feature and from the more experienced members here.
I don't have much experience w I/B installs and suitable drivers, but I did have the pleasure of recently listening to fellow member MTT's install... he was running one 15" JBL GTi in an I/B set up. I absolutely loved it! So much so, that if I were in a position of not already having most of the gear I plan on using in my next install, I would be very very seriously considering this driver and approach.

I'm sure there are others worthy of consideration as well...