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AR3 Woofers


Guest Choatpadda

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Guest Choatpadda

Were the AR3a Woofers ever used in the AR3? I am Re-furbing a pair of AR3's, which had the AR3a woofs in them when I bought them. I was told some of the latter AR3's used this woofer.

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Were the AR3a Woofers ever used in the AR3? I am Re-furbing a pair of AR3's, which had the AR3a woofs in them when I bought them. I was told some of the latter AR3's used this woofer.

AR had a habit of making substitutions at the end of a model's life when they ran out of its original spec components. Considering how long the 3 remained in the lineup after the 3a was introduced, it's probably so.

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Were the AR3a Woofers ever used in the AR3? I am Re-furbing a pair of AR3's, which had the AR3a woofs in them when I bought them. I was told some of the latter AR3's used this woofer.

The cloth surround/alnico magnet AR-3 woofer was used in the early AR-3a until the foam surround/ceramic magnet 3a woofer came along...which also included an inductor change in the 3a crossover. That later foam surround woofer appearing as original equipment in an AR-3 would be unusual.

What are the serial numbers on the back of your cabinets?

Roy

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Were the AR3a Woofers ever used in the AR3? I am Re-furbing a pair of AR3's, which had the AR3a woofs in them when I bought them. I was told some of the latter AR3's used this woofer.

Choatpadda,

What are the serial numbers of your pair of AR-3s? If I had to guess, I'd say they were in the 25,000-35,000 range. If they are in the 70,000+ range, then likely they built at the last of the model run and might have had the ceramic woofer. But I notice that the AR-3 shown in the picture has an AR-3a midrange with the AR-3 original tweeter, and this is definitely wrong. There was a special midrange version of the AR-3a that could be used, but it also required an extensive crossover change. There was also the AR-3-to-AR-3a upgrade, which also completely changed the crossover from an AR-3 to an AR-3a, but that would include the 3/4-inch tweeter rather than the 1-3/8-inch tweeter shown in your picture. Therefore, as far as I can tell, what is really needed for this speaker shown in the picture would be the 2-inch AR-3 midrange and the Alnico woofer, if the speaker is to be brought back correctly. The AR-3a midrange is not designed to perform properly all the way up to the 7500 Hz crossover; it was designed for a 5000 Hz crossover in the AR-3a.

The Alnico woofer, originally used in different versions in the AR-1 and the AR-3, was migrated over to the AR-3a in 1967 and used until 1969, I believe, before the new ceramic woofer was put into service. The two woofers are nearly identical in performance, but there were slight differences, and the crossover eventually was changed in the AR-3a to better accomodate the difference. For the AR-3, the important thing was to have a woofer that would respond up to approximately 900-1000 Hz smoothly, and therefore damping rings were used on the Alnico woofer to smooth the response at the upper end. There have been some images floating around showing damping rings on the ceramic woofer, and perhaps this was intended to be used in the last production models of the AR-3, but I believe that crossover changes were made at that point as well.

Image (1) AR-3-style Alnico 12-inch woofer used in the AR-3 and early AR-3as from 1967 until 1969.

Image (2) AR 12-inch ceramic woofer with damping rings, possibly for late-model AR-3 production units (not confirmed).

--Tom Tyson

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Guest Choatpadda
Choatpadda,

What are the serial numbers of your pair of AR-3s? If I had to guess, I'd say they were in the 25,000-35,000 range. If they are in the 70,000+ range, then likely they built at the last of the model run and might have had the ceramic woofer. But I notice that the AR-3 shown in the picture has an AR-3a midrange with the AR-3 original tweeter, and this is definitely wrong. There was a special midrange version of the AR-3a that could be used, but it also required an extensive crossover change. There was also the AR-3-to-AR-3a upgrade, which also completely changed the crossover from an AR-3 to an AR-3a, but that would include the 3/4-inch tweeter rather than the 1-3/8-inch tweeter shown in your picture. Therefore, as far as I can tell, what is really needed for this speaker shown in the picture would be the 2-inch AR-3 midrange and the Alnico woofer, if the speaker is to be brought back correctly. The AR-3a midrange is not designed to perform properly all the way up to the 7500 Hz crossover; it was designed for a 5000 Hz crossover in the AR-3a.

The Alnico woofer, originally used in different versions in the AR-1 and the AR-3, was migrated over to the AR-3a in 1967 and used until 1969, I believe, before the new ceramic woofer was put into service. The two woofers are nearly identical in performance, but there were slight differences, and the crossover eventually was changed in the AR-3a to better accomodate the difference. For the AR-3, the important thing was to have a woofer that would respond up to approximately 900-1000 Hz smoothly, and therefore damping rings were used on the Alnico woofer to smooth the response at the upper end. There have been some images floating around showing damping rings on the ceramic woofer, and perhaps this was intended to be used in the last production models of the AR-3, but I believe that crossover changes were made at that point as well.

Image (1) AR-3-style Alnico 12-inch woofer used in the AR-3 and early AR-3as from 1967 until 1969.

Image (2) AR 12-inch ceramic woofer with damping rings, possibly for late-model AR-3 production units (not confirmed).

--Tom Tyson

Thanks for the great feedback! The serial number on the pictured speaker is 70255. The guy I bought these from insists they are the original components. Which almost made sense with the High Serial Number until you pointed out that the Mid is from the AR3a and the Tweeter is the AR3 which you said the AR3 Networks were not set up for.

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Thanks for the great feedback! The serial number on the pictured speaker is 70255. The guy I bought these from insists they are the original components. Which almost made sense with the High Serial Number until you pointed out that the Mid is from the AR3a and the Tweeter is the AR3 which you said the AR3 Networks were not set up for.

On close inspection, I notice that the cabinet for this speaker is definitely the later AR-3a-style cabinet; i.e., the grill is placed down in the area around the molding and glued in place, rather than wedged up under a groove. So this would confirm that this speaker is one of the last ones made. The only questionable thing would be the AR-3a midrange (it is the early vintage AR-3a midrange, 1967-1972 or so), so maybe it was retrofitted somewhere along the way. You will need to see what is in the crossover, and I don't think that version midrange would ever be completely compatible with the 1-3/8-inch tweeter. The attached image is the "modified" AR-3a midrange for use in the AR-3 as a replacement unit, with crossover updates.

--Tom Tyson

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Guest John Faulkner

Maybe I am just confused, but that midrange looks just like the one original mid from my pair of ar3s that I purchased used in maybe 1969. Same red goo holding mesh etc. I definitely have ar3 crossover and 1 3/8 tweeter. I am now reduced to one replacement mid from maybe mid 70s, NO original tweeters but will steal a pair from my $78 ar-2a I just purchased, one original cloth woofer and one ar replacement woofer with failed foam surround. Also have complete set of woofers with rotted foam and magnets with 3 indentations, mids and 3/4 tweeters from a pair 1970 vintage ar-3as and a pair of 3a cabinets with crossover for rebuilding. I will have to sacrifice the 2as originality to get a pair of 3s and a pair of 3as. My wife threw out the rock wool from a 3 I was working on thinking it was a bag of garbage, so will replace with 20 oz of pink fiberglass - is that right? THe 2as have original aluminum frame woofers but have been re-coned, not just re-foamed, so are no longer original anyway. old style double mid, maybe 1962 vintage, consecutive serial numbers 18364 and 18365, lacquered walnut in a little rough shape, really ugly multi-color grill cloth. Suggestions? replace 2a woofers with original cloth surround models? re-wire bypassed pots? I am afraid my 3s will be a strange pair with one later woofer and one replacement mid. Oh well, I have plenty to work on. All cabinets will likely remain rough, but it is all about the sound anyway.

JOhn

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My wife threw out the rock wool from a 3 I was working on thinking it was a bag of garbage, so will replace with 20 oz of pink fiberglass - is that right?

The 3a with alnico magnet woofer used 28-30 oz, with the later ceramic magnet woofer, 20 oz. I would guess that the 3 is similar, but maybe you should wait for Tom's opinion on that.

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