Late 70's Custom JBL Builds - Info gathering mission - All help truly appreciated

[MyLittleViking]

Looks like a great home-made job... with great components from that period... leave them alone, of course you could change them... but I am sure they were built for "his" listening preferences as its obvious he knew what he was doing... not worth selling IMO as they are not factory JBL enclosures.. yeah you could part them, but why? You have a unique and interesting speaker that I know will sound like nothing else in the world...

just play them and enjoy them... Like driving a kit Shelby vs. the original..

[MyLittleViking]

I'd pull the foam out of the ports... Can u confirm the model number of the woofers??

[medwardb]

Hey Viking,
Yes the woofers are 124H's. I just re-did the surrounds and they're breaking in very nicely. As I mentioned before, without the port "stuffing" listening is restricted to low to mid volume levels, in my opinion, as at louder volumes the bass becomes quite dominant. And I"m not sure about whether or not the excursion of the cone is being compromised had they been calculated to perform best in the aperodic vent structure model. At high volumes, with the "stuffing" in, the bass is deliciously tight & crisp & hit's you right in the chest!
I never thought I'd be such a fan of the 12"in. 124H but in this config they work quite nicely.

Thanks for the suggestions "Vik", but I never had any intention of selling them. As far as I know I have the only George Valentine JBL's on the planet! And because I believe that he did a bit of research before designing them I think that he's taken a lot of the best qualities of various designs and incorporated them into his own special design. With fabulous results indeed!

-MEdz> *

I'd pull the foam out of the ports... Can u confirm the model number of the woofers??

[4313B]

At high volumes, with the "stuffing" in, the bass is deliciously tight & crisp & hit's you right in the chest!

Well, that's what the 124/2203 does best. It's an extremely powerful, grossly overdamped transducer.

[medwardb]

Well, that's what the 124/2203 does best. It's an
extremely powerful, grossly overdamped transducer.

That's good to know. I'm going to check the Max cone excursion in the specs, pull the port wadding and see what I've got at high volume. If while playing some reggae or something I don't get an inordinate amount of movement then
I may play around with a less constricting baffle material. Right now it's just the regular white/poly-synthetic insulation type material that's being used.
If I find a less constricting material I may be able to find a nice sweet spot.

Thanks "4313B"
Take care,

-MEdz> *

[medwardb]

[quote=medwardb;248592]That's good to know. I'm going to check the Max cone excursion in the specs, pull the port wadding and see what I've got at high volume. If while playing some reggae or something I don't get an inordinate amount of movement then
I may play around with a less constricting baffle material. Right now it's just the regular white/poly-synthetic insulation type material that's being used.
If I find a less constricting material I may be able to find a nice sweet spot.

Well, it looks like the 124's will need some sort of repair. I may have to redo- the surrounds and shim them this time as there seems to be a bit of rub on one. It may be the spider as they seemed a bit loosish when I did the surrounds. The tollerance for these is quite small so shimming may be the only way to go. I've done dozens of JBL re-surrounds but these are the only pair I've had trouble with after the job was finished. Hmm?
Anyway, I"m also looking for something that may be a good substitute for the 124's if anyone has a suggestion. I also have a pair of minty 123-A1's that I've been thinking about selling or trading as well.
So, again all suggestions / offers welcome.

Thanks all,

-MEDz> *

[musicaudition]

This is my first note in this web site.
I just purchased a pair of JBL factory built speakers using the same components as yours with original LX-30 crossover networks.
They looks very similar to JBL L-65 Jubal speakers but a little bit taller than Jubal.
It produces excellent bass compared with other 12" woofer speaker.

The all units are built with all Alnico magents, 124 woofers, LE-5, 077 tweeters. All 8 Ohm units.
Someone did woofer reconed a while ago.
It sounds good but I found a little bit mid-range is thin compared with my other speakers.
I am wondering the woofer polarity was reversed or not.
Would anybody kindly suggest what the correct connection is for the set?
According to the LX-30 schematic, woofer red terminal is opposite polarity to the mid and tweeter terminals.

Thank you very much.
Music Lover in Chicago.