Discoloration of Accutons?

michaelpage26 · 2nd August 2008, 08:28 AM

Can the accuton ceramic tweeters become yellowish on the voice coil "circle" in one place ?

michaelpage26 · 28th November 2008, 12:48 PM

Ι have seen it in the recent Athens High End Show, in a pair of Gryphon loudspeakers...

Now I have a link to show what I mean by saying discoloration of accutons...

http://www.johneekels.nl/images/MilestonesWS130.jpg
http://www.johneekels.nl/images/Milestones%20WS140.jpg

The Gryphon dealer told me in the local High End Show that this is normal as the accuton tweeters break in...What do you think?

Ron E · 28th November 2008, 01:43 PM

Being that the cones feel rather like eggshells, it would not surprise me if the adhesive migrated through on strong heating. OTOH, if the adhesive is looking like that I would wonder about long term reliability. I would question the manufacturer as to what is actually discoloring.

Rainer Weber · 28th November 2008, 09:04 PM

Hi,
for me it seems that due to transportation or mechanical shock there is ferrofluid out of the gap on the membrane.
I had this experience myself.

Best regards
Rainer

michaelpage26 · 28th November 2008, 09:15 PM

Thank you for your answers !

What Rainer Weber says sounds logic , as I have observed in all the times the yellowish discoloration appears on the circle that the voice coil touches the ceramic diaphragm and never in the center of the circle. As a result only the accuton tweeters will have this "problem" because they have ferrofluid. Why accuton can't solve this?

Cal Weldon · 28th November 2008, 11:14 PM

Hi Michael,

I tried to fix the first link but was unsuccessful

Ron E · 28th November 2008, 11:47 PM

Quote:

Originally posted by Cal Weldon
Hi Michael,

I tried to fix the first link but was unsuccessful

http://www.johneekels.nl/images/Milestones%20WS130.jpg

Cal Weldon · 29th November 2008, 12:13 AM

Thanks Ron

454Casull · 29th November 2008, 04:05 AM

Maybe the ceramic is slightly porous?

michaelpage26 · 29th November 2008, 09:41 AM

It has to be as a ceramic. But is not very ok to have a tweeter that costs 200-300-400Euro each and have a brown/yellow circle on it...Not to mention if you have a loudspeaker that costs 10-40000Euro that has an accuton loudspeaker...

Is there any acoustic problem if someone puts more ferrofluid than needed?

Also I have found that photos with broken/discoloured accutons are rare. I will attach a burnt tweeter that is discolored too and some broken accuton diaphragms...

2nd August 2008, 08:28 AM	#1
michaelpage26 diyAudio Member Join Date: Mar 2004 Location: Athens	Discoloration of Accutons? Can the accuton ceramic tweeters become yellowish on the voice coil "circle" in one place ?

28th November 2008, 01:43 PM	#3
Ron E diyAudio Member Join Date: Jun 2002 Location: USA, MN	Being that the cones feel rather like eggshells, it would not surprise me if the adhesive migrated through on strong heating. OTOH, if the adhesive is looking like that I would wonder about long term reliability. I would question the manufacturer as to what is actually discoloring. __________________ Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works. --Carl Sagan Science is a way of thinking much more than it is a body of knowledge. --Carl Sagan

28th November 2008, 11:14 PM	#6
Cal Weldon Speakerholic diyAudio Moderator Join Date: Jan 2004 Location: British Columbia	Hi Michael, I tried to fix the first link but was unsuccessful __________________ Next stop: Margaritaville Some of Cal's stuff \| Cal Weldon Consulting

29th November 2008, 12:13 AM	#8
Cal Weldon Speakerholic diyAudio Moderator Join Date: Jan 2004 Location: British Columbia	Thanks Ron __________________ Next stop: Margaritaville Some of Cal's stuff \| Cal Weldon Consulting

29th November 2008, 04:05 AM	#9
454Casull diyAudio Member Join Date: Jan 2004 Location: Toronto, ON, Canada	Maybe the ceramic is slightly porous? __________________ Building a 2.1 system out of a 3/4"x4'x8' sheet


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28th November 2008, 12:48 PM	#2
michaelpage26 diyAudio Member Join Date: Mar 2004 Location: Athens	Ι have seen it in the recent Athens High End Show, in a pair of Gryphon loudspeakers... Now I have a link to show what I mean by saying discoloration of accutons... http://www.johneekels.nl/images/MilestonesWS130.jpg http://www.johneekels.nl/images/Milestones%20WS140.jpg The Gryphon dealer told me in the local High End Show that this is normal as the accuton tweeters break in...What do you think?

28th November 2008, 09:04 PM	#4
Rainer Weber diyAudio Member Join Date: Aug 2001 Location: Germany	Hi, for me it seems that due to transportation or mechanical shock there is ferrofluid out of the gap on the membrane. I had this experience myself. Best regards Rainer

28th November 2008, 09:15 PM	#5
michaelpage26 diyAudio Member Join Date: Mar 2004 Location: Athens	Thank you for your answers ! What Rainer Weber says sounds logic , as I have observed in all the times the yellowish discoloration appears on the circle that the voice coil touches the ceramic diaphragm and never in the center of the circle. As a result only the accuton tweeters will have this "problem" because they have ferrofluid. Why accuton can't solve this?

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