JBL 4311 behaviour: nomal or faulty units?

[pos]

OOPs , same file as Pos , different location.

It looks like the heading section on your version has been redone with vector graphics!
It is nice to see that JBL putting some effort on the vintage stuff documentation (now if only they could also put some effort on the recone kits, old and new )

[macaroonie]

It looks like the heading section on your version has been redone with vector graphics!
It is nice to see that JBL putting some effort on the vintage stuff documentation (now if only they could also put some effort on the recone kits, old and new )

Don't hold your breath.

Here is the global link to tech pdf's http://www.jblproservice.com/NAVIGAT..._nav_tech.html

It does get updated as there is info on VTX although none I have seen on M2

[Malefoda]

Here is a drawing of the colors used.


As for the sound I did a Led Zeppelin "In My Time Of Dying" test... joyfull and all I was looking for, foot tapping by the firsts seconds! The drum kit sounded more alive than ever, the kick, the soundstage is far faaaaaaar better than my old B&Ws, I love them already! Wo needs anything else with all that life and body & soul pleasure? I don't! If can tune finely for a bit of clarity and it will be heaven! This is... yes I'll do that stupid joke Stairway to Heaven! We did not feel the need of trying the B&Ws back, just to package them and put them away!
(maybe it can't be seen on my room's picture but the are slanting by few degrees backward)

Matthieu, JBL worshiper now!

[hjames]

Here is a drawing of the colors used.
Attachment 59788

As for the sound I did a Led Zeppelin "In My Time Of Dying" test... joyfull and all I was looking for, foot tapping by the firsts seconds! The drum kit sounded more alive than ever, the kick, the soundstage is far faaaaaaar better than my old B&Ws, I love them already! Wo needs anything else with all that life and body & soul pleasure? I don't! If can tune finely for a bit of clarity and it will be heaven! This is... yes I'll do that stupid joke Stairway to Heaven! We did not feel the need of trying the B&Ws back, just to package them and put them away!
(maybe it can't be seen on my room's picture but the are slanting by few degrees backward)

Matthieu, JBL worshiper now!

AWESOME - so that was the problem, one woofer was out of phase with the other so the low bass simply got cancelled out!

Wish all problems were so easily solved! Kudos on your troubleshooting chops!

[macaroonie]

Hi Matthieu , you are still wrong.

look here is the schematic




You can see that Positive ( red ) terminal goes to the green / black wire which goes to the negative (black ) terminal on the bass driver

In your diagram this is the correct one



It is confusing and has been the cause of many sore heads over the years. Hope you get it fixed , it will be even better.
PS Check your other connections also

M

[Malefoda]

Oh yes you're right, in fact it's the plain black wich has been used instead of the plain green on the second speaker. And if it's even better that's great
Also that means all three speaker drivers are in phase, the way I've done it the woofer were in reverse phase. Anyone can confirm me that they should all perfom in phase please?

[hjames]

Oops - deleting my comment to avoid confusion -


I concede to the Glaswegian!

[macaroonie]

Sorry Heather but you are not quite right. The mid is oop with respect to the other drivers. Look at the incoming connections

The simplest way to do this is as follows.

For each driver the colour + black wire goes to the -ve terminal on the speaker ( black )

All the phase inversion is done at the crossover so you need not worry about that.

green / black to bass driver -ve Black terminal

white / black to mid -ve Black terminal

yellow / black to tweeter -ve Black terminal

[rdgrimes]

^^^
That's the default color scheme on virtually every JBL model. Where people usually get into trouble is when wires are swapped at the crossover board. Some models have them soldered onto the crossover, some use spade plugs. Using the available schematics from the library here will eliminate any doubts.

[Malefoda]

Now I know . Before I've been in doubt as one has a green - green/black and the other, black - green/black the later being on the red terminal.
So here we go with le black on the red... wire was too short, that's why in factory the bad guy inverted the wires, wanting to get his beer asap... I've exetended the wire, but can notice that short black wire is of thiner gauge than the green one. What kind of wire in there? Tinned copper?

[rdgrimes]

There's no reason to think that anything like that happened in the factory. I'd be more concerned with confirming that the wires are on the correct posts on the crossover. The presence of the black wire screams out that someone was messing with them at some point, (which is common in speakers of this age), meaning that the wires could be swapped at either end, or both.

[Malefoda]

We'll never know... but it seems famous that KBL did mistakes about polarity. Anyway, I've checked both sides of the wires, no doubt anymore. Thanks for the full check recommendation.

[pos]

it seems famous that JBL did mistakes about polarity

It is not a mistake, just a convention (and not only a JBL one I think).
Black = forward, why not? Think about a microphone...
The problem is when you want to mix those with speakers from other brands!
This is exactly like the British driving on the left side of the road: all is well until they disambark from the ferry boat at Calais :P

[Malefoda]

I mean the mistake is the reversed phase of only one woofer

[macaroonie]

Now I know . Before I've been in doubt as one has a green - green/black and the other, black - green/black the later being on the red terminal.
So here we go with le black on the red... wire was too short, that's why in factory the bad guy inverted the wires, wanting to get his beer asap... I've exetended the wire, but can notice that short black wire is of thiner gauge than the green one. What kind of wire in there? Tinned copper?

Bravo