Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Multi-Way Conventional loudspeakers with crossovers

recentering a Voice Coil
recentering a Voice Coil
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 22nd July 2004, 09:35 PM   #1
wrl is offline wrl  United States
diyAudio Member
Join Date: Jan 2003
Location: USA
Question recentering a Voice Coil


I have an 18 inch woofer that I picked up at a surplus store that didn't work. Right now I've dissasembled it into 3 pieces...some of it was already in different peices so not all the dissembling was my fault...

1) Voice Coil: Wound on a plastic former. The very top portion where it used to be attached to the suspension has some mild deformation, but other than that the majority of it looks fine. Electrical continuity is good so I suspect that on the whole it is ok.

2) Suspension and cone: Attached to eachother, I managed to detach both of these from the rest of the speaker without damaging them.

3) Magnet and frame: Still in good shape.

What I was wondering is how I would go about trying to repair this speaker, I know that I need to epoxy the VC back to the cone and reattach the tinsel leads, but is there an easy way to make sure that everything is all aligned? Also, is this even possible to save?

Any input would be appreciated.


Anything worth doing is worth doing right... and redoing to make it better... and again to fix it back the way it was.
  Reply With Quote
Old 22nd July 2004, 09:42 PM   #2
markp is offline markp  United States
diyAudio Member
Join Date: Oct 2003
Location: L.A., CA
Remove the dustcap and use very thin shims all the way around the pole piece between it and the voicecoil to center it. glue the spider and surround down without tension to any one direction. It is very hard to do right so dont be mad if you get a speaker that rubs. Remember to remove the shims when the glue is dry.
If it sounds good... it is good!
  Reply With Quote
Old 22nd July 2004, 09:47 PM   #3
mwmkravchenko is offline mwmkravchenko  Canada
Mark Kravchenko
diyAudio Member
mwmkravchenko's Avatar
Join Date: Jan 2002
Location: Perth Canada
recentering a Voice Coil
Default Time to play with cards

Not knowing the make or maodel of the driver I can give you some generic advice. To begin with be sure that the voice coil is still perpendicular to the motor structure ie: it slids in and out without touching the top plate or the pole piece. If this is still OK go to the next step. You have to remove the dust cap in the centre of the cone. With that off you should be able to see an even gap around the voicecoil former and the pole piece. You have to shim this space evenly with playing cards or business cards or what ever will fill the gap evenly. That should center the coil on the pole piece . It should do the trick. Use a good quality epoxy and make sure that if the cone is a polyprop type you clean the cone with some methyl alcohol. If it is a paper type than you will have no problems. You didn't say much about the spider. If it is still in good shape it can be glued back carefully with some epoxy to. Thing hard do a dry run and then glue it up.

Have fun!!

  Reply With Quote
Old 23rd July 2004, 05:25 AM   #4
rakeshln is offline rakeshln  India
diyAudio Member
Join Date: May 2004
Location: Mumbai
  Reply With Quote
Old 23rd July 2004, 09:53 AM   #5
hunter audio is offline hunter audio  India
diyAudio Member
Join Date: Dec 2003
Location: Mumbai

only thing left out is - check the length of the winding on the coil

measure the top plate thickness - subtract this from the length of the coil and devide by 2

mark off this amont on the inside of the voice coil , (starting from the begining of the winding when looking from top) and when setting the coil with shims - insert upto this mark

this way u will be maintaining the x - max of the coi

suranjan das gupta

transducer design engineer l
  Reply With Quote
Old 23rd July 2004, 01:42 PM   #6
rabbitz is offline rabbitz  Australia
diyAudio Member
rabbitz's Avatar
Join Date: Jul 2003
Location: Newcastle, Australia
These pdf's might help.




For voice coil shims I prefer using clear polypropylene or acrylic covers they use in book binding. It's 0.3mm thick, quite stiff, slippery and doesn't tear. It's great as you can still see what you are doing as it's clear. I cut the corners at 6mm x 45 (helps when inserting), length 3 x VC dia (allows a gap at the join). Just cut as many as you need to fill the gap.
Attached Images
File Type: jpg vc shim.jpg (6.8 KB, 76 views)
  Reply With Quote
Old 23rd July 2004, 02:25 PM   #7
ajju is offline ajju
diyAudio Member
Join Date: Mar 2003
Location: 77.38E, 12.58N
I've been using 35mm films, Xrays or OHP sheets.
3 pieces of them cut into equal widths such that their width is less than 1/3 the perimeter of the voice coil.. Not much of a precision work...

Insert the shims such that they form the three sides of a virtual equilateral triangle between teh VC and the pole piece..
The voice coil will be held away from the pole piece as well as equally spaced, since the sheets will be bend at near equal angles and their edges support the voice coil (see fig).
The equal but small force excerted by all the 6 edges provides a uniform gap around the pole piece. This coupled with the voice coil vertical allignment gives extremely good results.

Sounds difficult...but is actually quite easy.

Attached Images
File Type: gif vc_repair_allign.gif (5.5 KB, 87 views)
  Reply With Quote


recentering a Voice CoilHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Making A Voice Coil DKAudio Subwoofers 30 6th February 2015 08:11 AM
Voice coil cooling Moondog55 Multi-Way 32 8th October 2008 10:09 PM
Single Voice Coil Vs Double Voice Coil Subwoofer Workhorse Car Audio 6 12th April 2007 06:36 AM
ASV voice coil ? Nihilist Multi-Way 4 1st October 2006 07:16 PM
an amp for each voice coil? speekergeek Multi-Way 1 12th December 2003 02:31 AM

New To Site? Need Help?

All times are GMT. The time now is 10:07 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio