2235H enclosure tuning

[jim henderson]

Mr. Widget, in http://www.audioheritage.org/vbullet...highlight=2123 you described your 2235H in a 5 cf box tuned to 29Hz via two 4” dia. 11” long ports. My tuning software (the “ported” Excel spreadsheet) tells me that a single 4” dia. 5” long port will tune the enclosure to 29 Hz. Are the two configurations equivalent?

[Mr. Widget]

JBL in their enclosure guide:

http://www.jblpro.com/pub/manuals/enclgde.pdf

suggests this tuning and they call it 30 Hz.

I use BassBox Pro6 and they specify for a box with standard damping of all walls excluding the baffle lined, a 5 cu ft box + volume for drivers and ports the 2 11" ports yields a tuning of 29.34Hz.


Using BBPro6 in the same box with one 11" port they give it a 21.08Hz tuning.

[MikeM]

Heres all you need. Pick your cabnet size tunning frequency then this will do the rest. If you think 3/10 of an inch will make a diffrence your nuts. jbl woofers cannot handle 20 hz. so tune the box at 25 or 27.5. You will find that jbl mesurments are almost the same as you will get from the box worker. instead of going back and forth for posts for the nex 2 weeks use this program it will get you what you want. When jbl designs these boxes they donr use magic just a box that will fit the drivers then tune a bit. Stereo shop here has a pile of 2245H woofers with torn spiders from the 460 subwoofer system trying to reproduce 20 sine wave stuff. And its not the cabnet. Here the link http://www.eatel.net/~amptech/elecdisc/spboxnew2.htm

[Lee in Montreal]

Reviving a 7 years old thread. I have built a 6.9 cubic foot enclosure with a 2235h inside. I wasn't too sure to which frequency I should tune the ports. Driver's Fs or enclosure's. Therefore I made two 4" straight ports with a 1/2" radius. 4.5" long for 26Hz and a 9.5" for 20Hz. Blocking one with a sock to make the other operational.

The output is much higher at 26Hz than 20Hz. I didn't measure membrane excursion though. My conclusion to the experiment is that the highest output is at the enclosure's tuning frequency. If I want 20Hz, then I will have to make the enclosure much bigger and the gain is probably a shorter membrane excursion at 20Hz.

Lee