torn dustcap JBL

torn dustcap JBL

Postby tatittle » Fri Apr 10, 2015 11:36 am

I am totally baffled. I noticed my JBL D130F was making some high freq buzzing today on certain notes, so I opened up the cab and was shocked to find the dustcap is ripped open! A big jagged hole in the middle of the cap.

There was not any break in it that I could see previously, but it was dented slightly. I did not pull the dent out bc I have thought that caused similar buzzing issues in the past. Is it possible this happened spontaneously from low volume playing? I haven't had this cabinet out/played loud for over a year and the issue is brand new. Bizarre! The grill is pretty tight and I see no signs anything sharp penetrated the front of the grill to cut through the cap, but there are folks visiting the house as it is currently for sale. I guess the good news it isn't VC rub, but my original cone has taken a bad hit nonetheless. Suggestions for repair?

Any excellent source for original size caps? I think the 130 is the same size as the 120.
tatittle
Senior Member
 
Posts: 688
Joined: Tue Jul 10, 2012 8:44 am
Location: Johns Island, SC via NJ; Bklyn; Detroit; Charleston; Boulder; Miami; D.C.; etc

Re: torn dustcap JBL

Postby Smolder » Sat Apr 11, 2015 6:52 am

Sorry man, that sucks. I've never heard of that happening and have no idea how it would.

That said, if you have a steady hand and an exacto, you can cut a circle around the tear to eliminate the rattle in the short run... Keep it wash from dust and dirt though, you don't want loose crap getting in there and making its way to the voice coil.

The cap is the same as a D120 (4 inch voice coil)... And there are some stashes or OEM parts around... You might try one of the usual and reputeable re-cone guys. A little solvent and you should be able to carefully remove it, and a bit of adhesive and you can put a new one on. You might reach out to Speakerrepair.com, but I'm guessing that will be a repro. Not sure you'd notice a difference.
Smolder
Senior Member
 
Posts: 800
Joined: Sun Jan 01, 2012 11:42 am
Location: 8152 feet... in the rockies.

Re: torn dustcap JBL

Postby tatittle » Mon Apr 13, 2015 10:19 am

I have seen JBL's for sale with similar ripped up dustcaps come to think of it, I had always assumed something punctured the cap. It was making buzzing noises conspicuously only when I played around the D, D#, and E notes of the 3rd (unwound G) string. But not when I played the same notes on other strings. I already cut off the jagged edges but have remounted the speaker/played it yet. I was gonna sell it...if it sounds fine I may keep it I guess if the value is shot.
tatittle
Senior Member
 
Posts: 688
Joined: Tue Jul 10, 2012 8:44 am
Location: Johns Island, SC via NJ; Bklyn; Detroit; Charleston; Boulder; Miami; D.C.; etc

Re: torn dustcap JBL

Postby waldo041 » Mon Apr 13, 2015 12:19 pm

They sell slightly oversized dust caps for replacing damaged ones without having to do a complete recone.

http://www.soundspeakerrepair.com/speak ... tructions/

~waldo
Disclaimer: I only make, modify or build things for those that seek what i may be able to provide.
User avatar
waldo041
Senior Member
 
Posts: 3407
Joined: Thu May 19, 2005 10:58 am

Re: torn dustcap JBL

Postby tatittle » Mon Apr 13, 2015 4:39 pm

Much obliged waldo. I have heard that the JBL dustcaps are placed delicately directly on top of the voicecoil or something; the implication being that a different size would give different tone, if not merely less heat dissipation. Big deal or not?
tatittle
Senior Member
 
Posts: 688
Joined: Tue Jul 10, 2012 8:44 am
Location: Johns Island, SC via NJ; Bklyn; Detroit; Charleston; Boulder; Miami; D.C.; etc

Re: torn dustcap JBL

Postby waldo041 » Mon Apr 13, 2015 5:09 pm

dust caps are used to keep dust out of the voice coil, however their material will impart some response and are chosen accordingly. That said, if you use a 4 inch dust cap on a 2 inch coil the "effect" may more pronounced(ie.. weber cali's). However in your situation, using a 4 inch dust cap on a 4 inch voice coil, the ovesizing is minimal and should render no impact on the sound of that speaker. Of course that is if the job is done correctly, as you have witnessed, air escaping out of the dust cap is not a good thing.

~waldo
Disclaimer: I only make, modify or build things for those that seek what i may be able to provide.
User avatar
waldo041
Senior Member
 
Posts: 3407
Joined: Thu May 19, 2005 10:58 am

Re: torn dustcap JBL

Postby playingdead » Mon Apr 13, 2015 6:17 pm

I watched an authorized JBL repair center replace the dustcap on one of my E-120s a few years ago ... it took the guy about 6 seconds for him to hack the old one off with a box cutter, flow that black glue around the hole and stick the new one on there. Sounded just fine and I used to rock those cones back in the day :shock:
User avatar
playingdead
Senior Member
 
Posts: 1910
Joined: Wed Mar 26, 2008 9:55 am
Location: Boston, MA

Re: torn dustcap JBL

Postby Smolder » Mon Apr 13, 2015 6:51 pm

playingdead wrote:I watched an authorized JBL repair center replace the dustcap on one of my E-120s a few years ago ... it took the guy about 6 seconds for him to hack the old one off with a box cutter, flow that black glue around the hole and stick the new one on there. Sounded just fine and I used to rock those cones back in the day :shock:



A little acetone applied with a brush will go a long ways towards loosening the glue and pulling the old one off. If you get the slightly oversized dustcaps that Waldo recommended there probably isn't any need... just trim it back to the glue line and put the new one over top.
Smolder
Senior Member
 
Posts: 800
Joined: Sun Jan 01, 2012 11:42 am
Location: 8152 feet... in the rockies.

Re: torn dustcap JBL

Postby Jon S. » Sat May 09, 2015 8:22 am

I'm sorry about your issue and glad to see you're getting good advice here on how to fix it.

Thought I'd mention, though, that before they even made fuzz boxes, Frank Zappa reportedly removed the caps and cones from some of his cabinets, soaked them in brine, sliced up the caps and cones, and reinstalled them for among the earliest fuzz tone (I've also heard of people in the '50's leaving worn out or badly inserted tubes as is for the fuzz tones they delivered).
/ `--'(
< [] []////////|::: )
\_.--.(
User avatar
Jon S.
Senior Member
 
Posts: 1728
Joined: Wed Apr 30, 2008 12:34 pm

Re: torn dustcap JBL

Postby Smolder » Sat May 09, 2015 9:16 am

Jon S. wrote:I'm sorry about your issue and glad to see you're getting good advice here on how to fix it.

Thought I'd mention, though, that before they even made fuzz boxes, Frank Zappa reportedly removed the caps and cones from some of his cabinets, soaked them in brine, sliced up the caps and cones, and reinstalled them for among the earliest fuzz tone (I've also heard of people in the '50's leaving worn out or badly inserted tubes as is for the fuzz tones they delivered).



It's widely reported that Roy Buchanan played through speakers which he intentionally sliced the cones with a razor blade.
Smolder
Senior Member
 
Posts: 800
Joined: Sun Jan 01, 2012 11:42 am
Location: 8152 feet... in the rockies.


Return to Loudspeakers

Who is online

Users browsing this forum: No registered users and 1 guest

cron