Going to try winding a voice coil

johnthedoctor · 30th August 2006, 05:57 PM

Got given some Wharfedales with the drivers o/c, have dismantled one and fancy having a go at rewinding the voice coils. The bit of coil I've pulled off has 17 turns in 3.5mm of width, so about .020mm including varnish. What gauge is that?

planet10 · 30th August 2006, 09:48 PM

Good luck. I'll be very interested in your progress...

dave

vinylkid58 · 30th August 2006, 10:25 PM

Quote:

Originally posted by johnthedoctor
Got given some Wharfedales with the drivers o/c, have dismantled one and fancy having a go at rewinding the voice coils. The bit of coil I've pulled off has 17 turns in 3.5mm of width, so about .020mm including varnish. What gauge is that?

3.5MM/17=0.2059 ~0.008" = 32AWG assuming the varnish is very thin and doesn't add much to dia. It could be 33AWG =0.0071" dia.

Jeff

pinkmouse · 30th August 2006, 11:05 PM

Good luck!

The voice coil needs to be pretty tight on the VC former, so you may well need to make a circular jig that just slips inside, that will stop it distorting as you wind.

rjb · 31st August 2006, 02:36 AM

The voice coil must be both tight on the former. and the combination perfectly circular when finished. You will definitely need a very smooth rod that just slides into the existing former, (or some similar removeable jig).
You will not be able to make it circular after winding if you get it wrong.
Use only enough tension on the wire to keep it firm on the former.
(You may need to grease the rod, because the winding pressure will tend to shrink the former, but be very careful to keep grease off the winding side of the former itself, (use only a very light smear), or else the glue used to fix the winding into place won't take).
Good luck

PB2 · 31st August 2006, 02:52 AM

I did it years ago with excellent results. The first was a Dyna A-25
woofer, this was for Phillips AD8060 woofers:

http://members.aol.com/basconsultants/hand_vc.htm

One mistake was that the former was slightly thicker than the original,
and it was a tight fit. Most hobby shops in the US carry very thin stock
sheet of aluminum and often brass. I used copper to match the thermal
properties of the wire. Be sure to use the correct gauge wire.

The wire now comes in different grades with different temperature ratings
as I recall.

I used high temp two part epoxy.

Pete B.

AndrewT · 31st August 2006, 08:16 AM

Hi,
that's a very short VC @ 3.5mm.

Is it overhung (bass/mid) or underhung (treble and some mid)?

Looking forward to your solutions, conlusions and pics.

johnthedoctor · 31st August 2006, 02:48 PM

Thanks all for the help.

The 3.5mm is only part of the coil that I pulled off the former. Total coil is about 28 turns, single layer. Have a bad feeling that the cone has to be removed but will try doing it with the cone intact. 4 bolts holding the magnet to the basket so hoping there's enough play there for adjustments.

Wasn't expecting such interest in my progress, I'm a noob at diy audio and the drivers are dead anyway but I'll take pics as I go along for a 'How Not To' guide.

phase_accurate · 31st August 2006, 03:02 PM

Years ago I used to do this with the cone still attached to the coil-former. I removed the dustcap since it made things easier (especiallly the centering afterwards). If I couldn't find an adequate rod I used shets of thin paper or film negative inbetween. You definitely need to glue the wire to the former in the end.

Regards

Charles

AndrewT · 31st August 2006, 04:49 PM

Hi,
DO NOT unbolt the magnet from the pole pieces.

Due to the very strong magnetic attraction it will be extremely difficult to re-centre the pole gaps which must be concentric.

If the magnet surface is not plane (mine is not) and the pole piece is plane then there is a gap which I imagine reduces the total flux across the gap.

Q.
Is it better to fill the pole piece to magnet gap with a magnetic fluid before bolting it all back up?

I have still to design a jig to keep accurate alignment while offering up the pole to the magnet.

30th August 2006, 05:57 PM	#1
johnthedoctor diyAudio Member Join Date: Sep 2005	Going to try winding a voice coil Got given some Wharfedales with the drivers o/c, have dismantled one and fancy having a go at rewinding the voice coils. The bit of coil I've pulled off has 17 turns in 3.5mm of width, so about .020mm including varnish. What gauge is that?

30th August 2006, 09:48 PM	#2
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 5	Good luck. I'll be very interested in your progress... dave __________________ community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

30th August 2006, 11:05 PM	#4
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	Good luck! The voice coil needs to be pretty tight on the VC former, so you may well need to make a circular jig that just slips inside, that will stop it distorting as you wind. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

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31st August 2006, 02:36 AM	#5
rjb diyAudio Member Join Date: Jun 2004 Location: Piha	The voice coil must be both tight on the former. and the combination perfectly circular when finished. You will definitely need a very smooth rod that just slides into the existing former, (or some similar removeable jig). You will not be able to make it circular after winding if you get it wrong. Use only enough tension on the wire to keep it firm on the former. (You may need to grease the rod, because the winding pressure will tend to shrink the former, but be very careful to keep grease off the winding side of the former itself, (use only a very light smear), or else the glue used to fix the winding into place won't take). Good luck

31st August 2006, 02:52 AM	#6
PB2 diyAudio Member Join Date: Sep 2004 Location: North East Blog Entries: 1	I did it years ago with excellent results. The first was a Dyna A-25 woofer, this was for Phillips AD8060 woofers: http://members.aol.com/basconsultants/hand_vc.htm One mistake was that the former was slightly thicker than the original, and it was a tight fit. Most hobby shops in the US carry very thin stock sheet of aluminum and often brass. I used copper to match the thermal properties of the wire. Be sure to use the correct gauge wire. The wire now comes in different grades with different temperature ratings as I recall. I used high temp two part epoxy. Pete B.

31st August 2006, 08:16 AM	#7
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, that's a very short VC @ 3.5mm. Is it overhung (bass/mid) or underhung (treble and some mid)? Looking forward to your solutions, conlusions and pics.

31st August 2006, 02:48 PM	#8
johnthedoctor diyAudio Member Join Date: Sep 2005	Thanks all for the help. The 3.5mm is only part of the coil that I pulled off the former. Total coil is about 28 turns, single layer. Have a bad feeling that the cone has to be removed but will try doing it with the cone intact. 4 bolts holding the magnet to the basket so hoping there's enough play there for adjustments. Wasn't expecting such interest in my progress, I'm a noob at diy audio and the drivers are dead anyway but I'll take pics as I go along for a 'How Not To' guide.

31st August 2006, 03:02 PM	#9
phase_accurate diyAudio Member Join Date: May 2002 Location: Switzerland	Years ago I used to do this with the cone still attached to the coil-former. I removed the dustcap since it made things easier (especiallly the centering afterwards). If I couldn't find an adequate rod I used shets of thin paper or film negative inbetween. You definitely need to glue the wire to the former in the end. Regards Charles

31st August 2006, 04:49 PM	#10
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, DO NOT unbolt the magnet from the pole pieces. Due to the very strong magnetic attraction it will be extremely difficult to re-centre the pole gaps which must be concentric. If the magnet surface is not plane (mine is not) and the pole piece is plane then there is a gap which I imagine reduces the total flux across the gap. Q. Is it better to fill the pole piece to magnet gap with a magnetic fluid before bolting it all back up? I have still to design a jig to keep accurate alignment while offering up the pole to the magnet.

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