View Full Version : 136A & 2123H enclosure dimensions needed

Steve Gonzales
11-21-2005, 09:16 PM
Hello resident Guru's, I need some help figuring out the best dimensions for my 136A's and 2123H's. I am working on a 4 way project. I want to build some enclosures for the 136A's and want to know what port size, length and port position is. Here is the result I'm after: the LF section will play from 2?hz to 1??hz, the lo/mdbass (2123H) from that point to either 500hz (2441/2309/2310) or 800hz (2441 or 2421/2397) to 5k (076) or 7k (077). I have the drivers except the 2441's which might be a done deal soon. The crossover is electronic. I want to use 1" thick MDF and brace according to your reccomendations. Thank you for your input. I believe the 2123H is best in a sealed enclosure, not sure though...

BTW, I did do a search and if there is info there, I missed it, so forgive me if this is been covered before, Steve G

11-21-2005, 09:52 PM
Hello Steve

Your going to want to set it up along the same route as the classic 4 way monitors like 4343/4344/4355. Figure you would cross about 300Hz to the 2123's If you wanted to go lower you would need 2122's to get down to 100Hz of so. Both would be in sealed enclosures. The recommeded enclosure for the 2123 is on the spec for the driver. You would run the 10" up to about 1.2-1.5K or so and then bring in the compression drivers. With the 2123 you can run it up a little higher to try to match the DI on the horn for the transition between the two drivers. You can always change things but they chose those specific frequency ranges for a reason and that's where the drivers will give you their best.

Get a copy of WinIsd here and run the numbers on the 136's. My guess would be 5-6 cubic ft. around 30Hz like a 2235. The program will give you all you need to build the boxes



Uncle Paul
11-21-2005, 09:58 PM
Steve, the 2123 might not go that low. WinISD shows it -3dB at 200 Hz (sealed .5 cubic ft), and it is known for having a rising response as well. Ported, in the same enclosure -3dB at 100 Hz.

The 2122 goes lower, -3 dB at 125 Hz and 70 Hz respectively.

A good crossover point would likely be 3xx Hz range. The 136A should play nicely to there, but might not make much sense to use the 2123 to cover a single octave (350 to 500 ~ 800 Hz).

Maybe a 12" to cover 1xx Hz to 500 Hz instead?

Mr. Widget
11-21-2005, 10:06 PM
Even though the 2441 is fine at 500Hz, the 2397 is not. It is best above 1200Hz but will be acceptable at any frequency above 800Hz.

I would add, that while on paper it may not seem like a big deal, in practice jump through what ever hoops are necessary and get the 2441s on those 2397s. The 2397 sounds so much better with the 2" driver.

As for the UHF crossover frequency, I'd strongly urge you to try them at 10KHz. You may still prefer the 5KHz crossover point, but you should hear it for yourself.


11-22-2005, 05:41 AM

With your' love of passive radiators I'm suprised you don't go that route. A pr15c in a 6.25 cubic box.


Steve Gonzales
11-22-2005, 06:41 AM
Great info fellas, much appreciated.

11-22-2005, 11:30 AM
Using passive crossovers very close together can be a real problem. Bandpas networks that are only 1 or 2 octaves apart can have weird responses and can be difficult to alogn. If your going to use active crossovers it does not matter.