guidance in restoring AR-1's

[shadetreehifi]

Hi all,

Just received a battered pair of AR-1's from a family friend. My local speaker guru says they are repairable, but it will be several hundred bucks, which I do not have at the moment (ah, graduate school...). Also, since these speakers have some family history, I would enjoy restoring them myself as much as possible.

Woofer cones are good, but surrounds are nonexistent. The masonite ring under the spider has come unglued on both, and tinsel leads are broken near the basket on one of the woofers. I have saved on my computer Carl's write-up on repair of a AR-1 woofer. I would imagine that "while I'm in there" I might as well replace the spiders? One spider feels much more springy than the other.

These are the same woofers, in terms of spider and surround, used in AR-3, correct?

Now for the 755a's. I haven't taken the drivers apart yet, but visual and tactile inspections seems to indicate that voice coils and spiders are in good shape. Cones, however, both have large tears and holes, and both are very brittle.

I would like to replace the cones on these, but the only ones I have come across are on ebay, which it seems may or may not be similar in composition to the original cones. Any sources out there?

In any case, I would use either Vintage-AR's butyl mixture (from ebay) or my local speaker tech's butyl goop (I think it's made by a chem company like Advantage or something) to reseal the new surrounds.

As for the cabinets, they look like they have been dragged behind a chariot. But the joints look fairly tight. New laminate and some TLC for sure.

Thanks for reading. Any suggestions will be greatly appreciated.

[JKent]

Hi Shade and welcome to CSP!

Great pair of speakers, even if they DO need a lot of work. I'm glad they are in the hands of someone who will value them.

I'm sure Roy C will chime in here and I would heed his advice. I just have a couple of thoughts:

1. Be sure to look over the booklet "Restoring the AR-3a" http://www.classicspeakerpages.net/library/acoustic_research/original_models_1954-1974/original_models_schematicss/restoring_the_ar-3a/
2. Those drivers are valuable. Although I appreciate your desire to do the work yourself for the satisfaction and the economy, I would recommend sending them to Bill LeGall of Millersound in PA. He's is THE speaker guru and will bring them back to life in a professional way. His prices are fair, but it is a business. Another suggestion: Send a PM to RoyC and ask if he would repair the drivers. He has a LOT of experience.
3. If you are skilled at woodworking you can do the cabinets. That's the part that shows and will give you a lot of satisfaction.
4. No need for the butyl sealant if you have new surrounds. Another fun fact: The sealant sold by Vintage AR is the only stuff I know of that is properly formulated for cloth woofer surrounds and it is cooked up by RoyC, who sells it to Vintage AR.
5. I am not familiar with the innerds of the AR-1 but there will be capacitors inside. If they are big oil-filled cans you should probably leave them but if they are wax blocks they should be replaced. Apparently there were 2 different crossovers in the AR-1: a 2-post version and a 7-post version. How many terminal posts are on the back of yours? Here is a thread with diagrams: http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=1909
6. Regarding level controls, be sure to read about the infamous Aetna-Pollock pots in the AR-3a restoration guide.
7. Do you have grilles? I have a bit of the authentic AR-1/AR-3 grille material left. PM me if you want to buy some. I also have some AR INC badges.
8. Tom Tyson is an AR-1 expert and may have advice to share.

Good luck with this worthy restoration!

Kent

[shadetreehifi]

Thanks for the reply. I am definitely going to proceed carefully with these drivers. I'm willing to send out the Altecs at least for a competent technician to repair if I feel like I have a greater chance of making things worse than of making things better. Hippocratic oath of speaker repair.

These speakers have three posts surrounding a potentiometer, as well as three other posts aligned vertically off to the side, which I think are for activating or deactivating the midrange.

I've had luck rejuvenating the pots on a pair of AR4x's recently. These will definitely need a going-over. The speakers have spent many years in a damp basement on the Mississippi gulf coast, so there is plenty of oxidation to remove.

As far as the capacitor(s?) they are encased in a large metal housing, unlike the 4x's which are inside a wax block.

Thanks for the info on grille material and badges. I don't have either one.

[Carlspeak]

The cone on the woofer certainly doesn't look like an original AR-1 woofer cone. Does the woofer have a cast frame and alnico magnet?

[RoyC]

I was just about to post the same question as Carl. The woofer cone in the photo appears to be the one used with the later AR-3a, and would originally have had a foam surround.

As Kent mentioned above, Bill LeGall at Millersound is the best bet to repair the 755a tweeter/mid driver...if it is repairable.

The metal-cased oil filled capacitors are likely to be OK if they do not appear to have leaked. Of course it is always prudent to test them if possible.

Roy

[shadetreehifi]

I will take some more pictures when I'm around the drivers again, but I can say that the baskets are cast aluminum with raised AR lettering on them, and the magnets are tall and narrow. They look to me to be identical to the baskets in Carl's document on AR1 woofer repair.

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=4398

I removed the woofer cone whose tinsel leads were broken, and the masonite ring around the spider and the structure of the voice coil look the same as the photos in Carl's document.

The coloration of the woofer cones does seem to be lighter than the images of AR1 woofers that I have pulled up.

I'll look for some numbering on the magnets and see if that can shed some light. Both woofers were sealed to the cabinet by what looked like some clear silicone caulking of the same kind that held the front trim of the cabinet together (one piece has come unstuck but I still have it).

[tysontom]

Hi all,

Just received a battered pair of AR-1's from a family friend. My local speaker guru says they are repairable, but it will be several hundred bucks, which I do not have at the moment (ah, graduate school...). Also, since these speakers have some family history, I would enjoy restoring them myself as much as possible.

Woofer cones are good, but surrounds are nonexistent. The masonite ring under the spider has come unglued on both, and tinsel leads are broken near the basket on one of the woofers. I have saved on my computer Carl's write-up on repair of a AR-1 woofer. I would imagine that "while I'm in there" I might as well replace the spiders? One spider feels much more springy than the other.

These are the same woofers, in terms of spider and surround, used in AR-3, correct?

Now for the 755a's. I haven't taken the drivers apart yet, but visual and tactile inspections seems to indicate that voice coils and spiders are in good shape. Cones, however, both have large tears and holes, and both are very brittle.

I would like to replace the cones on these, but the only ones I have come across are on ebay, which it seems may or may not be similar in composition to the original cones. Any sources out there?

In any case, I would use either Vintage-AR's butyl mixture (from ebay) or my local speaker tech's butyl goop (I think it's made by a chem company like Advantage or something) to reseal the new surrounds.

As for the cabinets, they look like they have been dragged behind a chariot. But the joints look fairly tight. New laminate and some TLC for sure.

Thanks for reading. Any suggestions will be greatly appreciated.

I think the voice-coil/cone assembly has been replaced. It's definitely not the original AR-1 cone in any iteration. The cone texture looks strangely like the early-70s AR-3a type cone except for the tinsel-lead eyelets; these are totally alien to any AR I've ever seen. I think someone simply put in another cone assembly. Obviously, the cone had a foam suspension, and that foam has deteriorated. AR-1s never had foam surrounds ever, to my knowledge. Earliest cones had the accordion-pleat cloth surround; within a couple years, the half-round treated-cloth (almost tar-black in color) surround was used, and then a new orange-cloth version of the half-round cloth surround was developed to be used with the last of the AR-1s before the introduction of the AR-3 in 1958. The very first AR-3s also used a version of this orange-colored cloth surround (with no damping rings). Roy Allison added the damping rings sometime in early 1959.

—Tom Tyson

[ar_pro]

Quite a nice project system - congratulations!

Bill at Millersound will be very familiar with your drivers, and would be my choice to properly repair the Altec 755's.

If you could locate a pair of JansZen electrostatics for tweeters, you'd have a piece of Audio history to leave to your grandkids!

[Carnivore]

Bill LeGall at Millersound advised me that the best option for a pair of LSTs I had acquired was to strip out the drivers and sell the cabinets for parts as they weren't worth fixing. After being discouraged by that advice they sat in my basement for over 5 years until I finally decided to seek a second opinion from Carl, our forum moderator, earlier this year.

Carl did a fantastic job of getting them going, and I'm really glad I didn't go with Millersound's recommendation as the speakers were definitely worth fixing. I only wish I had done it sooner.

The reason I mention this is that I followed similar recommendations for Millersond from this forum, and in hindsight I feel it was a real setback. He probably does good work but I can't speak to that since I never had an opportunity to have him do any for me.

[RoyC]

Carnivore,

Providing a driver for Bill LeGall to repair is very different than requesting an opinion on what to do with a pair of old speakers requiring 8 new drivers and new (complex) crossovers. His primary expertise is in the repair of individual drivers, not total restoration of speaker systems. Having collaborated a bit with Carl on your huge LST project, I am not surprised Bill's recommendation was to sell the remaining parts. He was probably trying to save you money, and was not aware of the replacement and restoration options we have developed here at CSP.

Roy

[RoyC]

Tom,

I have seen some eyelets on mid-70's AR 12 inch cones. In fact, I recently repaired a bad connection at one of the eyelets.

Roy

[shadetreehifi]

I spoke to Bill at Millersound. He said he is no longer repairing these drivers at a distance due to difficulties in shipping resulting in damage to the drivers. I am thinking I will do a full recone on all the drivers, since upon further inspection the spiders in the 755a's look like they have warped due to moisture. There are mounds and valleys visible through the ports in the basket. The spiders on the woofers seem to sag.

The residual material on the woofer cones is dark and looks like baked earth, cracked and brittle. Seems plausible that it was at one time foam. Here are a few more pictures of the basket and woofer cone assembly, as well as crossover and output posts.

[JKent]

Bill at Millersound. He said he is no longer repairing these drivers at a distance due to difficulties in shipping resulting in damage to the drivers.

Gee--how far from Pennsylvania ARE you? And did he mean both the woofers and the Altecs? Do you know if you can get a cone with the ribbed surround to fix the Altecs?

The woofers may be fine if you re-cone them and use foam surrounds. If not you can keep an eye out for AR-3 woofers.

Sounds like you have some experience in speaker repair so I think that with a little help from some of the guys here you may be able to resurrect those from the dead!

Kent

[shadetreehifi]

I'm in East Tennessee. My understanding is that both the woofers and the midranges are no longer being serviced. I have seen some ribbed one-piece cones for the Altecs on Ebay that look okay, made by a company named FMR, but they have a zero-return policy, which sounds iffy. I'm putting out feelers to various speaker repair houses to see if a good source for those cones is available.

For the woofers, it looks like the most available option is for an AR3 or 3a cone setup with foam surround.

[shadetreehifi]

Both woofer cones have the number "8799" printed on the underside...

The woofer with the saggiest spider also has a voice coil that seems to have been buffeted around the bottom edge. Playing loud?

Wonder why one would show this evidence and not the other? Maybe the bad took a physical knock at some point.

[RoyC]

Both woofer cones have the number "8799" printed on the underside...

The woofer with the saggiest spider also has a voice coil that seems to have been buffeted around the bottom edge. Playing loud?

Wonder why one would show this evidence and not the other? Maybe the bad took a physical knock at some point.

It is not uncommon to see damage on the bottom edge of the woofer voice coil due to bottoming. Btw, the early spiders were very soft to begin with, and were somewhat supported by the cloth surrounds.

If you replace the voice coil, spider, and foam, it is advisable to retain your original AR-3a woofer cone. There is only one replacement cone available (regardless of retailer) and it is not as appropriate as any of the original iterations. It comes in a kit, and is designed to fit best in the later stamped steel basket.

Roy

[tysontom]

The woofer basket/magnet assembly is the original (in this case c1955) AR-1 item; i.e., aluminum basket and 9.3 lb. Alnico 5 magnet assembly, etc. This assembly (cone/voice coil) was retrofitted with a newer AR-3a Nomex-paper item, probably a 1970-1972 version judging by the voice coil and cone material. What puzzles me is the way the tinsel-lead pin-out exits at the apex of the cone; that part looks strange for some reason. Looks like a second set of wires was added, but maybe it's an optical illusion. Roy would know after looking at so many variations.

In any event, the coil is flattened on the end due to contact with the bottom plate of the magnet assembly from its original usage (in an AR-3a). It could not have occurred that way mounted in the pole piece of the Alnico magnet due to the height of the magnet itself. Therefore, the woofer probably never worked properly after it was updated. Usually, once the bobbin is damaged, the coil will scrape at some place in the gap.

--Tom Tyson

[tysontom]

One other detail: the AR-3a cone and voice coil were grafted onto an AR-1 spider assembly.

--Tom Tyson

[Carlspeak]

It has been my experience that the very old AR woofer frames and cones were much shallower than the later iterations. In other words, I find it surprising that the OP's 'new' cone even fit properly with the original AR-1 frame. The top edge of the cone should be sticking well up above the frame's surround glue surface if the VC is properly centered on the upper magnet plate.

On a second note, salvage the original spiders if at all possible. They were made from very fine fabric and to the best of my knowledge are no longer available from the US's largest speaker parts supplier. I've worked on many woofers of different types and brands over the years and have never seen a spider glued up the side of a cone like that on the very early AR alnico woofers. That can been seen in post #12, 3rd pic from the left.

[shadetreehifi]

What a resource this place is. Thanks everyone for all this information.

So, to recap for myself, it looks as if I have AR3-esque cones and voice coils with AR-1 spiders and shims glued on. Both the cones and spiders should be saved if possible because replacement parts will be differently composed.

The spiders are intact on both woofers. One looked like it was sagging to me, but it is also the case that its masonite shim was loose from the basket, which may have removed some stiffness and caused it to look worse than it actually is.

Regarding the fit of the cones in the baskets, did the original AR-1 woofers have masonite shims under the cloth surround? I found no shims on these baskets, although it looks like there is some masonite material still glued to the basket where the surround would be. Should I make some new shims even though the cones are different?

[Carlspeak]

IIRC, there were masonite shims for the original woofers w/cloth surrounds. That remained with the foam surround woofers as well. You will have to dry insert the parts and see where the top of the cone falls relative to the glue surface for the surround.

[RoyC]

There is no doubt that these are Frankenwoofers!

I agree with Tom...The longer "Y" tinsel leads (as well as the dust cap) are not typical. The voice coil was apparently added to the later AR-3a type cone for a time sufficient to become damaged in a ceramic magnet basket. At a later time the cone/voice coil assembly was then transplanted into the early AR-1 basket with a modified spider. Someone tried very hard to make everything fit together. I am not aware of any new re-cone kit or parts that will transform these woofers into anything resembling original AR-1 woofers.

Roy

[shadetreehifi]

Yes, these are Frankenwoofers, just in time for Halloween.

I took the 755a's today to my local speaker doctor, Bob Caton at Advanced Sound here in Knoxville, TN. He has reconed many Altecs, a few of them 755a's. He even happened to have a 755 replacement cone on hand. He is going to repair the less-damaged 755 cone with a suitable adhesive, and recone the other. The woofers I'll tackle myself.

I will keep the cones and the spiders, and replace the damaged voice coil on one of them, as well as replacing the warped masonite spider-shims with fresh material. I'll go with foam surrounds, possibly with masonite shims. When I get to that place in the repair, I'll dry fit the parts and post some pictures, and hopefully you all can tell me if the height of the cone is suitable.

I'll keep you posted.

[ra.ra]

Quite a specimen pair of speakers to fall out of the sky, eh? This is a very unique thread to follow, and it will be interesting to see how this revival project ends up.

I am aware that AR-1's are quite rare, and even rather precious with the Altec drivers, but I have a couple of curious questions. First (third pic in post 1), why does the Altec driver have a squarish cut-out in the baffle board instead of round? Next (middle pic in post 12), what's going on with this crossover? I assume the metal cube is an oil-filled cap, but:

1. is the small wire-wrapped slat serving as a coil?

2. is the ohmite pot original or a later replacement?

3. what are the two small masonite squares with the heavy penetrating threads?

[shadetreehifi]

I'll answer what I can, but I'm starting from absolute zero in my knowledge of these speakers. This forum is an enormous help.

I wonder about the square cutout on the mid/tweeter enclosure myself. The Altec driver has its own enclosure, so it's separate from the airspace of the rest of the cabinet. The enclosure is box-shaped, with reliefs cut around the edges to support the basket of the Altec driver. It could be that this was the most cost-efficient way to construct the enclosure: cut a square hole the size of the enclosure, then remove surrounding material to support the basket. The previous owner had put duct tape over the triangle-shaped spaces surrounding the driver.

I noticed that the pics of Tom's early AR-1's don't have the cutouts, but others do, like the included photo from another thread on this forum.

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=956

I don't have any idea what the slat is there for...

Neither do I know if the pot is original.

The masonite squares are sheltering two inductor coils.