Would like a little help here with a possible redesign of my sub bass units.
I have been playing around with some of the speaker design software- winISD and plugged in the info/specs on the JBL 2225h drivers in my sub speakers to see what popped out.
The volumne spec came out alot different than the boxes I built, way smaller! I built these about 30 years ago, and don't remember how I came up with the box dimensions, maybe from some Speakerlab info from that era.
JBL 2225h specs; Ots= 0.28, Qms= 2.50, Qes= 0.31, Vas- 169.9 l, FS= 40.0,Xmax 0.20 in, (specs for the 2225h were listed in the program data base) and I now have JBL full spec from their site.
I plugged in the called for values for the program and got a vol of 3107.1 cubic inches( 1.798 cubic ft) in a ported box with 4" rd vent 2.57" long and optim..ID dimensions of 14.79" x 23.67"x 8.88".
The existing as built dimensions/vol are ID 16.5" x 26"x 18" with vol of 7,722 cubic inches(4.47 cubic ft) with a 4" rd vent 12" long.
There is quite a bit of difference here, seems like the calculated optimal dimensions with one at 8.88 inches give shape I haven't seen to often.
Guess I'm asking for someone who knows their calcs to point me in the right direction so I can determine if any changes would make an improvement to the speakers. I do have an Audio Control Richter Scale for the sub it has a built in 1/2 band 6step EQ, which I haven't set up. Could it be used to compensate for the box size.
I'm at the point I've got this itch to build something, rather than build some new speakers maybe I'll just rebuild and improve what I've got if it makes sense.
I'm planning on getting rid of the 6' cabinet between the main speakers and build an open frame 3 bay unit 5' long. And move all the amps off the speakers and into this stand and also go with shorter interconnects. Also think by moving the speakers a foot or so closer together will improve imaging if you go by the rule of 1/3rds= a third from both walls, a third between.(19' long wall). And rotate the subs 90degrees to move the driver center up. any ideas on all this are welcome.
Bruce,