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Another pair of AR3's


Joel

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I traded an amp for a pair of AR3's last night. They are serial numbers C51890 and C51898. They appear to be all original. I haven't opened them yet, but they don't look like they have ever been opened.

The woofers work just fine. I get a reading at the posts of 3.8 ohms. None of the tweeters or mids work. The original owners said he could get the tweeters to work by playing with the pots, but I haven't had any such luck. The wires for the mids are disconnected, and I get no reading- can I assume they are dead?

Can I just put my meter on the front wires to read the tweeters, or do they need to be taken out of the speakers?

-Joel

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Joel, your AR are all original. I have two pairs, the first one came in with every loudspeaker in working order, I rotate gently the pots and mid and tweeter appears . In this case you have only to clean pots. My secon pair came in with one dead midrange. I remove woofer, putting rockwool in a plastic bag. Then with a tester ( or a battery ) I try to verify mid and tweeter connecting tester to yellow and black wire and then to green and the same negative black wire. Tweeter ok, but midrange was silent. Apparently on external the thin wires are ok, so I remove gently the black scotch over wires. Positive was broken and interrupt.With a proper aluminum solder and a short additional aluminum wire I solved the problem , You only must have precision and firm hand. In every way, if You want the best from your AR 3, You have to recap it , and in this case You have to operate inside the box. Before disassembling the woofer You have to remove the mortite all around, and replace it with new stripes when You put the woofer in its place. The cloth surround needs no replacement , but apply Permatex sealant on it. I hope my experience will help You in restoring this exceptional speaker, and I'm sorry for my home-made very poor english, I'm italian. Best regards, Adriano

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Nice find Joel. And Adriano--we've met and your English is very good!

As Adriano said, you must be very gentle. The mid and tweet are VERY heavy and the thin aluminum wires are very brittle. You may be able to repair a broken lead but it requires great skill and a steady hand. I had a similar problem with my AR-3's. As it turned out one mid and one tweet were dead. FWIW, I was able to sell the dead drivers on the auction site. I got a good price even though I stated very clearly that they were totally dead. Someone must be repairing them.

I ended up converting mine to 3a's but I do not recommend that. The 3 "may" be a more pleasing-sounding speaker and if you ever decide to sell them "restored" is preferable to "modded" (look at recent epay sales: $1K - $2K!!). The tweets are fairly common but the mids are hard to find. Worst case scenario you could use later mids from the 10 Pi or 11, as I did.

You should definitely re-cap them. The original wax block is well past its prime. Also disassemble and clean the pots. I normally recommend L-pads but agin, because these are highly collectible try to keep them 100% original. btw, there was a Korean AR fan selling replacement parts to rebuild A-P pots. Apparently they were too expensive because they didn't sell. See epay item # 281357810130

Regarding the woofers--they "may" not need resealing. You can use the 3-finger test to check. But if they do need it, do not use Permatex. It will eventually harden somewhat. Send RoyC a PM and see if he has any more of his toluene/butyl rubber sealant. Or buy it from Vintage-AR (same stuff. He buys it from Roy).

If you need new grille material, "3" badges or "AR INC" badges send me a PM.

Kent

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Sonnar,

Thanks. I've followed your posts with interest. I got one of the tweeters to work by adjusting the pot. I'll use your method for testing the other drivers.

I think I am going to recap and replace the pots first. I've replaced the pots on AR4x speakers- do these use the same L-pads.

-Joel

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Kent,

It looks like the wires for the mids will reach the pads. Can I just reheat the solder to reconnect the wire? The cabinets are well sealed- they pass the finger pressing test. I already have some of Roy's sealer, so I can always use that later if I decide too.

The grill cloth looks pretty good, but the plastic frames are broken. They still have the "AR" badges, but the "3"'s are missing. I'll get in touch with you when I get further along with these.

Is there a caps list anywhere for the replacements?

-Joel

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About caps, I prefer german made Mundorf supreme MCaps , polypropylene, fast and clean . But the originals were oil caps. However, with this modern caps AR 3 shows a mid and high range transparent and selective to match an Acoustat X .

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Joel,
Take a look in the CSP Library for "Thoughts on AR-3 Schematics" by John O'Hanlon & Tom Tyson. http://www.classicspeakerpages.net/library/acoustic_research/original_models_1954-1974/original_models_schematicss/thoughts_on_ar-3_schematics/

The AR-3 went through some changes. Mine straddled a change in xo that occurred with SN C19468.

C18051 had the "B" xo: Wax cap and 2 inductors: 0.4mH ("1") and 0.06mH ("3").

C21651 had the "C" xo: Wax cap and one inductor (0.4mH marked "1").

Your 51890/98 should have the August 1965 modification shown as "C" in J.O. & T.T.'s document so it should have just the wax block and the 0.4mH coil.
But look at the entire document. If you use a 3a (or 10Pi or 11) mid you'd want to use the "D" schematic which has a 30uF (or 24 + 6 in series) cap in addition to the 6uF and adds a 0,4mH inductor.

Anyway, this is just a brief summary. Be sure to look at the entire document because there is important information there for your restoration.

The selection of a capacitor brand is controversial. I'd probably use 3 of Madisound's 10uF surplus caps if going for 30uF, or two of them plus a Carli 3.9 or Solen 4uF. For the 6uF, Carli or Solen should be good. I don't know who sells the Mundorfs in a 6.0uF size although you could parallel a 5.6uF and 0.33 or 0.47 to make the approximate value but that will cost $46 per speaker!. I used the Clarity PX 6.0 in mine--they're premium but not horribly expensive ($6.20 each).

Kent

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I took the pots apart and cleaned them. I've got one of the tweeters working, but I think the other is bad. Both mids are gone as well. I know its possible to use a AR-3a mid- are there any others that are suitable? I've seen tweeter with a red dome and a black dome. Is there any difference between them.

-Joel

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It's hard to believe both mids and one tweeter are gone, do You have tested individually each loudspeaker disconnecting it from crossover network? Pots can be very insidious, also when cleaned. But , in case mids and tweeter are really gone, You can convert into a pair of AR 3a using 3a's mids and tweeters and rebuilding the crossover network. First series uses AR 3 Alnico woofer until '69. I 've never seen red dome tweeters, AR 3a tweeters are black rigid paper domes.

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I tested the tweeters by going to the wires from inside the cabinet. As I said, one is working, the other shows dead with both a battery and a ohm meter.

The front wires to both mids are broken at the front posts. I don't get any reading if I go directly to the broken wires. Is there another way to check these out?

-Joel

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No way, Joel. At this point You should disassembly the magnetic pot to see where is the failure, but it' s a very delicate " surgery ". It needs a professional work involving probably the coil.

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In my opinion, AR 3 alnico woofer is better than ferrite. Faster , deeper. But AR 3a' mid and tweeter offers a better tonal balance. So transplating 3a mid and tweeters and converting your AR 3 into 3a it's the best option.

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That tweeter looks right. You could try contacting Roy to ask if the mids can be salvaged or maybe contact Bill LeGall at Millersound and ask if he would tackle them. He's a real wizard.

As I've said, my advice is to RESTORE the 3s and not turn them into 3a's but if you do decide to do the mod, here's the thread on mine: http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=6284#entry87273

I used 10-Pi mids (identical to 3a except for the metal grille color) and Hi-Vi tweets. The speakers sound great I'm sure the resale value is low because of the mods.

Good luck with the project.

Kent

correction: The mids are AR-11

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This tweeter is on ebay at the moment. It is listed as from a AR2A. It looks identical to the tweeters in my AR3- would this work as a substitute?

-Joel

Joel,

The AR-2a and AR-3 used the same tweeter.

I've been having some luck repairing AR-3 mids for Larry L. ("Vintage AR") and others. It is worth a try.

Roy

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A bit of an update:

Roy was able to repair the midranges- I should get them on Monday. I also got the correct tweeter from ebay. The new tweeter works, but I still need to solder the aluminum wires. Roy is sending a bit of the correct solder.

I've recapped and cleaned the pots. A couple of the pots weren't great, but I had a pair of them from some AR4x's that were in good shape.

The cabinets are in really great shape, with no obvious flaws. I cleaned them up last night with Howards Restore. I am ordering new grill fabric and badges from Kent. They are going to look fabulous when finished- I hope they sound just as good.

-Joel

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I've got all the drivers installed and working. Roy did a great job fixing the midranges. He did more than fix them, he also cleaned them up so they look as great as they sound. He put regular wire leads on the new mids so I didn't have any problem soldering them.

I was worried about the aluminum wires on the one tweeter, but again, Roy saved the day by sending me some aluminum solder. It made soldering them a breeze.

I did find out that the pots aren't as good as they looked, and they have some dead spots. I am going to go with L-pads instead.

My new grille fabric and badges (thanks Kent!) should arrive tomorrow.

The speakers sound really good. I still have to put the stuffing back in the cabinets and make sure everything is sealed tight. I should have everything finished by this weekend. I'll give them a serious listen then.

-Joel

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