View Full Version : Purpose of a JBL 5234a with 80Hz cards

Lee in Montreal
03-18-2013, 04:19 PM
I bought that active crossover two years ago and never used it (I am currently running an active digital crossover). With a cut-off frequency of 80Hz, I wonder what was the intended purpose. I know the device itself is pretty common, but that few 80Hz/18db cards were made. TIA

Mike F
03-18-2013, 05:03 PM
Many PA companies used the 80hz low pass sections for driving subwoofers, perhaps yours is one of them.

03-19-2013, 06:37 AM
Yep, the 20 Hz and 30 Hz high pass bump filters along with the 80 Hz low pass made for some pretty solid subs back in the 80's.

Years ago we discussed how to modify the 5234A/5235 to change the 20 Hz bump filter to 25 Hz for consumer subs like the B380 and B460, as well as the 4645. Note that the 4645 came in two flavors, the 30 Hz box and the 25 Hz box.

The 2235H and 2245H didn't really turn out all that well used in 20 Hz boxes. 25 Hz is a realistic limit for them and 30 Hz yields the best survivability.

03-19-2013, 07:04 AM
Please explain how this works, do you mean the filter limits everything below 25 or 30hz? I have a 2235 in a tuned box and need some type of filtering on it besides just rolling off at its low limit, also for protection. Thanks

Lee in Montreal
03-19-2013, 07:21 AM
http://img.photobucket.com/albums/v668/Lee_Vuong/JBL parts factory/attachment.jpg