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View Full Version : JBL 4311 behaviour: nomal or faulty units?



Malefoda
08-17-2013, 01:47 AM
Hello there,

a first word to tell you the last mileI've done in speakers:
I am pleased with my silky sounding B&W DM4s. Well, as a rock head I want impact and sense of life. I've been advised to try 4311.

I'm now the owner of the serial 10027 and 10174.
My first exeprience is terrible. Lows, not much, highs, too much, way too much, and about mids... have that feeling of phase problem, if I move my head I can quickly shift from "deaf zone" to "mids! but only one side" like a story of peak waves and cancellations.
So my question is: can they be tricky to the point the way they are placed play that much? Do they sound that way? The fact the serial numbers are almost 150 units distant and that I've read they do changed the mids phase makes me wonder, and in my head or a real issue I d'ont know. I'm really worried in opening them, don't wan't to damage them therefore taking advices before surgery or sorrow...

Thanks fellows,
Matthieu

Mr. Widget
08-17-2013, 10:11 AM
Unfortunately with vintage speakers it is impossible to really know if all of the parts are original or are still operating within the original specifications.

With that in mind, I'll say that these speakers have very little bass if stand mounted in a large room... and the bass is extremely pumped up if the speakers are near room boundaries in more modest sized rooms, so placement and the room itself makes a huge difference. Regarding the high frequencies, realize the L-pads make a huge difference and need to be set properly. Due to age and not knowing if the speakers are still original and properly working I wouldn't expect the printed markings to be an accurate indication of where you will find flat response.

Then again these speakers were never really "flat". When operating as designed they have a slightly pronounced and forward midrange.


I hope this helps.


Widget

Malefoda
08-17-2013, 12:02 PM
Hi,

yes it helps, I've moved them just a bit and now their sound is better, not good but better.

I've taken screwdriver and, holding my breath, checked the wires: at least on mids they are the same color code, had no chance to check if they were inverted at the xo. I guess they deserve a xo refresh as suggested, and later a " real " xo ( Murphy vs Troels Gravesen ). Any direction to set the 4311s according to my room's picture? It's on the long wall, the room being 20m2.

Thanks!

hjames
08-17-2013, 01:22 PM
Aren't they upside down?
I had a pair of 4312As and on mine the Woofers were closer to the floor, the tweeters up near ear level ...




Hi,

yes it helps, I've moved them just a bit and now their sound is better, not good but better.

I've taken screwdriver and, holding my breath, checked the wires: at least on mids they are the same color code, had no chance to check if they were inverted at the xo. I guess they deserve a xo refresh as suggested, and later a " real " xo ( Murphy vs Troels Gravesen ). Any direction to set the 4311s according to my room's picture? It's on the long wall, the room being 20m2.

Thanks!

59760

Mr. Widget
08-17-2013, 01:53 PM
Aren't they upside down? Yes and no... the label is right reading in his orientation as they were designed to be placed upon the meter bridge so this orientation places the tweeters and mids near ear level when used in an old school studio. On these stands I would invert them with woofers near the floor. That said, I don't Malefoda will ever get this speaker to perform the way he wants... wrong speaker for this listener.


Widget

Malefoda
08-17-2013, 02:02 PM
That's quite hard to read but if, playing with l-pads to get my mono records sound even and centered, so in short l-pab balanced, if I don't like them I'll will agree, not for me.

Mr. Widget
08-17-2013, 04:58 PM
The L-pads are for balancing the individual speakers' tonal balance... not left-right balance. If you need to screw around with them to balance them to get a mono signal, it sounds like you might have other issues.

Unplug one speaker and balance the other until it sounds "right". Then do the same with the other... if they end up at different sensitivities try using your preamp to balance left-right. If there is something grossly wrong with your speakers they will not balance. With old speakers having a partially defective driver is pretty common. You can look at the networks, but these speakers essentially rely on their drivers... there is almost no network at all.


Widget

pos
08-17-2013, 07:55 PM
Lows, not much, highs, too much, way too much, and about mids... have that feeling of phase problem, if I move my head I can quickly shift from "deaf zone" to "mids!
This is probably due to Alnico demagnetization of the woofers (they might have seen too much power at some point...).
This affect both the sensitivity and the response of the woofers in the medium.
You should get your woofers recharged before attempting any costly xover modification...

Try contacting Christian from Restaur'audio in Rouen, he is probably the best specialist you could find in France to deal with your problem.

fabrice11
08-18-2013, 12:33 AM
This is probably due to Alnico demagnetization of the woofers (they might have seen too much power at some point...).
This affect both the sensitivity and the response of the woofers in the medium.
You should get your woofers recharged before attempting any costly xover modification...

Try contacting Christian from Restaur'audio in Rouen, he is probably the best specialist you could find in France to deal with your problem.


yes probably a fairly common problem demagnetization of these vintage models
I had to problem with my pair of 4310 for all re-magnetization of alnico speakers JBL ALTEC there are also EMS speakers in Béziers (34500)

Malefoda
08-18-2013, 12:49 AM
Great... and scary at the same time,

I still have to check phase on the woofer, but what you said makes sense as if I want a ear-matched level between the woofer and the mids I have to set mids not much than 2/3 on the 10 scale.
Money being a factor, I'm scared shipping via La Poste heavy speakers (magnets only?) will cost me much, the remagnet itself... add that to the price of the speaker... OMG costy like a used car!

pos
08-18-2013, 03:20 AM
Those woofers are not too heavy, probably less than 6kg each, but you need special care when shipping them. Bolting them to a wood board the size of the box with rigid protective material on top should still end up under 15kg, which I think cost around 20€ to send in colissimo.

Malefoda
08-18-2013, 04:02 AM
Can't wait to say it: one woofer in reverse phase!! I have the original "technical manual" and color scheme does not match, and each speakers feature different color wires... previous owners deaf? o_O
Woofer moves forward with a tiny battery polarity test, plus on red terminal... mid moves backward... o_O' is it normal?
At the end don't know what's in phase or not. At least the woofers were different. Quality control... not at JBL's at that time.
....
some screws later..
....
Having to decide which woofer is right and wich is wrongly wired, I've set both to: red-red and black-black, so if hooked a battery at the back panel they will both move forward. Did not touched the mids and even never unscrewed the highs.
Well, like said Boston "more than a feeling", now it images nicely and the very first record I've put in get me straight into the music!
If it sounds like a speaker is out of phase, it is. I'll keep that as true to my ears.

Still, anyone can tell me the real deal with the mids phase reverse? From factory? Or in short any real world XO drawing anyone?

I wonder about the previous owners...
Thanks gents, I'll still keep the remagnet as a "to do", I'm going to discover what they sound like now!

Matthieu

pos
08-18-2013, 06:21 AM
Problem solved! :applaud:

The black=forward is normal for JBL speakers of that era, and should still be the case at the binding posts of the speakers, so you should simply wire your woofer to get that positive black=forward behavior at the binding posts...
If you want to use them toghether with another speaker (center channel for example) then you should reverse the polarity of course.

Here is the technical manual with proper wiring colors:
http://manuals.harman.com/JBL/HOM/Technical Sheet/4311B ts.pdf

Mr. Widget
08-18-2013, 10:37 AM
If you want to use them toghether with another speaker (center channel for example) then you should reverse the polarity of course.
Yes, and the reversal if mating to other speakers should be done at the terminal posts don't change it internally.

Follow the wiring diagram and let us know if they've become more to your liking. Even properly working they really are great for vintage rock but not necessarily an "across the board does everything right" speaker.


Widget

macaroonie
08-18-2013, 12:14 PM
4311 wiring diagram and schematic diagram here ......

http://www.jblproservice.com/pdf/Studio%20Monitor%20Series/4311B.pdf

OOPs , same file as Pos , different location.

pos
08-18-2013, 11:38 PM
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
08-19-2013, 02:39 AM
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/NAVIGATION/pdf_nav_tech.html

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

Malefoda
08-19-2013, 01:38 PM
Here is a drawing of the colors used.
59796

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
08-19-2013, 02:35 PM
Here is a drawing of the colors used.
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
08-19-2013, 04:00 PM
Hi Matthieu , you are still wrong.

look here is the schematic

59789


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

59790

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
08-20-2013, 05:46 AM
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
08-20-2013, 07:59 AM
Oops - deleting my comment to avoid confusion -


I concede to the Glaswegian!

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=59789&d=1376952864

macaroonie
08-20-2013, 08:47 AM
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
08-20-2013, 11:02 AM
^^^
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
08-20-2013, 11:25 AM
Now I know :D. 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. :eek:
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?

59797

rdgrimes
08-20-2013, 01:34 PM
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
08-20-2013, 01:49 PM
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
08-20-2013, 01:55 PM
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
08-20-2013, 02:27 PM
I mean the mistake is the reversed phase of only one woofer ;)

macaroonie
08-20-2013, 05:48 PM
Now I know :D. 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. :eek:
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?

59797

Bravo :applaud:

Malefoda
08-21-2013, 12:18 PM
From my technical manual.

Wagner
08-30-2013, 04:22 PM
Member "4313B" has answered this question 100 times already that I know of, AND posted a chart indicating correct woofer behavior (in or out) when wired properly (all the 4310, L100 and derivatives).
The last woofer used in the LATE version L100A (123A-3) is the opposite from all the others, I do know that (VC winding) so the WIRES will look ass backwards inside the box.
I have searched for you but so far can't find the chart.
I printed myself a copy but can't find that either.
Most useful that chart; should be a "sticky".
I think this is the millionth time this subject has come up with this family of 3-ways!

IF I remember correctly, ALL of the L100s when properly wired (forget about colors) will have an OUTWARD cone excursion with the battery test (POS on "RED" at the speaker hookup terminals)
As for the 43xx models I seem to remember there was at least one exception.
Hopefully "4313B" will see this and answer your question as to what is the correct wiring.

Thomas

Malefoda
09-01-2013, 05:25 AM
Thanks =) , sadly it seems that these infos from member 4343B are drown into millions of threads, I haven't found these.
If anyone can point the posts or threads that would be great.

Wagner
09-02-2013, 11:29 PM
I still can't seem to find the link to the original thread and post by "4313B".
This is all I have for now.
Thomas
Note: It would appear that my original comment regarding ALL variations of the L100 woofer cone movement (ALL versions moving OUTWARD) may have been made in error based on the information found in this chart. I still think (seem to remember some discussion) that there's more information (data) on this as a companion to this piece and there MAY be a typo involved somehow? Also, the tweeters shown for the L100A, the LATE L100A should be the LE25, not the LE20-1. HF and MF appear to have been inadvertently switched while making up this chart as well. The original vertical L100 did use the LE20-1 tweeter (Alnico) as well as the C533 as far as I know (I would assume). ALL models did use the LE5-2 MID if the tech sheets are true. Sorry my memory is so faulty on the subject. I still don't know with certainty if my Late L-100As are wired correctly; the color coding also changed during the 3 production runs and the "tech" sheets don't identify the actual driver terminals to use (like the owner's manuals do).

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=72&stc=1&d=1052929064

Malefoda
11-12-2013, 03:16 PM
As it was pointed -prior to any troubleshooting- that theses speakers may not be of my taste, well right now I don't feel the need of building a crossover or such. I'm really pleased with the sound!
Yes it can have been clearer in the mids and a bit too much on "s" and "f" but it does rock! I think it's more an amp question now. Played a bit with a Sansui AU999, nice and round bass, even if not too deep sadly, made it a pleaseure to listen to at very low level. Highs and image are not that clear, my TK2050 amp does it better there, bass are more extended but tighter and/or less present. Will try some more, maybe more powerfull than these 50wpc amps... a TA3020...