My AR-3a restore

Discussion in 'Speakers' started by Rex81, Nov 13, 2017.

  1. Rex81

    Rex81 AK Subscriber Subscriber

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    I know there are a ton of these threads out there, but we never seem to get tired of reading about a new one, so here's another for you.

    I got these from a local AKer who just didn't have the time to get to these. I've never owned or heard a pair so I wanted to see what all the fuss was about. Plus I like to tinker, and these will keep my hands busy for awhile.

    They're a pretty good starter pair. Typical bumps and bruises, a couple of broken corners, scratchy audio cutting in and out from bad pots, one broken grill frame, and one missing badge. But they're early units (09111 and 15848) with alnico fabric woofers and all the drivers work.

    Couple shots of overall condition:
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    First project was to pull the woofers and clean off the black sealant with a thin putty knife. These things were on there pretty good. You have to be careful not to dent the baffle when prying them out. I had the best luck with slipping a paint can opener underneath, then pulling straight up.

    thumbnail_IMG_0794.jpg

    Next, I de-soldered the pots from the one speaker and opened them up. One looked pretty good, the other was oxidized pretty bad. I cleaned them both with some DeOxit and the wire brush on my Dremel. Then went over them with some #0000 steel wool to polish them up. They came out nice.

    When I moved on to the other speaker, I determined I didn't need to desolder them at all. I could just work on them right in place. I recommend doing that. That saved me some time. The other speaker's pots looked them same: One not bad at all, the other pretty green.

    thumbnail_IMG_0798.jpg

    I finished them up by applying some dielectric grease I bought at the local AutoZone. This smoothed out the action and should hopefully keep them for oxidizing over the next 50 years. They didn't have any little packets or small tubes in stock, so I left with enough for several lifetimes. Oh well. It was still only $6.

    That was all the work for day 1.
     
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  2. Rex81

    Rex81 AK Subscriber Subscriber

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    Now to order the parts I needed. After consulting THE AR-3a guide (http://www.classicspeakerpages.net/...ing_the_ar-3a/restoring_the_ar-3a_full_pd.pdf) which was super helpful, by the way, and researching some other threads around here, I decided on the following caps from Madisound:

    (2) Bennic 150uf NPE - https://www.madisoundspeakerstore.com/electrolytic-cap-100vdc/bennic-150-mfd-electrolytic-caps/
    (2) Bennic 50uf NPE - https://www.madisoundspeakerstore.com/electrolytic-cap-100vdc/bennic-50-mfd-electrolytic-caps/
    (2) Solen 6uf polypropylene - https://www.madisoundspeakerstore.com/solen-capacitors/solen-6-mfd-fast-cap-400v/

    I know some people will recommend using polys throughout, but that significantly increases the cost, and a lot of the old pros use the exact compliment of caps as above, and I'm ok with it.

    You can get very similar caps from Parts Express, but the NPEs are no-name brand, and the PP is Dayton (which I've had very good experience with in the past) and the price with shipping is almost identical so I just went with these from Madisound.
     
  3. Rex81

    Rex81 AK Subscriber Subscriber

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    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. :thumbsup: Plus the original frames are very flimsy and the ones from Vintage-AR are much more stout.
     
  4. Rex81

    Rex81 AK Subscriber Subscriber

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    I spent all yesterday morning sanding. Oh man, I much prefer finishing. Sanding is a lot of work! I'd rather just apply some Howard's Restore a Finish (which works remarkably well for removing way more blemishes and stains than you would think). But the scratches and gouges are deep enough that full sanding was required.

    I started with 120, then finished up with 220. I know there's a lot of debate on this subject, but if I had to do it again, I would use the exact same grits. 220 is plenty smooth for walnut, in my opinion. I used the palm sander on the sides, tops, and bottoms, and then hand sanded the fronts.

    thumbnail_IMG_0807.jpg


    Before vs after:
    thumbnail_IMG_0809.jpg
     
    Last edited: Nov 13, 2017
  5. Rex81

    Rex81 AK Subscriber Subscriber

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    I went back and forth about how to fill/repair the blemishes. I know some of you guys harvest old walnut veneer off other speakers and cut it so size and all that. That's awesome, but I didn't have any and honestly don't think I have the patience or skill required. So after a lot of research, decided to go with DAP Plastic Wood in walnut. I've had good luck with it on other projects. You can built it up in coats and it sands nicely, and actually color matches pretty well. I think it turned out fine.

    Here's building up the first coat. I put one more on this corner before I sanded it down because it was pretty deep.
    thumbnail_IMG_0822.jpg

    I even added some very sparingly to the fronts to fill in some pretty deep dents/gouges.
    thumbnail_IMG_0823.jpg

    I let the filler sit for about 6 hours before I came back and carefully hand-sanded it smooth.
     
  6. Rex81

    Rex81 AK Subscriber Subscriber

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    Then onto my favorite part: Finishing. There are few joys in this world more pronounced than applying the first coat of finish onto bare wood.

    I started with a light rub of mineral spirits to clean away the last of the dust.

    Then applied a healthy dose of Watkins Danish Oil in Natural. This is good stuff. The wood soaks it up pretty good, so multiple coats are needed.

    thumbnail_IMG_0830.jpg

    You can apply a second coat in as early as 30 minutes. I have 2 coats on now. When I get home tonight, I'll apply a 3rd and 4th and see where we're at.

    I'm still waiting on the caps and the grills, but once those are in, I'll add those stages to this thread too.
     
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  7. tyella

    tyella AK Subscriber Subscriber

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    Looking good! Well done!
     
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  8. GD70

    GD70 AK Subscriber Subscriber

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    Dejavou all over again! Looking good!
    I'm curious to see how the oil takes to the wood filler, especially with color match.
    Beautiful grain veneer on those too!
    Glenn
     
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  9. Rex81

    Rex81 AK Subscriber Subscriber

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    Thanks Glenn! Your threads were really helpful in getting me going on this set.

    I'll snap some more photos once I get a couple more coats of finish on. The filler won't look nearly as good as yours do with the aged walnut pieced in, but it looks better than bare broken plywood, that's for sure. So far the filler seems to "agree" with the stain. I doubt it's soaking much up, so it helps that it was already a walnut shade to begin with.

    Yes, this set has phenomenal grain patterns. In fact, one of the fronts has some figuring to it with a lot of color variation. Almost doesn't look like walnut. Very cool.

    Oh, and as soon as I posted this thread, I got an email telling me the woofer sealant and grills were delivered, so I'll snap some pics of those tonight too.
     
  10. GD70

    GD70 AK Subscriber Subscriber

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    May I suggest, BEFORE you put the sealer on the woofer surrounds, mount them with the putty and do the seal test. Gently push the woofer cones in and let go. If they return slowly, no sealer is necessary. Roy told me the cloth surround woofers rarely need resealing, unlike KLH woofers, which almost always need resealing. Roy developed the sealer primarily for KLH woofers because so many were being ruined with various concoctions that ended up making the surrounds stiff, basically ruining the woofer.

    Glenn
     
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  11. Rex81

    Rex81 AK Subscriber Subscriber

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    Great advice. This is the first I've heard of this. I assumed that ALL cloth woofers should be resealed.

    Once I receive the caps, I'll recap, install the foam (I prefer to use foam insulation tape for mounting drivers), mount the woofers, and test.
     
  12. StimpyWan

    StimpyWan Super Member

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    I always try and use polypro caps on the series high pass capacitors, and NPE's on the parallel shunt caps. That keeps high quality capacitors in the sonically critical positions, and NPE's, where they have less impact on sound. Also, Bennic manufactures the Dayton caps. So, there shouldn't be any difference between the Parts Express and Madisound NPE's. Otherwise, very nice work on the restore. It makes me wish I had level adjustments on my AR58s speakers. Then I could mimic the sound of a 3a!
     
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  13. Rex81

    Rex81 AK Subscriber Subscriber

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    A couple of pictures after 3 coats of finish.

    Here's the interesting color and figure on the front of one of the speakers. That's not a flash reflection or anything. The light color shown in the picture is accurate. Very cool.
    IMG_0834.JPG

    Nice straight grain on the sides:
    IMG_0835.JPG

    Here's a corner that was filled in. I'm happy with this one.
    IMG_0836.JPG

    Here's another that I'm less happy about. I think I'm going to sand it down and build it up again. There's no confusing the putty for real veneer, that's for sure. The larger repairs are more obvious of course. I just need to decided what I'm ok with, since they'll never get perfect.
    IMG_0837.JPG
     
  14. bcbud3

    bcbud3 Active Member

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    You could try furniture felt markers on the filler. The markers are cheap enough. Dab a little and wipe off. Might be worth a try before you go ruining your hard work.
     
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  15. Rex81

    Rex81 AK Subscriber Subscriber

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    That's a good idea. I think if I could match the reddish tint of the vintage walnut better, it would look less noticeable. I don't know how well the filler will take the stain, but it's worth a shot.
     
  16. centsless

    centsless Well-Known Member

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  17. Vintage999

    Vintage999 AK Subscriber Subscriber

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    Tweeters - the original tweets in the 3a's were pretty phenomenal. In my rebuild I came across one huge problem...the original tweets sounded pretty bad. Have a friend that can do some basic frequency sweeps and distortion analysis. Nothing fancy, but by our calculations, the distortion was through the roof, and it sounded pretty harsh.

    What to do? Replacing the tweeters with someting new wipes out the value of the speaker. Leaving the old tweets in maintained the value of the speaker, but the more I listened, the more I couldn't overlook the depressed as well as distorted highs. I considered purchasing some second hand tweets, but who is to say that the used tweets wouldn't be as bad as my originals?

    I bit the bullet, put in new tweets and the improvement was obvious. (I also did the inductor upgrade to the crossover) I looked inside the dome on the worst tweeter and saw a little piece of foam turned to dust. Dynamics had turned to dust also...

    Just a heads up...
     
  18. StimpyWan

    StimpyWan Super Member

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    Classic Speaker Pages member "chris1this1" can rebuild the early 3 and 3a tweeters. It's reported that he does a great job, and the rebuilt tweeters sound and behave as new.

    Also, Midwest Speaker Repair has a new AR tweeter they've designed and had built, that's being discussed, and it seems to be testing very well. It's a possibility too, if replacement tweeters are needed?
     
  19. Rex81

    Rex81 AK Subscriber Subscriber

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    I think I got lucky. My tweeters sound just right.
     
  20. Rex81

    Rex81 AK Subscriber Subscriber

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    Location:
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    Final day. The project is 99% complete. I'm going to spend a little more time cleaning up or redoing the filled areas, trying some different products out, but for the most part, these are ready to listen to.

    I applied a 4th and final coat of Danish Oil to the cabs, did the recap (which is very straight forward), and remounted the woofers.

    I did the push test and there is definitely some delay before they return, but not a ton. It maybe takes them 1.5-2 seconds to return. Is this about right for this model? Whenever I did the push test with SDAs, the woofers would take about 3 seconds to return. I have the woofer sealant, but haven't applied it yet. Should I just go ahead and do it?

    I got the new grills from Vintage-AR in and they're sweet. The frames are definitely sturdier than the originals, but look almost identical. The badges look good too. I'm happy.

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