JBL 4310's and Century JBL L100 year made?

[SDsailor7]

Hi all,
This has probably been asked before but I searched and did not come up with anything.
I have a pair of each that I bought at a thrift store a while back I recently finished "restoring the 4310's and painted them grey that was the original color beneath the black" It was an amateur (Me) restoration but they look way better than how I got them.
My question is, when where these speakers made? I am including the serial # if that is any help.
The 4310's are the following SN 11235 and 11236 on the front bottom label it says JBL model 4310 control monitor all I know about these is that the last year they where made was 1973 is that correct? where these made in the 60's 70's?
The Century L100's SN's are 171420A and 171421A. Do the serial numbers help in identifying the year month they where made?
I do have some pictures that I can post if I can figure how to do it.
Thank you for any help that you can provide.

 

[mech986]

Welcome!

This article from Lansing Heritage (another website dedicated to JBL, is de rigeur reading for fans of the JBL 4310 / L100 evolution.

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

http://www.lansingheritage.org/html/jbl/specs/pro-speakers/1972-4310.htm



Show us some pictures of your speakers. The 4310 dates from about 1969 and was superceeded by the 4311 soon afterwards. The earliest L100’s were inline or vertically arrayed drivers. This was changed to an offset cluster to reflect the 4310/4311 relationship. The first L100’s showed up in 1970, and versions with L100 and Century names evolved after that, probably starting around 1971-72.

http://www.lansingheritage.org/html/jbl/specs/home-speakers/1973-l100.htm

The iconic lineup: 4311, L100 offset, L100 Vertical, 4310

 

[mech986]

Unfortunately, it is rare to see date codes on JBL drivers. You might get lucky and find a date code on the capacitors or resistors on the crossover board or maybe the back of the woofer cones. If you’re really lucky, occasionally a build sheet is found under the fiberglass inner lining of the speaker cabinet.

AFAIK, there was no particular dating encoded in the serial numbers other than a letter at the end designating an upgraded A or B model. At Lansing Heritage, you can dig into the library’s product brochures, spec sheets, and catalogs for dating purposes.

 

[SDsailor7]

@ mech986,
Thank you for the links to the articles and yes I will post some pictures as soon as I take them. Its nice to know that the 4310 was the model that started it all.
I see that you are right up the road from me. I was thinking of contacting JBL to see if they had info on when they were made.
I have not done any restoration on the Century L100's they are still scratched up and the finish is faded so now that I got the 4310's in service I can start on the L100's. One of the 4310's had one of the woofers replaced unfortunately with a black face on but at least it is a jbl replacement speaker I could tell because it has the red jbl wax plugs over the screws so you could say I got a ying and yang pair of speakers but they do sound good! I will see about getting a white one so they look even.

 

[SaturationPt]

Your L100As look like (from the S/N) they are near the end of the 2nd-generation of L100s, should still say Century on the foilcals and have white speaker pegs with the woofer tinsels oriented toward the left side (when CENTURY lettering is upright the short edge nearest to the woofer). If it has black speaker pegs and only L100 on the foilcal it is at the beginning of the L100A (late) production, tinsels should originally have been oriented at 8:00 position with the speakers laying in the same position (L100 lettering upright).

As far as year produced, I'm guessing '75-ish. This guess is by no means scientific, just an interpolation based on my speakers' production/sale dates.

On the 4311s, I was an L166 guy at that time, didn't get into monitors until the 4312As (dome tweeters had me after the L166s).

 

[SDsailor7]

Hi all,
So now I have a little more info thank you SaturationPt.
As you can see I missed some spots on the 4310's I will have to correct that but they still look better than when I got them.

 

[SDsailor7]

Still learning to navigate this site somehow I lost the comments I started above when I was uploading the pics.
I will look for the before pics and post them latter.
White pegs on the L100's is what I got.
So ProductionPt what is a foilcal? is that the nameplate where is says Century?
I was not sure if it is better to upload the pics full size or thumbnail.
As you can see the L100's need a lot of work. They will be next when I get some time. Way to many projects!

 

[SDsailor7]

@ ProductionPt So what are woofer tinsels? I just looked again at the pics in the links that mech986 posted and found my L100's
it is the one next to the 4311 I had not noticed the difference before! now I see what you mean.
Now I got a better idea on where they came in the production period.
Thank you guys!

 

[SaturationPt]

Yes, "foilcal" is the foil sticker that has the L100 Century and serial number on it.
Tinsel is the wire-lead that goes from the speaker driver terminals, up to the cone and is then glued to the cone on the front side giving you those black epoxy lines up to the dust-cap. The L100A drivers appear to all be in the original position, a good sign. They need a replacement tweeter (if you can find a perfect original), some will repair the dome or glue in a new one, ... but being that matched tweeter pairs are extremely important for imaging I don't agree with that direction, ... not that the Century is known much for imaging anyway.

The 4310s, not so original. The biggest problem there is the non-original cone, were they mine I'd look for an original-cone woofer, I'm obsessive though. With sequential serial numbers I'd look to make them as original as possible.

Interesting treatment on the 4310s, I like the grille cloth and probably wouldn't change it. The rest of the cabinet color probably wouldn't work for me, but if they work for you then that's what matters. It is highly unusual to find them with sequential serial numbers however and that would be a factor for me in making them original.