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Author Topic: Question about JBL CBT system  (Read 849 times)

James Hicks

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Question about JBL CBT system
« on: May 05, 2017, 12:06:59 pm »

We've been asked to possibly work on a sound system in a church. It appears the speakers consist of one JBL CBT-70J-1 and three of the CBT-70JE-1 extension cabinets on each side.

The system was installed by a well-known reputable company. The new media minister (or whatever his title is) had decided to have his maintenance guys re-aim the speakers, but predictably they fouled things up.

In the process of trying to find out more about the system, a sales rep told us that the usual configuration for that system is supposed to be just one 70J-1 and one 70JE-1. Is that correct? He said he has never seen anyone use three extensions for one main cabinet.

Having no experience working with the CBTs, I was hoping to get some opinions on that.
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John Rutirasiri

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Re: Question about JBL CBT system
« Reply #1 on: May 05, 2017, 08:12:12 pm »

a sales rep told us that the usual configuration for that system is supposed to be just one 70J-1 and one 70JE-1. Is that correct? He said he has never seen anyone use three extensions for one main cabinet.

I've never seen more than one 70JE-1 on top of the 70J-1.  Yes, physically it's possible to string 3x 70JE-1's because the coupler brackets will work.  But I'm not sure the pan and tilt wall mount bracket is rated for 4 boxes.

One normally attaches the pan & tilt bracket to the middle of the coupling plate.  How did these folks support the entire column?  Multiple wall brackets? (but then the column can't tilt.)    The pan and tilt bracket is only attached to the middle of the coupling plate.  I would be worried if there's just one wall bracket with 4 boxes stacked.

John R.


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ClearImpact Sound & Event Services, Inc.
Sound/Lighting/Corporate A/V

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Caleb Dueck

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Re: Question about JBL CBT system
« Reply #2 on: May 06, 2017, 08:40:47 am »

Sounds like they are trying to (poorly) emulate a proper subwoofer.
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Excel AV Group

James Hicks

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Re: Question about JBL CBT system
« Reply #3 on: July 13, 2017, 10:27:07 pm »

We've been asked to possibly work on a sound system in a church. It appears the speakers consist of one JBL CBT-70J-1 and three of the CBT-70JE-1 extension cabinets on each side.

The system was installed by a well-known reputable company. The new media minister (or whatever his title is) had decided to have his maintenance guys re-aim the speakers, but predictably they fouled things up.

In the process of trying to find out more about the system, a sales rep told us that the usual configuration for that system is supposed to be just one 70J-1 and one 70JE-1. Is that correct? He said he has never seen anyone use three extensions for one main cabinet.

Having no experience working with the CBTs, I was hoping to get some opinions on that.

Finally revisiting this topic.

We were able to do some experimental re-aiming of the speakers, as well as switching the J cabinet from 25 degree vertical to 45 degree vertical dispersion. I was also able to get a little better balance between the mains and the delay speakers covering the balcony. The delays were turned up a little too high at the amp compared to the mains, and with the mix position up in the balcony I think the sound man was hearing them too much and not getting a good representation of what was going on overall. Plus, it turns out the two "extra" JE cabinets on each side were barely turned up, so they may or may not have been doing anything good or bad. Those are turned off for now.

I'm hoping we get to go back and tinker a little more (EQ for example) but the customer was pretty happy with the results we got today.
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