[Mike P.]

A Fi Q18 D2 wired for 4 ohms in 23 cu.ft tuned to 15 hz looks good. A 10 inch diameter port 33.5 inches long would keep the air speed under 20 m/s. With 1000 watts input you can expect 120 db down to 14 hz, with room gain.

 

[nitble]

would a little lower tune give me less chance of the speaker bottoming out at low frequency?

What low frequency is good to shoot for where the excursion spikes up?

 

[SteveCallas]

If the long term plan is just a single sub, I'd keep the tuning around where Mike suggested, about 15hz. If you ever plan to build a second, I'd tune a little lower, about 12-13hz. Not a huge difference either way.

You should be safe with either tuning in regards to low frequency effects. Just don't run continuous sine waves through your sub below tuning at spirited volumes. Really, I don't know why people run continuous sine waves at all - RoomEQ does a sweep, and that yields a much more reliable FR measurement.

 

[nitble]

Everythings in the works now. I decided to build ~23ft3 box for one FiQ18" ran off an EP2500. I'm not sure exactly which port tune to go with, kinda leaning towards splitting the difference at 14hz. The speaker and amp have arrived, bought construction material and the build has begun.

Questions:
I didn't know the LF(RCA) output from my receiver wouldn't plug into the ep2500!? What do you recomend to use?(art cleanbox, reckhorn b1, rolls mb15)?

In the box I'm building, do you recomend any eggcrate or absorption material of any kind?

thanks again,
Mike

 

[Mike P.]

If you tuned it to 13 hz Xmax wouldn't be exceeded until under 12 hz, less chance of bottoming out the sub without a high pass filter. A 10 inch diameter port would need to be 47 inches long. If you get 6 db room gain, you'd have 120 db down to 12 hz. :blink:

Although it's debatable, lots of people line the cabinet walls with egg crate foam, I use it on all my subs.

I'm not familiar with the EP2500, someone else will have to chime in here.

 

[Ricci]

Mike,

The Fi Q doesn't exceed xmax with into it in a 23ft 13hz tuned enclosure?:scratch: I'm showing it way past xmax with over 1000w and the EP2500 should do around 1700w.

I like a 15hz tune better for just one driver. It raises the power handling and sensitivity a bit and shortens the port length of a 10" to under 34", while still giving full power output to 13-14hz range.