Hello! Calling all dual 2235 sub owners

[speakerdave]

In the Lansing Heritage Library you will find posted some enclosure guides from back in the days when JBL actively supported DIY speaker building.

Here's a good place to start.

http://www.lansingheritage.org/html/.../jbl-plans.htm

Good luck!

David

[Mr. Widget]

Hi Slider,

I use 4" PVC pipe for my ports.

As for how to build a cabinet that depends a lot on what you want the final cabinet to look like and what tools you have at your disposal.

Here is a pic of one of the JBL recommended cabinets. It now houses a JBL Sub1500 but it used to house a 2235H. It is butt jointed out of plywood because aesthetics was not a concern and portability was. If they will not be moved I would highly recommend MDF as is denser and less resonant. I can not stress enough the importance of internal bracing. Put twice what you think it needs. If you read the notes on the JBL enclosure guide and try to find one of the recommended books you should be fine. Using the older JBL guides like the one posted by Speakerdave is good too, but they didn't use enough bracing back then. For tight bass you want these things to be brick sh_ _ houses.

Good luck and have fun!

Widget

[Zilch]

Ports = 4" Foam Core ABS pipe.

It's beefier, and I can pretend it's less resonant....

[4313B]

The nice thing about using dual ports and tuning the volume to 28 Hz is that if you block one of the ports you end up with a tuning frequency of 20 Hz and can then apply the 20 Hz high pass bump filter. I mention this because back then we had 5234's laying about and they had dip switches for assisted alignments which made trying them out quite easy. With the 2235H and 2245H you will still end up with a maximum electrical input power sag in the 25 Hz region but it shouldn't be so bad as to not be able to reach your 105 dB SPL.

If you need to read about assisted tunings I would recommend starting with D.B. Keele's "A New Set of Sixth-Order Vented-Box Loudspeaker System Alignments." AES Journal, June 1975, Volume 23, Number 5.

Anyway... they can be fun to play around with.

[Robh3606]

I was using 3" PVC but switched to 3" mailing tubes. You can use the outside as a sleeve to change the port length and then glue in place. You can also beef up the inner sleeve with the outer for a double thickness port. I am running in a pair of 2235 right now in 5 cu. Ft. 30Hz . They are nice! Have not measured them yet will wait a while but they go low just fine considering they have zero hours on them. They do Also Sprach Zarathustra just fine.

Rob

[4313B]

"I am running in a pair of 2235 right now in 5 cu. Ft. 30Hz . They are nice!"

Yeah, that's what I always ended up doing as well. Fb = 28 to 30 Hz. The 34 Hz tuning of the stock 4430 is a bit too aggressive for home use. I wouldn't tune the 2235H or 2245H below 28 Hz without assist.

Incidentally, Keele's "best compromise solution" for the 2235H was 4.55 cubic feet tuned to 29 Hz. I've built that specific configuration a couple of times with "perfect" results, sounded fantastic, never smacked a mass ring or blew a driver. The only 2235H's I ever blew were those placed in volumes larger than 5.5 cubic feet (bigger than a 4343 volume) and tuned lower than 28 Hz without using assist.

I believe Keele also did the original BX63. Note that the B380 was also 4.5 cubic feet but tuned a bit lower and assisted. It's pretty much indestructible up to full rated input.