Best box size for 2123, as mid-bass driver?

[Doc Mark]

Greetings, All,

I am wondering what box size is best used with a JBL 2123, when setup as a mid-bass driver? I know that it needs to be on the small side, and was thinking somewhere between .25-.50 cubic feet. Am I on the right track, or does the sub enclosure need to be smaller, still? Thanks for any suggestions, comments, or ideas you can share. As always, much appreciated, and God Bless!

Every Good Wish,
Doc

P.S. This setup will be used in my big 4-way project: 2245's on the bottom; 2123's for mid-bass; 2445's + 2397 Smith horns for high frequency; and, 2405's for UHF. Starting out with the 18's in JBL 4645 cabinets, with separate enclosures for the other components. Oh, and Edgewound said he should have the 2245's finished soon! I know, as always, that the wait will have been more than worth it!!

[hjames]

In the big 4 way designs, the 2121 has its own isolated enclosure within the main cabinet, called a "dogbox".
Just find out the size of that in one of the 434x construction threads, and that should give you the optimal size


Greetings, All,

I am wondering what box size is best used with a JBL 2123, when setup as a mid-bass driver? I know that it needs to be on the small side, and was thinking somewhere between .25-.50 cubic feet. Am I on the right track, or does the sub enclosure need to be smaller, still? Thanks for any suggestions, comments, or ideas you can share. As always, much appreciated, and God Bless!

Every Good Wish,
Doc

P.S. This setup will be used in my big 4-way project: 2245's on the bottom; 2123's for mid-bass; 2445's + 2397 Smith horns for high frequency; and, 2405's for UHF. Starting out with the 18's in JBL 4645 cabinets, with separate enclosures for the other components. Oh, and Edgewound said he should have the 2245's finished soon! I know, as always, that the wait will have been more than worth it!!

[pos]

The dogbox is 14L in the 434x series.
In this application any size will do really, as long as you take the resulting natural 2nd order high pass filter Q and frequency into account when designing your crossover.

[Lee in Montreal]

Hi Doc

The cabinet volume will dependent on the frequency range in which the 10" mid bass driver will be used. Optimally, it will have a flat response throughout that range. Too small a box and you risk missing something at its bottom. So, the question I'll ask is how will you use the 2245 and what you consider midbass. Indeed, if you crossover at 85Hz or 200Hz, you will not need the same volume for the 2123 driver. Will it be ported or closed? I suggest closed/sealed in your application in order to avoid compounding group delays.

[Doc Mark]

Good Evening, Friends,

Many thanks for your comments and suggestions. I am planning to electronically cross all the drivers in this system, and will use whatever attenuation is needed for each driver. The 2123 will be crossed around 300HZ +/-. Right now, I want to cobble up a small enclosure for the 2123, alone, so I can hear how it sounds. Later, I may well incorporate the 2123, 2445/2397, and the 2405's in a single box, compartmentalized to work with the 10". Or, I may end up with each component in it's own enclosure, stacked on top of one another. But, one box for all seems a better way to go, esthetically. Thanks, again, and I'll keep you all posted. Everything is finally falling into place, and hopefully, I'll soon be able to start putting all this together. Ken should be finished with the 2245's fairly soon, and when that happens, then the fun can begin! Thanks, again, and God Bless!

Every Good Wish,
Doc

[Ian Mackenzie]

If you are adventurous, have a look at the PI Speaker mid horn kit. The 2123 will run 200 - 1200 hertz and will be physically aligned with the 2397

[hjames]

If you are adventurous, have a look at the PI Speaker mid horn kit. The 2123 will run 200 - 1200 hertz and will be physically aligned with the 2397

Interesting - thank you!

http://audioroundtable.com/forum/index.php?t=msg&th=16581

[Doc Mark]

Greetings, Ian, Heather, and All,

WOW! Ian, that is a very interesting mid-horn design, and I do like the fact that it aligns the mid with the HF horn setup. However, after reading what the designer wrote about this system, it seems best used in corner placement, which we cannot do in our listening room. He does mention using it in a bass reflex system, too, but unless I'm wrong, used in that manner would necessitate raising the crossover to 300HZ. Since I was going to use that point, originally, that's not a real problem for me, though. The designer does mention that he highly recommends making sure the mids and woofers are aligned, though, or phase problems might occur. So, it seems that I can either align the mids and HF, or align the mids and woofers, but not both. Guess I could build a horn cabinet for the 2245's, and align woofs, mids, and HF. But that's not going to work for us, and I'm thinking the 2245's would not like it that much, either. In any case, I'll have to give that design some consideration, as it certainly merits that, and might be really fun to put together, too. Thanks, Heather for the link, as it was a very interesting read. Thanks, again, to you both, and God Bless!

Every Good Wish,
Doc