4343 crossover modifications

[B&KMan]

Can you verify the voltage drives using 8 ohm resisters please per the table in the 3145 nework?

Ian

bonjour,

To afflict for this long deadlines and thank you at all for your patience, But work first !!! And this test takes a few hours to dismount and go up
and measure and adjust and print and compare and comments and...


-------------

Here the complete graph of the electric response of the 3145. I put all L-pads at the max and I substituted for turn of role the HP
measured by a resistance of 8ohms.
(note for this test I reconnect the resistances in UHF section: so all conform to schematic exposed )

( I hope that it is the good way of making... )

-------

The point of crossing of the curves is to indicate as follows with respectively
variation with the maximum:


LF - MF : is 294 Hz variation: LF is 5,82 dB, MF is 3,24

MF - HF : is 1560 Hz variation: MF is 9 dB, HF is 1.58

HF - UHF : is 8540 Hz variation: HF is 8.35 dB, UHF is 8.35

[B&KMan]

This next picture compare the electrical schematic
(est 1225 , p 1 of 2 3145 voltage control full on , 8 Ohms load " internal position" )
versus the response electric of bignet in same situation...

I suspect the variation is my error, I supose one at time, I replace driver by 8 Ohms but I'm feeling in original approach; all drivers is replaced by 8 Ohms (all the time) ...

but 2 schema of voltage is posted By Mr widget and I dont know what expression internal position and external position is....



or

the L_PAD is scrap and loss to much power by age
( I recycling the original L_PAD (the cost is realy higher...)


anybody have idea, please post it....

thanks for all

Jean.

[Ian Mackenzie]

Compare

[Ian Mackenzie]

Small adjustment of the L pads 'Levels should compensate for the variations.

Ian

[B&KMan]

Compare

thanks !!!

It is possible to fill explanation of legend what is goud curve of hf uhf ???



jean.

[B&KMan]

Small adjustment of the L pads 'Levels should compensate for the variations.

Ian

So I suppose right, if your conclusion of the elecrical set-up is correct ???

Jean

[Ian Mackenzie]

Note you must use either 2421 or 2426 drive specification with the 3145 crossover. The 4343 uses 2420.

Ian

[B&KMan]

Note you must use either 2421 or 2426 drive specification with the 3145 crossover. The 4343 uses 2420.

Ian

Thanks for reply,

yes the drivers is not same and it is my hypothesis for the nature of the problem

http://www.audioheritage.org/vbullet...&postcount=418

i have a feeling the 2420 have problem to go more higher and is have a big notch instability arround 2 k. So impossible situation here in this set-up : big upper notch in start and too drop hole at finish. I'm shure the 2405 is pushed more lower in version of 4343 for patch this problem. But creat a notch response on start.


--- the first conclusion of this upgrade is not fully success if you keep the original diaphram of the 2420...

Of course the soundresult is, for many aspects, better . But, because more transparent: the notch and hole is.... more exposed...



if any members have idea, please post-it




Jean.

[Ian Mackenzie]

Well buy a 2426 diaphram!

[B&KMan]

Well buy a 2426 diaphram!

Hello Mr.. Mackenzie,

I hope not to appear too critical to you with all your good councils, but I read several point of sights which regard the titanium as too
metalic and which the best choice would be the 2421...

Can more expose your opignion please.

Thnaks

Jean.


In other way I suspect maybe the L-Pad is part of problem so I tried to work benchtest of pad befare running big money for diaghragm.

[B&KMan]

I have no idea why you decided to upgrade to a new equivalent crossover without upgrading your drivers...you appear hopelessly confused:dont-know and while your predisposition with vibrations is interesting its not the point of the exercise.
My expertise in vibrations extends well into the sub octaves, Pooo!

The 2121 diaphrams are very expensive and less robust then the 2426 diaphrams. The latter is still much better than the 2420 dias, smoother and sweeter. Its the best improvement along with a 2122 recone for your system.

I have used the 2426 diaphrams from some years now and you never hear me complain.

I dont know what is the problem with you and me but actually the level of insult is higher and only on your way...

I write with difficulty in english, and I started a modification of my 4343,

I sended over 10 posts for verified the compatibility with drivers....
for your great expertise is maybe appear stupid to not upgrade at same time but...
this is exactly the interest of the forum... share information.

it is easy to shit on the guy is not know..
and you have not only to posess the truth...



because I have tool and expertise into vibration, I have decided to exchange information with members. it is my gift action for recognize the helps of members in my quest. This aspect is big aspect of 4343 modification and it is include in many serious design...

nobody is perfect,

(look as your own post : you wrote 2121 instead of 2421 ).


I appreciate your reply information and thanks for that...

I hope your "bad vibration" on me is not too low and power.


Peace Mr. Mackenzie !!!!

[Tom Loizeaux]

Jean,
Your work on your 4343s has been of some interest to me as I too have a vintage pair of these. Your zest for rebuilding these and efforts in trying to improve these is all a bit over my head. Your interest in re-designing these crossovers in more ambitious then anything I would attempt.
When I rebuilt mine, I tried to restore them to original specs. I had to repair the cabinets, do major clean up on everything, replace the fiberglass, repair the grille frames, find replacement nameplates (thanks Guido), and re-foam or re-cone drivers. I also tried to upgrade the caps in the original crossovers. I installed some quality caps and did some bypassing, especially on the HF and UHF circuits.
Over the past year I've carefully adjusted my active crossover, set levels and adjusted the balance with my power amps and L pads to get what I think is nearing the perfect balance.
I did buy a pair of JBL 2421 diaphragms, but haven't installed them yet because the original ones still sound really great.
I feel that one needs to make small changes, and make them one at a time, in order to know what difference they're actually hearing. Too much too fast only leads to uncertainty.
This fall or winter I plan to open my 4343s up again. Then I'll install the new diaphragms and I might put in a few more high end caps. I consider this part of my slow, fine-tuning process.

I will read about your efforts and percieved results, but I'll take your experiences and advice very cautiously.
Thanks again for your enthusiasm!

Tom

[B&KMan]

THANKS AGAIN AT ALL MEMBERS IS KEEP TIME TO PERMIT REALISATION OF THIS PROJECT, SORRY IF I PUSH YOU TO REPEAT AND STANDY... BUT I SEND TON OF PICT AND TEST RECOMMANDED BY YOU, I FEEL HONEST IN MY WAY BUT FEW MEMBERS IS NOT REALIZE THE DIFFICULTY TO PLAY IN FUNDAMENTAL THEORY WITH A POOR LANGUAGE AND NOT FORMATION IN THIS FIELD...

I'M KEEP SUPER FEELING FOR SUPPORT OF THIS FORUM AT ME WITH THIS LONG THREAD BUT MANY FUNDAMENTAL QUESTION IS TALKING AND I HOPE TRACE OF THIS QUEST HELP MANY MANY GUYS. THIS PROCESS EXPOSE THE DIFFICULTY TO SURPASS THE ENGENEERING CONCEPT. AND MANY CONTROVERSE EXPOSE THE WAY OF EACH AND COMPROMISE...

OF COURSE BETTER SIMPLE NETWORK BETTER OUTPUT BUT IN FEW CASE MANY TWEAK IS BETTER THAN SIMPE APPROACH.

IN FACT YOU HAVE OVER 8000 VISITS IN THIS THREAD EXPOSE THE INTEREST OF FEW POEPLES.

I SEND THE FINAL PICT ON THE COVER OF THE BACK PLATE OF "BIGNET" (DEFAULT NAME).

THANKS PARTICULARY AT
:
MR MACKENZIE,
MR WIDGET,
MR GISKARD,
MR ZILCH,
MR EARL K,
MR GUIDO,
MR ROBH3606,
MR TOM LOIZEAUX,


AND FEW OTHER IS INSPIRE SUPPORT AND TRACE THE WAY OF THIS PROJECT BY EXCELLENT REMARKS, SUPPORT SPEC AND MATERIAL AND EXPERIENCES.

I HOPE MY LITTLE EXPERIENCE IN VIBRATION IS EXPOSE CERTAINS UNUSUAL ASPECT OF CONCEPTION AND FEEL FREE TO HOPE ANY QUESTIONS IN THIS REGARDS. ( THIS IS MY CONTRIBUTION)



NOW I LIVE FOR MONTH IN VACANCY AND IT IS TIME TO PLAY LOUD BEFORE !!!!






THANKS JBL GANG


Jean.

[B&KMan]

I SEND THE FINAL PICT ON THE COVER OF THE BACK PLATE.

heres.

put hand soap for fill in the plywood : it is really tight set-up anf tuff the speaker is go away... shure it is not fill on sand...

by the sand this sans is silice sans (same as sand blaw of pool filter it is more weight of sand and it is more density... for abrasif fume (be shure you run this with adaquate instruction)

[B&KMan]

by the sand this sans is silice sans (same as sand blaw of pool filter it is more weight of sand and it is more density... for abrasif fume (be shure you run this with adaquate instruction)

OHHH BTW I put 1 and 1/2 bag of this sand so the speaker is increase weight by another 120 LBS (50 Kilos) add 50 lbs for network + 180 lbs of original weight of speaker the final is 250 LBS

Why the bass is snap realy tight and fast ???

anyway this is a first 4343 beach JBL. ans the sound is the sea


AHHHH paradise ???