RL-p18 VS Fi Q18 ... (1 Viewer)

[matt steele]

Which 18" subwoofer is best for my application?

I have decided on getting one 18" woofer. Now the question is which one would be best?

Sound splinter RL-p 18" or
FI Q18"

I will be powering with a EP-2500 so there is lots of power.

I was thinking of doing the FI q18 BP power upgrade. Is this worth $60 to get some more power handling out of it? This is what the website says about the BP power option...

"This new option adds a machined aluminum compression plug to the pole which helps channel all of the air under the dustcap around the coil for better cooling. To aid with this increased airflow we also add 6 axial cooling channels in the top plate. Along with increased thermal capacity comes the addition of an extra spider and a changed spider pack.
All of these new features increase power handling from 200-500 Watts depending on the application."

I have at max 12.13 cuft worth of space to build a box. This space will be smaller when the port is added.

Which sub would work the best for me? What one would be best with the space that i have and the power i can give it? I want to tune the box really low 14-16 hz, would that be about right?

Maybe 11 cuft after port displacement isnt even enough for an 18" sub, im not sure. Would this be enough room?

 

[Robert_J]

I modeled both in an 11cf enclosure with a 6" flared port tuned to 15 hz and 1,200w of power (that's realistically what the EP-2500 puts out below 20hz). Both designs have output at 120db. The frequency response of the soundsplinter is slightly smoother.

Based on the differences in modeling and price, I'd go with the Q. It's cheaper and you probably would never tell a difference in sound. You don't need the BP upgrade unless you are going to drop the sub in your car and push 3,000w to it. For the ultimate upgrade, contact Scott and tell him your design and amp and he may be able to tweak it to work even better. That's a huge advantage on subs that are built only when ordered.

-Robert

 

[matt steele]

Ya, i agree with you. The Q would probably be just great.

I am confused at why i should tune the box so low. When i plot the sub in winIsd with tuning frequencies from 14 hz up to about 20hz, i don't see why one would want to tune at 14 or 15 hz over tuning it to 18hz, 19hz or 20hz.

See the picture attached.



Seems to me that you want to have the higher output for as much of the sound spectrum as possible. When you tune really low (14,15hz) everything from about the tuning frequency up to about 50hz is -3db from the higher tuned box of about 18 or 19hz.

I'm assuming that the low tune is because you get way more output in the 10hz-15hz range. But really is there that much to feel / pretend to hear below 15hz? It there not more to hear from 15hz to 50hz than below 15hz? So wouldn't i wan't the higher tune and the higher output for more of the notes?

Thanks

 

[Robert_J]

Steve Callas has a lot more info on his large, low tuned designs - LLT Explained.

Simulations like WinISD and Unibox don't take into account room gain. That's the natural boost on the low end that you get from putting a sub in a room. Since gain is dependent on room size, it's not easily written into the program but it is definitely there unless your room is the size of a warehouse. So your low end will get anywhere from a 3db to 10db increase down low. With such a low tune, that can give you a flat response down to 10hz.

Edit - I see you posted the same question on AVS and Steve replied.

-Robert

 

[matt steele]

Yes, thank you.