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Munkenissen
12-16-2020, 05:54 AM
Hello, and thanks for letting me join this great forum.
First off I will apologize for not using the correct technical terms and (maybe) broken english.
I hope my thread will be understandable either way. :D

I have been lurking for a while, but I only recently aquired a couple sets of JBL bookshelf speakers.
---- The legendary L100 Century and a couple of L166A (Horizons). The latter cost me $100 each speaker.

The cabinets is in rather good shape after a gentle sanding and some bees wax, but one driver and one tweeter is faulty.
I have a couple of questions regarding these faulty parts, which I hope someone in here is kind and knowledgeable to answer.

Driver 122A-1: One of the drivers have a busted foam surround. I have been browsing for the correct foam kit, but I can't seem to find an exact match.
Two import measures of my drivers are - Outer roll diameter: 10.75in (273mm) , Conediameter: 9.375in (238mm).

The closest fitting foams i can find are.:
1. Outer roll diameter: 10.75in (273mm) , Cone diameter: 9.625in (244mm)
2. Outer roll diameter: 10.5in (267mm) , Cone diameter: 9.375in (238mm).

I guess the best option will be the foam with correct cone diameter?

Maybe theres a third option for a foam, where both measures fit?


Tweeter 066: One of the tweeters are bad. Symptoms are:
- Playing like theres a carpet over the speaker.
- Tweeter will produce some subdued and harsh sound.
- Sound from the tweeter is falling in and out, if it even plays.
- The problem is isolated to the tweeter, it has been in both cabinets. (For some reason i feel like its more noticable in one cabinet, though the sound is still falling in and out).
- The cabinet with a good tweeter doesen't have any of the problems mentioned above!

I have measured both tweeters, and resistance rougly fits. It seems the bad tweeter have been rapaired (or at least tried to), because it has some pen writing on the foilcal badge.
I have opened the bad tweeter. It doesn't seem to have loose connections from solder points to diaphragm.

Is the tweeter fried or do I have some fixable issue maybe?

I would like to keep the tweeter all original, so if it's dead I guess I will buy a "new" functioning 066.

Any help will be greatly appreciated!
I will include a picture of the set if I can figure how. :dont-know:

//Rasmus, Denmark

macaroonie
12-16-2020, 08:10 AM
Welcome to the forum. Looks like a nice pair , just a little fixing up.

These folks should be able to help

https://reconingspeakers.com/product/12-jbl-122-128-refoam-kit-rfk128-jbl/

If you have any Q's e mail Cathy. She's very knowledgable.

Good luck.

There are a few posts re keeping 066 running , you are going to get a response or two on that one. If the coil is reading proper ohms ( 6~) then you are half way there.

Skol !

Munkenissen
12-16-2020, 08:38 AM
Hi Macaroonie.

Thanks for your reply.

I just send reconingspeakers an e-mail, asking for a foam with my specific mentions.

Regardig the 066 tweeter, are you thinking of any thread in particular? I have tried to search the forum.

- Rasmus

jbl4ever
12-17-2020, 12:21 AM
Hello Rasmus, have you tried working the Lpad pots on the tweeter. Some times oxidation can be some of the problem.

macaroonie
12-17-2020, 05:23 AM
https://www.youtube.com/watch?v=1aZGtaiLSH4

Please remind me , did you get good ohm readings on both tweeters. Any chance of pics of your readings.

Other thing to do is download a sweep test from NCH free online and run that at low volume through both tweets.
Don't use anything below 1KHz

While I remember have you exercised the L pad controls. They do get carroded and repeated movement of the controls will clean the track and wiper contact.
They do get scratchy sounding.