port frequencies?

can you tell me the frequensis for spl and sql ?

i think sql is around 30 hz but can you tell me for the spl cuz im makin interchangeble ports.

this is my box: 9.8 cubic ft the port is 33 hertz and the sub is a re audio sx 18 inch wat you think

Here's my take, and it's just me.  There is no such thing as SQL.  There's SPL and there's SQ...and not a twixt between.  For SPL, tune to about 40 for a peaked response at about 50.  Of course, you have to use a good modeling program to see the results.  The best for SQ is a sealed box, but that depends on the sub. Some of them don't respond well in sealed.  Porting for SQ generally means using a sub that has a low Fs and tuning the box at about the same Hz as the Fs, which should result in less of a peak in the response.  The term SQL was made up by those wishy-washy people who want the best of both worlds.  So they made up a term to suit their desires.  If you want loud, you can get that with either SQ or SPL.

Edit:  I went to the website to look at these subs and I see that RE uses the SQL term.  They are playing for the crowd with that.  They don't want these subs to be confused with SPL subs, but at the same time they want the potential buyer to know how he can get maximum output.  You see that they included a porting option for the extra db's it provides, so it now becomes SQL.

That box is a little to big for that subwoofer, but you didn't mention how much wattage you plan on running to the sub either.... If you plan on running everything by the recommended specs, then the port tuning frequency is just about right on, but the box is too big.

There is not a "specific" frequency for SPL and SQ. The loudest frequency differs for different setups. It depends on many factors such as enclosure size, subwoofer type, port tuning frequency, cabin gain, etc....  In SPL your basically just trying to find the frequency that "hits" the hardest in your specific setup. (which frequency yields the most decibels?) Since that varies from system to system, so must the frequency. There are many other factors that play their part in how many decibels you hit in SPL, but the frequency at which you play when taking the meter reading is crucial.

What stevdart said IS correct. (of course)lol

to would tune an SX18 to ~33hz for daily...thats just me though.

thats wath marshall white told me for my box and he said the box will sound loud and good and he saw the picture of the box.

one more question, is true that if i tune a box to the freq of sub it will act as free air (example: i have the re audio sx 18 inch the freq is 33hz, if i tune the box to 33 or 32 it will act as free air ? or not and stick with the 33 hz)

thanks alot