AR3--- How to Remove Enamel from Mid Spkr Wire?

[Guest Deafears]

Unfortunately I removed a mid driver before realizing the pot was dirty. Looked easy enough to reinstall BUT...for the life of me I can't solder an extension wire to the now too short speaker wires. I tried scraping with my pocket knife, sandpaper and melting the enamel with a blob of solder. So far all I've managed to do is break the brittle tiny wire a couple times.

The speaker worked on the bench so I know it's still good. Any suggestions on how to solder to this hair-like wire would be appreciated.

http://www.classicspeakerpages.net/dc/user_files/2250.jpg

[RoyC]

Arkie,

The tweeter and mid leads of that era are made of aluminum. Consequently, they are very brittle, and difficult to solder. Flux and solder specific to soldering aluminum electrical wire should be used.

You can also try strands of the tinned wire used in the AR crossover (today's "marine wire"). It is easier to solder to the aluminum leads than bare copper.

Roy

[Guest Deafears]

Well, that'll certainly make a difference. Now that you mention it I did notice they were VERY sliver after sanding the coating. Never dawned on me they would be aluminum. Thanks Roy.

[dynaco_dan]

Hi there;

I was going to suggest de-soldering braid, which I believe is flux impregnated fine braided copper wire.

It comes in several small diameters in small rolls.

It also appears to be what most maufacturers use as their braided speaker wire for connecting the cones to the terminal connections on the rear of the frames.

Aluminum compatible solder and flux I have not seen recently but one sample I've seen was produced by Sears-Roebuck and Co. many decades ago.

[Guest Deafears]

Vern,

I use what I think you are talking about on occassion, but I think it is just finely braided copper wick which is used to suck up solder from a terminal, etc. My problem is I can't get the 60/40 solder I have to stick to the fine aluminum (according to Roy) wire. I found some aluminum solder on the net, but as you say it certainly is not common. I thought the problem was the coating on the wire, but maybe I do need something that will stick to aluminum at a lower temp or something.

[RoyC]

>My problem is I can't

>get the 60/40 solder I have to stick to the fine aluminum

>(according to Roy) wire.

Arkie,

I recommended tinned (copper) wire, not aluminum wire. You can borrow a few strands from one of your crossover wires and twist them together.

You may be able to make the connection using common 60/40 solder...although the preferred solder for aluminum wire is over 90% tin.

Roy

[dynaco_dan]

Hi Roy;

At plumbing wholesalers, at least here in Canada, they carry 1 pound rolls of 50/50, tin/lead, solder, 1/8" diameter.

They also carry 1 pound rolls of 95/5 tin/lead solder.

This may be available at 1/2 pound or smaller rolls.

These are only solid core as well.

A member here mentioned last year obtaining aluminum solder from an un-mentioned source, if I remember correctly.

[RoyC]

Hi Vern,

Some time ago I made the aluminum wire to tinned wire connection work on a couple of AR-3 drivers using common Kester "44" rosin core 60/40 solder, but have no idea how those repairs held up. This was after unsuccessful attempts to solder it to bare copper tinsel lead. Aluminum oxidizes quickly, and just hates to be soldered :-).

Roy

[Guest Deafears]

Roy,

I originally tinned some strands of copper wire (about the same diameter as the hair-like driver wires) and tried soldering those together. Problem is the solder doesn't want to stick to the driver leads. If I try to twist the wires together to solder, the brittle speaker wire just breaks. I thought you were suggesting getting solder/flux specifically for aluminum wire. I did find a few references to solder for aluminum, but it was more in the vain of use for raidator repair.

I'm wondering if silver solder (readily available) would work. I assume it has a lower melting point, but again, not sure about adhesion to aluminum.

I gotta believe I'm doing something wrong as this has to be a common procedure for anyone replacing AR3/3a midi/tweets and probably alot of other speakers as well. If it were that difficult, I'd think there would be lots of information about the procedure. What do the repair shops do? Is the problem the wire has just become so brittle with age that it's very difficult? So far I still have enough length left to play with, but too many more "tries" and the speaker leads will be too short to work with.

[RoyC]

Arkie,

I twist the strands of tinned wire together, and then "hook" the ends of the driver leads and twisted strands together with tweezers. Maybe the composition of tinned wire is more compatible than your solder-tinned wire...don't know. Common electrical solder has a high lead content, which is not good for aluminum soldering.

Keep us posted...

Roy

[Guest Deafears]

Roy,

Ever hear of "old" solder deteriorating? One thought I had is that the solder I'm using is 60/40, but several years old from a large spool. I'll pick up some fresh smaller diameter solder next week and give that a try along with some tinned wire. Will post back then.

[Guest Deafears]

GOT IT!

Roy's comment about hooking the wire gave me an idea. I had a burned out led back panel light with nice fine stranded wire leads. Cut a length of that, soldered each end, leaving an unsoldered gap in the middle. Then weaved the driver lead thru several strands of the led wire. Hit that with solder and all is well again. I tested the speaker with a meter from the crossover and got 2.5 ohms and some speaker noise which is what I got on the bench. Wiggled the wires where I soldered and meter stayed stable so I think this is permanent.

Now I have all 4 pots working and corrected the crossover wiring. Will put the woofer back in tomorrow and assuming all sounds good at that point will proceed with getting a surround kit for the woofers.

Thanks guys. Great forum!

[dynaco_dan]

Hi again;

As for buying solder, there has been a major change in the metal industry over the past few decades.

Scares from environmental pollution and health safety from lead from solder leaching into plumbing pipes.

Some solders, content unknown, can be bought in smaller hardware stores.

I once wrote to one of those manufactures and asked for the content breakdown.

I received a reply but no breakdown.

Leadfree solder has become predominant, at least here in Canada, for the plumbing trade.

Electronic parts suppliers have a more specialized solder inventory.

I wrote here a year or so ago about a product stocked by electronic parts suppliers, GC? perhaps.

It is a pure silver based 2-part epoxy mix, and is electricaly conductive.

It is in small, 0.1 gram or smaller tubes, expensive, as there is a tube of pure silver powder.

It is used to repair breaks in circuit traces on circuit boards for one example.

Usually I would not recommend connecting disimilar metals but in this case we do not have too many options and the material disimilarity here isn't all that critical if bonding is near perfect.

If the end of the aluminum wire, perhaps only 1/2" or so, is very carefully cleaned with sandpaper or equivalent, this etches the surface and allows for a much better bond.

With all of the many years I was in sheetmetal I never ever soldered aluminum sheets.

I did see Argon welding being done from a distance, but this is way off the topic.

A warning about solder, acid core is very corrosive and must be avoided at all cost.

I do not believe that rosin core or paste is the correct cleaning compound.

I am not certain what flux is actually needed to properly chemicaly clean aluminum.

As far as silver solder goes, electronic solder today can be bought with 1 - 2 - 3 - 4% silver content, with rosin or equivalent type flux included, works beautifully with copper wire, I never tried it with aluminum though.

Works very well with a soldering iron.

The silver is an added alloy making the connection a little stronger and shinier.

When I first read about silver solder, I thought back to my apprenticeship days when we would use silver solder to seal off or join copper tubing.

You needed to get the tubing fairly red hot, thank goodness this is not the case with electronics.

[Guest Deafears]

Vern,

I had sanded the speaker wire previously with no luck getting solder to stick. Why it bonded this time using the LED stranded wire around the speaker wire, I'm not sure. Maybe it's just being "squeezed" by the solder bonding to the led wires, but electrically it's measuring exactly what it did on the bench, so that's good enough for me at this point.

Somehow I have to believe that using rosin core solder is standard procedure and works for aluminum in applications like soldering speaker coils to terminals like this. If not, seems like it would be fairly common knowledge that something diffrerent was needed. I understand the dissimilar metals scenario and who knows...Maybe in another 40 years the speaker impedance will grow a half ohm. But for now I'm happy I got it in and functional without breaking the wire off where I couldn't attach to it. Does make me wonder if the design engineer at AR gave any thought to the service guy when he designed this method of attaching the speakers!

Again, thanks for your thoughts and to all who contribute with such knowledge to this forum.

[johnieo]

Arkie:

Some care is necessary to connect aluminum to other metals with good long-term, reliable, low-resistance interfaces.

Aluminum forms intermetallic compounds with materials such as silver and gold. (In the beginnings of the semiconductor business in the sixties, we used to solder Al wires to Ag and Au pads. Both eventually failed with formation high resistance intermetallic compounds at the interface.

Why mention silver? because one easy way to get a high Sn content, low melting point alloy is to use one of the new 96% Sn, 4% Ag alloys. However, these are NOT suitable for soldering aluminum as the silver will eventually react with the aluminum and form a high resistance joint. (Sn-Ag solders are mandatory when soldering Ag-plated copper wire.)

One choice would be 95%-Sn, 5%-Pb solder. Its melting point is highr but it will bond if a good flux is used.

Alternatively, some years ago, a forum member noted that one can form a compression bond. Find a small diameter, hollow Sn- or Ni-plated copper or brass connection pin (not Au-plated!!) from some kind of miniature connector and cut out a section, or drill a #54 hole in a small piece of copper. Push the Al wire in one end, crimp, and repeat with the copper lead wire. I would personally use a crimp seal as Ni, Sn, and Cu do not form intemetallics with Al and no aluminum flux is needed.

ps: solder does not get old! It oxidizes on the surface; that's what flux is for.

Cheers

[tysontom]

>Unfortunately I removed a mid driver before realizing the pot

>was dirty. Looked easy enough to reinstall BUT...for the life

>of me I can't solder an extension wire to the now too short

>speaker wires. I tried scraping with my pocket knife,

>sandpaper and melting the enamel with a blob of solder. So

>far all I've managed to do is break the brittle tiny wire a

>couple times.

Probably the best way (there are no good ways) to re-attach the aluminum wire is to take a single, small strand of copper wire (or aluminum wire if you can find it) and form a loop on both ends to be connected to extend the length of the broken speaker lead-out wire. Compress the loops (using small needle-nose pliers) into a physical bond and then you can attempt to solder using, preferably, Alumasol solder. Sometime regular solder will work, but the bond is always tenious at best. Alumasol aluminum solder is difficult to use, but it will work satisfactorily with the proper heat and with patience.

--Tom Tyson

[RoyC]

Congrats Arkie!

...VERY glad to see John and Tom jump in here!

Tom, the method you described is essentially what I use with all of the front wired leads. I should have mentioned squeezing the "hooks" together.

Of course another limitation is that the aluminum leads break so easily, so handling has to be very careful, and kept to a minimum.

Tom, do you know what years the aluminum leads were used? They appear to have been changed to copper sometime in the late 60's. Didn't it have something to do with copper prices and/or availability?

Roy

[dynaco_dan]

>

>

>Probably the best way (there are no good ways) to re-attach

>the aluminum wire is to take a single, small strand of copper

>wire (or aluminum wire if you can find it) and form a loop on

>both ends to be connected to extend the length of the broken

>speaker lead-out wire. Compress the loops (using small

>needle-nose pliers) into a physical bond and then you can

>attempt to solder using, preferably, Alumasol solder.

>Sometime regular solder will work, but the bond is always

>tenious at best. Alumasol aluminum solder is difficult to

>use, but it will work satisfactorily with the proper heat and

>with patience.

>

>--Tom Tyson

>

Hi Tom;

Your are the man with the name, Alumasol, brand solder, thank you.

Do you know very much about using this product?

In electronic stores they usually carry NTE or other pre-packaged electronic parts.

They sell thermal fuses with a pair of tiny crimpon couplings to attach the leads to existing wires.

A coupling can be made from a common furnace/water heater thermocouple, if it is still copper tubing, that is.

A thermocouple tubing is similar in design to your cablevision wire, a tiny copper tubing, perhaps 1/16" ID, and an insulated high temperature inner wire.

Using copper tubing cutters, much easier, or a fine hacksaw blade, 100's of couplings can be made from just one thermocouple.

These can be squeezed or crimped onto the copper and aluminum wires.

[soundminded]

Here is an entirely different idea. Do not bend the aluminimu wire as it may break because it is so fragile and brittle. Instead, wrap a single strand of copper wire around it for a half an inch to an inch near its end so that it is in contact along its length and apply a single drop of glue. If the glue does not get between the two wires to form an insulation between them, this may be satisfactory, therefore try a glue which is not too thin. Elmers or contact cement might do the trick. Just a thought.

[dynaco_dan]

Hi there;

Good thought, Soundminded, almost like the, old wire wrap method.

Bending aluminum wire is an invitation to break at that point for sure, if not done very gently.

Aluminum house wire was notorious for breaking off if the electrician nicked the wire while stripping the insulation off.

There certainly is a lot of ideas for this topic.

My main concern is the the aluminum lead be taped to the drivers plate and only the loose end be manipulated.

[kkantor]

Dear Deafears,

Easy(ish).

1- Carefully make a stable mechanical contact between the wires. I would recommend taping them down touching one another.

2- Apply a drop, to two, of liquid solder, ("wire glue"), to the joint, and leave it overnight.

Here's the stuff I am talking about:

http://www.allelectronics.com/cgi-bin/item....3_FL.OZ._.html

-k

www.kenkantor.com

http://kkantor.spaces.live.com

[dynaco_dan]

Hi Ken;

Thank you very much.

I don't think it will get any easier than this solution, and cheap too!

The two part epoxy/silver solution I was writing about is about $20 - $30.00 CDN.

[tysontom]

>Congrats Arkie!

>

>...VERY glad to see John and Tom jump in here!

>

>Tom, the method you described is essentially what I use with

>all of the front wired leads. I should have mentioned

>squeezing the "hooks" together.

>

>Of course another limitation is that the aluminum leads break

>so easily, so handling has to be very careful, and kept to a

>minimum.

>

Roy, this is very true. I also think the best method is to use tweezers (with a magnifying glass or loop), rather than the usual needle-nose plyers, to carefully make a loop and crimp. The suggestion to tape the wire down before making any connections is also a good idea.

>Tom, do you know what years the aluminum leads were used? They

>appear to have been changed to copper sometime in the late

>60's. Didn't it have something to do with copper prices and/or

>availability?

Well, aluminum wire was always used in the AR-3 midrange and tweeter, from 1958 up until the end of production. It was also used in the AR-2a and AR-2ax (prior to 1970) tweeters as well. Later on, AR did copper-clad the lead-in wires on the AR-3, but this came sometime in the mid-to-late 1960s. Of course, the AR-3a always had copper wire for both midrange and tweeter. It is much more reliable. I believe that Altec Lansing and JBL used quite a bit of aluminum wire in some of their voice coils, so it is not a unique practice by any means.

To understand one of the advantages of formerless aluminum-wire voice coils, take a look at the tone-burst photos taken of the AR-3 midrange and tweeter. There was no ringing or overshoot at any frequency, a phenomenon that can usually be found to some extent in most tweeters.

--Tom Tyson

[dynaco_dan]

Hi there;

To add to Ken's very reasonable conductive glue suggestion of just laying one on top and glueing them.

If perhaps the end 1/2" of aluminum wire is gently cleaned with sandpaper and a fine stranded copper wire is wrapped around, similar to a sheet metal or woodscrew thread, not a fine machine screw thread, around the end of the aluminum wire and then glue with this adhesive.

It will not place too much strain on the aluminum wire and with all of that exposed surface making contact, there should never be a future problem with it.

Ken thank you for a simple solution and reasonably priced method of repair.

It certainly is within easy reach of all members with this type of issue now or in the future.

At least we don't need to buy a gallon or a case of it.

Maybe 35 years ago, The Audio Amatuer Magazine had an article about building electrostatic speakers from scratch.

In it was mention of using a electricly conductive glue to bind a bare copper wire to steel rods, this may be that adhesive.

[kkantor]

By request:

BUMP!

-k

www.kenkantor.com

http://kkantor.spaces.live.com