Jbl 4345 crossover 2245, 2123 h 2420 2405 biamp

[biankez]

Hi evrebody,

i'm on the project to build JBL 4345 clones with2245 h, 2123h, 2420, 2405h. I want to biamp them JBL m 552, phase linear 700b, bryston 4b.

The problem is building the crossover. 2 solutions:
1) classic jbl 4345 for 2122h, 2421 b, 2405h. The problem is swaping 2123h and 2122h, 2420 and 2421 b are both 16 ohms.
2) 4344 mkII the problem, 2420 (16 ohms) 275 nd (8 ohms).

Give me your opinion. Thank you.

[Mannermusic]

Hi evrebody,

i'm on the project to build JBL 4345 clones with2245 h, 2123h, 2420, 2405h. I want to biamp them JBL m 552, phase linear 700b, bryston 4b.

The problem is building the crossover. 2 solutions:
1) classic jbl 4345 for 2122h, 2421 b, 2405h. The problem is swaping 2123h and 2122h, 2420 and 2421 b are both 16 ohms.
2) 4344 mkII the problem, 2420 (16 ohms) 275 nd (8 ohms).

Give me your opinion. Thank you.

How 'bout going a step further and swap the 2420 for a 2441 and then use 3155 crossover (4355). It's designed for bi-amp only (simple) and there is a DC bias version (not so simple) here on site (courtesy of Dr. Giskard) if that interests you. A number of us have gone there - it sounds pretty good. If I were doing that project I would abandoned the classic 4345 config. and build it in two sections so you can experiment with different horns . . . but that's just a hang-up I have for never letting well enough alone! MM

[martin2395]

Best solution - 2450J with TrueXtent Be diaphragms
The "2 driver on the shorther 2311 horn is less shouty and more pleasant compared to 2421B+2307 combo, at least to my ears it is.

Do you have any 2122H laying around? They are almost impossible to come by these days whereas there are still plenty of 2123H's around.
The 2123H is also more efficient than 2122H and they are not 100% interchangeable. You can do it but YMMV.

I'd opt for a "2 driver, 2123H and 3155 CC crossover which is not that complex to build but it involves a lot of components ($$$$ when using good caps!)

When you decide to go for a 2-inch driver, keep in mind that the 2445/2446J with ferrite magnet assembly are BIG and very heavy and so is the AlNiCo 2441 (11kg).
Technically the 2450J is the best (light, strong neodymium magnet and better phase plug) but also the most expensive.
A nice pair of 2450J with original D16R2450 diaphragms goes for around €650-800 depeding on overall condition.