Putting a new surround on a woofer for the first time -- surround has been adhered to cone, now to center it and glue to the frame.
Don't really want to pull the dust cap and shim the voice coil and was wondering
-- could I run a low volume test tone, 1K or so to the speaker and would it then center itself ? hmmm ?
"mkr5000"
** The voice coil (VC) will never centre itself.You must use a slow setting adhesive on the frame - then you can adjust the surround and get the VC coil right in the middle. A low level tone at say
50Hz will assist you by only sounding clean when the VC is centred.Another check is to push lightly at various spots around the edge of the cone and find the VC is still clear each time.
... Phil
Thanks Phil -- if you don't touch the cone it seems to want to "fall in place" and center pretty well by itself? usually the case?
I may just mark it where it sits and use the slow cure adhesive I have.
I guess I don't understand voice coils that well -- I was thinking that the field would be equal around the circumference and it would therefore center.
Guess not. Not a speaker "freak".
place" and center pretty well by itself? usually the case?
field would be equal around the circumference and it would therefore center.
Nope.
About 10 Amps DC could get it to center. :)...
As suggested. you could use a low frequency tone (say 20Hz) and get the speaker moving pretty good with your fingers holding the surround in place. You won't hear any mechanical rubbing sound when you get it right. The spider will help you with centering somewhat. Figure out a way to clip the surround (maybe clothes pins) to hold it is place the second time when you do it with glue.
You might want to make a ring the fits on the flat part of the surround that glues to the frame. You can put this down and use the clothes pins to clip that in place.
Of course once you have it centered you have the woofer straight you turn off the tone and let the glue set.
When doing this you will change he woofer parameters somewhat. if the surround is stiffer than the original the Vas will be lower and the Fs may be higher. It may sound different that the opposite one when done if your only repairing one of a pair.
"mkr5000"
** Huh ??VCs are non magnetic.
... Phil
Shimming the voice coil should be done first, before you glue the surround.
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