• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Voice coil rub Kef b160 sp1261

Gustavsson

Gustavsson

Member
I'm refoaming the woofers in a pair of kef 102.2. The first speaker went great with no issues. The second however is causing me some headache.

Symptoms : Scraping sound and resistance when I push the cone straight down. The sound and resistance goes away if I push the cone down at an angle on a specific point of the cone.

What I've done so far : Scraped away what remained of the old surround foam. Cut of the dustcap. Placed shims to align the cone. Wetted the spider with acetone and placed the driver up side down to dry. Refoamed the speaker with shims in place. Result - still voice coil rub.

Anything else I could try? (I'm currently waiting for a reply from a repair shop here in Barcelona.)

(I've tested both speakers with an ohm meter and they are both good.)

This guy is performing some pretty invasive surgery on his.
 
Register to hide this ad
Just a guess but could try mounting it and see if the frame deflects in orig. position to align.
 
Binkman said:
Just a guess but could try mounting it and see if the frame deflects in orig. position to align.
Click to expand...

I don't know about that. Don't want to risk damaging it. There's a huge difference in how the two speaker feel after the refoaming. I'm going to take it down to a local repair shop and have them take a look at it later this afternoon. Said they would charge €40 + tax. In the end it will hopefully save me another headache.
 
If the speaker was fine before the refoam, suspect from your work and do it again. Don't fit very tight shims. If the shims are too thick, you risk the VC is hold at a wrong angle. Happened to me a couple of times. Now I use shims that slide easily in the gap. Or just a test tone, no shims.

Is the basket too thick to try to bend it? Seems the magnet not perfectly aligned with the basket.

Things I've tried and worked in different speakers:

following the angle you see correct, try to bend the basket with 2 tools working as levers. This worked in a pair of speakers rubbing after they were drop from some height.

Several times, I have cut the spider all around, centering the VC by hand and feel, glueing all around with wood glue, same glue used for the refoam. This is the method I use more often when I fix a rubbing VC.

In one extreme case, the magnet gap was off center. In that case I had to send the speaker to a speakers factory to demagnetize, center, and magnetize again.
 
elnaldo said:
If the speaker was fine before the refoam, suspect from your work and do it again. Don't fit very tight shims. If the shims are too thick, you risk the VC is hold at a wrong angle. Happened to me a couple of times. Now I use shims that slide easily in the gap. Or just a test tone, no shims.

Is the basket too thick to try to bend it? Seems the magnet not perfectly aligned with the basket.

Things I've tried and worked in different speakers:

following the angle you see correct, try to bend the basket with 2 tools working as levers. This worked in a pair of speakers rubbing after they were drop from some height.

Several times, I have cut the spider all around, centering the VC by hand and feel, glueing all around with wood glue, same glue used for the refoam. This is the method I use more often when I fix a rubbing VC.

In one extreme case, the magnet gap was off center. In that case I had to send the speaker to a speakers factory to demagnetize, center, and magnetize again.
Click to expand...

It wasn't just my refoam as they were scraping before that unfortunately.

I've seen videos on both the bending of the basket and cutting away the spider. If the repair shop can't fix it or say I have to recone etc I will consider doing both of your above mentioned techniques as last options. Especially bending the basket seem risky. Since I'm guessing there is no way saving them if I bodge it.
 
I'm guessing they're not the same as the B160 SP1203 drivers as used in the C80.
 
leesonic said:
I'm guessing they're not the same as the B160 SP1203 drivers as used in the C80.
Click to expand...

I have no idea what kind of drivers would be suitable as replacements.

They are not the same as far as I can tell. SP1203 is 6 ohm compared to my 4. The sp1203 is listed as midrange and the sp1261 as woofer. The sp1261 is paper cone which the other does not seem to be.

The B160 sp1275 from the 103.4 is a 6.5" paper cone woofer. Think it's 8 ohm though. Also they have a steel rod going through them. Not sure if that additionally messes with compatability.
 
I wonder if it was bottomed out by being driven too hard. This could distort the voice coil. Might be best just to send it to someone like Simply Speakers to see if they can repair it.

EDIT: I see you are in Barcelona. Hopefully you have someone close by that can do a repair to your driver.
 
redk9258 said:
I wonder if it was bottomed out by being driven too hard. This could distort the voice coil. Might be best just to send it to someone like Simply Speakers to see if they can repair it.

EDIT: I see you are in Barcelona. Hopefully you have someone close by that can do a repair to your driver.
Click to expand...

Waiting to hear from the repair guy next week. His shop has been in business since the early 90's so hoping that counts for something.
 
If the basket or the magnet are not bent (they shouldn't if they didn't drop from some height), I think cutting the spider is the way to go. I did it several times in drivers that started rubbing without reason. Only times when it was not successful was when the VC was damaged by excessive power (coil burned or unglued from the former core).

Your repair guy will tell you if the VC is OK.
 
elnaldo said:
If the basket or the magnet are not bent (they shouldn't if they didn't drop from some height), I think cutting the spider is the way to go. I did it several times in drivers that started rubbing without reason. Only times when it was not successful was when the VC was damaged by excessive power (coil burned or unglued from the former core).

Your repair guy will tell you if the VC is OK.
Click to expand...

If the VC would be damaged in any way that you mention, would it still be playable? The speaker sounds as it should except for the buzzing/distortion coming from the rubbing.
 
Yes, it could work and measure fine, but rubbing. I've seen a few times a VC detached from the former collar at some point, that was able to play music but rubbing at certain freqs, the only way to diagnose it was to cut the spider and foam edge and look inside. I did that after several tries to center the VC without success.
 
elnaldo said:
Yes, it could work and measure fine, but rubbing. I've seen a few times a VC detached from the former collar at some point, that was able to play music but rubbing at certain freqs, the only way to diagnose it was to cut the spider and foam edge and look inside. I did that after several tries to center the VC without success.
Click to expand...

Ok, thanks.
 
You must log in or register to reply here.
Back
Top Bottom