Tweeters! Just need help with something different... Juball II, Olympus (2405, 077)

[SARRAFO]

Hello! It's a privilege to make part of this group. My JBL history is, my father married my mother in 1977, and he took her for Honeymoon where? In California, just to see the JBL factory (she didn't knew that),
and he make some shop, now in 2010 he made an upgrade and changed his system to Wilson Audio Alexandrias and Holland amplifiers, and i'm lucky because i'm earned all his system, that i've always loved.
Since i've put my hand on it, i've saw a loooot of problems, and want to make some modifications, i would love to have some opinions on it. The system is:
2 2405 16 OHMS
2 JUBAL (077 TWEETERS + MEDIUM + 12"WOOFER 126A)
4 15" 16 OHMS WOOFERS (2 are passives, no wires)
2 HORNS 2440
2 LENSES 2310
LUXMAN VALVE CROSSOVER 2003
2 CROWN DC300A MONO - WOOFERS
1 CROWN D150A - HORNS
1 CROWN D60A - TWEETERS
1 CROWN D300A - JUBAL

My main problem is with the tweeters. When i've opened the Jubals, was one 077 tweeter and one 2405, and on the main system, one 077 and one 2405. i don't know why, and my father neither.
i've opened it and for my surprise, the kit on jubal was with blue diaphragm and cristal lenses, so i've figure that someone has made changes and don't know why someone has putted one blue diaphragm
on 2405 and the crystal lenses... I've taked to a repair center to see the impedance of the golden diaphragm and the blue diaphragm, the golden date of 1997 and the blue 1977, and supriselly
both are 8 ohms! I've saw someone here saying that is normal 2405 ship with 8 ohms diaphragm, i think is crazy, because it says 16 ohms, how you buy a tweeter and is different that shows.
He putted the blue diaphragm on the 077 and the golden on 2405, and i've opened now and saw that the polarity is inverted.
Sooo. Here are my questions:

1- De black dot on the Diaphagm is the negative or the positive?
2- the 4 diaphragms are in great condition, worth buy 2 - 16 ohms diaphragms for the 2405? will result in better sound, or something better? (i have separate amplifiers so i can adjust the gain)
or i can use this 8 ohms and it's the same of the 16 ohms in sound quality?
3- If i use this 8 ohms diaphragms in all of them (077 and 2405) with one is better? the blue dated 1977 or the gold dated 1997?
4- I simply LOVE the cristal point, my father said that the 2405 is newer and professional, so it has some difference in why they changed to metal, i don't know about that, so here i am
like a child asking, can i use the crystal point on the 2405? (that's because i'm guessing that the 2405 is better to use like my main tweeters, i don't know) or the metal is better? If i hit the
plastic part with my nail it sounds like TAC TAC, if i do the same on the metal part it does TINNNN TINNNN, i don't know if it's metal just because it's stronger and its the pro series, or it
make difference in the sound...
5- How can i figure it out that the golden diaphragm is from JBl and not aftermarket? The blue is different one from another, as the pictures show.

Here are some pictures, thank for your time and patience to make a very happy guy!
5715457155571565715757158

[SARRAFO]

5715957160571615716257163

[1audiohack]

Hi SARRAFO;

Welcome to Lansing Heritage!

Do you like to read? There is a thread here under the title "Ring Radiator Comparisons" started by Widget. It is quite long however I doubt there is another single source with so many pictures, measurements, graphs and general information. This thread comes up on the first page using the search function.

Just to get you going, ALLthese tweeters have an actual impedance of about 10Ω throughout the passband, they are all the same regardless of what the plate on the back is stamped. Crazy no?

The blue diaphragms belong in the 077's along with the "crystal" phase plugs. Be SUPER gentle when tightening the screw into the plastic phase plugs, don't tighten the screw much more than you could if you used your thumbnail as the tool. They break at the stem very easily and are virtually impossible to find.

There is no difference between the gray color "pro / commercial" motor assemblies and the black "consumer" motor besides the 077's are much more valuable.

Hope this helps a bit.

All the best,
Barry.

[ivica]

[QUOTE=SARRAFO;339034]Hello! It's a privilege to make part of this group. My JBL history is, ................
Since i've put my hand on it, i've saw a loooot of problems, and want to make some modifications, i would love to have some opinions on it. The system is:
2 2405 16 OHMS
2 JUBAL (077 TWEETERS + MEDIUM + 12"WOOFER 126A)
4 15" 16 OHMS WOOFERS (2 are passives, no wires)
2 HORNS 2440
2 LENSES 2310

My main problem is with the tweeters. When i've opened the Jubals, was one 077 tweeter and one 2405,
and on the main system, one 077 and one 2405....................... Here are my questions:

1- De black dot on the Diaphagm is the negative or the positive?
2- the 4 diaphragms are in great condition, worth buy 2 - 16 ohms diaphragms for the 2405? will result in better sound, or something better? .... or i can use this 8 ohms and it's the same of the 16 ohms in sound quality?
3- If i use this 8 ohms diaphragms in all of them (077 and 2405) with one is better? the blue dated 1977 or the gold dated 1997?
4- I simply LOVE the cristal point, my father said that the 2405 is newer and professional, so it has some difference in why they changed to metal, i don't know about that, so here i am like a child asking, can i use the crystal point on the 2405? (that's because i'm guessing that the 2405 is better to use like my main tweeters, i don't know) or the metal is better? ............
5- How can i figure it out that the golden diaphragm is from JBl and not aftermarket? The blue is different one from another, as the pictures show.

[QUOTE]


1.
I think BALCK (dot) on BLACK terminal.....
2.
for 077 driver and 2405 ( A /H ) JBL suggest the same diaphragm D16R2405 which are now gold-gold rings.
3.
As I know on 077 blue-blue diaphragms were used
4.
I believe that phase plug either metal or "crystal", has the same dimensions
5.
Not absolutely sure, but from the figure it seems to me that you have original golden-golden diaphragms.

BUT ONE VERY IMPORTANT: I do not suggest You to fix phase plug by rotating it instead of screw-unscrew
the long screw that is accessible after removing the back-label metal foil. From your figures it seems to me that
You have not removed the mentioned back-label foils (only on one there is no foil).


Regards
Ivica

[SARRAFO]

5735257351573535735457355

[SARRAFO]

More pictures

[Mike F]

You may want to rotate the 2405 90 degrees

[Ken Andrew]

I thought the transparent phase plug was a heaven sent inspiration from the Marketing Dept that fortuitously actually improved the product.

The blue colour always intrigued me. I reasoned that it was some form of internal reflection or refraction causing interference colours. I am so dumb. The pictures make it obvious. It was just paint on the magnet housing !

[Mannermusic]

That's all old stuff. Been there! You will have to restore every piece to original specs before you do anything. I guess you know that there is a 3/4" thick baffle that goes between the big serpentine lens and the cast aluminum horn (didn't see one in the photos). Will also have to check out the Luxman 2003 - they get old too. Those little cards can be adjusted if needed but are probably set to 500 and 7000 which is good. Try to find a manual for setting up the crossover. Back in the day, all that stuff sounded fantastic but, to be honest, it isn't easy to get it all up to speed - a lot of stuff interacting that can spoil the overall result. Takes know-how and patience. I'd find a JBL pro shop for starters, if you're really serious. They can give you an idea where to start and the cost involved. Not cheap or easy. Mike

[SARRAFO]

That's all old stuff. Been there! You will have to restore every piece to original specs before you do anything. I guess you know that there is a 3/4" thick baffle that goes between the big serpentine lens and the cast aluminum horn (didn't see one in the photos). Will also have to check out the Luxman 2003 - they get old too. Those little cards can be adjusted if needed but are probably set to 500 and 7000 which is good. Try to find a manual for setting up the crossover. Back in the day, all that stuff sounded fantastic but, to be honest, it isn't easy to get it all up to speed - a lot of stuff interacting that can spoil the overall result. Takes know-how and patience. I'd find a JBL pro shop for starters, if you're really serious. They can give you an idea where to start and the cost involved. Not cheap or easy. Mike

Dear Mike, thanks for the advice. I'm lucky that all of the stuff are working since 1970 in the same room, that was projected by a jbl designer. But, i'm having 2 difficulties, 1 is the Luxman, or tweeters, they make noise when there's no sound, i think is because they have a very high db, i think more then 100, i've heard somewhere that the tube can be bad too, but i've tried with a behringer DCX-2496 digital crossover that i love, but is the same. The amp i've tried to change, and the same, and the tweeters too (2405 and 077). So i think they are very strong (sensitive) and make noise... Instead of that, do you think i can use the behringer DCX-2496 instead of the Luxman? I will have 1000 more types of curve, and a lot lot more possibilities, but, don't know about the quality, even because i will use a Denon receiver 3313 before the luxman...

Thanks!

[robertbartsch]

this old stuff is now iconic. what made you want to piant the components silver... that probably devalued the drivers and horns quite a bit.

[4313B]

this old stuff is now iconic. what made you want to piant the components silver... that probably devalued the drivers and horns quite a bitPeople have different value systems.

I personally would have preferred it if he had painted all the components piano white. But I wasn't asked for my opinion. :rotfl:

I always liked the gold serpentines too.


As far as devaluation, please keep in mind that 99% of humanity would either repurpose this stuff or toss it in the landfill. :)

[SARRAFO]

this old stuff is now iconic. what made you want to piant the components silver... that probably devalued the drivers and horns quite a bit.
They are iconic, but let's face it, we are in 2013, this old 50 years old stuff cost 200 US$ on ebay, it's the price of my computer speakers, or less... I will not put an black Giant Horn in my living room,
but i love this speakers, so, that's the way i've found to do both. I rather gold too, but, didn't that ship has sailed kkkk.

[NickH]

Why not??????


They are iconic, but let's face it, we are in 2013, this old 50 years old stuff cost 200 US$ on ebay, it's the price of my computer speakers, or less... I will not put an black Giant Horn in my living room,
but i love this speakers, so, that's the way i've found to do both. I rather gold too, but, didn't that ship has sailed kkkk.

[SARRAFO]

Why not??????
Because, it's not a home theater, and they do not have a speaker, just the components. I think a black horn with lenses and the tweeter in black, in a white modern living room will not fit... The gold will be amasing, but i was afraid...
I will send a picture next week when i finish the room! I've just installed the Silver 15" Wilson Sub Woofers.

[Mike F]

Because, it's not a home theater, and they do not have a speaker, just the components. I think a black horn with lenses and the tweeter in black, in a white modern living room will not fit... The gold will be amasing, but i was afraid...
I will send a picture next week when i finish the room! I've just installed the Silver 15" Wilson Sub Woofers.

I think you have your priorities reversed. One must decorate and furnish around the speakers :D

[Mannermusic]

That's all old stuff. Been there! You will have to restore every piece to original specs before you do anything. I guess you know that there is a 3/4" thick baffle that goes between the big serpentine lens and the cast aluminum horn (didn't see one in the photos). Will also have to check out the Luxman 2003 - they get old too. Those little cards can be adjusted if needed but are probably set to 500 and 7000 which is good. Try to find a manual for setting up the crossover. Back in the day, all that stuff sounded fantastic but, to be honest, it isn't easy to get it all up to speed - a lot of stuff interacting that can spoil the overall result. Takes know-how and patience. I'd find a JBL pro shop for starters, if you're really serious. They can give you an idea where to start and the cost involved. Not cheap or easy. Mike

Just to follow up on the baffle mentioned above: The JBL kit MA25 included the baffle, mounting brackets & hardware to mount those horns on top of the enclosure. You can make the baffle yourself (24"X8"X3/4") but you gotta have it to make the horn/lens work correctly. ;) Mike