How to check speakers before refoaming

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
So I picked up a pair of Snell K II's recently and they both woofer need to be refoamed. Ive ordered the kit from Simply Speakers and it occurred to me that I may be replacing the surrounds on speakers that could be broken somewhere else, and I have no way of knowing. All I can say is that I have played them for just a few seconds on low volume and sound cam out. The surrounds are completely gone.

Also it was my plan to just glue on the surrounds and center them as best I could and hope for the best. Then I pushed on the cones to see what it felt like to center the VC, and noticed that it didn’t seem to take much to get the VC to rub, it took more effort for tham not to rub. This may be normal, except that on one of the YouTube vids I watched, the person refoaming actually made note to demonstrate that if you simply press the cone, it will not rub. That it only rubbed when the cone was pressed on one side or the other. Now I am thinking that maybe I should put some more thought and effort into centering the voice coils either by shimming, or probably by the low frequency tone method.

So I guess my two questions are: 1. Is there a way to determine if the speakers are OK, to go ahead and replace the foam?

2. Whats the best way to center the voice coil as part of the foam surrounds replacement?

Any other thoughts would be greatly appreciated, Rob
 
remove dustcap,shim with paper between pole piece and voice coil former apply new surrounds, re-install dust cap.
i personally have tried the "run low frequency" and hope everything centers and gotten lucky on a few tries but most devellop problems with glue joints creeping or coming apart in the process and becoming "re-cones" instead of "refoams".
 
So I guess my two questions are:
1. Is there a way to determine if the speakers are OK, to go ahead and replace the foam?

2. Whats the best way to center the voice coil as part of the foam surrounds replacement?

1. You could try temporarily centering the cone with some painters tape or something, then play to see if they make sound. 4 pieces should do it.

2. You need to remove the dust cap and shim it for best results. The dustcaps that came with my refoam kit (different speakers) were too small so I just carefully cut a "c" leaving a flap to fold the dustcap back. I then folded it back and tacked it in place with superglue.
 
sorry i guess i didn't answer the first question.
as long as the nominal impedance is not out of spec (as in resonably close to the rated impedance)
things should be fine.

You can't measure nominal impedance. You can measure DC resistance of coil and they should be about the same. Most often DC resistance is somewhere between half to 3/4 the "rated" or "nominal" impedance.
 
Finished Update

I bought a digital multi meter. Removed the woofers and measured the resistance. Both woofers measured 3.4-3.5, I didn't get it knowing that they are 8 ohm speakers. Until I noticed on the back of the woofers themselves are 4 ohm. So I figured that the readings are right where they should be.

I didn't shim the voice coils or use the low frequency center method, I simply allowed the cones to self center like the SimplySpeakers instructions suggest and everything work perfectly and they sound great.

The only issue I came across was that the surround is glued across the the mounting holes in the cage. The result was that the foam is twisted with the screw head when it is tightened causing the the foam to dent/dimple where it touches the screw. It took a few trys, some poking and pinching with my fingertips, and now looks fine but if you look real close you can see it.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.