I found a 4320 pair !!

[alias_greg]

Hi everybody !

I found a JBL 4320 Studio Monitor pair wich belongs to my father who hid them in the garage. He bought them in the 70's and havn't been used for 10 years.

I need your advice for an actual amplification system. I would like to buy something quite cheap (for the moment - i'm a student) but optimum for my loudspeakers.

They've never been repaired since 1970, what sort of things should I do to have them in work conditions ?

Do you think they're still competitive compared to modern models from others or newer ones from JBL ?

Thx
Greg

[northwood]

Congrats:)
I think vintage tube amp would drive it well,cheap and easy to find on ebay.

[Fred Sanford]

Great find! Good luck with them. I'd think you could really grow with them, they look like excellent candidates for upgrades in the future as you gain knowledge.

Where are you located? Maybe somebody local has something you could use, and that would save you shipping.

Folks more familiar with that model will probably chime in soon, but my first suggestion is to check the surround on the woofers, if they're cracked or brittle (or missing) then stop playing the speaker until you get that repaired. Take your time, there's lots of good advice to find here and a bunch of helpful people.

OEM lit here:

http://www.lansingheritage.org/html/jbl/specs/pro-speakers/1972-4320.htm

je

[alias_greg]

Thanks for your advices.
I'm from Paris, France so i think i would find somebody there who is for sure a specialist about JBL's monitors but i need to know maximum details about how to proceed and i think this place is the definitive place to be ! lol
I'll take care of the woofer's surround and try to test them.

:)

[mech986]

Hi Greg,

Welcome to the forum and Nice find/recovery for you and your dad! Is your 4320's the textured grey or walnut cabinet?

Here's a link to the JBL Pro brochure on the 4320 here in the LH archives from 1972:
http://www.lansingheritage.org/html/jbl/specs/pro-speakers/1972-4320.htm

Here's a similar link for the original grey monitor in .pdf form from JBL Pro website from 1970:
http://www.jblpro.com/pub/obsolete/4320.pdf

Here's information about the components from a reference chart:


JBL PROFESSIONAL


CUSTOMER SERVICE DEPARTMENT

STUDIO MONITOR REFERENCE CHART
Revision U - March 17, 2006
Page 2 of 5



Model LF Mid X-over Horn Last made Lens


4320 2215B 2420 3110 2307 1974 2308


You'll have to check the 2215B to see if it has been refoamed or reconed in its service lifetime. JBL would recommend a full recone as below:

2215B Price of kit $174.00 Kit# C16R2215

If you can, upload some pics to let us see the condition and what they look like. Congrats again.

Regards,

Bart

[hjames]

Hi everybody !

I found a JBL 4320 Studio Monitor pair which belongs to my father who hid them in the garage. He bought them in the 70's and havn't been used for 10 years.

I need your advice for an actual amplification system. I would like to buy something quite cheap (for the moment - i'm a student) but optimum for my loudspeakers.

They've never been repaired since 1970, what sort of things should I do to have them in work conditions ?

Do you think they're still competitive compared to modern models from others or newer ones from JBL ?

Thx
Greg
Hi Greg!
You don't say if they are working right now - but lets assume that they are!
Those big old JBL speakers are pretty efficient - its really doesn't take a lot of power to push sound through them, as long as you don't overdrive your amp into distortion - distorted sound is what can damage good speakers.

I'd never heard of this model before this year, but I bought a pair of 4320 Monitors in February and did a few things to fix them up. Mine didn't have grills, so I made a set of grills for them.

Also, the 4320 is a very nice 2 way monitor, but may be a bit lacking in the higher frequency sounds (above 15,000 hertz). At some point you may want to look into making them into 3-way speakers by upgrading the crossover networks and adding a pair of slot tweeters (JBL model 2405).

I asked a lot of questions (and got answers) when I was fixing mine up - you can read those threads here -

http://audioheritage.org/vbulletin/showthread.php?t=9273&highlight=4320
and here:
http://audioheritage.org/vbulletin/showthread.php?t=9796&highlight=4320


Or just do a search in these Forums for "4320" and see what comes up!

I'm currently running mine with a 110 watt per channel JVC receiver I already had - but I don't have to crank them much to get good sound. If you want to buy an Amp for them, first, figure out your budget then look within your price range. Sometimes you may find a deal within your prices that you weren't expecting!

[alias_greg]

Welcome to the forum and Nice find/recovery for you and your dad! Is your 4320's the textured grey or walnut cabinet?
Thanks, :) Mine is the walnut one. I would have preferred the textured grey but nevermind ...



You'll have to check the 2215B to see if it has been refoamed or reconed in its service lifetime. JBL would recommend a full recone as below: 2215B Price of kit $174.00 Kit# C16R2215 Well, I wouldn't have found this information somewhere else ... I think I would change these woofers ASAP. Should I change the tweeter too ? Do you know the model and where I can find it ?


upload some pics to let us see the condition and what they look like I don't have them in my appartment now but when I would have time I would do so.


You don't say if they are working right now - but lets assume that they are! In fact I havn't test them for the moment since they are in my father's house and they have not been used for 10 yrs.



as long as you don't overdrive your amp into distortion - distorted sound is what can damage good speakers But I hope I can listen and play some Rock (crunch) music on it without damaging them, as this model was used in woodstock ? I'm not a metal fan.


Mine didn't have grills, so I made a set of grills for them Mine have ones but one of them is damaged and I wonder if I will use them


At some point you may want to look into making them into 3-way speakers by upgrading the crossover networks and adding a pair of slot tweeters (JBL model 2405). For the moment I think I won't but I maybe one day ... if I find a qualified guy in Paris who could do the work fine.


110 watt per channel JVC receiver I already had [...] figure out your budget then look within your price range I'll begin to search it when I'll have some money but, should I use a Lamp Amp or a transistor one ?

++

[Mr. Widget]

Well, I wouldn't have found this information somewhere else ... I think I would change these woofers ASAP. Should I change the tweeter too ? Do you know the model and where I can find it ?Don't change the woofer. You may eventually decide to go down the DIY road, but give these speakers a good listen first.

The woofers will definitely need to be repaired. If the speakers are very old the woofer will be called an LE15A. If they are newer they will be called 2215 or 2215B... all three of these woofers are essentially identical. If the rubber surround is yellow or tan then you have an earlier version and they have not been serviced. The yellow or tan surrounds get stiff with time. If they are played in this condition the speakers will produce very little low bass and the surround may crack. If your woofers have been serviced or are of a newer generation they will have a gray foam surround. This material lasts about 15 years and then needs to be replaced. The surround can be replaced for around $40 each. The complete recone is better, but at a significantly higher cost. I see someone quoted a price above. If you have the yellowish surround and they are not cracked there is a third option but it comes with it's own set of problems. If you apply DOT 3 brake fluid to the surround it will regain it's compliance. To do this right you need measurement equipment as too much and the fs goes too low and not enough and it remains too high.

As for the tweeter. The 2420 or LE85 (mid tweeter horns) in your system will not really play that last octave of music without some encouragement from a tone control or equalizer... you can add a 2405/077 to your system and make them a quasi 4333/L300 or you can get by with some EQ help. I really doubt you will need to do any work on the existing tweeters... if your dad wasn't abusive they should be fine.

I haven't read all of the above posts thoroughly so please excuse any redundant info. The reason for the dual model numbers 2420/LE85 for example is that there are Pro Series model numbers and consumer and historical part numbers... they are usually absolutely equivalent., however occasionally there are exceptions.

One other note. The your speakers will have components that say they are 16 ohms... don't worry about it, they will work perfectly fine with any quality amp.


Widget

[boputnam]

"greg"...

Post some pics, when you get a chance...

[alias_greg]

Hello !

So, I got new informations about my 4320s :

Tweeter type is L91 (serial n°38046)

LoudsSpeaker type 4502 WX | Enclosure (serial n° 51034)

Frequency divided network LX5 (serial n° 27566)

Just a few things :

1 - What is the Frequency divided network (Low Mid High) for (the back left pannel) ?
2 - What is the back right pannel (LF HF with Button noted 1 2 3 4) utility ?

I've post some pictures on attachment :

[Zilch]

Not 4320s, but even better, actually, your speakers are three-ways with 2405 "slot" UHF drivers, though these are improperly oriented. The slots should be vertical to be used standing as shown.

The LX5 (500 Hz as opposed to 4320's 800 Hz) crossover on the rear is for the midrange, with variable (three choices) attenuation.

The second crossover network, probably 3105 or 3106, is for the UHF driver, with continuously variable attenuation control.

The two crossovers are cascaded; wires from the LX5 HF output (3 and 4) connect to the input of the UHF crossover. LX5 outputs 1 and 2 are going directly to the woofer.

From the UHF crossovers, the LF outputs connect to the MF drivers, probably 2420s, and the HF outputs connect to the 2405 slot tweeters.

The lenses on the MF horns are upside down. See illustrations of similars in the library.

Your woofers still have the original Lansaloy surrounds which, unless still soft and pliable (unlikely) will need to be replaced with new foam types to restore bass performance of the sytem.

These are quite a wonderful find, actually. They were precursors to several lines of large-format monitors JBL subsequently produced.

Your father knew what he was doing when configuring these systems, right down to phase alignment of the drivers (the MF is inverted). Once properly restored, their sound will be nothing short of spectacular. :thmbsup:

[alias_greg]

Thanks for your informations !

Which Adjustments should I use for the two crossover (the better one for home use) ? Since I'm no audio engineer it doesn't mean much to me (low, mid, high with 1, 2, 3 or 4 ???) ...

I'll try to find a good place to restore them in Paris but maybe you know one place which fit my needs ?

Another thing is that the walnut varnish is really damaged (there are big spots on it) and I wonder what I should use to fix it, any suggestion ???


Your father knew what he was doing when configuring these systems, right down to phase alignment of the drivers (the MF is inverted). Once properly restored, their sound will be nothing short of spectacular. :thmbsup:
Excuse me but I don't understand this part : "right down to phase alignment of the drivers (the MF is inverted).". Is it the trouble you noticed when you said : "The slots should be vertical" ? If so, how can I fix it ?

Good evening

[Zilch]

Which Adjustments should I use for the two crossover (the better one for home use) ?Begin by having new surrounds installed on the woofers if they are no longer soft and pliable. Carefully remove the woofers from the cabinets and take them to someone who does that professionally. The authorized JBL Service facility there would be able to do it, though we have other forum members in France who might have a specific recommendation.

While that's being done, loosen the UHF drivers and reorient them so that the slot is vertical, and invert the lenses on the MF horns. With the woofers out, you may be able to determine the MF driver and horn types. Take a pic of them inside the cabinet and post it here for identification.

Crossover adjustment is easy. Turn the level control on the UHF crossover all the way to the left (off) while playing the system in your listening space. Adjust the switch on the LX5 crossover for the most pleasing balance between the woofer and midrange horn output. The midrange should be full, but well integrated with the woofer output.

Then, advance the UHF level control to bring in the high frequencies to your taste. Ignore the numbers on the knob. You'll easily arrive at a balance of both controls for most pleasing reproduction of the music you like....


Another thing is that the walnut varnish is really damaged (there are big spots on it) and I wonder what I should use to fix it, any suggestion ?There are several threads in these forums which describe how to restore the cabinets. Use "Search" to find them.

Generally speaking, a light sanding and application of the original JBL oil finish (formula also in these forums) will work, although you may have to take specific measures to remove or conceal the stains. There is no varnish; it's oil. Remember that the walnut is a veneer; you can't sand very deeply without going all the way through, so that's not a good way to remove any deep stains.

You'll want to remove or somehow otherwise protect the drivers when doing work on the cabinets. They'll not like the dust from sanding, for example.


Excuse me but I don't understand this part : "right down to phase alignment of the drivers (the MF is inverted)."I can see from the colors of the wires and where they are connected on the crossovers that the MF drivers are connected correctly out-of-phase with respect to the woofers and tweeters. Carefully document the present connections when disassembling the systems or removing drivers so that you can put them back the way they are for best performance.

The terminals on the drivers themselves are color coded, as well. Mark which wire pairs go to which drivers inside with tape, as there are two pairs of green and black wires, which must not be confused....

[Rolf]

Zilch...you must be the master of explaining. Thank you for taking the time for the "newbies". To you all in this thread: nice to that not all is "as*hl** on this site.

[majick47]

Alias greg if you get a chance send some pictures of the grills. From what I read one grill frame is damaged and it is quite possible it can be repaired. If all else fails a new grill frame can be made. Lastly the grill cloth can also be replaced if necessary and your speakers will look spectacular in JBL blue. If you are unsucessful removing the stains from the tops of the speakers I'd recommend placeing plate glass on the tops and with some decorative items they will camoflage the stains. Another option would be to put felt cloth or paper under the plate glass similar to the L65/L300.

[Zilch]

Thank you for taking the time for the "newbies".No problem Rolf. It's Sunday, so I have the time today, and this particularly beautiful vintage JBL system easily warrants whatever effort is necessary to have them proudly playing once again.... :thmbsup:

[Rolf]

How is not possible to love you.:D

[alias_greg]

How is not possible to love you.:D That's for sure a good tell ...

Thanks a lot Zilch for all of your time !

For the grills, I don't know if i can repair them and I really don't know why they made them with plywood ? I think i will design new ones.

I'm now going to sleep a little 'cause it's 0:50 AM here, and dreaming about my new project :bouncy:.

++