Finally finishing up AR3a restoration

[FireGuruMN]

First off, if you want a complete restoration guide go here:
http://www.classicspeakerpages.net/...ginal_models_schematicss/restoring_the_ar-3a/
There is absolutely nothing that they did not cover in that document.

I bought a pair of AR3a's back in 5/5/19. $250.00 on CL with known issues. But that is a good price. I had a local speaker shop refoam the woofers. They charged $40 each which is more than their usual $30 each. Apparently the diameter requires a more rare replacement foam but somehow I'm thinking they charge more for people that can afford nice speakers. Whatever. I also replace the L-pads with some from E-Pray, $130 for four of them with shipping. Getting in deeper. The l-pads were significantly larger than than the old ones but I managed to fit them after moving some wires out of the way. I considered restoring the old ones but two were beyond repair for me. I will end up putting the two good ones in some AR4's. At some point I might find the pictures I took and post them. Right now they are lost on my 4tb NAS somewhere.

After the refoam and lpad's the speakers sounded very good. Really I could have stopped there. But that is not my nature. So the capacitors are coming out:

Here is how I opened it up:

The woofer wires are long enough that they don't need to be disconnected. Inside you will find a cloth piece that prevents the yellow insulation getting into the woofer. Save it and put it back in. If it is trashed find an old t-shirt or something to replace it. Remove enough of the insulation that you can get to the crossover. I found that insulation was tucked under the inductor wires possibly to support them and keep them out of contact from other things. I was sure to restuff insulation in there when I was done. These guys knew what they were doing.

"Compulytic" capacitors. Cool. probably high quality for computers in the 1960's? Probably full of PCB's and other nasty things. Dispose of properly or leave them in place. I left mine in place.
Keep the insulation somewhere handy:

The crossover with l-pads previously replaced:

I love old school capacitor. It's staying in place also. I will just remove it from the circuit. Air core inductors! Quality again and again.
Be careful around this wire:

It is a nichrome resistor of a specific value (0.5ohms I think). You could replace it with a modern resistor if you like but it is just fine and will never need replacement just like the inductors.

Continued. . .

 

[FireGuruMN]

Here are the capacitors I am swapping in:

150uF 100V Electrolytic Non-Polarized Crossover Capacitor Part # 027-364
Combine these in parallel to make a 50uf because 50uf is out of stock or does not exist.
33uF 100V Electrolytic Non-Polarized Crossover Capacitor Part # 027-350
17uF 100V Electrolytic Non-Polarized Crossover Capacitor Part # 027-346
Solen 6.2uF 400V Polypropylene Capacitor Part # 027-558
I put a bypass capacitor across the 50uf pair because those caps are in the audio path. Choose whatever boutique bypass capacitor makes you feel good about yourself. Here is what I used:
Dayton Audio PMPC-0.10 0.10uF 250V Precision Audio Capacitor Part # 027-200

Here is what it looks like soldered up and before hot gluing:

I put heat shrink over the connection because it makes me feel good. Really there are so many exposed connections it doesn't make much difference. But if I can add $0.50 worth of heat shrink and have the next guy that opens this up say "he cared about what he did" then that is worth the effort. Here it is all hot glued in place.

All the lettering facing up to make the next guy's job easier. Be sure to hot glue all of the leads in place. The solid wires will be vibrating every time the speakers are played or moved and will eventually fail.
Love the size of this magnet:

More magnet=less power needed and this speaker was back in the days of tube amps so power was more scarce than now.

Continued. . .

 

[FireGuruMN]

This really is ugly behind the grill:


My understanding is that is the way they came from the factory. I'm leaving mine looking just like that.
With the grills on no one will know:

Mine still have the original stickers on the back. Here they are in case someone cares:

Wouldn't be fun to send in the warranty card:

The terminals. Apparently you could bi-amp them? One think I don't like about the L-pads is that they are round shafts without a flat spot. It is not possible to tighten the set screws enough to keep them from turning. That makes it hard to use the knobs. Oh well.

Usually I will re-cap one speakers and then do a comparison by switching the balance left and right. But I was having a full-on brain fart and had a different pair of speakers switched on when I did the comparison. But from memory the speakers had a wonderfully delicate sound before I recapped them. It's hard to describe. It was a very full sound with no harshness at all. I am happy to say that after the re-cap they still have the same delicate sound. So nothing lost. And they seem to have picked up a lot of low end now also. So much so that I raised the high and mid level to compensate. Cool.

I did put a capacitance meter on all the old caps. Every one read about 10% high. But that was just a simple multimeter and not a proper capacitance tester. I suspect there was much ESR and other issues gathered over the years. Good for another 52 years. Maybe.

 

[Chilibrother]

Nice work! But I'm afraid you voided the warranty by opening it up
The line "I'm thinking they charge more for people that can afford nice speakers" gave me a chuckle.

 

[FireGuruMN]

Hey, lookie there what I found, the terabyte on my NAS with the lpad replacement steps. I didn't take as many picture of thing then as I do now but it's always nice to share. The original parts:

A close up:

I can't even remember what I had for breakfast but as I recall the copper wire at the top was not even soldered on. What was I saying about quality workmanship on these speakers in a previous post?
Here is what it looks like behind the tweeter and midrange. It't not useful information but it was interesting how much prettier it was than the other side.

This is what it looks like with one new lpad in place. The blue wires have to move to get the new larger lpad in place. They are connected to the input terminals so all I could do is rotate them. There is goo on them so it is a little challenging. The dark blue one gets pretty tight and should probably be extended if I was making good choices.

It matters how you orient these if you plan on reusing the old wire. Here is a top view. You can see that I added some heatshrink to the blue wires where they connect to the terminals. They were touching the shell of the lpad and that would have ended badly.
:
It is possible to tighten the nuts hard enough to twist them off. I had to solder one of mine in place. It's a fine line between tight-enough and failure. Someone made a comment once about some speakers "you have to have 50 watts go make them sound good and they burnout at 55 watts". It's like that. Maybe some lock washers would have helped? Either way, it;s done now:

Also, one of my best $35 investments is a really good crimping tool. I think I bought a Kline with a yellow handle if that helps. It makes crimping SOOO much easier and SOOO much better. I bought the automatic wire stripper at the same time and it's mostly eye candy because it is too hard to get in tight places. And I have to use it in my right hand (I'm left handed) in order to make it work correctly. I have not found a way to reverse the operation. But I do use it when I have a bunch of speaker wires to assemble or such. But I digress. . .
Here are my badges before and after:

I used 0000 steel wool (which is fabulous for glass cleaning shower doors also). The letters are recessed so you can put some elbow grease into it. I put some spray goo on to protect the finish. I can't remember what it was anymore. But it is working so far. No, those are not scratches, just some left over streaks.

If you think of it you might try grinding a flat spot in the shafts so the knobs can be set better. It's probably easier before you install them. I don't have any specific advice on how to proceed with that.

 

[baco99]

You used the correct rheostats. Worry free operation for decades. Much better option than trying to clean the old ones.

 

[Copa1934]

You used the correct rheostats. Worry free operation for decades. Much better option than trying to clean the old ones.

After restoring mine and subsequently acting up, again, I'm replacing mine.

 

[Copa1934]

Looking forward to more images and narration. Always interested in how others have done there's.