AR-1X Rehabilitation

Last May I found a pair of Acoustic Research AR-1X speakers at a thrift. It turns out that these are pretty rare, so I thought I'd document my progress as I refurbish these for use in the home. The serial numbers are quite low and almost consecutive (20083 and 20086). Some of this information has already been posted, but here it is in one place.

Here they are after I brought them home:




I listened to them. One of the tweets wasn't working and the other was really scratchy, only playing with the wiper in a specific position.


First step was opening them up and seeing what I was working with. I'm not sure if this is yellow fiberglass or rockwool, but either way, it went into a bag for weighing. If there's interest, I'll reweight the bag, as I forgot the actual weight (it was approximately 36 ounces if I recall):


The crossover:


I checked the non-working tweeter with my multimeter, and it seemed fine. I bypassed the wiper, fired it up and the tweeter sang. I had trouble pulling the knob from one of the potentiometers (rheostat? I'm calling them "pots" from here out) because the set screw was corroded so badly. This was coincidentally the same speaker with the bad pot. That closed the deal for me. I purchased 2 replacements from vintage-ar. One pot came right out, the other set screw was still stuck fast, even after soaking the hole in liquid wrench for a couple of days. I had to cut the knob off with bolt cutters. The shaft is still fine and I retained the pots, just in case I want to refurb them and put them back.

I replaced the pots with L-pads from vintage-ar and bypassed the original caps in favor of new Dayton 5% polys. Rather than using hot glue or similar to affix the new caps, I drove a small screw through a zip tie. I think that should hold for some time.


I stuffed the cabinet with fluffy new fiberglass, but needed a new shroud since the old ones disintegrated when I removed them. I couldn't find cheesecloth, my first choice. While at Walmart anyway, I tried the fabric section. I found this light, airy backer material and purchased a couple of yards.


Here is the stuffing in place.Please ignore the funky wall of my basement. That's another story, but suffice it to say, there is no real danger of spousal encroachment in this part of the house. The funkier the man cave, the safer it is from co-opting.



Replaced the woofers and used some moretite caulk to seal them up. I had white, so hopefully it won't be visible through the grill cloth.
Tested the speakers and they sound just fine. I was in my basement using a home theater receiver that was specifically rated for the 4-ohm load, so critical listening will have to wait.

Next up, dealing with the scratched to hell surfaces. There were water rings, paint splatters and what-not. 220 grit sandpaper, Restore-a-Finish followed by Feed and Wax and they look pretty good. One corner is swollen thanks to (I assume) a plant on top. The veneer is wrinkled there, too. If I get a wild hair, I'll pull all of the veneer off, pull the corner together and re-veneer. On second thought, that would take several wild hairs. Maybe in a year or two if I run out of projects.

Here's the swollen corner:


The pictures I took of the wood refinishing have somehow vanished from my computer. I'll take more soon.

Next up is the grill cloth. Technically, the existing cloth is just fine. However, to be used in the real world (i.e. the wife's house), this movie theater carpet looking stuff will have to go. It's actually really cool cloth with gold thread woven throughout. I will pull the staples carefully and try to save it. What for, I don't know, but that's how I roll. It will probably get pitched in a couple of years, along with that box for the toaster I bought in 2009.



I plan to re-cloth the grill using this Charlescraft Irish Linen:


Here are the two side-by-side. The linen isn't nearly as groovy, but neither is our home decor, so linen it is.:


That's as far as I've gotten. I will hopefully attach the new cloth today. To avoid splitting the wood, I think I'll glue it and will pick up some adhesive today. Wish me luck!

Wonderful work so far. BTW, what was in there kinda looks like fiberglass; you will definitely know rockwool if you come accros it.

Looks like a productive project. Some might consider converting them to AR3a's because of the market value and sound. I had thought the AR-1s were just woofers. Good luck with your work.

Not knowing if the original grille cloth is too damaged to keep or not, I'd vote for keeping it if it is still in good shape. It will add value and maintains the period look. Great speaker project.

luddite said:

Not knowing if the original grille cloth is too damaged to keep or not, I'd vote for keeping it if it is still in good shape. It will add value and maintains the period look. Great speaker project.

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Maybe I'll just cut new grill panels out of plywood and keep the originals in the basement.

Freds.Bands said:

Looks like a productive project. Some might consider converting them to AR3a's because of the market value and sound. I had thought the AR-1s were just woofers. Good luck with your work.

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The woofer-only model was the AR-1W. These can be converted to woofer only by removing a jumper in back. I won't convert to AR-3s. Given how rare these are, I'm going to keep them as original as possible.

woodj said:

Wonderful work so far. BTW, what was in there kinda looks like fiberglass; you will definitely know rockwool if you come accros it.

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Then this was fiberglass. I still didn't want to mess with the old stuff. It seemed awfully "brittle."

Nice project and interesting work with the re-hab. I had never even heard of this model until I saw your earlier post about these, so I would agree that they are quite rare and keeping them mostly original is probably a sound decision (no pun intended). I'm having a hard time believing AR made 20,000 units of this model, so who knows - - - maybe they began the serial numbers at 20K and yours are within the first 100 made (?!?!?).

Sounds like the pots were just too much to deal with since they did not cooperate, and you also made a good choice with the simple Dayton replacement caps - - what is that cap's value? That grille looks like it's in pretty good shape, so if both of them are fully presentable, maybe it's best to keep them as is. Is the fabric made from a man-made poly fiber? Also, it's difficult to tell from the pics - - is the tweeter installed in a mounting plate made to fit the cabinet cut-out for a 3a midrange?

I'm thinking they started with the 2000 serial number, based only on the rarity of these speakers.

I decided to keep the original grills intact and cut new ones from 1/4" hardboard. I'll post pics soon.

The cap is a 20mf, based on the original AR schematic I found on classicspeakerpages. I chose not to cut out the original cap to read it's value so that they could be reinstalled later if desired. The cabinet and mid/tweet is the same as used with the 3a, I believe. There is simply a plate over the hole where the 3a's tweeter would go. The mid serves tweeter duty. I'll research more later to verify, but that seems to be the case.

Great project so far! What I tend to do when restoring a pair of AR's like this is to sand and paint the front baffle a flat black. Something to consider. That way it won't look completely offensive if you decide to leave the grills off

tyella said:

I'm thinking they started with the 2000 serial number, based only on the rarity of these speakers.

I decided to keep the original grills intact and cut new ones from 1/4" hardboard. I'll post pics soon.

The cap is a 20mf, based on the original AR schematic I found on classicspeakerpages. I chose not to cut out the original cap to read it's value so that they could be reinstalled later if desired. The cabinet and mid/tweet is the same as used with the 3a, I believe. There is simply a plate over the hole where the 3a's tweeter would go. The mid serves tweeter duty. I'll research more later to verify, but that seems to be the case.

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Great project!

Glad you're keeping the original grills and making another pair for the WAF! Down the road these would be worth repairing the corner and re_veneering the top, if necessary.
The mid is not the same as in the 3A or 3.
Here's a pic of a 3 and 3a for reference.
The 3.

The 3A on the left.
.

GD70 said:

Great project!

Glad you're keeping the original grills and making another pair for the WAF! Down the road these would be worth repairing the corner and re_veneering the top, if necessary.
The mid is not the same as in the 3A or 3.
Here's a pic of a 3 and 3a for reference.
The 3.

Click to expand...

Interesting. There's a felt pad over the top, as you can probably see in the picture. I just assumed it was a 3a tweeter, apparently. I'd rather not pull that foam off, so I'll check the back of the tweeter for any info.

tmad40blue said:

Great project so far! What I tend to do when restoring a pair of AR's like this is to sand and paint the front baffle a flat black. Something to consider. That way it won't look completely offensive if you decide to leave the grills off

Click to expand...

Thanks for the tip. I may do that since I'm not in any big hurry to bring these into rotation. What's a couple of extra days, right?

I cut new grills from 1/4" hardboard. The thought was I could go thinner than the original ~3/8" plywood, especially if I was going to use velcro to hold the new grills on. The velcro should force the grills forward toward the frame and make up the difference in thickness. Obligatory picture with a beer.



Here is one installed. I probably should have painted the hardboard black. My thought was that the beige-ish color would disappear behind the linen fabric. What actually happens is that the black baffle makes the hardboard really stand out. The camera flash makes it look worse than it really is. The wife, oddly, likes the look. If they bother me, I'll cut new ones and paint them this time.

M-m-m-m-m, beer.
Nice layout and carpentry job on that new grille, but yeah, it's too bad the frame shows up so much. I know the flash does accentuate the effect, but black paint would probably help even it all out.

The tweeter in your speakers is the same driver as (left to right in pic) the tweet in the AR-4 and the early AR-2x; and was also use as a mid-range in the AR-2ax.

ra.ra said:

M-m-m-m-m, beer.
Nice layout and carpentry job on that new grille, but yeah, it's too bad the frame shows up so much. I know the flash does accentuate the effect, but black paint would probably help even it all out.

The tweeter in your speakers is the same driver as (left to right in pic) the tweet in the AR-4 and the early AR-2x; and was also use as a mid-range in the AR-2ax.

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Conversation about the cone type from the AR-4x in this thread or this thread. Clearly that's not the case here. Perhaps they're both original.

RxDx said:

Conversation about the cone type from the AR-4x in this thread or this thread. Clearly that's not the case here. Perhaps they're both original.

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Thanks for the post. Same link on both counts, though. That is the thread where I got the crossover schematic. I've tried to register at classicspeakerpages, but I don't get any return verification. Lots of great AR info over there.

tyella said:

Thanks for the post. Same link on both counts, though. That is the thread where I got the crossover schematic. I've tried to register at classicspeakerpages, but I don't get any return verification. Lots of great AR info over there.

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Yes, I too have been unsuccessful at attempting to register at classicspeakers. No one home I guess.

Interesting thread on this speaker. I am a long time owner of AR and have never seen this particular speaker.

Don't know why you're having problems registering at the CSP site - - I'd suggest just try again in a day or two - - the site administrators are usually pretty responsive to problems that crop up.

I'm enjoying the OP's speaker find and learning about these rare speakers, but now I'm a bit confused (again) about this tweeter. Based on the documentation attached, at least some version of the AR-1x originally used the 2-1/2" tweeter from AR-4x. The schematic drawing does note the 20uf cap for the 1x, which is consistent with the cap value when this tweeter is used in the 4x speaker.

However, the OP's speakers show the 3-1/2" driver which, when used in the AR-4 and AR-2ax was paired with a 6uf cap, so I'm just wondering out loud, is this tweeter (felt pad, wire mesh) original to this rare bird, the AR-1x?

ra.ra said:

Don't know why you're having problems registering at the CSP site - - I'd suggest just try again in a day or two - - the site administrators are usually pretty responsive to problems that crop up.

I'm enjoying the OP's speaker find and learning about these rare speakers, but now I'm a bit confused (again) about this tweeter. Based on the documentation attached, at least some version of the AR-1x originally used the 2-1/2" tweeter from AR-4x. The schematic drawing does note the 20uf cap for the 1x, which is consistent with the cap value when this tweeter is used in the 4x speaker.

However, the OP's speakers show the 3-1/2" driver which, when used in the AR-4 and AR-2ax was paired with a 6uf cap, so I'm just wondering out loud, is this tweeter (felt pad, wire mesh) original to this rare bird, the AR-1x?

Click to expand...

Well, that cinches it. I'm going to pull the tweet and get some photos of it when I get home from work. I'll post any numbers I find. If these speakers are supposed to have a 6uf cap, I want to know. I'd hate to have to re-re-cap these speakers, but I won't hesitate to if that's what they require.

Should I cut the strap on the original cap to try to see the value? I was hoping to not molest it, if possible. However, anything in the name of science!

Attached are pics of tweeters from AR-4 (left) and AR-4x (right). Each measures 4-1/2" O.D. on flange plate, so they are basically drop-in replacements (along with corresponding cap) in most cabinets. The magnet on the 4 tweet is about 2-1/4" dia., whereas the magnet is a bit smaller on the 4x tweet, about 2" dia.

I can't pretend to know much about the AR-1x, but I'm just scratching my head a bit over this. If the documents I attached in post 18 represent the one-and-only version of the AR-1x, then what you have is a correct cap value (20uf) matched with the incorrect tweeter. And about that cap, most (but not all) of the original 20uf caps found in AR-4x's benefit from replacement, but there are one or two types that sometimes maintain close to their initial value over these many years. Include a pic, but no need to cut the strap just yet - - take a look at both speakers, maybe one will give a clue.

Alternatively, you may have a perfectly fine woof-tweet combo (w/o original 1x tweet) that play together very well, but they might also benefit from a new 6uf cap replacing the original 20uf cap. Remember, I'm just guessing at all of this, too, so you just might want to experiment a little.

BTW, how does the speaker pair sound at this time? If you have the original 20uf wax block caps and the AR-4 tweeter, I am guessing that the high end is not terribly spectacular just yet.