AR4x project and questions

[elitopus]

So I ended up with this trio of AR4x (thank you @bowtie427ss)

Two have the papers still on the back, and the third doesn’t. The two with the papers are S/N
FX176846
FX176843

I took the orphan apart first, cleaned the pot, and it’s operational now. I did not recap it. The pair I will recap.

The first to be opened up is S/N FX176843. It has date codes on the tweeter of 7/23/68, and on the woofer 5/2/68.


Check out that cad powder. Yum

This one has a 20uf cap, and a -4 coil. I thought they usually came with a -5 except for the oddballs, but whatever.

My first question is the edge of the tweeter is pulling off from the metal frame on both speakers. Can I just glue these back with some Aleenes?


Second, the pot is pretty crusty in the first one I opened. Even after cleaning it it doesn’t make a good full sweep. In my drawer of parts I found these two metal shaft pots that I think came out of some earlier AR4x (at one point I had AR4, AR4x, AR4ax, and multiple parts speakers). Maybe they even came out of some AR4? IDK.


Anyways, the plan is to use those. One looks brand new inside, and the other looks pretty nice.
The new looking one goes from .1 ohms, all the way to 15.1 ohms over its operating range. The other one goes from .7 to 14.9 ohms. So not bad.


One woofer has a little tear in it that I’ll patch up from the back with Aleenes.

Also, when I measured the 20uf cap in the first speaker, it measures over 39uf. When I measure the new caps going into the speaker and it reads 20.2uf, so I don’t think it’s an LCR error. I’ll measure the other speaker and see what it is.


I’ll take some of the exterior soon. They’re in pretty good shape.

I think I’ll put some new wire inside. The old wires are always so short. Another 6” would help out a lot.

 

[baco99]

nice pictorial. Not surprised on the caps being out of spec. This is what I've been preaching for a while now. vintage AR caps all need to be replaced. Running that speaker with a cap valued at 2x it's spec is going to send bass frequencies to the tweeter that the tweeter can't handle. Those AR "brick" capacitors are all trash by now.

Also, yes, some adhesive on the tweeter cone should be all you need. Run a low volume 800Hz signal through it while the glue sets.

 

[elitopus]

I got the first one all wired up. The tweeter output sounds low compared to the orphan AR4x I worked on first. It might be that the super out of spec cap damaged the tweeter. I’ll have to see how the second one sounds.

I double checked to make sure I wired it correctly, and the tweeter and woofer are wired backwards of each other like they should be.

Pic of the new wire. I removed the stock cap, and hot glued the coil down.
I got a stick of duct seal and made sure the drivers are well sealed. Looks like vintage-ar just got some more surround dope in. I should order some and redope the woofers.

 

[elitopus]

I finally finished the other speaker of this set. I tested that cap and it was over 40uf also. I also found another cap out of an AR4x when I was going through a box of speaker parts. It tested 60uf! That one came out of a working speaker I parted out

I used to not feel bad using these with original caps, but that will never happen again.

The final pic is my LCR meter testing a 14uf cap just to prove it isn’t a piece of shite.

 

[GD70]

The 4x is a terrific small bookshelf or floor stander in some stands.
That tweeter can be glued back down, though I’d work on very carefully removing as much of that surface rust as possible before gluing it down. This is a common problem. That pot may be salvageable but you need to thoroughly clean it to inspect it.
Mine still had the original caps and sounded fabulous before I sold them. They were also 1968 vintage.
Look forward to your impressions once they are singing again.

Cheers, Glenn

 

[elitopus]

Hi Glenn
I’ve really liked the AR4(x)(xa) speakers I’ve had in the past. I think the AR4 were my favorite for jazz/blues, and the AR4x were my favorite for newer music. The AR4xa sounded good, but IMO not as good as the other two.

I’ve never recapped a pair of AR before so this is my first. I do have a bunch of of parts laying around from some speakers I have parted out in the past for various reasons. That’s where I got the metal shaft pots. They work really well.

The third AR4x that I got at the same time has the original cap in it still. It’s sounds great, but I would bet the cap is out of spec also. If the stock xover freq is 1khz with a 20uf cap, a 40uf cap would move it down to 500hz. Those tweeters are lucky the pots were so corroded or else they might have been blown a long time ago.

I’ve been playing around with these speakers after the recap, and it’s interesting how different they sound on different amps. Even after being recapped they are still pretty laid back. I prefer them with a brighter system.

 

[elitopus]

This is how they look without really doing anything to the cabs except wiping them down. I might put some restore a finish on to cover up the few scratches they have and then oil them up.

The AR emblems are both attached so the speakers would be laying on their sides. All sides of the speakers are in great shape, and I think they must have been used on some book shelves.

 

[Bicyclist]

Excellent work and Im jealous that you had 2 usable tweeters. I ended up replacing the tweeter with dayton audio silk dome 11/8 tweeters and it seems to be an excellent match with a very smooth top end. Nothing beats the original I'm sure but for someone desperate these can really help in my view.

 

[WaynerN]

My tweeter's paper surrounds were loose in some areas around the perimeter so I used some black silicone on the very edge and went around them completely, avoiding any of the pleats of the surround. Worked really good. I did not have to deal with rust, but Glenn's comments about removing it is spot on. The caps are all out of spec. by now.

 

[Buck Hopkins]

I picked up a nice looking AR-4x pair on FB marketplace the other day and I'm not getting sound from the tweeters. I tried removing and cleaning the pots for the tweeter controls as well as bypassing them altogether and still nothing. Anybody have any suggestions? I don't know a whole lot about this stuff. Also is there anybody in Nashville that does repairs anymore? Thank you!

 

[alteclipsch]

Capacitors should be replaced, but I'd isolate the tweeters from the circuit and test them with a multimeter first. Old caps frequently go bad on those. With a bit of luck, new caps of the same value will wake them up. It did on my 4Xs. And they're cheap and easy to do.

 

[Puckster]

Hello Buck,
I’m in Nashville and recently picked up a pair of AR-4x as well. I haven’t had a chance to inspect mine yet. Please let me know if you find a skilled, trustworthy and reliable repair tech.
Sadly, I work right around the corner from Hi Tech Service and had no clue they were closing down.

 

[simplynuts]

I got the first one all wired up. The tweeter output sounds low compared to the orphan AR4x I worked on first. It might be that the super out of spec cap damaged the tweeter. I’ll have to see how the second one sounds.

I double checked to make sure I wired it correctly, and the tweeter and woofer are wired backwards of each other like they should be.

Pic of the new wire. I removed the stock cap, and hot glued the coil down.
I got a stick of duct seal and made sure the drivers are well sealed. Looks like vintage-ar just got some more surround dope in. I should order some and redope the woofers.

View attachment 1895629 View attachment 1895630

These look like the set I picked up, with one tweeter not working, but either a bad cap or corrosion on the pot. Tweeter tests out fine.

 

[inperson]

I've had my AR4x speakers for years and it was hard for me to get them situated to where I really liked what I heard. Last night I said the heck with it and went un-audiophile placing them directly on the floor (cement basement with an area rug in between) and they never sounded better. About 5 feet apart and 5 feet from me with slight toe in.
But due to this thread I see I really need to replace those caps.

 

[Blackdog61]

I restored a pair a few years ago and really enjoyed them on 24” steel stands out in the room. Wish I hadn’t sold them.

 

[elitopus]

I just sold my last pair of AR4x. They were recapped and had the pots bypassed. The local market here sucks. Took me months to get 100 bucks for them.

The buyer drove a ways to get them, and was very happy with the sound. It was one of those moments where as I was demoing them I had some regrets about selling. But they had to go. I have too many speakers.

The last pair had Jantzen caps with Panasonic bypass caps also. It was a good sounding combo that I’ve used in a few pairs of these.