4343 crossover modifications

[Zilch]

I trying to analyse all info for build Dc biais circuit on my speaker this week...

SO, no more concers about potentially losing the JBL "Signature Sound?"

[Sorry, low blow....]

[Earl K]

Hi Jean

I re-read my post and I add other info of solen Cristian Opignion.

1--- Caps is fragile in vibration and it is important to fix for minimize the tribo-electric effect.

A-- never glue with hot gun glue it is too hot and destroy the caps
B-- Never tarap in center you deform the caps and altering the result
c-- Tarap on each side is really better or glue with epoxy of glue.

(My experience of ingeneering vibration is the result is great if you fix caps
with the harder glue as possible for minimize the signature vibration of glue: epoxy or crazy glue is top.
Bee wax for temporary set up is best.

Personnally I put crazy glue of all caps Into my modification. So all is fixed by other caps and glue into board of network... It is " crazy" but realy best solution

I hope this info is happy for build better set-up.

- Your views on "Micro-Vibrations" are very interesting .

- My favourite cap ( in the house ) has the film fully "encased" within a layer of epoxy ( I cut one open to look at why it was so big ).

- I can't talk now / since I'm on shows till next weekend .

- Maybe sometime we can just talk about capacitors & micro-vibrations ( best , in the Off-Topic section ).

- As I mentioned before, I don't have a 4343 / so my usefulness in this thread has just about expired except to act as a cheerlleader for DC biasing .

[B&KMan]

SO, no more concers about potentially losing the JBL "Signature Sound?"

[Sorry, low blow....]

execellent touch point...

Unfortunatly, this is my big hauting memory in this adventure... :shock:

well, in one hand: the driver, cabinet and cable is build a particular équilibrium sound. And any upgrade is maybe destroy this equlibrium by improvement one aspect in regards to the rest.

And other hand the original part is scrap and not available, many upgrade in regards of theorical approach... multi-caps, dc charge, upgrade cable to monster cable, pressWood to MDF on Jbl evolution proof to improve design with out loose signature...

Well I try to keep signature of each and try to respect that, But, never I put third part diaghram into driver (ex)...

So I hope to build improvement with not loose the JBL equilibrium signature...

It is delicate process and I try to keep the maximum info before attemps any modification.

In this case I big respect and recognition of this forum to help improvement with minimum wander in the ways of upgrade ...


Jean.

P.S. The final result is post after complete test rodage (5 weeks) I promise...


==========

[Ian Mackenzie]

SO, no more concerns about potentially losing the JBL "Signature Sound?"

[Sorry, low blow....]

What exactly is that?

East Coast you mean...LOL, and more recently Mid West tending towards East Coast...I mean hello. Then there is a Japanese signature?

Perhaps the best approach is a crossover network that has no undue influence in terms of distortions and colourations. The signature therefore transends from the drivers* themselves and the voicing and blend created the the network.

If we look at the evolution of JBL crossovers, the trend has been on capacitors mainly. Non polarised film, then bypassing and more recently charge coupling. Obviously they are looking to extract the most from these passive elements comensurate with cost as distinct from the behaviour of the drivers*.

Ian

[B&KMan]

3144/3145 biased ( post 100 in this tread )

Hi Giskard

I analyse many informations and schematic 3144/3145...


1--- Why you change serial caps to parralle caps ???
the 3 set caps for med hi and uhf is mounted in parrallele ....

2--- I'm not familiar in DCR expression what is this and why not change by a air core ???

3--- the value of the schematic is not for my component 2231 , 2121, 2420...
The value it is equivalent and compatible ????


Thanks again Giskard for your time.

[4313B]

1--- Why you change serial caps to parralle caps ???
the 3 set caps for med hi and uhf is mounted in parrallele ....

I did alot of quick cutting and pasting. I'll fix the schematic and replace it.

2--- I'm not familiar in DCR expression what is this and why not change by a air core ???

DC resistance of the coil. In this schematic the specific DCR values are selected to properly affect the knees of the curves (parallel coils) and the attenuation (series coils) for the HF and UHF circuits. The iron core inductors on the LF and MF transducers should be replaced by air cores where possible. A DCR value for them in the 0.4 ohm to 0.6 ohm range should be fine.

3--- the value of the schematic is not for my component 2231 , 2121, 2420...
The value it is equivalent and compatible ????

The values of the schematic are for the transducers specified. The 2420 should work "ok". The 2121 should be replaced by a 2122 or should be reconed as a 2122. The 136 and 2231 were long ago replaced by the 2235H. The 2235H recone kit (C8R2235) is the recone kit for the 136 and 2231.

[B&KMan]

I did alot of quick cutting and pasting. I'll fix the schematic and replace it.


[i] The values of the schematic are for the transducers specified. The 2420 should work "ok". The 2121 should be replaced by a 2122 or should be reconed as a 2122. The 136 and 2231 were long ago replaced by the 2235H. The 2235H recone kit (C8R2235) is the recone kit for the 136 and 2231.

Hi Giskard,

Thanks for specification,

1-- The 2231A is recently recone (last year ) By 2235 kit replacement
2-- The 2121a is recone in same time by last original cone kit 2121
3-- The 2420 is run ok so I'm happy to not change (over 500$ for 2)
4-- The 2405 is recone yesterday by original cone kit...

well you redraw the schematic it is possible to change value for air core please ???

And finally what is big difference in 2121 in compare in 2122
(all is 8 ohms dc resistance... right ??)
the big difference is :

---inpedence ??
---frequency response ??
--- Sensibility ??


Thanks again for all.

Jean.

[B&KMan]

What exactly is that?

Ian

this guys is tease me because I'm start my investigation in effect of modification and respect in same time the JBL Sound signature...

It is fair and proof to read seriously the entire thread...

For complete my info pict...

Look the difference of the 2231 after cancel switch and put fresh caps film and foil of solen in higher section...

What a big difference....

Of course my monitor is not slam same because the response around 40-50 hz is more 6 dB of normal response (in mic at near field) so the correction is sound more flat but more correct, the texture of the entire sprectre is better, but less slam... but the pict is value of 1000 words...
the elect2231 is response before modification
the after2231 is response after modification
the thin line is the fr. cut of crossover
the bold line is explain fr.

What the difference !!! no rodage in this case because never altering diaghram and soldering....

Realy better....

[B&KMan]

this is probably the higher controverse result of this modification.

In touch directly the problem on fast caps versus slow caps in according the compression driver.

the result before is more smooth curve because the caps absorbe the harmonic response of diaghram driver....

but in other hand the drive is more fast and more details because the caps is more fast...

P.S. the caps is not burn-out complete, so, maybe the response is change in the time...

What your feeling in this regards.....

[4313B]

well you redraw the schematic it is possible to change value for air core please ???

Done - I replaced the schematic in post #100

All the inductors are air cores except the two largest on the LF and MF. Those can be heavy gauge air cores or something like an Erse iron core if desired.

[Guido]

A-- never glue with hot gun glue it is too hot and destroy the caps

I don't see that. JBL and many other speaker companys did that. I did that too.
Soldering is more dangerous.

[4313B]

The hot melt glue can damage the capacitors but not if you're careful. I've personally never had a problem as I was warned from the get go to let the glue cool a tad before jamming the components into it. You're right - soldering is more harmful, so an alligator clip heat sink helps.

[Robh3606]

"Soldering is more dangerous."

Only if you really are a novice. As long as you don't heat the lead for more than a couple of seconds 3-4 you should be fine. You have to remember the parts are rugged enough to withstand the normal commercial manufacturing process. That includes hand soldering, wave soldering and IR reflow both of which preheat the part to within about 50 degrees of the solder reflow temp. With the new no lead solders used overseas and eventually in the US the temperatures are even greater than the lead solders here. If the part cannot survive what is considered normal handling without significant degredation this is commercial suicide for the manufacturer.

Rob

[Ian Mackenzie]

Jean,

Your work is interesting, But are these curves the calibrated mic response or are they the measured voltage drive to the actual drivers?

Ian

[B&KMan]

I don't see that. JBL and many other speaker companys did that. I did that too.
Soldering is more dangerous.

Hi again,

Now your enter in my specialisation...

all vibration cancellation is tribute to the type of system you work !!!

Any material have a signature coloration ( )

So the first modal response or ( in ingeneering) , 3 first modal responses create a strong signature material, So if you put your caps, in steel : probably your result sound with little taste of steel.

All test vibration is intimate associate with the method of fixation of accelerometer transducer ( mic of material) and any type of glue or mechanical system is exaustively explain in ANSI and ISO methods around the world...

The signature of all smooth material include hot glue, rubber, sarbothane or any other have a heavily damping factor absorbtion vibration. the problem in this question is simple and complex. and probably send a complete thread just for this question....

the problem is " the time dissipation is more slow" in regarsd of the intervale of next exictation... ( I resume very fast). So, the time to energie is down is limited in regards to the next excitation create a higher level noise (rms) floor and induce a higher interference by a hard mecanical system.

this is the same reason any hard and heavy weigh surface is more efficience for dissipation of peak (not rms) ....

But for now nylon and any hard glue is more preferable to soft fixation because the energie dissipation is more fast and the caps and other sensible electronic parts is transfert more fast bad vibration in other material...

Maybe it's possible to put a hot glue with-out damage the caps, but anyway,
Maybe glue maybe not , maybe altering inside material with-out exterior sign...
Anyway, this method is poor if you compare at epoxy or crazy glue or any hard fixation !!!!!!!!!!!!!!

By the way, any crossover system is really improvement if you build in composite heavy weight swandwitch board !!! No difference ??

yuk yuk yuk Copernicus say " nontheless is turn !!! "

Any down bkgnd level vibration more clarity and micro information, more dissipate any halo effect and signature!!! If you put down fast dissipation below more than 10 Db you realize a drastic benefict effet on natural and clarity sound result...



I hope start a complete thread in this major aspect on all electronical and mecanical parts if you hope

Jean.