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Thiel 04a VC rubbing intermittently

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Posted on January 10, 2017 at 21:12:49
MannyE
Audiophile

Posts: 1847
Location: Miami Beach
Joined: March 4, 2001
Contributor
  Since:
September 22, 2014
I have a pair of Thiel 04a speakers that I really like.

They have been great since I replaced the foam surrounds that were gone but it's been close to a year and they are developing something that sounds like the VC rubbing on the woofer. Only one of them does it and it only happens with certain sections of the song.

I thought that if I screwed up the foam surround, the rubbing would have started right away, but they have many many perfect hours on them.

A few questions...can the electrolytic caps in the crossover cause this? They are 30+ years old and have never been replaced. They sounded great before the rubbing started. But could them starting to fail cause an intermittent VC rub sound?



 

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RE: Thiel 04a VC rubbing intermittently , posted on January 11, 2017 at 07:07:16
airtime
Audiophile

Posts: 8773
Location: Arizona
Joined: February 4, 2003
You could try the old trick to rotate the speaker 180 degrees. I know older speakers developed "sag" and caused VC rub.

If it continues it will eat up the speaker.

heck, call madisound and see if they can fix it. It STILL may be cheaper in the long run to have them look at it then the alternative if it goes.

 

This worked for me, posted on January 11, 2017 at 08:27:22
M3 lover
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Posts: 5072
Location: So. California
Joined: May 29, 2005
Contributor
  Since:
July 4, 2007
Just as airtime suggested. After hearing a strange "scraping" sound from one Dynaudio woofer (yes, it can happen with quality drivers too) in my Duntechs I rotated it 180 degrees. That eliminated the problem and it never returned. No harm in trying.

"The piano ain't got no wrong notes." Thelonious Monk

 

Take out the woofer, and rotate 180 degrees..., posted on January 11, 2017 at 11:36:16
3+4=5
Audiophile

Posts: 711
Location: Midwest
Joined: December 24, 2016
One good way to balance the cone in the gap after aging is to rotate the speaker basket 180 degrees.
If the speaker basket is 'stuck' IE glued or sticky taped in.. Just clean off the back and use some more sticky tape before bolting it back down.
If the screws are into wood.. snug them down good without overdoing it. Old wood/fiberboard may strip out. Check them for snugness after a week.

 

RE: Thiel 04a VC rubbing intermittently , posted on January 11, 2017 at 12:40:57
Coner
Audiophile

Posts: 1882
Location: S.W. Washington state, USA
Joined: November 17, 2001
Wonder if you shimmed the coil, this is what can happen if you
don't, even though it didn't show up right away.

 

RE: Thiel 04a VC rubbing intermittently , posted on January 11, 2017 at 17:31:42
airtime
Audiophile

Posts: 8773
Location: Arizona
Joined: February 4, 2003
If rotating the speaker doesn't work he should remove the surround and see if it's still rubbing. And redo the surround.

 

RE: Thiel 04a VC rubbing intermittently , posted on January 11, 2017 at 19:15:29
Coner
Audiophile

Posts: 1882
Location: S.W. Washington state, USA
Joined: November 17, 2001
Correct. If the water-based dope was used, I'd keep it damp for
a few hours, and try to peel it up. Usually works.

 

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