Original issue AR-3 renovation

[snl]

I just acquired these AR-3 speakers. Serial numbers C1379 and C1733 which I believe puts them into the ultra vintage category. All the speakers appear to work although the highs are somewhat weak. From what I gather so far it seams that cleaning the pots could remedy the weak high problem. So far I have seen posts that show the pots to have a wire hold down that can be removed to open them and clean them. These have tabs that look like they can be bent back. Does any one have experience with these? I am also interested in any ones thoughts about upgrading the crossovers. Is this possible? Will it gain me sound quality? Are these too old to care about? Do these have more value or nostalgia because of the early age and should I even touch them if I can get them to work as is?

[genek]

They're basically the same pots. The older versions have tabs instead of wire bales, and may have wipers stamped from thick brass and mounted with coil springs rather than the thin spring-metal wipers of later units.

[JKent]

Hey SNL. Welcome to CSP!

Coincidentally I, too, am restoring a pair of AR3s. Be sure to consult the AR-3a restoration guide. Much of the information also applies to the 3

http://www.classicspeakerpages.net/library/acoustic_research/original_models_1954-1974/original_models_schematicss/restoring_the_ar-3a/

Definitely clean the pots. Be SURE they are thoroughly clean. That may fix any problem. My 3s have the wax capacitors but yours have what I think are oil-filled caps that are highly regarded (more knowledgeable members correct me if I'm wrong). So I "think" once your pots are cleaned or replaced you should be good to go. Try to keep them as original as possible.

These have become collectible. according to some info provided by John O'Hanlon and Tom Tyson, the initial production run was through serial number C1413, so yours straddle the 1st and 2nd iteration of the AR-3, circa 1959-60. That higher SN had the phase of the mid & tweet reversed relative to the woofer, so if you are using these as a stereo pair you might want to check that and change one (1379) so they match regarding phase.

Don't know if yours have already been modified. Those tweeter & mid connections don't look right to me. Warning: Do NOT remove the tweeter or mid. They have ultra-fine aluminum "tinsel" leads that break easily and are VERY hard to fix.

btw--do any members know a source for a suitable replacement for the brass numeral "3" on the grille? See attached photo of Tom Tyson's AR-3 donated to the Smithsonian.

Kent

[dynaco_dan]

Hey SNL. Welcome to CSP!

Coincidentally I, too, am restoring a pair of AR3s. Be sure to consult the AR-3a restoration guide. Much of the information also applies to the 3

http://www.classicspeakerpages.net/library/acoustic_research/original_models_1954-1974/original_models_schematicss/restoring_the_ar-3a/

Definitely clean the pots. Be SURE they are thoroughly clean. That may fix any problem. My 3s have the wax capacitors but yours have what I think are oil-filled caps that are highly regarded (more knowledgeable members correct me if I'm wrong). So I "think" once your pots are cleaned or replaced you should be good to go. Try to keep them as original as possible. These have become collectible.

Don't know if yours have already been modified. Those tweeter & mid connections don't look right to me. Warning: Do NOT remove the tweeter or mid. They have ultra-fine aluminum "tinsel" leads that break easily and are VERY hard to fix.

btw--do any members know a source for a suitable replacement for the brass numeral "3" on the grille? See attached photo of Tom Tyson's AR-3 donated to the Smithsonian.

Kent

Hi Kent

If I might suggest, replacing the old insulation with sulphur free fibreglass, if, and only if,

it was in the old, but obviously very beautiful AR-3 cabinet.

This may be the main cause of pot corrosion.

Just a thought for tonight.

[speaker dave]

Aside from the 3 tabs the ceramic parts of the pots look pretty much like the later pots. I'm guessing they are similar internally. Careful with the curly nichrome wire inside. For cleaning concentrate on getting a smooth and bright center contact. You might need to use emory cloth or fine wet dry.

The last pair I worked on the midrange suspensions had hardened to the point where an Octave or 2 of midrange was missing. Hope your luck is better.

David S.

[JKent]

Hi Kent

If I might suggest, replacing the old insulation with sulphur free fibreglass, if, and only if, it was in the old, but obviously very beautiful AR-3 cabinet.

This may be the main cause of pot corrosion.

Just a thought for tonight.

Vern, you may be right. btw, my 3s had 40 oz of fiberglass in one, 42 oz in the other. Early 3a's had 28 oz. of FG.

Kent

[genek]

Aside from the 3 tabs the ceramic parts of the pots look pretty much like the later pots. I'm guessing they are similar internally.

The older ones were actually better inside, IMO. Instead of that thin, springy wiper that often corrodes through, the wiper was stamped out of solid brass about .040 thick, pivoted on the knob post and was pressed against the wiper by a small coil spring. No chance of those being eaten away. I lucked on a set from an old AR-2a that had that internally and the wire bale back, and after cleaning and lubing they're living happily in my refurbed AR-3as.

[snl]

Thanks for the replies. My main concern with cleaning the pots is bending the tabs back and then re-bending them without breaking them. The first thing I did was print out the AR-3a restoration guide. Great stuff there. One of the mid connections is already broken, both leads, so I will have to repair it. I notice on later models that the fine tinsel wire is protected with tape, these aren't. I will be happy to upgrade the insulation. That stuff is nasty. The pictures are form the earlier SN. I haven't got the other one open yet. I am curious to see if there is any difference. I can see where this can become an obsession. I started looking for old speakers after I was in a Habitat for Humanity store and a lady had just donated a pair of BA 40's and a small Harmon Cardon receiver. I refoamed them

and started dropping into thrift stores to see what else I could find. I have a pair of Genesis, another pair of BA 40's and these AR-3's that I got at the same Habitat store for $30, it was a BOGO deal I had to take a pair of BA 60's with them.

[JKent]

WOW! That's some GREAT thrift store you have there!

Don't rush into anything. The authors of the 3a manual are real experts on the 3s as well, so if you get a reply from one of them, it's good. You have a very early pair, possibly all original.

There has been some discussion here on repairing those leads on your monster mid. you have to attach a short piece of very fine copper wire. Copper will not solder to aluminum. This is addressed in the 3a manual, p20. I also noticed someone suggested making a good mechanical connection, then coating that with solder, then crimping the solder when cold. Sounds plausible. The aluminum lead must be clean--hard to accomplish without causing damage.

Re insulation: Don't be tempted to use Acousta-Stuff. See pp 9 and 21. I don't know if there is anything special about yellow FG. Home Despot or Lowes sells small bags of white Johns Manville FG. A personal note from member RoyC states:

"3 bags of JM fiberglass per cabinet will be perfect for your 3's"

It is supposedly less itchy and although it costs more than a big roll of FG it's more convenient.

You probably OK bending the tabs once but if they do break you can either buy Ohmite pots (they have gotten very expensive though) or a member here would probably sell you original A-P pots for a fair price.

I would wait on replacing those can caps until someone who is a REAL expert (like one of the 3a authors) advises you. IF you do have to replace them, I'd go with quality film caps. The 3s will have resale value so you don't want to be a cheapskate (IMHO). Solens are good, not too expensive, and recognized as quality caps. For just a wee bit more, I ordered Clarity PX caps. Electrolytics are certainly OK and should last 20 years, but most enthusiasts prefer film caps (as Craig Ferguson says, "I look forward to your emails")

How are the grilles and badges? If you have the "3" numbers you're in luck. The square AR plate is probably tarnished. There are aftermarket replacements available that look pretty good. My 3s have vinyl grille material over plastic frames. Those frames are a bugger and break easily. They can be repaired with Plas-t-pair or ebay seller Vintage AR sells replacements.

Many members here willing to help. Those are super nice speakers and should be preserved.

Kent

[snl]

Thanks for the advice. I think i can fix the wires with one crimp and the other is broken right at the solder point so I should be able to re-solder it. What is the tape that is used to cover and protect the wires? Regular electrical tape would get gooey with time I would think.

The grills and badges are pretty much intact. I am missing one of the 3's. Signs are my business so if I can't find an original 3 I will see if I can fabricate and acceptable substitute. I am hoping that I will be able to clean and reattach the grill cloth. I was having trouble getting off the other grill so I stopped until I can work it loose. I think I need to get a flat tool behind it and work it loose inch by inch. So far I haven't broken anything.

The finish on the cabinets is in pretty bad shape so I will have to completely refinish them. I don't think I will have to replace any of the veneer. I have all the equipment and ability to do a this part. It seems like I read somewhere that these have a lacquer finish, is that true?

[JKent]

Quick note

Most were oiled walnut, but other finishes were available. Have a look at the attached to see what matches your speakers.

If you DO make some "3" badges I for one would be interested in purchasing.

Be careful when using a tool to pry off the grilles

Are yours plastic frames with vinyl (?) cream-color cover, like the photo in post #3? That's what I'm dealing with now. So far have repaired a break, cleaned them with 409 and bleach. Now trying to figure out what kind of adhesive to use to re-attach the long sides. Will keep you posted.

Kent

[snl]

Mine are mahogany which is just perfect for my 1950 house. They have a pretty heavy finish on them like lacquer would be.

The grill cloth is like in post #3. It has gold woven into it. It reminds me of Fender amp grill cloth.

I don't know what the frames are. I will check when I get home.

I will let you know about the badges.

[dynaco_dan]

Vern, you may be right. btw, my 3s had 40 oz of fiberglass in one, 42 oz in the other. AR guru johnieo says these were over-damped and recommends 28 oz of new fiberglass.

Kent

Hi Kent

I mentioned the high sulphur laden fiberglass only because that may have been a big corrosion factor when used.

Recently, I've read so much hifi stuff here lately, I read somewhere that particular bad insulation was only used for a 2 year period

because of a regular household fiberglass shortage for some reason.

It still may have been used intermittantly, over the years though undocumented.

Just a thought for today, Kent.

Have a great day.

[genek]

Recently, I've read so much hifi stuff here lately, I read somewhere that particular bad insulation was only used for a 2 year period because of a regular household fiberglass shortage for some reason.

The stuff you're referring to was rock wool, not FG. Much nastier stuff in loose form than FG.

[JKent]

JM item # B-777 is formaldehyde-free and not as bad to work with as the original, dirty & crumbling FG. 16" x 4' roll, weighs abou 9 oz.

Kent

[npt3]

JM item # B-777 is formaldehyde-free and not as bad to work with as the original, dirty & crumbling FG. 16" x 4' roll, weighs abou 9 oz.

Kent

I used the JM stuff (no pun intended!) in a recent 2ax restoration - just great.

[snl]

The frames for my grills are made of plywood and came off pretty well. Here is a photo of the grill fabric. It is more of a plastic though. I think I will be able to salvage it. It is stretched out and a little uneven but with some careful heating it looks like I can even it out.

I was just discussing the "3" badge with one of my fellow fabricators and we are going to see how well we can replicate them. We will do a run of them in a couple of weeks. and yes I will have extras. The one I have has a pin soldered to the back. Is this how they were all made?

Does any one know of the legalities of replicating parts for sale?

On the fiberglass fill: Is the original fiberglass not good to re-use? Was it the rock wool that was sulfur laden or the fiberglass? When I got my other speaker open it was so gorgeously untouched that I would like to push the fiberglass to one side taking out a minimal amount to get the pots out to clean them and leave the rest untouched.

[JKent]

You're lucky the frames were plywood. The plastic ones are a dog to get off without breaking.

Here's a photo of my plastic grille material. Similar but no gold threads.

If you have to re-glue the edges, you might try Alene's Tacky Glue.

Yes--the soldered on pin is original. My AR2a's have similar pins.

I'm not a lawyer, but I doubt making reproduction parts for restorers is a problem. The AR company is long gone and other sellers, like "Vintage AR" sell reproduction labels and other parts.

Besides, I won't tell! Please put me down for a pair.

I understand your concern about the fiberglass. It is probably FG and not rock wool. Vilchur was opposed to using rock wool and yours are early speakers. And yes, rock wool is the sulfur-laden stuff. But there is another consideration: If your 3s are like mine, you probably have about 40 oz or so in each box, and AR may have later determined that was over-damped. 28 oz may be better. So you might want to weigh the 'glass you remove and take out about 12 oz when you replace it. Or if you're ambitious, try them both ways and see which you prefer.

Kent

[snl]

Thank you for all the information. This forum is a treasure trove. Next week I will actually be able to work on these and get the pots cleaned to see what I have.

I will let you know as soon as we fabricate some badges.

[genek]

In theory, Audiovox, who now owns AR, could probably put a stop to the AR logo reproductions if they wanted to, but I've not heard of any such thing happening. Maybe they think the cult status of classic era ARs is good for them.

Be especially careful with that grill fabric. There are several options for people wanting to replace the later linen grills, but that waffle weave material is really tough to find, with or without the metallic threads. Everything I've found with that weave has been all vinyl.

[JKent]

I must apologize for some misleading information on the FG stuffing.

The early 3 had 40 oz, and by the time the early 3a came out using nominally the same woofer, the stuffing weight had been reduced to 28-32 oz.

Whether the original was "overdamped" and the 3a was "right" is apparently subject to debate/discussion.

Kent

[rwalton46]

The frames for my grills are made of plywood and came off pretty well. Here is a photo of the grill fabric. It is more of a plastic though. I think I will be able to salvage it. It is stretched out and a little uneven but with some careful heating it looks like I can even it out.

I was just discussing the "3" badge with one of my fellow fabricators and we are going to see how well we can replicate them. We will do a run of them in a couple of weeks. and yes I will have extras. The one I have has a pin soldered to the back. Is this how they were all made?

Does any one know of the legalities of replicating parts for sale?

On the fiberglass fill: Is the original fiberglass not good to re-use? Was it the rock wool that was sulfur laden or the fiberglass? When I got my other speaker open it was so gorgeously untouched that I would like to push the fiberglass to one side taking out a minimal amount to get the pots out to clean them and leave the rest untouched.

I'm another owner of a pair of 3's that has only one of the "3" badges. I'd be interested, perhaps, in one of your extras.

Rick

[snl]

I will let you know. I just have to find the time to do it. It should be pretty soon.

[jag]

snl, put me down for two of them if you're still going to make some.

Thanks!

[gary_wong5]

Anyone has the detail "technical" drawing of "3" badge? I am going to ask my client to fabricate for my AR3s.

Thanks in advance.

Gary