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Late 70's Custom JBL Builds - Info gathering mission - All help truly appreciated
Hi folks,
I purchased a pair of custom JBL builds from an old gentleman (86) recently who built these back in the 70's. The cab dimensions are:
18"in wide, 14-1/4"in deep & 28-3/4"in high.
The driver compliment, [ea.] is:12"in 124H woofers, 2105 mids & 2405 HF rads. At the time of purchase the 124H's needed to be re-surrounded, and this I accomplished with the very kind assistance of Rick C. in Florida and his high quality JBL surround kits.
[Thanks again Rick! Breakin' them in as I write. They're great. I'll be talking to you again soon. Very soon.]
The cabinets are almost as impressive as the driver compliment. 7/8"in think solid marine grade ply w/ walnut vaneer. Nice and heavy.
There is also a 1/2"in lag bolt goning through the rear straight through the front baffle, half-way up from bottom up but slightly "inside" from center (hmm?). Each "plane" "sandwiched" between a pair of nuts & 1.5"in washers inside & out. I imagine for front baffle and overall support. [The horizontal line on the right speaker is a stain drip, not a crack]
Grills are quite solid also with 3 lateral 7.5" x 1."in. slots in each side due to their 2-3/4"in. thickness.
Cabinet construction is s.o.l.i.d. solid. Not sure about which model the design que was taken from though not like any cab design I've seen as I recall.
As for the crossovers they're HUGE. I'd say that the layout takes up most of the inside of one side of the 28"in. high cab!
They provide two controls similar to that which is found on L100's/4311's etc. But I'm not sure if they are "Brillience & Prescence" or just [0-100 or cut-unity-boost] attenuation for mids and tweets.
(I'm exploring the possiblity of opening one of one cabs for a clear pic and possible upgrade of the crosssovers, as the rear panels seem to be connected using "Allen" head type screws at the very least.)
Crossover component quality is high, and build quality is capable though, from what I can see, was done by someone that had obviously built on this level before. The 3 inductors (at least the size of hocky pucks) are hand built and very well done.
So, I've included some pics and am open to all impressions, info and hints.
If and when I get the rear off of one I"ll include pics of the crossovers and attempt an interpretation of a schematic.(..uh,huh..)
I'm very curious about whether there were home designed or taken from existing crossover design.
Thanks to all for reading through this and letting me benefit from your cumulitive knowledge and experience. This is a great site and I truly appreciate everyones participation. Things are kind of rough here in Michigan but when I get the chance I will be making a $ contribution to the site in appreciation. Peace everyone,
M.Edz
Reply: Rob:...70's JBL Customs:
Quote:
Originally Posted by
robertbartsch
Was the seller 86 when he built the boxes or when he sold them to you? ...Anyway, 86 is not old.~
...What else can the young man who sold them to you tell you about their history?
Rob,
The gentleman was 86 when he sold them to me. [He'd be over 110 otherwise.]
This was just before he relocated to, I believe, an assisted living community. He was a chemest and built them in the late '70's. As for the high freq rad.
I"m not ab.positive about it being a 2405 or an 077. I didn't take it out though I did take out the woofer and the mid. Since he's moved I no longer have accesss to him. He had a beautiful pair of 3 way Dynaudio cabs he had built around that time also. Sounded great.
They weren't for sale:D So, I can learn no more about them from him.
His name is G. Valentine. A very nice man indeed, he was to me.
I realy wish I could have spent more time with him.
Thanks Rob,
M. Edz
Reply:[hjames] ....70's Custom JBL's...
Quote:
Originally Posted by
hjames
Generally, access to the big boxes is by removing the clamps and the woofers.~
....Remove the woofers and carefully put them aside.
Now you can photograph or examine your crossover or whatever on the inside.
hjames,
thanks for the reply and instructions. I thought I mentioned in the original post that I had replaced the surrounds, so, I'm good with a good deal of repair. But thanks, I do appreciate it. Honestly I realy didn't think about putting a digi-cam inside the cab and trying to take an individual or composite pic of the crossover w/the aid of a flash.
Hence, not needing to open the back of the cab. There's a good deal of insulation, and the inner enclosure for the mid, but hopefully it should be possible.
Though that would be the only way to do any repairs on it. As I mentioned it's on a rather large board that has to be at least 18"x14" I'd guess. So taking it out of the woofer port is in no way possible. I"m going to attempt to take photos of the crossover now. Wish me luck, and thanks again for your reply.
-M.Edz>
Do you have a woofer tester?
You could test it in the current state of the ports stuffed, then test it without.
Regards, Ron