200003 woofer voice coil former

[fedeleluigi]

Using my 80 watt valve amplifier,one of my AR 3a woofer began to play badly. I found out that the paper voice coil former broke completely by the connection with the spider.

I don't know if the problem depends on the age or perhaps becouse the woofers were used without surround by the previous owner for some time.

As far as I know ( I have disassembled many AR woofers) AR used paper former for its woofers until about 1977 then it began to use aluminium with AR 10 pi, 11, 12, 14 etc. "MKII". As I have seen aluminium former in 3a midranges produced in 1970, I wonder why AR preferred to use paper former for its woofers until about 1977. Does anybody know why?

Now I have to change my woofer voice coils, what sort of voice coil former is better for AR 3a woofers ? paper, aluminium or kapton?

The 200003 woofers produced after 1977 (they have aluminium coil formers) look almost the same as the ones with paper coil formers but I don't Know if the paper cones of the ones with aluminium formers are lighter to compensate for the higher weight of metal formers.

Do you know who makes custom-made voice coils?

Do you know where I can buy spiders for Ar 3a woofers (i.e. with the same pliability) and adhesives for speakers.

Thank you in advance for any answeer and suggestion.

Luigi

[tysontom]

Luigi,

The voice-coil former, or "bobbin" as it used to be called, on the ceramic woofer (200003 and 1210003) is made from a Nomex material, not paper. It is a very good dielectric, and at the same time has excellent ability to absorb heat. It bonds extremely well to the paper cone, naturally. On the other hand, the original AR-1 and AR-3 Alnico woofers used bronze for the former, but it was not as stable as Nomex, and it could easily break at the point of bonding with the cone -- and often did.

To my knowledge, AR never used anything but this Nomex-type material with all of the ceramic woofers, certainly well up through the late 1970s. I have seen and dissected failed woofers all the way up through the 1980s and have not seen aluminum voice-coil formers on that woofer. If they used aluminum I have certainly missed it, and it is certainly possible that they did use it. The newer Tonegen woofer may have a different material for the former.

Most likely what happened to your woofers is what you alluded to in your opening paragraph, "...I don't know if the problem depends on the age or perhaps becouse the woofers were used without surround by the previous owner for some time...." Without an air-tight seal, the woofer would easily bang against the bottom plate of the magnet structure ("bottoming"), causing the cone to crush the top of the voice-coil former, and ultimately causing it to fail. The voice coil itself would also be likely to scrape the sides of the gap on long excursions, causing damage to the insulation material on the bell wire. The ultimate destruction of the voice-coil former is not a failure of the AR design, but negligence on the part of the original owner who allowed the speaker to bottom. This is what AR used to refer to as "abuse, accidental or otherwise."

--Tom Tyson

[ninohernes]

What is the bobbin on the AR-2 woofer made of (just curious)? My AR-2 woofers are the early alnico version. The magnet looks just like and AR-3, except a bit smaller. These speakers have been great, I have only had an issue where they bottomed out, once. I was playing a recording of a rock musical, which had copius bass (and sub bass) content, and all of the sudden, durring a particularly copuis section, "CRACK". Very loud crack, scared me half to death. Now when I play this album, I use a low end filter.

[tysontom]

>What is the bobbin on the AR-2 woofer made of (just curious)?

>My AR-2 woofers are the early alnico version. The magnet looks

>just like and AR-3, except a bit smaller. These speakers have

>been great, I have only had an issue where they bottomed out,

>once. I was playing a recording of a rock musical, which had

>copius bass (and sub bass) content, and all of the sudden,

>durring a particularly copuis section, "CRACK". Very loud

>crack, scared me half to death. Now when I play this album, I

>use a low end filter.

Joe,

The bobbin on the AR-2 woofer is also bronze, the same material as in the AR-1 and AR-3 woofer. The "crack" sound was not the voice coil actually bottoming against the bottom plate or back plate, but the cone and skiver actually hitting the *top* plate. If you look at the construction of the early Alnico woofers, the magnet structure is such that the bottom plate is way back away from the end of the voice coil. In the newer ceramic woofers, such as the 200003 used in the AR-3a, etc., with the flatter ceramic-ferrite magnets, the end of the voice coil can actually "bottom" against the back plate, and the noise it makes is frightening.

--Tom Tyson

[Guest Droog]

I assume the above information applies to an original 1965 2ax woofer as well ? What am I hearing when I cut

amplifier power and a slight pop is heard plus an echoing sound from the woofer, I also notice the woofer cone

travels forward about 1/3" at this time? The speaker performs very well at all volumes.

[fedeleluigi]

Tom

Thank you very much for answering.

Now I would like to repair the broken woofer and try to make it sound as good as new. I live in Italy but I would like to use USA spare parts becouse this woofer was made in USA.

Do you know who makes custom-made voice coils?

Do you think it' s better to use Nomex than aluminium or kapton for the bobbins ?

Do you know who makes spiders for Ar 3a woofers (i.e. with the same pliability) and what adhesives are better for it.

Thank you in advance for any answeer and suggestion.

Luigi

[tysontom]

>Tom

>Thank you very much for answering.

>Now I would like to repair the broken woofer and try to make

>it sound as good as new. I live in Italy but I would like to

>use USA spare parts becouse this woofer was made in USA.

>

>Do you know who makes custom-made voice coils?

>Do you think it' s better to use Nomex than aluminium or

>kapton for the bobbins ?

>Do you know who makes spiders for Ar 3a woofers (i.e. with the

>same pliability) and what adhesives are better for it.

>Thank you in advance for any answeer and suggestion.

>

>Luigi

Hello Luigi,

I think you would be better served to find another AR 200003 woofer, perhaps from eBay, and have it shipped to you rather than try to locate all the adhesives, suspension pieces and coils, and so forth to rebuild from the ground up. I honestly don't know who makes that sort of thing available to the consumer; and if they did, the question would be if it were like the original. Also, most companies that specialize in that sort of thing probably don't want to sell you just one voice coil, they want to sell you 10,000. And by the time you went in and tried to re-build the broken woofer using the new parts, you could have probably found a good-working AR woofer somewhere. I'm not trying to rain on your parade, but just trying to be realistic. It's sort of like the tweeter voice-coil winding proposal made by someone in another post. It's not impossible, but it is highly impractical, and the results would be questionable.

AR used parts, spec'd to their designs, from various places, such as Loudspeaker Components, CTS, and other places, and then assembled these components in-house. They did wind voice coils and magnetize magnets, but most cones, glues, fabric materials, baskets and magnet steel and so forth were purchased to spec from outside vendors. Most of the glues that were used were commercial-grade, two-part epoxies and special-purpose glues applied with air-pressure guns on the production line.

--Tom Tyson

[tysontom]

>I assume the above information applies to an original 1965

>2ax woofer as well ? What am I hearing when I cut

>amplifier power and a slight pop is heard plus an echoing

>sound from the woofer, I also notice the woofer cone

>travels forward about 1/3" at this time? The speaker performs

>very well at all volumes.

What you are really describing is an amplifier power-on, power-off variation in DC offset, which occurs in all amplifiers during the brief seconds when the power supply is stabilizing on turn-on, or draining down on turn-off. If your amp does not have a turn-on, turn-off timed relay, which it sounds like it doesn't, the dc offset goes straight to the woofer in the form of a thump or pop, accompanied by some cone travel. In nearly all cases this is harmless -- if unnerving -- but you want to be sure that it does not cause the woofer to move too far during those transients. If it is troublesome, you can fashion a speaker switch to disable the speakers during turn-on and turn-off, a sort of manual "turn-on relay."

The six-bolt, aluminum-frame, Alnico-magnet 10-inch woofer (this is the one that is closest to 11" in diameter) was used in all AR-2 speaker variations, including your 1965 model, all the way up to 1970. After that, a new, four-bolt stamped-basket woofer was introduced, and this woofer is characterized by the foam surround and flat dust cap. The first ones used a pole-piece Alnico magnet; later ones used ceramic square magets with some slight changes in the surrounds.

What you have to watch out for on this older woofer is the surround separating from the masonite ring on the edge of the speaker frame, and occasionally the voice coil separating from the cone. The glue gets more brittle as it ages, I think, and this makes these older speakers more susceptible to breaking. Fortunately, this can usually be repaired with a little patience.

--Tom Tyson

[r_laski]

Luigi,

To add to what Tom has written. There are many speaker repair businesses in the US who can re-cone an AR 12 inch woofer. Buying a used AR woofer on eBay or a new replacement AR woofer are viable options and may prove to be less costly to you, given shipping charges to Italy.

I had an AR woofer that required re-coning and I wanted to do it myself. I tried to find a source for adhesives, braided wire, cones, voice coils, and spiders. I hit a brick wall. There are several voice coil, cone, and spider companies and wholesalers out there. I didn’t find any of these that will sell to a “consumer.” You have to be an owner of or technician in a speaker building or speaker repair business before they will sell the parts to you. Especially in small quantities. I also tried to get a local speaker repair shop to sell me the parts with no luck. I ended up having them re-cone the woofer. The parts cost about $30 US and labor was $60 US. Having said all this, here are two web sites of speaker part manufactures:

Custom voice coils and other speaker parts-

http://www.mwaspeakerparts.com/index.html

Cones, spiders, dust caps-

http://www.nuway-speaker.com/

There is one retail business in Australia that sells re-coning parts to consumers.

http://www.speakerbits.com/devdefault.aspx

>>Do you think it' s better to use Nomex than aluminum or Kapton for the bobbins ?<<

Kapton (made by DuPont) is currently the “standard” or most common former material because of its high temperature capability and electrical properties. In my opinion, as long as the voice coil is made to the exact specifications you need, the bobbin material won’t matter. If you want to be “historically correct,” use what was originally used.

Rich

[r_laski]

>>To my knowledge, AR never used anything but this Nomex-type material with all of the ceramic woofers, certainly well up through the late 1970s. I have seen and dissected failed woofers all the way up through the 1980s and have not seen aluminum voice-coil formers on that woofer. If they used aluminum I have certainly missed it, and it is certainly possible that they did use it. The newer Tonegen woofer may have a different material for the former.<<

Tom,

Just some information from my experiences. I’ve re-foamed several AR 12” woofers over the past year. When I re-foam, I remove the dust cap and shim the voice coil gap.

The two woofers in a pair of LSTs have Nomex voice coil formers (looks like paper). These are early ferrite/ceramic woofers (2000003) with the wider gasket on the basket flange the surround is glued to. I believe these are the ones you call the “most compliant.” I’ve re-foamed five AR11 woofers and eight AR9 woofers (2000003 / 2000003-1). All these have Aluminum voice coil formers. I’ve also re-foamed Tonegen / AR 12” woofers from a pair of AR9 LSIs. These also have Aluminum voice coil formers. All the 10” and 8” AR & Tonegen drivers I’ve re-foamed have Aluminum voice coil formers.

The leading edge of the aluminum formers is razor sharp. You have to be careful inserting shims so as not to “shave” them leaving debris in the voice coil gap.

Rich

[tysontom]

>

>Tom,

> Just some information from my experiences. I’ve re-foamed

>several AR 12” woofers over the past year. When I re-foam, I

>remove the dust cap and shim the voice coil gap.

>

> The two woofers in a pair of LSTs have Nomex voice coil

>formers (looks like paper). These are early ferrite/ceramic

>woofers (2000003) with the wider gasket on the basket flange

>the surround is glued to. I believe these are the ones you

>call the “most compliant.” I’ve re-foamed five AR11 woofers

>and eight AR9 woofers (2000003 / 2000003-1). All these have

>Aluminum voice coil formers. I’ve also re-foamed Tonegen / AR

>12” woofers from a pair of AR9 LSIs. These also have Aluminum

>voice coil formers. All the 10” and 8” AR & Tonegen drivers

>I’ve re-foamed have Aluminum voice coil formers.

>

> The leading edge of the aluminum formers is razor sharp. You

>have to be careful inserting shims so as not to “shave” them

>leaving debris in the voice coil gap.

Rich,

Thanks very much for the informative update. I did not realize that aluminum had later been used for the former, was clearly out to lunch and missed that one. I think that all the woofers I've repaired were earlier versions, and the majority of times I did not have to shim the voice coils anyway. I do have several voice coils from the original AR-10Pi/AR-11 era, but AR must have changed to aluminum formers somewhere in the late 1970s as Luigi mentioned.

It is also quite true that if the voice coil is done properly, the former material is probably not critical anyway with today's adhesives. Aluminum formers would do a good job of dissipating heat, but Kapton is probably the best overall, and is certainly one of the standard materials used today. Kapton is also used on high-temp, mil-spec soderless connectors made by AMP, T&B and others due to its high flash point.

--Tom Tyson

[fedeleluigi]

I’ve re-foamed five AR11 woofers

>and eight AR9 woofers (2000003 / 2000003-1).

Rich

thank you for the information about web sites.

Did you note any differences between 200003 and 200003-1 woofers? I've never seen the latter.

How do you remove the dust cups of these woofers? Do you use a solvent or a cutter?

Luigi

fedeleluigi@inwind.it

[fedeleluigi]

>

> >

> >Hello Luigi,

> >

> >I think you would be better served to find another AR 200003

> >woofer, perhaps from eBay, and have it shipped to you rather

> >than try to locate all the adhesives, suspension pieces and

> >coils, and so forth to rebuild from the ground up.>

> >--Tom Tyson

Tom

thank you again for answering.

The problem is that most users did not know (and do not know) that a speaker should not be used when the surronds broke. So I think that many 200003 woofers have damaged voice coil formers without that the users know it. My 3a woofer at the beginning sounded perfectly than, after playing loudly for same time, it began to emit very weak vibrations very hard to hear (I had to turn completely down midrange and tweeter and play loudly to hear them clearly).I could not understand what the cause was becouse evrything seemed to be right ( moving the cone up and down there wasn't any bobbin scrape !!!, the surround was good etc). I did not think at all that the voice coil former was going to break.

So I think that many 200003 woofers have damaged voice coil formers without owners know it.

 After my woofer break I have checked the 200003 wofers of all my speakers and I can hear weak vibrations emitted by some of them when I play loudly ( It is very hard to hear these vibrations when midrange and tweeter are connected so if someone wants to check his woofers it's better to turn down completely midrange and tweeter and play loudly a music containing low frequencies).

So I'd prefer trying to re-build my broken woofer rather than buying another that can probably be already damaged.

If anyone can give me any suggestions I will be gratefull.

 

Luigi

[r_laski]

>>Did you note any differences between 200003 and 200003-1 woofers? I've never seen the latter.<<

Luigi,

From what I know and see these woofers are exactly the same. The 2000003-1 woofers are all service replacement units. I believe AR used the “-1” on the part number to distinguish a service replacement unit woofer from a production unit woofer. The “-1” replacement woofer also has a red and white service replacement sticker.

As a side note, either part number can have a round or square magnet. I’ve seen both part numbers with both types of magnets.

>>How do you remove the dust cups of these woofers? Do you use a solvent or a cutter?<<

I tried using isopropyl alcohol once when I wanted to completed remove a bad and oversized dust cap on a re-coned AR woofer. I was removing it to re-foam and I was replacing it with a smaller dust cap. I didn’t want a big ring on the cone between the new dust cap and the surround. Alcohol softens the cone paper and you end up taking small bits of the cone with the dust cap. Not a good way to remove the dust cap and one I strongly urge you to not to try this.

I use a razor knife, like an X-Acto knife. I cut as close to the fold as possible on the convex side (inside the fold). The glue underneath the dust cap and around the top of the voice coil will determine how close to the fold you can go. You must be very careful around the voice coil lead wires so as not to cut them. I only remove the convex “bulb” part. I leave the mounting ring on the cone.

When I reinstall the dust cap, I apply a VERY SMALL bead of glue to both edges and line up the cut edges exactly. This is a little tricky as the dust cap likes to pucker in some spots along the edge. I use a toothpick to push the edges together where necessary until the glue sets up. In another thread I wrote about needing patience and a steady hand to re-foam a speaker. This is one step where you definitely need both. If you lined up the edges exactly it is very hard to see the seam.

Rich

[r_laski]

>>If anyone can give me any suggestions I will be gratefull.<<

Luigi,

The best suggestion I can give you is to try to find a repair shop that can re-cone your woofer(s) for you. This will be much easier than trying to find a source for all the materials you need to recone them yourself. You should be able to, but if you can't find one in Italy or the rest of Europe, there are hundreds in the US.

If you want them re-coned in the US, you might try contacting Bill Miller of Millersound:

Millersound

1422 Taylor RD

Landsdale PA 19446

215-412-7700

(no e-mail?)

He has an excellent reputation for repairing AR speakers.

Rich