Jim DiFalco
12-31-2003, 04:09 AM
Question on 123A-1 for subwoofer use?
I currently own a set of L-100s. The cabinets although solid are pretty beat up with veneer missing in a couple of places. The high frequency drivers have long since been replaced with a set of silk dome tweeters from Sound Design. (sound much nicer than the original HF drivers)
I’m giving consideration to taking the low frequency drivers out of the speakers and using them to build subwoofers. Now I realize that a 15 or 18-inch driver may be a better choice but I have the 123A-1s available and with an fs of 25 they seem to be quite capable of some decent low-end performance.
Using Martin King’s MathCAD program I’ve modeled a transmission-line enclosure for these speakers with some very decent specs:
30 to 525Hz at 90.5 to 91db, 20Hz at 87db, 18Hz at 85db
Internal dimensions 14.5" wide x 23.5" deep x 44.5" long with a 5” dia. By 7” long port
I’ll be using an active 2nd or 4th order crossover (haven’t decided which yet) and will be crossing the speakers around 80 to 120 Hz
Is there any reason that one of you who is more experienced and knowledgeable than I can see why I can’t reasonably expect to use the 123A-1s in this manner (as subwoofers) and get decent performance out of them?
Since I will be driving the speakers to lower frequencies than I imagine JBL intended is there a higher likelihood that I can overdrive or damage the speakers at lower power levels than in the L-100 cabinets?
I would appreciate any assistance or comments.
Thanks in advance!
Jim DiFalco
I currently own a set of L-100s. The cabinets although solid are pretty beat up with veneer missing in a couple of places. The high frequency drivers have long since been replaced with a set of silk dome tweeters from Sound Design. (sound much nicer than the original HF drivers)
I’m giving consideration to taking the low frequency drivers out of the speakers and using them to build subwoofers. Now I realize that a 15 or 18-inch driver may be a better choice but I have the 123A-1s available and with an fs of 25 they seem to be quite capable of some decent low-end performance.
Using Martin King’s MathCAD program I’ve modeled a transmission-line enclosure for these speakers with some very decent specs:
30 to 525Hz at 90.5 to 91db, 20Hz at 87db, 18Hz at 85db
Internal dimensions 14.5" wide x 23.5" deep x 44.5" long with a 5” dia. By 7” long port
I’ll be using an active 2nd or 4th order crossover (haven’t decided which yet) and will be crossing the speakers around 80 to 120 Hz
Is there any reason that one of you who is more experienced and knowledgeable than I can see why I can’t reasonably expect to use the 123A-1s in this manner (as subwoofers) and get decent performance out of them?
Since I will be driving the speakers to lower frequencies than I imagine JBL intended is there a higher likelihood that I can overdrive or damage the speakers at lower power levels than in the L-100 cabinets?
I would appreciate any assistance or comments.
Thanks in advance!
Jim DiFalco