Film-Tech Forum ARCHIVE: JBL 2360 Horn Placement

This is topic JBL 2360 Horn Placement in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Jeremy Weigel (Member # 4208) on 01-29-2011, 11:05 PM:

I just acquired some 2360 horns to mount on our 4648's and need to find out what is the proper placement of the bracket. This combination essentially makes a 4675A system. I found this diagram on JBL's site, but it doesn't show the bolt hole location specs. Judging by drawing, they look to be centered.

Posted by Louis Bornwasser (Member # 3063) on 01-30-2011, 09:40 AM:

That is about right. See if there is a drawing for the 4648a, l.f. part of the 4675 that shows the dimensions of the top. Later models had nut-serts permanently installed.

It won't matter much if you are bi-amped and the crossover has time delay. Louis

Posted by Jeremy Weigel (Member # 4208) on 01-30-2011, 04:13 PM:

Thanks Louis. I've looked at every drawing of the different versions of the 4675 and the related components that I could find and none have the bolt location specs. In particular though, the bracket these 2360's came with the wooden version. They will be on a 3160 network.

Posted by Louis Bornwasser (Member # 3063) on 01-31-2011, 09:12 AM:

Wooden bracket is most commonly installed flush with the front using the passive crossover. yes, the horn is quite far "in front."

In the old days, we used a "warble tone" (500hz with frequency modulation) to find the NULL, with the hf wiring reversed. then put back to normal. You will be time aligned at 500 hz. louis

Posted by Jeremy Weigel (Member # 4208) on 02-13-2011, 08:33 PM:

I have a screen that has 2 4648-8 (2 15" 16ohm 2225 drivers paralleled) and 1 4648 (2 15" 8ohm 2225 drivers paralleled) that I am mounting 2360A horns (2445J drivers) with the 3160 passive x-overs. What is the proper x-over configuration for these?

Posted by Lionel Fouillen (Member # 1475) on 02-14-2011, 01:53 AM:

This document from the JBL vintage website features "Recommended system settings" for the 3160 crossover with a 4675A speaker.

3105-3115A.pdf

Posted by Joshua Waaland (Member # 287) on 02-14-2011, 09:14 AM:

I have another new 2360 horn, three 3160 crossovers and three of the 2506B steel horn mounting brackets for sale if interested. I had the wooden brackets too and switched to the steel brackets.

I had the original 4508 cabinets and they did not have the threaded inserts in them. The newer 4508A cabinets did so I switched to them.

Posted by Jeremy Weigel (Member # 4208) on 02-14-2011, 11:19 AM:

I see on the specs chart for the 3160 that it only specifies 4 ohm low frequency. Is it not compatible with the 8 ohm cabinets?

Posted by Jeremy Weigel (Member # 4208) on 03-02-2011, 05:37 PM:

I've been asked if a matching transformer will work to make the 4648-8's into 4648's (4 ohm version) so that the 3160 x-over will have the required 4 ohm load for the low frequency. If so, what would be a recommended transformer?

Posted by Louis Bornwasser (Member # 3063) on 03-02-2011, 07:07 PM:

Don't bother. It will work OK with only that small mismatch. The quality loss in the transformer is the greater of the two evils. Louis