Changing Enclosure Tuning

[mat3833 10+ year member]

OK so i just checked the tuning on the sub enclosure that came with the Klipsch Promedia 2.1 settup i got(AMAZING speakers BTW. seriously, for the money, they sound great! im just a perfectionist), and it is between 50 and 52hz. i want it to be somewhere in the 30hz range 25 hz if possible. i plan to build a new enclosure but i want to modify the existing enclosure until i get the new sub. the current enclosure is 9.5" (24.13cm) x 9.8" (24.9cm) x 10.2" (25.9cm) according to the Klipsch website. im not entirely sure how large the port is but the diameter is 2.5 inches and it looks to be 8-9 inches long. the port is an aero port that is a halfish moon shape.

im thinking that if i remove the port from inside the enclosure and make it an external port i may change the tuning to a bit lower, or i could be completley wrong. for some reason i cant find a box calculator that will tell me what the tuning is based on port volume, port length, and box volume.

can someone please give me a link to a GOOD enclosure design program. hell, even copy and paste the Aero port formulas and whatnot and let me figure it out. im just sick of trying to find this crap and getting nothing.

Matt

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[bhsdriller 10+ year member]

psp-inc.com has a calculator for aero ports

 

[mat3833 10+ year member]

hmm, well looks like i cant just put the port on the outside. that would make the tuning like 70hz.... how does external porting affect everything?

Matt

 

[mat3833 10+ year member]

well i managed to lower the tuning of the enclosure by extending the port outside of the enclosure. oddly enough i used a plastic cup that i found under my couch. the tuning is sitting at about 40HZ after adding about 8inches of extra port. im looking around trying to find some PVC pipe with the right OD so that i can make a permanent port untill i design and build a Tapped Horn enclosure.

Matt

 

[dbjunior 10+ year member]

i have bbp6 i put in the box size and guessed they used 1/2in mdf and with a 9in long port it put you at 51.13hz tuning adding 8in retunes it to 38.97 giving total port length of 17in. port length for 30hz would need to be 30in and 25hz 44in

 

[mat3833 10+ year member]

hmmm, well based on cone excursion while playing test tones the box is now tuned at 39-41 hz. im having trouble finding PVC pipe with a correct OD so that i can actually make a port. and im also semi-concerned about tuning the sub to 30HZ considering i know basicly nothing about it. i wish i could find more information on the Promedia 2.1 sub so i could find Xmax, the Fs value, etc.

you also have to remember that there is a plate amp used as part of one of the side walls. it takes up some space inside the enclosure as well. im not sure if when i build the new enclosure if im going to put the plate amp inside the new enclosure, or just make a seperate small enclosure and add a fan to it to help cool the amp. it seems to get prety hot as is.

Matt

 

[dbjunior 10+ year member]

tuning lower will not hurt the sub the lower tuning will acctually help prevent bottoming out on lower notes. if you plan on just listening to music on the system i wouldnt tune much lower if you watch a lot of movies the lower the better

 

[mat3833 10+ year member]

well i plan on a mix of both. but ive noticed that on music it can seem a bit "boomy". and i still hear some not so nice noises comming from the sub on the really low notes on some rap songs so im defff going to tune it alot lower. it seems that 28 hz would be about perfect for this enclosure. for th tapped horn im going to aim for about 25hz possibly lower considering the flat response from the horn.

Matt