Jbl 4520

[FrederikH]

Dear Lansing Forum members,Anyone here has building plans for a rear horn cabinet like JBL 4520, but for 2 18 inch woofers (2242H) ?Anyone has experience with such a cabinet?Thanks in advance !FrederikH

[Riley Casey]

Dual 18 versions of the 4520 were popular with portable rock concert sound vendors in the late 1970s. I know that RCI Sound near Washington DC was one company that built those and I[d imagine companies in Europe did as well.

[maxserg]

I remember at the end of the 70’s Solotech built a lot of them(dual18 inches) and built starting to make boxes scaled at 15/18 size. This was maybe a starting point, but I guess there was no scientific calculations.

[RMC]

I've never seen a JBL MADE AND APPROVED 4520 style cabinet with two 18". Not even a genuine documentation regarding such cab with a pair of 18". In my book it simply doesn't exist, although DIY may have built some.

The JBL C55, ancestor of the 4520, didn't have a larger brother either. I can go back to about 1962 and still no official larger one. Its possible that some technical issue(s) e.g. related to the horn prevented JBL from releasing one, or for the intended purpose and sound expected (punchy bass) a larger cab was deemed undesirable or unnecessary, who knows.

Richard

[Riley Casey]

By the time JBL published the W18 horn plans it had become pretty clear that the 4520 in either a stock dual 15 but even more so with the dual 18 versions were really unwieldy in portable use and something that more truck & labor friendly was needed. In portable concert sound transport practicality wins over audio performance. The 4520s had some uptake in disco installs but that market was dwarfed by concert sound users.

I've never seen a JBL MADE AND APPROVED 4520 style cabinet with two 18". Not even a genuine documentation regarding such cab with a pair of 18". In my book it simply doesn't exist, although DIY may have built some.

The JBL C55, ancestor of the 4520, didn't have a larger brother either. I can go back to about 1962 and still no official larger one. Its possible that some technical issue(s) e.g. related to the horn prevented JBL from releasing one, or for the intended purpose and sound expected (punchy bass) a larger cab was deemed undesirable or unnecessary, who knows.

Richard

[RMC]

The 4560 and 4550 type cabs, front loaded horns, lived some years longer than 4520 in the JBL catalog (in 1986 they're still there in 46XX series). Most probably because they were long throw units, therefore having increased usefulness for shows, touring, theater, particularly for the various versions they made of the 4560. The latter was more manageable on the road, even stacking some for increased output.

As for the 4550, at 195 lb empty and a net bass-reflex enclosure volume of 20 cu.ft.!, size and weight (loaded) made it sort of a monster to carry left and right... (btw 4520: 215 lb empty).

Richard