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AR12 disaster !!!!!!!!!!


Wally

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I have been having a problem with my AR12's for a few days and couldn't figure out what was wrong. The imaging was off center...to the left. Even when i reversed channels on the amp. The speakers seemed ok so I measured the amp. Virtually perfect match on both channels....

Today I found the problem. Hairline crack around the perimeter of the surround on the right midrange speaker. IT is still working but obviously not as efficiently as the left. Couldn't see it before. Today I checked with a flashlight close up..... there it was.... damn...

Does anyone have a good ar12 midrange. It's the 5" oval style speaker. Or possibly the AR48 or AR2ax style mid which is a approximately 5" circular.

It's a foam surround.... guess that means the other will go soon and maybe replacements will also be fragile ?????

Has anyone fixed this size of speaker? I'm just assuming because of their small size they can't be re-foamed...????

Failing an exact replacement I could put in AR3a style dome mids.

Does anyone have a crossover schematic for the AR12 and the AR5? I'll compare the xovers and see what it takes to modify it to a quasi AR5. Mind this is my last resort if I can't get appropriate replacements for the AR12 mids. I suppose the AR2ax or AR48 mid would be an easier and closer replacement.

HELP!!!!!!

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I can't think of any reason that your midrange isn't repairable.

I'd call any, or several, of the speaker-fixers you've seen mentioned on the forum many times before and see what they say.

Simply Speakers claims to have surround replacements available for "all" sizes of AR-drivers. Of course, "all" might mean "all woofers.

I'd let someone else do it. I suspect the repair is more noticably critical than a woofer and I won't even do a woofer. I'm chicken.

IMO you'd be sinning to stick the wrong midrange in there because it will fit.

Bret

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>I have been having a problem with my AR12's for a few days

>and couldn't figure out what was wrong. The imaging was off

>center...to the left. Even when i reversed channels on the

>amp. The speakers seemed ok so I measured the amp. Virtually

>perfect match on both channels....

>

>Today I found the problem. Hairline crack around the perimeter

>of the surround on the right midrange speaker. IT is still

>working but obviously not as efficiently as the left. Couldn't

>see it before. Today I checked with a flashlight close up.....

>there it was.... damn...

>

>Does anyone have a good ar12 midrange. It's the 5" oval style

>speaker. Or possibly the AR48 or AR2ax style mid which is a

>approximately 5" circular.

>

>It's a foam surround.... guess that means the other will go

>soon and maybe replacements will also be fragile ?????

>

>Has anyone fixed this size of speaker? I'm just assuming

>because of their small size they can't be re-foamed...????

>

>Failing an exact replacement I could put in AR3a style dome

>mids.

>

>Does anyone have a crossover schematic for the AR12 and the

>AR5? I'll compare the xovers and see what it takes to modify

>it to a quasi AR5. Mind this is my last resort if I can't get

>appropriate replacements for the AR12 mids. I suppose the

>AR2ax or AR48 mid would be an easier and closer replacement.

>

>HELP!!!!!!

Repairing the original AR-12 midrange isn't going to be an easy task considering that the outer surround suspension is a flat-type piece of foam(half-roll is shown in the depiction below, but it is flat), and I haven't seen any reproduction pieces. Someone probably makes one, but I have not seen anything like it. The speaker also does *not* have a spider (voice-coil suspension), but uses Ferro-Fluid in the voice-coil gap to align (and dampen) the voice coil. The foam surround at the top edge is responsible for "centering," as such, and keeps the cone aligned vertically. Search around with the speaker repair people to see if they have anything like it; what you do to one speaker you should also do to the other to make the sound similar. It would be difficult, short of changing the crossover values, to put a different midrange in lieu of the original and have it sound correct.

http://www.classicspeakerpages.net/dc/user_files/744.jpg

(1) AR-12 Midrange Driver with Ferro-Fluid Voice-Coil Damping/Suspension

http://www.classicspeakerpages.net/dc/user_files/745.jpg

(2) AR-12 Midrange Driver Details. Sorry for the poor-quality image

--Tom Tyson

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Bret and Tom, thanks for getting back to me. .

I was kind of hoping someone would come back and tell me how they were able to repair their AR12 mids since I'm sure other Ar12 mids have died by now also.

A friend of mine says his supplier of surrounds has been doing speaker surrounds for years and he has been custom making surrounds for speakers for which surrounds are not available. I will send them to him along with your notes and pictures so he has a good understanding of what he's up against.

Failing that I will look for AR2ax or AR5 or AR48 mids and hope they come close in sound to the original mids.

Can either of you advise which mid would be closest in response and sensitivity to the AR12. (is there a series I missed with similar mids?)I know the AR5 was the 1.5" mid dome of the AR3A.

Have you guys seen schematics of the AR12 xover?

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  • 1 month later...

Yea...........

Got my repaired mids back today. Installed and playing... they sound great.

Expensive repair. Cost me as much as a replecement pair of mids for an AR3 would have been but they are original. ( Bret and Vern pls take note and give me gold stars in the big AR book....... :-)LOL)

The repair guy couldn't get surrounds for these of course so he took the next nearest size, cut it down, butted the ends together and installed. You have to look with a magnifier to see where he did the joint. Amazing. Looks original and they sound much different than they did. Midrange is now quite prominent. It was virually non existent before and louder in one speaker than the other.

Quick impresion, the 12's sound brighter than the AR2ax's that I have. Both with switches in the 0 position.

One day I will do some testing of the AR2ax vs AR12 vs AR48 and submit my evaluation to this forum. Should be interesting because these are different vintages of the same speaker.

Anyway, I'm very happy.

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>Bret and Vern pls take note and give me gold stars in the big AR book.......<

I love how far you went to get your 12s back as close as you possibly could to "stock."

>Quick impresion, the 12's sound brighter than the AR2ax's that I have. Both with switches in the 0 position<

A scene from "Airplane" and a line from Leslie Neilson went through my head. "I'm sorry, I don't do impressions." Sometimes at 1:30 in the morning, I can't help things like that.

You said the midrange is loud, and you've said brighter. In what area (cymbal tink, female voice, drum strike) do you find "brighter?"

This is purely a curiosity question because I doubt I'll ever get to hear a pair of 12s, so I'm trying to imagine them compared to a 2ax.

Bret

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Guest MPPurcell

Bret, in this situation might it not make sense for him to also refoam the woofers now? I am wondering about the difference in age and stiffness between the mids and the woofers after this repair. Or it might be simply a question of allowing more time for the mid's to break in. They are no doubt going to sound harsh at first.

Michael

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Micheal,

>Bret, in this situation might it not make sense for him to also refoam the woofers now?<

Well, you know - if it ain't broke; don't fix it. But I'd be looking for signs of "broke."

Bret

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