AR-3a Newbie Restoration

[sWilly]

Hi, new member here. I just purchased a pair of AR-3a's at an estate sale for $350. To be honest, I did not know much about these speakers, but a quick eBay price check convinced me to snap them up. From what I can tell, they likely had one owner who took amazingly good care of them. The cabinets are in excellent condition with only a few minor scratches and dents. The grills are near perfect with only a couple light stains. After some internet research I've come to understand the history and significance of these speakers and I'm now excited to get these speakers running their best. I did a low volume test and, after a lot of turning of the pots, everything works! I listened to some jazz and was really impressed by the sound, piano was fantastic. I did my usual Donald Fagan test and was not so impressed- really limited highs and not much punch. My suspicion is that these will benefit from a recap, but I'm hoping to get some suggestions from the experts here.

After reading through the restoration guide (what a fantastic resource) I opened up one up to determine what year these are. Removing the grill proved extremely challenging. Starting with a screw in the badge hole, I worked on it for an hour with putty knives, long screwdrivers and whole host of other items. I got it off without any damage to the cabinet but did crack the grill frame in one spot. So there's my first question: are there any suggestions for removing the grills without damage before I attack the second one? The glue on these is crazy strong. 

I pulled out the woofer but the year on the date stamp is not legible so I'll have to wait until I dig in a little further to know exactly what year these are. Maybe late 60's base on the look of the drivers? In any case, I'm excited to get these restored and welcome any information and suggestions as I move forward. A second question for now: should I attempt to restore the pots before buying new one's? Thanks in advance. More photos and questions to come.

 

[sWilly]

I made a little progress tonight. The date stamps on the drivers are 1968. That makes them almost as old as me. Almost! I opened up and cleaned the pots. They didn't look too bad so hopefully they're going to work. 

I haven't tested the capacitors yet but I plan to replace them regardless. Can anyone guide me on purchasing new caps and the appropriate wiring? I'll need to replace the 6mfd 50v as well as the large brick. I could really use some help there. 

Also, I believe I have the alnico woofers with fabric surrounds. Should I treat the surrounds in any way?? 

[dxho]

Yes, your pots are in great shape and might serve you well.

There are so many choices on caps. Dayton caps from parts-express.com
are a good, middle of the road start. There are probably hundreds of posts
on other choices, though, so it's easy to get overwhelmed.

If the surrounds are not dried out, they may not need sealer.

[Aadams]

Go to the last page of this thread and download the AR3a restoration guide. The download link will be unavailable unless you are logged in.

 

[sWilly]

1 minute ago, Aadams said:

Go to the last page of this thread and download the AR3a restoration guide. The download link will be unavailable unless you are logged in.

 

Yes, I've been referring to it. Thanks!

[sWilly]

After digging through these pages a bit it looks like I need:  50uf 100v, 150uf 100v, and 6uf 100v bipolar caps. Is this correct?

[DavidR]

On 12/6/2022 at 3:28 AM, sWilly said:

I haven't tested the capacitors yet but I plan to replace them regardless. Can anyone guide me on purchasing new caps and the appropriate wiring? I'll need to replace the 6mfd 50v as well as the large brick. I could really use some help there. 

I suggest you go with Non-Polar caps as were originally installed and not go the film cap route. The speakers will sound as they were intended/designed to. I have gone both routes with other AR speakers. One thing you can do is add a 0.01uF bypass film cap in parallel to the mid and tweeter series caps.

You can get good NPE caps at   https://www.partsconnexion.com/capacitors-ele.html

Mundorf and Jantzen (both made by F&T, a German company) are of good quality. They will match caps for a $1 per pair. The president of the company is very helpful. Can't think of his first name atm but last name is Johnson. I've used the ECap70 Mundorf series. IIRC LARybody has used the Jantzen and has used both NPE and film in AR9s. I don't know if he ever gave his impressions.

[sWilly]

54 minutes ago, DavidR said:

I suggest you go with Non-Polar caps as were originally installed and not go the film cap route. They will sound as they were intended to. I have gone both routes with other AR speakers. One thing you can do is add a 0.01uF bypass film cap in parallel to the mid and tweeter caps.

You can get good NPE caps at   https://www.partsconnexion.com/capacitors-ele.html

Mundorf and Jantzen (both made by F&T, a German company) are of good quality. They will match caps for a $1 per pair. The president of the company is very helpful. Can't think of his first name atm but last name is Johnson. I've used the ECap70 Mundorf series. IIRC LARybody has used the Jantzen and has used both NPE and film in AR9s. I don't know if he ever gave his impressions.

Thanks, this is helpful. The ECap 70 series looks interesting and reasonably priced but I'm not seeing the higher uF values available. I'll keep searching.

[DavidR]

https://www.partsconnexion.com/capacitors-ele-mundorf-e-cap-ac-series.html

scroll down the page.

Part Express has larger values, too :    https://www.parts-express.com/electronic-parts/capacitors/non-polarized-electrolytic-capacitors

[sWilly]

9 minutes ago, DavidR said:

https://www.partsconnexion.com/capacitors-ele-mundorf-e-cap-ac-series.html

scroll down the page.

Part Express has larger values, too (made by Solen):    https://www.parts-express.com/electronic-parts/capacitors/non-polarized-electrolytic-capacitors

Thanks, weird, I don't know why those didn't show up when I searched.

[sWilly]

7 minutes ago, DavidR said:

https://www.partsconnexion.com/capacitors-ele-mundorf-e-cap-ac-series.html

scroll down the page.

Part Express has larger values, too (made by Solen):    https://www.parts-express.com/electronic-parts/capacitors/non-polarized-electrolytic-capacitors

Are the Solen's any good? They have exact uF value's for everything which would make the install nice and clean.

[sWilly]

Ok, I'm liking the 5% tolerance on the Mundorf's. I will need to combine 47's and 3.3's to replace 50uF cap. I'm assuming that will be ok to be slightly off?

 

 

[DavidR]

I've used the Parts Express caps in my AR90 and AR9 large value caps.

Personally I'd combine the 47uF with a 2.7uF. This is where Parts Connxtion is good. An email to them saying you need a 50uF without being higher than 50uF. A buck a pair to match. No one else will do that at that price.

 

[lARrybody]

I agree with what David R suggest for the 50uf and 150uf caps. Here is what I plan to use on my next set of AR3a's. 

 

These are caps I had in stock and may not be available anymore, but Parts Connexion  has comparable examples.  The 100uf caps are Jantzen Audio Smooth NPE's which are the same as the Mundorf E-cap Plain. Both are no longer available, but you should be able to get the Mundorf E-cap Raw and the Jantzen EleCap.  Mine are running around 104uf. Same with the Mundorf E-cap 47uf Plain. You can get them in the Mundorf Raw and EleCap. As you can see mine are running closer to 50uf so no need to parallel a smaller value cap. For the 6uf tweeter cap I plan on paralleling two Clarity CSA 3uf film caps. The Clarity's run very true to spec. I will be finishing these AR3a up right after Christmas and things get back to normal around here.

[sWilly]

15 hours ago, lARrybody said:

I agree with what David R suggest for the 50uf and 150uf caps. Here is what I plan to use on my next set of AR3a's. 

 

These are caps I had in stock and may not be available anymore, but Parts Connexion  has comparable examples.  The 100uf caps are Jantzen Audio Smooth NPE's which are the same as the Mundorf E-cap Plain. Both are no longer available, but you should be able to get the Mundorf E-cap Raw and the Jantzen EleCap.  Mine are running around 104uf. Same with the Mundorf E-cap 47uf Plain. You can get them in the Mundorf Raw and EleCap. As you can see mine are running closer to 50uf so no need to parallel a smaller value cap. For the 6uf tweeter cap I plan on paralleling two Clarity CSA 3uf film caps. The Clarity's run very true to spec. I will be finishing these AR3a up right after Christmas and things get back to normal around here.

Thanks, I just ordered a full set of the Mundorf E-Caps. They seem like a good middle ground. We'll see!

[DavidR]

@lARrybody IIRC you re-capped 2 air of 9s and one was with NPE and the other with film. If so what were your impressions between the two ?

@sWilly The Mundorf ECaps are a well made NPE. My meter allows me to test for things like Dissipation Factor, Quality and Theta (phase angle). The Bennic, MDL and Dayton NPE were all pretty much the same - minor differences, if any, for same capacitance. The Mundorf (F&T) measured better.

[Reel Man]

I recommend the daytons for a clean install. This 6.2 has a 1% tolerance, the rest 5%. https://www.parts-express.com/Dayton-Audio-PMPC-6.2-6.2uF-250V-Precision-Audio-Capacitor-027-236?quantity=1   .   https://www.parts-express.com/speaker-components/crossover-components/crossover-capacitors/metalized-polypropylene-crossover-capacitors/capacitance/50-uF   https://www.parts-express.com/speaker-components/crossover-components/crossover-capacitors/metalized-polypropylene-crossover-capacitors/capacitance/100-uF,50-uF

[Reel Man]

Check other thread photos for installation ideas, also.

[jnolan5784]

I would also recommend having both tweeters rebuilt by Chris (contact info is on this site). I have a pair of 68 3a's that I did the restoration using the Dayton caps and new correct potentiometers (CLS with ceramic housing). After re-assembly, they sounded amazing - so I thought. I had the tweeters rebuilt and am totally amazed - didn't realize what I wasn't hearing. If you do the caps, new potentiometers, and rebuild the tweeters -they will be good for another 30 years. This particular woofer and the mids rarely if ever have issues. I didn't reseal the cloth on the woofer as per Roy on this site. 

[jnolan5784]

Also the other thing that is really important for these is a good higher power amp. I would recommend at least 150wpc of good power. You will be amazed how much they open up with higher power. This design is extremely inefficient but with good power they come alive and sound like nothing else. 

[sWilly]

4 hours ago, jnolan5784 said:

I would also recommend having both tweeters rebuilt by Chris (contact info is on this site). I have a pair of 68 3a's that I did the restoration using the Dayton caps and new correct potentiometers (CLS with ceramic housing). After re-assembly, they sounded amazing - so I thought. I had the tweeters rebuilt and am totally amazed - didn't realize what I wasn't hearing. If you do the caps, new potentiometers, and rebuild the tweeters -they will be good for another 30 years. This particular woofer and the mids rarely if ever have issues. I didn't reseal the cloth on the woofer as per Roy on this site. 

Good to know, thanks! I'll see how it sounds when I'm done. What was the cost of the tweeter rebuild? 

I live in Colorado. Our climate is really dry so the potentiometers were almost perfect. I cleaned them and hope to keep them but we'll see. 

I've heard that about having a good powerful amp. I have several nice vintage amps but none over 50 watts. I guess I'm going to have to seek out another one. Bummer.

[Reel Man]

Your pots look pretty good, real good, in fact.It seems that the fiberglass used earlier in AR history was/is harder on the pots than the later fiberglass. My very moldy AR3-a speakers had pretty good pots. I did use a little dielectric grease when I put them back together.

[jnolan5784]

The tweeter rebuild was about 75 - 80 per unit. Well worth it, even though I thought they sounded great before. My own opinion, but the amp selection for these is one of the most important choices. I think the reason these models are under appreciated is that the amps of that time frame were not up to the speaker's potential. A good, restored set with proper modern amplification and room placement will hold there own with anything new under 10k. 

[jnolan5784]

There are a lot of good options for amps. Units from the 80-90's are great - adcom, krell, crown, hafler, levinson, mac, and even some of the NAD stuff would be great with these. Just make sure they can deliver the power and the current. These can dip down to 2ohms in areas of the curve.  

[sWilly]

Thanks for the info. NAD might be a good option for me. I could use my 3020 as a pre and get a power amp to match.