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Finally got a good look at the speakers behind our screen. Left and right screen channels are JBL 4722N, but the center channel is not. The LF enclosure is narrower and the horn is even narrower still. I climbed up there and it looks like this speaker was custom assembled from separate components. There's a JBL 2385a horn and 3160 crossover bolted to the top of the LF unit (with no adjustability at all). The LF unit has two 15" drivers but I'm unable to maneuver it to look at the back for a model number. Anybody have experience with this kind of setup who knows what might have been used for the LF unit? I'm trying to get a better picture of our systems capabilities and I'm at a loss for this center channel.
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Pictures go a long way here. -
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This is the best I got since it didn't occur to me at all to take pictures today. Center channel is the upper left speaker, 4722N is on the right, 4642a sub on the bottom. This is from our other theater during our COVID renovation but they are identical speakers. You can see the crossover just peeking out from behind the 2385a horn on the left side of the center channel.
I'm aware that the speakers are not where they should be height wise. Nobody paid any attention to that when the screen was first built.Comment
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Looks like a 4638 LF cabinet.Comment
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It's a rough image to judge but I'd say 4670 or in that family for the left most speaker in the image. Since you say it is a 2385 horn, then it is a long-throw (60x40) and not the standard 4670 system, which used the 2380 (90x40). That horn will use either the 2445 or the 2446 driver and the 3160 would be a correct crossover. The LF section would be called the 4648. Depending on vintage, stuffed with 2225 drivers (double rolled surrounds) or 2226 drivers (pleated surrounds). My guess is 2226 because the frame of the baskets are black. Back in the 2225 days, they were brushed aluminum and one had to paint them or they would shine through the screen...we had cardboard covers for the drivers so they could be painted quickly (and the mounting screws too...the little shiny things).
4642A for the speaker on the hand truck and 4722 for the rightmost speaker. Note, the 4622 and 4722 look identical from the front and the "N" version puts a crossover network up by the HF bracket.Comment
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I've found identifying speaker models to be be a growing problem, because computer-based audio processors and amplifiers increasingly need to know this, in order to know frequency ranges and crossover points.
On Thursday, I upgraded a house from a deceased CP750 (power supply blew and took the mobo with it) with QSC MX1500a amps, one of which had a dying XC-1 crossover, to a CP950 with LEA Professional 354Ns. The stage speakers were JBL and bi-amped, but no-one knew the model number for sure, and digging them out of the baffle wall in which they were encased (15ft above ground level), to see the label on the back, simply wasn't viable. And, not being Spiderman, climbing up the wall to find the model of surround speakers wasn't an option, either. The theater staff didn't know, and neither did my boss for sure (these were sold to them 15-20 years ago), but made an educated guess. Both Dolby Atmos Designer (in order to use the CP950's internal crossover capability) and the web UI of the LEA amps needed that info, and I didn't have it. With the model numbers I was given, playing pink produced a big dip between around 200 to 230Hz, and I had to try several JBL model numbers in DAD until I got a reasonably flat curve, from where I could begin to tune.Comment
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Yah know...there could be a business in making the equivalent of the XC-3 crossover for the QSC DCA amps again. Those things never died. Yeah...you did have set the resistor networks and if one changed speakers...go find that bag/box...but, honestly speakers just don't seem to change that often. Alternately, make a 3-channel configurable crossover or crossover/monitor. QSC can't be depended upon for such things anymore (DCM's paused as are DPMs) but DCA amps are in production.
One of the things I'm not eager to do is jump in with another proprietary DSP based Class-D amplifier system. They don't have the longevity of analog stuff. With things like Q-SYS, it comes along for the ride and a minimal amount of spares on site can back up an entire site.Comment
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It's not a stock 4670 as the horn is literally screwed to the top of the LF unit with two small generic 'L' brackets, and it looks like a DIY job as there's no angle adjustability on it at all. And it's definitely a 2385 horn as the sticker was slapped on the front of it. But the LF cabinet is right up against the back wall, 12 feet in the air, on a platform barely deeper than the enclosure. Being at the top rung of a ladder, I wasn't going to try to maneuver it to see if the LF unit had a label on the back. Sorry for not getting better pictures.
The left and right channels are confirmed as 4722Ns as I could see the label on the top once the dust was wiped off. Based on appearance I thought they were 3722Ns at first.
I'm not 100% sure on side surrounds but they sure look like moldy oldy JBL 8330s with 8320s for the rear surrounds. Near as I can figure the side surrounds and center screen channel have been here forever but the 4722N, 4642A and 8320 speakers were installed as part of a 7.1 upgrade several years back (before I came along). The owner is a bit hazy on the details of what showed up when.
I'm wanting to track this down so I can get an accurate picture of what our system is capable of if I can get the owner to pony up the cash for another sub and a few more amps. I don't know if the owner went cheap or the installers were idiots but on paper we're seriously underpowered on everything except the screen channels.
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Jon, The 4670 did not always come with an HF mounting bracket. The mounting bracket evolved too. The first iteration of a JBL bracket for it was just a large "L" that the compression and horn sandwiched. So, one could pivot but not tilt. Originally, it was VERY common for people to shoot drywall or like screws through the horn mounting holes (though the heads of a typical drywall screw was on the same order as the size of the hole) right into the top plate of the 4648 cabinet (and, if old enough...didn't even have that designation...it was a 4508 cabinet stuffed with the drivers ordered. Mind you, in the mid-80s one still received the speaker as a "kit." That is, you could order a 4670 but you got a cabinet, drivers, horn and, maybe an HF bracket but, again, maybe not.
People found that the boot on the magnet of the HF driver allowed it to rest on the cabinet with the horn affixed as described. You can always tell when an HF system was affixed that way...the top plate will pucker in the front from the space that had to be made for the screws.
You "kids" are just used to completed systems where one just had to affix the HF section with the supplied hardware with T-Nuts already installed on the top.Comment
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No argument there. Convenience rules.Originally posted by Steve Guttag View Post
Appreciate your information in any case.Comment
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