Crossover for JBL 4311-4312 series?

[ole]

Hi!
This is my first post, but I have followed the forum for some time.

I have been away from DIY for many years but decided to try and build something out of a couple of JBL 2213H, LE5H and Dynaudio D21-AF as a clone of the famous monitors. I have these drivers since 15 years and thought I might as well do something useful with then if possible.

I wonder if anyone knows about the crossover design or even has a schematic of the old studio monitors from JBL.
Or maybe any alternative ideas?

I'll be happy of any input regarding this subject.

[Dieter]

Hi,

here are the different componetts of 4311 -4312. (att)

regards dieter

the schematics are:

http://www.jblproservice.com/pdf/Network%20Schematics/

[ole]

Wow, thank you very much!
This is great info.
Not very complicated filters back then...
Well, let's get the soldering iron hot and the ears ready

[Doug]

Hi OLE

Here are some more links for JBL

http://audioheritage.csdco.com/vbulletin/

http://www.audioheritage.org/html/profiles/jbl/l100.htm

http://www.jblpro.com/pages/obsolete.htm

http://www.audioasylum.com/forums/vi...ges/75262.html

Doug

[ole]

Thank you for the interesting reading.

Seems like opinons differ about how they sound(ed)

I myself like the JBL bass-kick and detailed upper mids but on some later recordings they really sound sharp (as in razor edge).

I have four ways to go here:
1. Build boxes as close to the original as possible, small bass reflex with drivers placed scattered around.
2. Modern in line alignment of drivers.
3. Bigger box, say 100 l sealed to improve low end.
4. Upgrade filters with sobels and LP inductors to reduce cone break up. Any filter change may take away some of the JBL sound of course, don't want that to happen too much.
What would you suggest?
I am going to use them as reference near/midfield monitors in my home studio.

[deluxreverb]

It is probably to late but I have a pair with tone controls. $30.00
Jim

[badman]

http://www.troelsgravesen.dk/JBL_L100.htm

This is also way late, but there are a lot of L100s and their associated parts (or other variants, like 4311) out there, that someone could make a 'modern' speaker out of. And that JBL bass kick is still present in the 123As I'm using

But make sure to test your driver Qts if you can, (or whatever tests you can run) to make sure the AlNiCo motors haven't de-juiced. Higher than spec Qts, lower than spec sensitivity, and lower than spec Vas are all clue-offs.

[Gioxtream]

I saw your post.And.I could not help in giving you this information.I been having nightmares about crossovers.The final conclusion and as a rule:

1.never change the coils or inductors in the original crossover.

2. Never think that ...by having the original schematics you will be able to have your speakers back at 100%. it does not work like that.I have found out that the majority of schematics out there are not 100% accurate as the original speaker.However ...is close but not 100% accurate.I can actually say this to the JBL on their faces.(shame on you JBL)so you dont blow your speakers they give you measurements on the crossovers.The safe ones.

3.I imagine that you want to tweak the crossovers right?
if so. Just upgrade the capacitors to a good quality polypropylene.Also.if the crossovers came with bypass caps...do not remove them.

4.resistors can be upgrade too.maybe to MOX or a better quality out there.

5.Keep same values as close as possible in caps and resistors ...otherwise you will have a total different speaker.

good luck.

Gio

Originally Posted by ole

Hi!
This is my first post, but I have followed the forum for some time.

I have been away from DIY for many years but decided to try and build something out of a couple of JBL 2213H, LE5H and Dynaudio D21-AF as a clone of the famous monitors. I have these drivers since 15 years and thought I might as well do something useful with then if possible.

I wonder if anyone knows about the crossover design or even has a schematic of the old studio monitors from JBL.
Or maybe any alternative ideas?

I'll be happy of any input regarding this subject.

[Bojay7]

Originally Posted by Dieter

Hi,

here are the different componetts of 4311 -4312. (att)

regards dieter

the schematics are:

http://www.jblproservice.com/pdf/Network%20Schematics/

Howdy. I just recently joined the forum but I've been 'dropping in' from time to time reading all the fantastic information posted here from you guys. This time, I need your help. Can anyone tell me where I can download a copy of the JBL 4311A schematic? I tried the link above but all I get is a "Directory Listing Denied" message. Or yet, does anyone know the proper internal wire color code connections to each respective driver? A friend gave me a pair of 4311A's with pristine drivers that were removed for enclosure restoration but they don't remember the factory wiring color coded 'hook-up' to each driver. Someone told me he thinks the LF driver is to be connected 'out of phase' with the MF & HF drivers. Is this true? I found schematics on the Internet for the L series, the 4310, 4312, A, B, & C ... but I can't seem to locate a schematic for the 4311 series. Any info would help and be greatly appreciated. Thanks ...

[Robh3606]

The network number is 3112 There are 3 there

Rob

http://www.jblproservice.com/pdf/Net...%20Network.pdf