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Analogean

Ar-7 replacement woofers and tweeters

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Hello, I bought a pair of ar-7 speakers at a flea market, pretty beat up, but with wood veneer and nice grills. Unfortunately I couldn't get the grills off at the market so I took a chance. When I got them home I found both surrounds were disintegrated and one woofer was frozen or scratching. Also one tweeter is dead. Now I'm having a hell of a time finding replacement drivers. The 8" woofers have a square magnet on the back. Are there no replacement woofers out there? Are the tweeters the same as the ar-4 series? I hope i can get these going again. Thanks in advance!

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IIRC woofer is the same as the AR17,18&25 (PN 1200001), and the tweet is the same as the 6&8, and the same as the 17/18/25, except the newer ones has ferrofluid

the 8" woofer out of the 18S, 18B, and Rock Partners will work, too, and the tweeter is very similar (PN ends in 038)

 

 

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Thanks, but I'm talking about a set of ar-7 speakers. Are you saying those models will fit and have a resonance frequency of 25 Hz? If so I will check them out. I think in the end I will just fit what I can get my hands on here in Europe. Monacor seem to have some good stuff.

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On 14/9/2016 at 11:46 PM, Analogean said:

Thanks, but I'm talking about a set of ar-7 speakers. Are you saying those models will fit and have a resonance frequency of 25 Hz? If so I will check them out. I think in the end I will just fit what I can get my hands on here in Europe. Monacor seem to have some good stuff.

Hi Analogean,

For the restoring take a look at the work I've done on my AR 7 & AR MST at the following links ... I hope you will find something that will be useful .

 

Regards

Alessandro

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Analogean, your AR-7's are very much worth restoring properly and really not all that difficult. Without seeing pics, it's a little difficult to advise with specifics on your situation, but I am pretty certain that the AR-7 woofer and tweeter are each not all that rare in the Euro market. With a little effort, you should be able to locate one of each for your project. 

The square magnet woofer with flat dust cap is the correct original woofer (see pic of some of my AR-7's), and like michiganpat stated, some other AR 8" woofers should also be suitable as replacements, including a similar sq.-mag. woofer from the AR-6. Same thing for the tweeter - - this exact driver, and a few others very similar, were very common for a number of years of production.

      

woofers, front, rear.jpg

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Thank you all for your good advice. The Monacor chassis were not fitting properly in the cut out, but luckily Alessando came to my rescue and now I am the proud new owner of a whole set of woofers and tweeters, reconed, original square magnet. So while waiting for those to arrive I've started to sand the boxes...

image.jpg

image.jpgimage.jpgimage.jpg

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I have encountered a new problem!! The sanding is finished, the cabinets oiled and looking lovely. I was just about to fit the newly arrived woofers and tweeters when I noticed that tapping on the baffle of one of the cabinets produced a rattle. I looked a bit closer and found that on one side of the cabinet the seal is broken or has become unglued, thus causing the rattle. Darn it, how the heck am I going to fix that? Calking it won't be enough and I cannot re-glue it  properly without destroying the whole cabinet. I think if I chip away the white sealant and pull the wood apart as much as I can without breaking it, I might be able to get a syringe in the crack, but what glue will work through a syringe? Has anyone else here had this problem before?

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1 hour ago, Analogean said:

I have encountered a new problem!! The sanding is finished, the cabinets oiled and looking lovely. I was just about to fit the newly arrived woofers and tweeters when I noticed that tapping on the baffle of one of the cabinets produced a rattle. I looked a bit closer and found that on one side of the cabinet the seal is broken or has become unglued, thus causing the rattle. Darn it, how the heck am I going to fix that? Calking it won't be enough and I cannot re-glue it  properly without destroying the whole cabinet. I think if I chip away the white sealant and pull the wood apart as much as I can without breaking it, I might be able to get a syringe in the crack, but what glue will work through a syringe? Has anyone else here had this problem before?

Get some poly resin and pour a fillet around the inside of the baffle. Epoxy is also an option ala "stitch and glue" boat building technique.

I did it here with dumpster-grade AR-4x speaker(s).

http://www.classicspeakerpages.net/IP.Board/index.php?/topic/8453-would-the-inspector-be-pleased/&do=findComment&comment=103831

Roger

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The cabinet refinishing is looking real good so far - - those will end up being real beauties. Your description of the structural problem with your cabinet is a little unclear, so it is difficult to advise, but there are syringes sold in woodworking stores for tight situations. When I first saw your pics, I was curious about that perimeter bead of white caulking - - it may be original, but it looks unfamiliar to me, and it may represent a previous attempt at a structural repair.

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Mmmmmm. The white bead I assumed to be original. Now it is brittle and can be chipped off. Poly resin hardens like stone when it has dried.

There are two problems here. First the wood against wood rattle caused by the broken joint. This in my opinion needs to be glued rigid. Second is the air leak caused by the broken joint. This in my opinion can be calked or sealed with an epoxy or some other flexible material. 

Question, all you ar owners out there. Tap on the baffles of a set of speakers. Do they sound the same, make the same tonal resonance?? Just curious. When I hold the cracked joint together, the rattle ceases, but the tonal resonance is still different.

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Both sets here have glue caulking around the seams. You can always use pva or wood glue which is certainly easy enough to work with. I don't think the box resonance will be an issue as long as you have an acoustic seal.

Roger

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You could also use a two-component wood glue. However on my AR 7 is not a white adhesive is instead present a rubbery adhesive semitransparent. I always face the presence of such adhesives on all AR 7 but the reason lies in the fact that the size of the hole that houses the woofer and almost indentical to the internal width of the cabinet so you have to make that part more tough. If desired inside you may paste the strips 1cm square and the problem would be doubly solved for both the robustness that for the seal.

Alessandro

 

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Thanks for the advice. I have opted for wood glue and clamp plus a 2 component power putty from Pattex. I had thought about a wood brace on the inside but hope the gluing will work. I wii find out when I take the clamp off tomorrow. Does anyone know the polarities of the woofers and tweeters? Neither are marked. Woofer part # 200001-1.                 Tweeter part # 200014-3

lucas

 

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Neither of my two pairs of AR-7's has the caulking along the front perimeter of the baffle board, but in the pics of this pair from 1973, two  items are noteworthy. First, it can be seen that all of the panel seams on the cabinet interior have been thoroughly sealed, and second; it was surprising to find that the T-nuts included a staple across the flange. I had never seen this detail before inside an AR cabinet, and the intention was immediately clear - - - to further protect the T-nut from spinning in place if its teeth become disengaged from the particle board. Even though this staple is a nice little detail, I still prefer a smear of epoxy to keep the T-nut more firmly situated, and once you've experienced the difficulty that ensues from a free-spinning T-nut while trying to remove a woofer, you'll always appreciate the added security that epoxy, or perhaps even a single staple, provides in minimizing this potential disaster.     

AR-7 t-nuts.jpg

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So, I wanted to round up this thread and thank everyone for their help. The AR-7's are finished and sounding (and looking) great. The glueing and kitting with 2 component putty worked fine. The driver polarities I found by testing with a battery for the woofers, and critical listening for the tweeters. I did encounter one more problem, one of the newly foamed woofers had a bent magnet and was slightly scratching. At first I thought this was going to be unfixable, but I carefully hammered wooden wedges in between the cone and magnet to get it straight again and was happily able to get it back within critical parameters. To me the speakers sound very open and full. Definitely keepers.

thanks again! 

Lucas

image.jpg

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On 9/26/2016 at 7:31 AM, Analogean said:

Thanks for the advice. I have opted for wood glue and clamp plus a 2 component power putty from Pattex. I had thought about a wood brace on the inside but hope the gluing will work. I wii find out when I take the clamp off tomorrow. Does anyone know the polarities of the woofers and tweeters? Neither are marked. Woofer part # 200001-1.                 Tweeter part # 200014-3

lucas

 

Okay, well the AR-7 drivers seem to be wired out-of-phase with all of AR's other speakers so you are at liberty here to experiment. In their factory configuration post #1 would wire to the amplifier positive or red terminal if you plan on phasing them with another set of speakers; otherwise, not an issue.

Roger

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