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Restoring the AR-3a


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I would think a local hardware store in your country should carry boiled linseed oil. Have you checked with any in your area?

Yep, we have it here.

They sell a lot of different "versions/types" but I have found a firm that has been producing "original" Boiled Linseed.

So Vintage-AR uses Linseed?

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Here is a link to an earlier thread on oiled veneer. Even Tom Tyson has some advice.

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=581&hl=linseed#entry51242

You can also use the search function to find more threads on the subject. Just enter "linseed" into the search word window, click on "Acoustic Research" to confine the search to AR and click 'search'

I took a quick look in the CSP library but could find anything. I'm sure there was something published by AR about the care of veneered finishes.

BTW, I would be surprised if vintage-AR's linseed oil (don't know if they sell it) is any different from what you'd get from a hardware store. It's pretty generic stuff.

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  • 1 month later...

I want to thank Roy Champagne, Ken Kantor, Minh Luong, John O'Hanlon, Bret Thiel, and Tom Tyson for their great Restoring the AR-3a document. I used it to fix the problems in a pair which I originally bought in 1971 or 72; they had off-spec capacitors, bad pots, one torn woofer foam, and a tweeter that didn't sound right and had too low an impedance.

I'm an experimental physicist and not a bad guy around electronics, but I doubt that I would have gotten things right without their guidance--at best it would have been a lot harder and much more time consuming. Everything--the schematics, photos, production history, organization, and writing--is top notch.

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In addition to the notes from Kimmo and VintageMan, I received a welcome from JKent, who suggested I post anything that might be of interest to others. I did a fairly standard job, using AR Teledyne 12000840 tweeters with the recommended parallel inductor. I've done a little experimenting with room position, but found (as I remember from the past) that the positions can be changed within reason and the speakers still sound very good..

The one unusal thing that I did was to refinish them. I bought the unfinished pine cases to save $50 a pair in 1971 or 72; at the time, I was earning $1.65 an hour in a summer job and that was a lot of money. When I first bought them I stained and then put a coating of shellac and oil ("French polish".) The look didn't work with the living room, my wife and I had just finished buying nice black and white modern furniture, so Ipainted the speakers and the stands that I made black to go with the decor. This was at my wife's request, but to tell the truth we both like the furniture and good music reproduction, and I like how they came out. The stands were pretty inexpensive, made from a extruded aluminum called 80/20 that you can buy on Amazon. ( The straight pieces can be cut to any length, and the corners are tapped into the aluminum making a very tight fit. It allows you to make the speakers any height that you want, and to change the height later by replacing the vertical pieces. I've attached a picture to show speaker plus stand look like.

post-177679-0-87502300-1446661907_thumb.

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Very clever and simple stands!

I looked at Amazon and only saw the T-slotted type but Outwater has the square tubing in silver or black anodized, and on the next few pages are the tap-in corners etc. http://www.outwatercatalogs.com/lg_display.cfm/catalog/Master_Catalog_Vol_42/page/204

Looks like all you need is some kind of jig to make square cuts, a hammer and saw. Cool!

-Kent

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I forgot to post a link to Amazon, http://www.amazon.com/80-20-Quick-Square-Profile/dp/B00J3VBFCO. You can get them in different lengths. I couldn't find the black anodized frames at Amazon, so Outwater is a good bet.

I made a simple jig for a band saw, then smoothed the ends on a milling machine, but I think with care you could cut the stuff with a hack saw , it is just anodized aluminum, if you used a jig.

I used a flanged version for the tops of the stands, http://www.amazon.com/80-20-Square-Single-Flanged/dp/B00J3WC23O/ref=sr_1_5?s=industrial&ie=UTF8&qid=1446673989&sr=1-5&keywords=80%2F20+9005, and dropped a piece of fiber board in making the top into a table so that the speakers wouldn't fall down if they slipped a little. Again, they come in various lengths.

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  • 4 weeks later...

I was not sure if it was correct to start a new thread about a single documents, so that's why I am posting here.

Several days a go oh HFE, a nice resolution scan of AR3a technical data was posted here: http://www.hifiengine.com/manual_library/acoustic-research/ar-3.shtml

So I am taking the liberty of reposting here. I hope that's ok?

I believe the info in this pdf is nothing new except for the higher quality scan.

hfe_acoustic_research_ar-3a_tech_data_en.pdf

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  • 3 months later...

I just spent some time today tracing down an interesting problem with the pots on my 3as while trying different treble and midrange settings.  When I restored the speakers, I replaced the pots with new ones which tested fine on the bench.  For some reason, one of the tweeter pots doesn't like to be on the maximum treble position, with the wiper all the way to one side.  If I back it off very slightly, so it is touching the winding, it is fine, and it varies smoothy up to that point.  On the maximum position, the treble level drops noticeably.  It is an easy problem to avoid if you are aware of it, but I thought for a while something was wrong with one of the drivers.

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  • 3 weeks later...

On a couple pots I have, after trying to clean them up it seemed the wiper would fall into a hole at the end (what it felt like) - almost give and click into the end.  Even took a littlw more force to get it going back the other direction.

 

I have kinda given up on old pots unless they are in really good shape. I try to determine in my mind if I was Roy A, or EV or HK if I was restoring of these, what would I do if I went over to my old parts bin and there were no originally specified pots left from the old days to use.  I'm not sure if the LPad would be their first choice, But i doubt they would worry to much about it not being the exact original.

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10 hours ago, DavidDru said:

On a couple pots I have, after trying to clean them up it seemed the wiper would fall into a hole at the end (what it felt like) - almost give and click into the end.  Even took a littlw more force to get it going back the other direction.

 

I have kinda given up on old pots unless they are in really good shape. I try to determine in my mind if I was Roy A, or EV or HK if I was restoring of these, what would I do if I went over to my old parts bin and there were no originally specified pots left from the old days to use.  I'm not sure if the LPad would be their first choice, But i doubt they would worry to much about it not being the exact original.

I'm with you regarding the original pots, David. Grinding away at a crusty green pot only to end up with a compromised component with a limited lifespan is silly, imo.

Actually AR began using a 15w 15ohm replacement pot (see attached photos) physically identical to a modern 15 watt 8 ohm L-pad in the 80's. It was made in Japan and very reliable. I run across them occasionally, and often find them to still be functional. In the AR-3a Limited in the early 90's, AR used conventional 15 watt 8 ohm L-pads with a slight crossover adjustment. The AP pots were a weak link from the very beginning, and I replace them with 8 ohm L-pads (with or without a 25 ohm parallel resistor) at every opportunity, and I have little doubt AR would be using them today. Frankly, I only retain original pots if they are in excellent condition to begin with, and only in restorations/repairs for people who value "authenticity" over function and long term reliability.

Roy

AR replacement pot.JPG

AR Replacement pot 2.JPG

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  • 1 year later...

Roy - Can you elaborate on that "25 ohm parallel resistor" please?  I've read that it corrects a crossover problem with the MID speaker (assuming you're talking about connecting the resistor to 2 of the lugs on the pot), but I haven't read anything about exactly how the frequencies are affected without that resistor.  I'm planning on installing that resistor, but since it's such a hassle to open up a 2Ax, it would help to know that installing the resistor makes a significant difference in the sound.  Thanks, Thorne

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  • 4 months later...

08/22/2018

Dear Forum Members:

I personally thank Roy Champagne, Ken Kantor, Minh Luong, John O’Hanlon, Bret Thiel, and Tom Tyson of this forum for their excellent restoration guide, which was our Bible 4 years ago.

4 years ago, Mr. Mullens agreed to restore a pair of Acoustic Research 3A loudspeakers from the early 1970s.  I supplied the stuffing, linen, caps and L-pads.  Mr. Brett Mullens (High-Fi Heaven in Falls Church VA) determined that he could clean the pots, so the L-pads were unnecessary.  He tested a deformed mid-range, finding it functional.  He replaced the tweeters and refoamed the woofers in accord with Classic Speaker's protocols.  At all stages, he was knowledgeable, cooperative, courteous and a pleasure to know.  The end result was a dream restoration and excellent listening.  I shall readily do business with Hi-Fi Heaven's Mr. Mullens again.  I heartily recommend to those of you too faint of heart to tackle the restoration yourselves.

https://hifiheavenrepairs.com/#/contact

Kit

Washington DC

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  • 1 year later...
  • 2 months later...

The AR-3a guide mentions using Permatex High Tack Gasket Sealant to reseal the fabric woofers, but I heard some complaints about this stuff, so I just bit the bullet and ordered the good stuff from Vintage-AR on eBay. It's about double the cost, but a lot cheaper than ruined woofers!

While I was there I just decided to order their complete grill package: New grills, fabric, and badges. Once I priced out what another badge was going to cost me along with grill cloth and then figuring out how I was going to rebuild the broken grill frame, I just decided to go all out and get it all new and already assembled. It will be fun to just pull them out of the box and pop them in. No extra work required.  Plus the original frames are very flimsy and the ones from Vintage-AR are much more stout. shareit app vidmate

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10 hours ago, roundcubenine said:

The AR-3a guide mentions using Permatex High Tack Gasket Sealant to reseal the fabric woofers, but I heard some complaints about this stuff, so I just bit the bullet and ordered the good stuff from Vintage-AR on eBay. It's about double the cost, but a lot cheaper than ruined woofers!

Good call! That recommendation to use Permatex slipped into the Guide before it was thoroughly tested over time and it turns out the stuff eventually gets stiff and ruins the surround. RoyC, an author of the Guide cooked up the stuff sold by Vintage AR and it's authentic to the original goo. Also perfect for vintage KLH speakers.

Welcome to CSP! Enjoy the 3a's and keep us posted.

Kent

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  • 10 months later...
  • 1 month later...
23 minutes ago, totsuka said:

I just bought these off CL. $350.00. They have issues but not opened up. One is dead and should be a bit of fun. No serial numbers and painted cabinets over plywood. Going to strip off.

IMG_20210927_132611409.jpg

 

Those are AR-3's, not 3a's...and the badges are not properly located.

Roy

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