Defect capacitor on JBL 4344 ??

[Madien3388]

I would like to learn more about modern capacitors and their benefits in comparison with old JBL original ones. Has anyone already tested several types of new capacitors to replace the original ones of the vintage JBL filters ?

To summarize, there are the following brands:
-Kimber
-Auricap
-Solen
-Hovland

Chas and Ian adviced me some of these. As I might have to replace the damaged capacitor (and also I will probably upgrade the filters in the next months), I would like to know what would be the better choice.

Modern capacitors bring better resolution, more accurate sounding, so if someone knows the different benefits of some of these models, it would be great.

Many thanks!
Damien

[Ian Mackenzie]

If you can find a cheap Mylar capacitor put that in there but frankly I dont see the point if you test the capacitor and its okay or you plan to upgrade.

[doodlebug]

Has anyone already tested several types of new capacitors to replace the original ones of the vintage JBL filters ?

To summarize, there are the following brands:
-Kimber
-Auricap
-Solen
-Hovland

Many thanks!
Damien

Here's a thread over at AudioKarma with links to quite a few capacitor shootouts.

http://www.audiokarma.org/forums/sho...citor+shootout

IMHO, you are asking question that has as many opinions as there are posts. Ultimately, there is no right answer.

Hope that helps.

Cheers,

David

[Madien3388]

Thanks !

Yes I will test the capacitor and will of course keep it if it is OK.
If it is damaged, I will indeed find a Mylar one to let the filters as orginal as possible.
And in the next weeks/months, I'm going to find another pair of filters to tweak them with better components.
Damien

[Madien3388]

So, I have tried to remove the board where the capacitor is but bad surprised, the inner wires from the L-pads has been soldered to the filter! There is no way to remove them. I have tried very hard but I am afraid to damage the cables or connexions.
Because of these solderings, there is no way to remove the filters from the cabinets.

Now it is impossible to bring the filter to the shop to measure the capacitor...
I have to remove the solderings but if I make a mistake, it will be very difficult to put the cables in place afterwards.

Is it possible to remove the solder on this little connexion ?

Many thanks
Damien

[Ian Mackenzie]

I am not surprised.

The terminals were loose on the 3145's I have examined.

You would need to suck/wick out any surplus solder and possibly heat while lifting with pliers.

Given the way this is panning out I would leave sleeping dogs well alone.

Ian

[Madien3388]

I am not surprised.

The terminals were loose on the 3145's I have examined.

You would need to suck/wick out any surplus solder and possibly heat while lifting with pliers.

Given the way this is panning out I would leave sleeping dogs well alone.

Ian

Thanks Ian
By "Given the way this is panning out I would leave sleeping dogs well alone", do you mean that I should let the filter as it is and avoid to try to unsolder the pliers ?

I have 2 possibilities

1) Test the speaker without removing the capacitor:
- a) First test : In bi-amp mode, I turn the L-pad gain at the minimum for the 2122 and 2405, and switch the bass amplifier off. So that only the horn will be at normal level. In this way, I could listen (women voice track for example) to see if I can hear some differences between the 2 speakers.
I don't know if it is a good test or not, but I least I could isolate the horn sound.
- b) Other test possible: With my measurement device, I could also do some measures with horn L-pad gain to the minimum on both speakers, and another measure with gain at maximum to see if the horn curves are the same.
- c) Last possibility, to use a LCR meter directly on the "damaged" capacitor and measure the value (without unsoldering a leg). Then do the same measure on the other speaker's capacitor. Even I do not measure the capacitor value itself, I should find the same value in both speaker, shouldn't I ?

2) If I want to improve the original filters or replace them with modern ones, I will be obligated to remove these solderings on the pliers... So, even if the solution 1) is a good idea, I have to find a way to remove these pliers.

What do you think. Are solution 1) possible or irrelevant ?

I am very impressed of the knowlegde of most JBL forumers on audioheritage. It's great to learn so much about improving and better using such great speakers.
Thanks again for your help !
Damien

[Ian Mackenzie]

I think you will have great trouble making any measurments and comparing them.

Save your effort the upgrading the networks.

What you should do is calibrate the L Pads.

I wrote a simple but highly accurate means of doing this in the 4343-4344 upgrde thread.

Ian

[Madien3388]

I think you will have great trouble making any measurments and comparing them.

Save your effort the upgrading the networks.

What you should do is calibrate the L Pads.

I wrote a simple but highly accurate means of doing this in the 4343-4344 upgrde thread.

Ian

Thank you Ian

To upgrate the network, I will need to remove the original ones. Do you think it will be feasible to remove the solder on the pliers, without damaging them ?
Damien

[ratitifb]

from my opinion it would be better to remove all terminals and re soldering all stripped wires directly on PCB

(depending on your skill and hardware availability)

take pictures and schematics before removing all wires

[Madien3388]

from my opinion it would be better to remove all terminals and re soldering all stripped wires directly on PCB

(depending on your skill and hardware availability)

take pictures and schematics before removing all wires

Thanks Ratitifb, but if I do that, I will not be able to remove the filters from the cabinets anymore.
I would like to replace the networks within the next months, so I need to keep the connexions with "pliers", so that the cables can be easily deconnected.
Damien

[Ian Mackenzie]

I could not comment without working on it directly.

As I said leave it alone .....look for trouble and you will find it.

Based on your posts you really need someone qualified on site to look at it.



Ian

[Madien3388]

I could not comment without working on it directly.

As I said leave it alone .....look for trouble and you will find it.

Based on your posts you really need someone qualified on site to look at it.



Ian

Thanks Ian, you didn't plan to come for a trip to Paris in the next months ?

[Madien3388]

Ian, one question please: Are you sure this capacitor is linked to the 2421 horn ? Would it be the 2405 instead ?
Because I have noticed (with my measurement device) a significant difference of level between the 2405 level between the 2 speakers.
Thanks
Damien

[ratitifb]

By doublechecking the 3145 Xover schematic and seeing your previous picture of the gooped capacitor (printed as C7 on PCB) we can understand that only C7 in HF section is equal to 3µF

A new problem with UHF

http://audioheritage.org/vbulletin/s...3144+schematic