Vintage JBL Driver Ideas

[Yardstick]

There have been at least a couple of other vintage speaker threads that got me thinking about some vintage drivers that I have around.

I have a pair of JBL D123 12" woofers and a pair of JBL 075 tweeters.


They were in boxes that were too small for the D123 driver and had some kind of universal (junk) crossovers.



I have never heard these at their full potential. I had an idea to make an MLTL box for them but then life happened and I never did it. I also have all of the parts to make proper crossovers based on a design that was common for these drivers. I'm not very well equipped for the woodworking that it would take to make an appropriate box. The crossover network wouldn't be a big deal to wire up though. Does anyone make custom speaker box kits? Would an MLTL box be the right thing to do? Are there any other ideas I should consider for these things?

 

[lovinthehd]

You'd be best off modeling the boxes for the drivers based on their T/S parameters (if you can get them). Sometimes JBL will have box guidelines. Custom box kits are generally sold with specific drivers and a crossover (or plans for a crossover) designed for the whole package. You might find someone has based a speaker design on those drivers and provided plans for the box/crossover at least, might not find anyone making that particular box needed. Might start here https://www.lansingheritage.org/

 

[Yardstick]

I have a lot of information from that site. That's how I designed the MLTL box. I think they had T/S parameters. I downloaded other box designs they had too.

 

[Eppie]

Some cities may have wood shops that offer custom work. You'll have to research your area. Any cabinet maker should be able to build a speaker box but the final cost will depend on the quality of finish you want. They will likely need the drivers to cut the openings properly. The volume of the box is determined by the woofer parameters and how much low end extension you want and whether it is a ported or sealed design. There is software available to calculate that.

Is that crossover design specific to those two drivers? I would definitely check the parameters on the woofer in particular. Every design that I've seen with that bullet tweeter was a 3-way. I would be surprised if those two drivers would cross over properly in a two way design but then I haven't researched the parameters either.

 

[highfigh]

There have been at least a couple of other vintage speaker threads that got me thinking about some vintage drivers that I have around.

I have a pair of JBL D123 12" woofers and a pair of JBL 075 tweeters.
View attachment 59734View attachment 59735

They were in boxes that were too small for the D123 driver and had some kind of universal (junk) crossovers.
View attachment 59736


I have never heard these at their full potential. I had an idea to make an MLTL box for them but then life happened and I never did it. I also have all of the parts to make proper crossovers based on a design that was common for these drivers. I'm not very well equipped for the woodworking that it would take to make an appropriate box. The crossover network wouldn't be a big deal to wire up though. Does anyone make custom speaker box kits? Would an MLTL box be the right thing to do? Are there any other ideas I should consider for these things?

https://lansingheritage.org/images/jbl/specs/home-comp/d123/page2.jpg

 

[Yardstick]

I found the thread I started on the Lansing Heritage site: https://www.audioheritage.org/vbulletin/showthread.php?35139-Info-on-Vintage-JBL-speakers-tweeters

I settled on the N2400 crossover design. That seemed appropriate for those two drivers. That 12" driver can apparently play quite high so there's no issue with crossing over to that tweeter. It's built like a giant mid-range driver. I came up with an MLTL design to try to improve the low end but now that I have subs maybe that's not necessary. I don't recall how that tweeter works.