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AR3a midrange-is this normal?


swanng
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I acquired a pair of AR3a's gratis that have been sitting around for a number of years, and I am in the beginning stages of restoration.

I am not familiar with the design of the midrange driver and wanted to ask the knowledgeable folks here if it is normal for the midranges (both speakers) to look like the images I took.

Please let me know if this is normal for them to look this way, as a normal (i.e., what I am used to looking at) speaker would be considered cosmetically damaged if it looked this way.

I have not connected these to any of my amplifiers, and have not tested resistance (or impedance) with a meter (yet). Neither have I tested the crossover components.

Thanks in advance, oh sages of AR.

Greg

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1 hour ago, swanng said:

as a normal (i.e., what I am used to looking at) speaker would be considered cosmetically damaged if it looked this way.

Looked what way?  The mid range is usually among the least of your problems in an unrestored AR3a that is showing signs of age but not abuse.   You could supply more photos and if you have not already done so,  download the restoration guide.

Adams

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At their best, all AR speakers look cosmetically damaged. They are downright ugly with the grills off.

I do not see anything unusual about your mids. Your pictures look like a bunch of other mids I see doing a google image search.

The true test is do they work? Put some music to them to see if they reproduce the sound.

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14 hours ago, swanng said:

t looks like the cone is torn or separated.

image.png.b09019a822fb044b7ab21fcd31b7e4b9.pngIf you are referring to this area of the midrange dome, that is normal.  RE: woofer: That appears to be a cloth surround woofer.  If the woofers are identical you have scored a real prize.   Post full front photos with grills off I am sure you will get more help.

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That's not a tear in the dome.  It's various layers of material, attached to the protective mesh, in front of the actual dome.  I assume these materials act as damping, and help with dispersion?  The black material, seen through that tear, is the dome itself, underneath the layers.

Also, I just picked up a pair of AR-5's.  When I start a refurb on them, I'll definitely check my domes, to see if they match your mids?  Just to be sure...

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Latest news: Connected both speakers to my SAE-A502 testing amplifier, which is preamplified by my CX-1000, playing a Saint-Saens Symphony No.3 CD on my CDX-720. I had two pairs of speakers connected, my old faithful Cerwin Vega U-321's and the AR3a's. After verifying everything was connected correctly and having tested audio out with the U321's, I switched over to the AR3a's. Bass driver working OK, although muted, no abnormal noises, driving with about 2 watts. No output from either left or right channel mids and tweeters. Rotated pots-very, very rough feeling and horrible sounding. Powered everything off, disconnected AR3a's, tested voice coil resistance, both mids tested about 3.8 ohms, both tweeters, between 3.5 to 4 ohms. So the voice coils are good. Now I'm in the process of testing components on the crossover-my AR3a's have serial numbers indicating first generation, verified by the crossover and especially the woofer design. Adams was asking for more photos, so here they are. Troubleshooting is ongoing, trying to figure out how to replace that big giant 5 pound capacitor block with Al non polarized low ESR caps. Ideas are welcome. I have the restoration document. And I used an old-school can opener to remove the woofer safely without damaging the cabinet.

Greg

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  • 2 weeks later...

Once you have the pots removed and opened up, post pics. Then clean them up and post pics. 

The contact disks and pot wipers condition will determine if they are salvageable or need replacing. Closely inspect the disk surfaces for pits and missing material, very common from the corrosion. The wipers often have holes from sera of the spinning frictions against the coils. Sometimes this is repairable with a blob of solder if the hole is small. If most of the tip is gone, a replacement is necessary.

As an alternative, there's a gent selling new replacement pots on eBay for 30 bucks each. They look great and a few have installed them with great results.

The 3a's tweeters are the weak spot. If their output is low once the pots are back in place, Chris can rebuild them to sounding new again. He did a set for me on a set I restored and they sounded great. 

Regarding the woofers, check the Masonite rings the surrounds are glued to, and the spiders are glued to, make sure they are not loosing from the basket.

Glenn

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On 4/26/2019 at 8:59 PM, swanng said:

trying to figure out how to replace that big giant 5 pound capacitor block with Al non polarized low ESR caps.

Welcome to CSP!

Those are some beautiful early 3a's! As far as the capacitors go, your choice of any NPE or film caps should be fine. The old bricks can be left in place with the leads snipped off or remove them. I used Dayton film caps in mine. Some people have recommended Mundorf NPEs. Some people use NPEs for the 150 and 50uF caps and film for the 6uF. The possibilities are seemingly endless.

Glenn wrote about restoring the pots but they may go bad again in short order. L-pads are pretty much trouble-free. Check the restoration guide.

Ditto on Glenn's comments regarding your tweeters. Chris is the go-to guy for those.

If your mids aren't up to par, Roy can rebuild those. And speaking of Roy, you should use his sealant on the cloth woofer surrounds. It's available from Vintage AR on ebay.

One other thing that may not be completely necessary. I'd replace the with 28-30 oz of new formaldehyde-free fiberglass. The stuff in your photos looks pretty crumbly and nasty.

-Kent

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22 hours ago, GD70 said:

Once you have the pots removed and opened up, post pics. Then clean them up and post pics. 

The contact disks and pot wipers condition will determine if they are salvageable or need replacing. Closely inspect the disk surfaces for pits and missing material, very common from the corrosion. The wipers often have holes from sera of the spinning frictions against the coils. Sometimes this is repairable with a blob of solder if the hole is small. If most of the tip is gone, a replacement is necessary.

As an alternative, there's a gent selling new replacement pots on eBay for 30 bucks each. They look great and a few have installed them with great results.

The 3a's tweeters are the weak spot. If their output is low once the pots are back in place, Chris can rebuild them to sounding new again. He did a set for me on a set I restored and they sounded great. 

Regarding the woofers, check the Masonite rings the surrounds are glued to, and the spiders are glued to, make sure they are not loosing from the basket.

Glenn

I agree with Glenn completely.

I recently updated my old AR3a rebuild post from 2012, because the original pots I thoroughly cleaned and reused had failed once again, after only 4 or 5  years. I had also replaced the woofer's foam surrounds, and rebuilt the crossovers.

This time, however, I decided to purchase the pots currently being sold on eBay by "capatianfantastic07" instead of once again dealing with the original and problematic pots, only to risk them failing again very soon. Beginning on pg. 5 of the post (here: http://www.classicspeakerpages.net/IP.Board/index.php?/topic/7440-upcoming-ar3a-project/), I documented the installation of these new pots. They are a drop-in replacement, and don't require any modifications to the crossover networks, or cabinets. Yes, they're a bit pricey compared to L-Pads for sure but, I still wanted to maintain them as close to original as possible. 

I couldn't be happier with the results, and installation was very straightforward and simple. I did need to make a couple of creative decisions as to how they should be installed, because of the tabs, and threaded mount differences - you can read those observations in my post. Nothing anyone else couldn't have done on their own.

Also, Chris rebuilt my tweeters this time. One was effectively dead. Like others here, I can attest to the quality of his work, and tell you you'll be very happy with the results. It's no wonder they still command such a high value on the vintage audio market. 

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Be careful with your woofers.  The white dust on the magnets is cadmium corrosion.  It IS toxic.  If it is not too late, you should wear nitrile or latex gloves and wipe it off with a dampened rag.  Windex or other gentle cleaner will work.  Then promptly dispose of the rag and gloves.

DO NOT try to blow or vacuum it off.

As other have said rebuilding the crossovers is pretty straightforward.

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  • 2 years later...
On 5/5/2019 at 10:56 AM, GD70 said:

Once you have the pots removed and opened up, post pics. Then clean them up and post pics. 

The contact disks and pot wipers condition will determine if they are salvageable or need replacing. Closely inspect the disk surfaces for pits and missing material, very common from the corrosion. The wipers often have holes from sera of the spinning frictions against the coils. Sometimes this is repairable with a blob of solder if the hole is small. If most of the tip is gone, a replacement is necessary.

As an alternative, there's a gent selling new replacement pots on eBay for 30 bucks each. They look great and a few have installed them with great results.

The 3a's tweeters are the weak spot. If their output is low once the pots are back in place, Chris can rebuild them to sounding new again. He did a set for me on a set I restored and they sounded great. 

Regarding the woofers, check the Masonite rings the surrounds are glued to, and the spiders are glued to, make sure they are not loosing from the basket.

Glenn

Hi Glenn, I get around I guess...I have a pair of the original red/orange 1 3/8ths" dome tweeter for a set of ar2ax's actually.  One tweet crackled a brief moment, I shut it off, and so it needs to be rebuilt, the pair im sure is right behind me.  This is my personal set so it's imp. To me that they function. 

You and jkent right after mention "Chris" is a guy who can repair these woofers.  Is this something he commonly does for a fee?  Is he still around?  Any chance you could get me contact info and would you mind if I mentioned to him that im an aquitance of yours initially so he doesn't think im a wake job?

Any help is greatly appreciated.

Thanks for your time Glenn.

Scottie

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  • 1 month later...

I just purchased 6 pots for my 3a's and 6's. The 3a's have L-pads without the resistors(as far as I can tell as the volume is much too high just a hair from 'off'). I don't like the way that they sound.  As far as L-pads being trouble free, I have a bad one already on one 3a.  

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11 hours ago, Phxjohn said:

I just purchased 6 pots for my 3a's and 6's. The 3a's have L-pads without the resistors(as far as I can tell as the volume is much too high just a hair from 'off'). I don't like the way that they sound.  As far as L-pads being trouble free, I have a bad one already on one 3a.  

Just a note for other members who want to use real pots. Please see the For Sale section: https://community.classicspeakerpages.net/topic/13225-potentiometers-for-ar/

 

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