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AR factory goofs?


2chanman

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I have just received a pair of AR9 speaker systems as a gift from the party that I advised 30 years ago to purchase these speakers. They have been in that individuals home during that time and have been fallow for several years due to the inevitable foam rot of the woofers and upper bass drivers. I removed the 4 woofers and 2 bass drivers last evening and made some interesting discoveries. First, one of the woofers had only 7 mounting screws. The 8th hole was there, but was open. So much for a sealed enclosure. In one of the systems, the upper bass driver was hooked up backwards! The positive terminal of the driver was connected to common, confirmed by ohmmeter to the speaker input ground connector. I wonder what that AR technician had been smoking.

I noted that the rear spiders of all 4 woofers were dished to varying degrees towards the rear of each driver. This surely would result in an offset of the cone when driven by a signal, not to mention distortion. I would have expected the phenolic ring that the surround was glued to would tend to pull the cone forward to counteract the tendency for the spider to develop a rearward set, but the opposite was true.

These speakers systems were always standing vertical during their previous use, never abused or overdriven and were never opened up other than to remove the grills periodically to inspect their condition, so at least the first 2 problems were "factory installed". As for the dishing of the spiders, I can only guess.

Have any other AR9 rebuilders had similar experiences?

2chanman

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The foam surrounds on those woofers & lower mids have most likely been bad for 15 years - perhaps even longer; so unless your friend knew to check for incipient foam-rot, the speakers were probably operated for some time with the bad surrounds, which might account for the "dished" spiders.

After opening up maybe 20 pairs of AR-9s and six or seven AR-90s, I've never observed any issues with improper wiring, or missing bolts.

It seems possible that someone has been into these speakers at some point - a reversed-polarity lower midrange should stand out like a sore thumb.

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I can say with absolute certainty that no one but AR was ever into those AR9's but me as described in my post. I was there when they arrived in factory sealed cartons. They were owned by a woman who would never have dared to go at them with a tool of any sort nor would she have the required Allen wrench or the skill to use it or the inclination to do so. The defects noted were courtesy of Acoustic Research.

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I can say with absolute certainty that no one but AR was ever into those AR9's but me as described in my post. I was there when they arrived in factory sealed cartons. They were owned by a woman who would never have dared to go at them with a tool of any sort nor would she have the required Allen wrench or the skill to use it or the inclination to do so. The defects noted were courtesy of Acoustic Research.

Your comments are interesting. I have just opened up a pair of UK manufactured AR-2ax's with a view to re-commissioning them. I've just had the woofers tested by an audio engineer (they are both shot!) and he has confirmed that they are actually of completely different design, so not a matched pair, not even two drivers of the same manufacture!

Just like you, I know these speakers were previously undisturbed and as deliverd from the factory!

Ian.

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Your comments are interesting. I have just opened up a pair of UK manufactured AR-2ax's with a view to re-commissioning them. I've just had the woofers tested by an audio engineer (they are both shot!) and he has confirmed that they are actually of completely different design, so not a matched pair, not even two drivers of the same manufacture!

Just like you, I know these speakers were previously undisturbed and as deliverd from the factory!

Ian.

Not quite in the same league as different woofers or reversed polarity. I have just been given a 1976 pair of AR-6. The stuffing was jammed between the cabinet and the gasket pulling it tight behind the woofer. I know for a fact they have never been opened since manufacture. UK model.

Mike.

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