AR-2ax Refurbishment

[mikepick]

I've come into a set of AR-2ax speakers and they need a refresh to get them working again. There is a ton of info here on the board, and I've been reading as much as I can, including the AR-3 repair manual and various threads.

These seem to me to be early models, the serials are AX97XXX and AX100XXX. The boxes are in great shape, so I am hoping to do much more than a refresh with Howard's or the like. The grills were typically discolored and yellow, so the cloth will need replacing.

A low-volume test run revealed no sound from the tweets or mids, and one woofer was very slightly buzzy.

I could not find staples on the front, so I ended up cutting the cloth and gently freeing the first grill from the glue. I've pulled the woofer and put the stuffing aside to put back in later.

My first questions are about the woofer. It has the cloth surround. There is no date stamp or markings other than the stamped AR logo and a medical cross sticker for the positive terminal. The surrounds look well glued down, and the surround ring looks solidly attached as well. What I can see of the spider looks OK. There is no rub when the speaker is sat on the magnet. My MM measures a resistance of 5.9 Ohms.

I am a bit concerned about the foam ring in the middle, it is deteriorating, but I don't know what purpose it serves.

I have some of Roy's dope from a KLH project (hopefully enough left for this set) and that's on the list, but is there anything else I should look for with it? Pics attached.

Thanks,

Mike

 

[mikepick]

Been working away on these for the last couple of weeks, and I'm getting pretty close to done! Had a listening session with both hooked up last night and they are sounding pretty good, initially!

I did quite a bit more reading after the initial post, the Bungled AR 2ax repair thread proved a great source of information. One of my woofers had both masonite rings detached, while the other had the lower ring detached. I had glued the top ring done before getting at the lower rings, and so it was a bit tricky to get them done.

I ended up levering the rings up with popsicle sticks so I could get under to clean and then spread the glue with a toothpick around the lower ring. Getting the coils centered was a little tricky, but not too difficult, they seem to naturally center into a place where a could not detect any rub when pushing on the dust caps.

I ended up replacing the big wax cap with the Solens poly caps.

For the pots, I initially tried to clean them, and they came out reasonably well... so I thought. There was still some pitting, and I tried smearing some conductive carbon grease on the plates to even out the conductivity (and prevent further corrosion.) One of the center buttons was also a bit loose, and so I tried a ring of solder around it to get conductivity to the center post.

When I reassembled the first speaker, there were too many dead spots in the pot rotation, so I decided to try rebuilding the pots. The coils and lower buttons were in decent shape, so the plan was to replace the center contact. I ended up 1/2 inch copper discs from Amazon, drilled out a 3/16th hole, and riveted them in place, after drilling out the old rivet and disc.

Removing the old center plates revealed more corrosion underneath, so I soaked the pots in a vinegar / water mix after disassembly. I dried them thoroughly with the heat gun, and included a dollop of dielectric grease under the new copper contact. I also flooded the coil area with dielectric grease, wiping it from contact areas, and applied some conductive grease to the exposed conductive areas in hopes of preventing further corrosion.

(The black goo on the wiper in the picture below is conductive grease.)

I have no idea how long they will last but they seem to work pretty well at the moment.

I've done an initial treatment of Howards restore finish on the cabs, they're pretty good, aside from one dent which I am patching with some old veneer. Going to try a little stain and then hit the whole side with Howards to see if it can even out.

Right now I'm putting a coat of flat black spray paint on the second baffle, and then its on the the grills, the 123stitch order came in last week...

 

[JKent]

Great work Mike!

I love the old 2ax with the Alnico/cast aluminum/cloth surround woofers. Looks like you're doing a first class job on everything.

Very clever pot repair. We'll be interested to know how it works out.

You asked earlier about the deteriorated diffraction ring on the woofer. I wouldn't lose any sleep over it.

Keep the pictures coming!

[ar_pro]

Very nice work, Mike, and excellent documentation. The 2ax was my very first AR speaker - literally, because I bought a single floor model for $60, and had to wait a few months to afford to buy a second.  

As Kent mentioned, this is a great combination of drivers which should sound really fine when you're finished.