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Post by jamiesego on Oct 23, 2018 14:57:32 GMT -6
The space I'm in right now was built in 1978 and originally had soffit mounted dual 15" monitors with horns. The boxes and horns are still there but the drivers and crossovers are gone. I'm told they were originally TAD drivers but I've also seen literature suggesting they were JBL. I believe the horn model is a JBL 2397. I've been researching newer less expensive driver options. I'm not sure how useful these will be and I definitely don't have a lot of spare cash. I wanted to see what more knowledgeable minds thought before I proceed.  |
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ericn
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Post by ericn on Oct 23, 2018 21:25:31 GMT -6
It’s not that simple your going to need cabinet volume, port length and width to start then a Thiele- small calculator to figure out what drivers are going to work as well as what will fit in the actual driver cut outs.
Is there a passive crossover? Honestly if there is or isn’t it would probably be easier to simply Bi- amp with an active and 4 channels of amplification rather than experimenting on getting a passive right.
Now for the good news, TAD are 16in chassis’s so the cut outs would be larger and pretty obvious of course TAD’s are any thing but inexpensive ( well I got my 3 matched and one differ in need of a recons for $99ea but that is still one of the top audio steals ever).
Cabinets designed for any JBL 15 will pretty much work with any JBL 15 (your going to want 4 of the same model) or EV or any of the inexpensive JBL copies, also used JBL 2xxx are not that expensive ( check with Clairusedgear.com, send an email or call.
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ericn
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Post by ericn on Oct 23, 2018 21:30:01 GMT -6
Also are those horns metal or wood? Do they have drivers on them ? Are they they 2in or 1in throats?
Lately I have been liking the Radian drivers and their replacement diagaprams, even in TAD’s
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Post by jamiesego on Oct 24, 2018 7:02:08 GMT -6
The horns don’t have any drivers. I’m not sure what the material is. I’ll check when I go in. I believe that model takes a 1” driver but I’ll have to verify. I think bi-amping is the way to go.
I figured this was more complicated than I anticipated.
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Post by johneppstein on Oct 24, 2018 14:27:23 GMT -6
The space I'm in right now was built in 1978 and originally had soffit mounted dual 15" monitors with horns. The boxes and horns are still there but the drivers and crossovers are gone. I'm told they were originally TAD drivers but I've also seen literature suggesting they were JBL. I believe the horn model is a JBL 2397. I've been researching newer less expensive driver options. I'm not sure how useful these will be and I definitely don't have a lot of spare cash. I wanted to see what more knowledgeable minds thought before I proceed. You should cough up for original drivers or not bother. The 2397 horn is made out of pressed wood - they're pretty amazing horns, 100 degree dispersion and non-resonant. It takes a 2", I used to have a pair. If memory serves there should be a metal throat adapter*, model 2328. The correct driver would be JBL 2440/2441. If they're not there try to get the old Alnico version - the newer ceramic (2445) is much heavier and is a lot larger diamater - it might not fit the box. If you can't get 2440/2441, Gauss HF4000s are equivalent but might be harder to find diaphragms for. Careful with the horns - they're somewhat fragile. It will probably require a support for the driver. You don't want to support the weight of the driver by the horn - it can crack the pressed wood in the throat.
There is also a small round hole (approximately 4" across.) It is NOT a port. This hole is for a 2402 "bullet" or 2405 "slot" ring radiator tweeter. I believe the correct one is the 2405.
IIRC the original woofers were 2220s or possibly 2225s, but D 130s or D140s will do in a pinch if you replace the aluminum domes with paper. 2220s and D130s are significantly more efficient than 2225s and D140s.
Again, do not bother installing cheaper parts, it's a waste of money and you'll regret it.
If you go biamp, check the boxes for holes for mounting JBL passive crossovers. If they're not filled with crossovers they need to be covered with 3/4" plywood. There will probably be two such holes per cab.
Crossover frequencies should be around 1200- 1500 HZ and 8KHz. Lowest reccommended frequency for the horn is 800 Hz but they can sound a little "hornish" fown there.
Loaded with the correct parts these are awesome monitors. Take your time as you can get the cash. It's worth the wait.
* - it's possible that the throat adapters may be missing or might have been swapped out for 1" adapters - if the latter I strongly recommend replacing them with the correct 2" adapter, if you want your monitors to be in balance. JBL states that the horns were designed for one or two 2440s. In a studio monitor one would be correct.
EDIT: Since the 1" adapter mounts to the back of the 2" adapter there may not be sufficient cabinet depth to use 1" drivers in the cab, anyway.
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Post by jamiesego on Oct 24, 2018 15:03:40 GMT -6
If it's a choice between coughing up for original drivers or nothing then I probably won't bother with it. One, I don't have that kind of money floating around, and two, if I move out of this space the investment will be useless. On the other hand the resale of vintage drivers would probably be a lot better.
Maybe if I jump a few tiers in the projects I get I'll outfit them with original parts.
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Post by johneppstein on Oct 24, 2018 15:47:03 GMT -6
If it's a choice between coughing up for original drivers or nothing then I probably won't bother with it. One, I don't have that kind of money floating around, and two, if I move out of this space the investment will be useless. On the other hand the resale of vintage drivers would probably be a lot better. Maybe if I jump a few tiers in the projects I get I'll outfit them with original parts. Check the touring PA companies for surplus parts. Also there are a lot of JBL parts on Evilbay, but prices are often high. Sometimes a deal comes around though.
BTW, since they're 3-way boxes it'll actually be tri-amping......
They'd probably impress the hell out of clients....
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ericn
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Post by ericn on Oct 24, 2018 17:56:45 GMT -6
The space I'm in right now was built in 1978 and originally had soffit mounted dual 15" monitors with horns. The boxes and horns are still there but the drivers and crossovers are gone. I'm told they were originally TAD drivers but I've also seen literature suggesting they were JBL. I believe the horn model is a JBL 2397. I've been researching newer less expensive driver options. I'm not sure how useful these will be and I definitely don't have a lot of spare cash. I wanted to see what more knowledgeable minds thought before I proceed. You should cough up for original drivers or not bother. The 2397 horn is made out of pressed wood - they're pretty amazing horns, 100 degree dispersion and non-resonant. It takes a 2", I used to have a pair. If memory serves there should be a metal throat adapter*, model 2328. The correct driver would be JBL 2440/2441. If they're not there try to get the old Alnico version - the newer ceramic (2445) is much heavier and is a lot larger diamater - it might not fit the box. If you can't get 2440/2441, Gauss HF4000s are equivalent but might be harder to find diaphragms for. Careful with the horns - they're somewhat fragile. It will probably require a support for the driver. You don't want to support the weight of the driver by the horn - it can crack the pressed wood in the throat.
There is also a small round hole (approximately 4" across.) It is NOT a port. This hole is for a 2402 "bullet" or 2405 "slot" ring radiator tweeter. I believe the correct one is the 2405.
IIRC the original woofers were 2220s or possibly 2225s, but D 130s or D140s will do in a pinch if you replace the aluminum domes with paper. 2220s and D130s are significantly more efficient than 2225s and D140s.
Again, do not bother installing cheaper parts, it's a waste of money and you'll regret it.
If you go biamp, check the boxes for holes for mounting JBL passive crossovers. If they're not filled with crossovers they need to be covered with 3/4" plywood. There will probably be two such holes per cab.
Crossover frequencies should be around 1200- 1500 HZ and 8KHz. Lowest reccommended frequency for the horn is 800 Hz but they can sound a little "hornish" fown there.
Loaded with the correct parts these are awesome monitors. Take your time as you can get the cash. It's worth the wait.
* - it's possible that the throat adapters may be missing or might have been swapped out for 1" adapters - if the latter I strongly recommend replacing them with the correct 2" adapter, if you want your monitors to be in balance. JBL states that the horns were designed for one or two 2440s. In a studio monitor one would be correct.
EDIT: Since the 1" adapter mounts to the back of the 2" adapter there may not be sufficient cabinet depth to use 1" drivers in the cab, anyway.
John your making assumptions based on a baffle picture, without dimensions! While that hole could be for a slot tweet it looks like there is a port tube and no mounting hole that I can see and 15 JBL’s are pretty useless in a sealed box. There were many custom soffit monitors out there some well engineered many not so much. |
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Post by johneppstein on Oct 24, 2018 21:46:24 GMT -6
You should cough up for original drivers or not bother. The 2397 horn is made out of pressed wood - they're pretty amazing horns, 100 degree dispersion and non-resonant. It takes a 2", I used to have a pair. If memory serves there should be a metal throat adapter*, model 2328. The correct driver would be JBL 2440/2441. If they're not there try to get the old Alnico version - the newer ceramic (2445) is much heavier and is a lot larger diamater - it might not fit the box. If you can't get 2440/2441, Gauss HF4000s are equivalent but might be harder to find diaphragms for. Careful with the horns - they're somewhat fragile. It will probably require a support for the driver. You don't want to support the weight of the driver by the horn - it can crack the pressed wood in the throat.
There is also a small round hole (approximately 4" across.) It is NOT a port. This hole is for a 2402 "bullet" or 2405 "slot" ring radiator tweeter. I believe the correct one is the 2405.
IIRC the original woofers were 2220s or possibly 2225s, but D 130s or D140s will do in a pinch if you replace the aluminum domes with paper. 2220s and D130s are significantly more efficient than 2225s and D140s.
Again, do not bother installing cheaper parts, it's a waste of money and you'll regret it.
If you go biamp, check the boxes for holes for mounting JBL passive crossovers. If they're not filled with crossovers they need to be covered with 3/4" plywood. There will probably be two such holes per cab.
Crossover frequencies should be around 1200- 1500 HZ and 8KHz. Lowest reccommended frequency for the horn is 800 Hz but they can sound a little "hornish" fown there.
Loaded with the correct parts these are awesome monitors. Take your time as you can get the cash. It's worth the wait.
* - it's possible that the throat adapters may be missing or might have been swapped out for 1" adapters - if the latter I strongly recommend replacing them with the correct 2" adapter, if you want your monitors to be in balance. JBL states that the horns were designed for one or two 2440s. In a studio monitor one would be correct.
EDIT: Since the 1" adapter mounts to the back of the 2" adapter there may not be sufficient cabinet depth to use 1" drivers in the cab, anyway.
John your making assumptions based on a baffle picture, without dimensions! While that hole could be for a slot tweet it looks like there is a port tube and no mounting hole that I can see and 15 JBL’s are pretty useless in a sealed box. There were many custom soffit monitors out there some well engineered many not so much.
I'm also pretty sure I've seen that box before - I don't think it's a one-off.
If I'm right about the 2405 there will be a mounting hole on each corner of the hole with a T-nut behind it (or used to have one) and I think that I see the shadowy image of such holes. Or it could be an artifact of the photo. Look at the image in enlarged mode if your browser supports it. If the hole was a port it would not have bolt holes. It would also have a cardboard tube. It looks to me that there is a hole on each side of the baffle and they don't look identical to me, but it could be an illusion.
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Post by jamiesego on Nov 2, 2018 16:04:05 GMT -6
Little update. I talked to the designer Steven Durr and he confirmed that they originally had TAD drivers, Bryston amps, and White crossovers and EQ's. I thinking it's going to be pretty costly to try to recreate that setup. The horns do have the JBL 2" adapters. I'll have to look at the tubes again but I don't think they're setup for tweeters. There's one on each side of the enclosure. Here's a better picture of the room.  |
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ericn
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Post by ericn on Nov 2, 2018 17:05:52 GMT -6
The tubes are the ports, after doing some modeling with various drivers, based on the dimensions you gave me, Yeah TAD’s are probably what would work best, JBL 2205’s would work but that would require a new baffle because the cut outs for the drivers for TAD is Larger than for JBL’s and the porting would be very different.
If the dimensions are accurate any of the Common JBL’s TAD’s or any other common 15 would require a lot of EQ.
The designer of these cabinets, based the dimensions you sent me are went with a larger cabinet volume than most would use for these drivers.
Here is what I would consider doing if you know somebody who has wood working skills: build a new box with the same baffle size optimized for 99% of the JBL 15’s out there ( I found 4 2205’s for a $100ea) reuse the horns and we try to find a pretty decent pair of 2in drivers. For Electronics the White EQ’s are easy to find used cheap, but finding the X over modules that would be needed is hit or miss.
2 Jim Williams modded Adcom 545’s or 555’s would play more than loud enough and would damage your hearing long before clipping ( a single TAD 16 and horn here has yet 2 clip a 25 watt amp).
I have been running different 15’s that are reasonable as I think of them but if those cabinets have opening for TAD’’s I don’t know of any others that would fit without a new baffle and at that point might as just build a new box,
If a new box we could incorporate a super tweet with a passive crossover and an Lpad to adjust the level and not need to tri amp.
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Post by jamiesego on Nov 2, 2018 17:15:01 GMT -6
I really appreciate you running those numbers Eric!
The cutout size really is a bummer. I'm leasing the room so I would probably have to talk to the building owner before I changed out the cabinets.
It's a bit of an eye sore having open holes up there but we just aren't making enough at this point to justify the cost of getting the original drivers. I was hoping there was any easier solution but it looks like we're stuck for the time being.
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ericn
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Post by ericn on Nov 2, 2018 20:27:27 GMT -6
I really appreciate you running those numbers Eric! The cutout size really is a bummer. I'm leasing the room so I would probably have to talk to the building owner before I changed out the cabinets. It's a bit of an eye sore having open holes up there but we just aren't making enough at this point to justify the cost of getting the original drivers. I was hoping there was any easier solution but it looks like we're stuck for the time being. No problem It was actually pretty interesting to see what would work. |
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Post by keymod on Nov 3, 2018 4:49:11 GMT -6
I really appreciate you running those numbers Eric! The cutout size really is a bummer. I'm leasing the room so I would probably have to talk to the building owner before I changed out the cabinets. It's a bit of an eye sore having open holes up there but we just aren't making enough at this point to justify the cost of getting the original drivers. I was hoping there was any easier solution but it looks like we're stuck for the time being. Why not make some simple frames & cover them with grille cloth to hide the holes? |
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Post by jamiesego on Nov 3, 2018 10:22:48 GMT -6
I really appreciate you running those numbers Eric! The cutout size really is a bummer. I'm leasing the room so I would probably have to talk to the building owner before I changed out the cabinets. It's a bit of an eye sore having open holes up there but we just aren't making enough at this point to justify the cost of getting the original drivers. I was hoping there was any easier solution but it looks like we're stuck for the time being. Why not make some simple frames & cover them with grille cloth to hide the holes? Yeah, that'll be the way to go. Not as cool as having speakers in there. Oh well. |
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Post by johneppstein on Nov 3, 2018 11:25:41 GMT -6
Well, if the baffles screw in just unscrew them, unbolt the horns, cut some new baffles and put the old ones in storage for the landlord. As far as the excessive cabinet volume is concerned, no problem - just fill some of it with blocks of wood.
If the baffles are glued in place it could be a more difficult problem, but not insurmountable.
When calculating cabinet volume make sure you compensate for the volume of the drivers and horn.
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ericn
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Post by ericn on Nov 3, 2018 17:31:44 GMT -6
Well, if the baffles screw in just unscrew them, unbolt the horns, cut some new baffles and put the old ones in storage for the landlord. As far as the excessive cabinet volume is concerned, no problem - just fill some of it with blocks of wood.
If the baffles are glued in place it could be a more difficult problem, but not insurmountable.
When calculating cabinet volume make sure you compensate for the volume of the drivers and horn.
Of course I compensated for horn and driver volume 😎 even figured in some bracing to boot, but for optimal response with most JBL’s we are still looking at 2-3 cubic feet bigger than needed. I ran it on bass box and a couple of other more esoteric platforms to see if I was nuts. |
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Post by jamiesego on Nov 3, 2018 17:45:18 GMT -6
Well, if the baffles screw in just unscrew them, unbolt the horns, cut some new baffles and put the old ones in storage for the landlord. As far as the excessive cabinet volume is concerned, no problem - just fill some of it with blocks of wood.
If the baffles are glued in place it could be a more difficult problem, but not insurmountable.
When calculating cabinet volume make sure you compensate for the volume of the drivers and horn.
Of course I compensated for horn and driver volume 😎 even figured in some bracing to boot, but for optimal response with most JBL’s we are still looking at 2-3 cubic feet bigger than needed. I ran it on bass box and a couple of other more esoteric platforms to see if I was nuts. I'll double check those measurements. I am curious about that. |
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Post by johneppstein on Nov 3, 2018 17:47:55 GMT -6
Well, if the baffles screw in just unscrew them, unbolt the horns, cut some new baffles and put the old ones in storage for the landlord. As far as the excessive cabinet volume is concerned, no problem - just fill some of it with blocks of wood.
If the baffles are glued in place it could be a more difficult problem, but not insurmountable.
When calculating cabinet volume make sure you compensate for the volume of the drivers and horn.
Of course I compensated for horn and driver volume 😎 even figured in some bracing to boot, but for optimal response with most JBL’s we are still looking at 2-3 cubic feet bigger than needed. I ran it on bass box and a couple of other more esoteric platforms to see if I was nuts. Well, it's a lot easier to decrease the volume than increase it.... A few nice 2x6 braces oughtta do it! |
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ericn
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Post by ericn on Nov 3, 2018 19:41:53 GMT -6
Of course I compensated for horn and driver volume 😎 even figured in some bracing to boot, but for optimal response with most JBL’s we are still looking at 2-3 cubic feet bigger than needed. I ran it on bass box and a couple of other more esoteric platforms to see if I was nuts. Well, it's a lot easier to decrease the volume than increase it.... A few nice 2x6 braces oughtta do it! It is but for a cubic foot your talking a lot Of braces 😁 |
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Post by johneppstein on Nov 3, 2018 20:06:09 GMT -6
Well, it's a lot easier to decrease the volume than increase it.... A few nice 2x6 braces oughtta do it! It is but for a cubic foot your talking a lot Of braces 😁 2x6s? 4x4s? really, not that much. Especially if they're unfinished. |
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