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AR3 3a


BrianO

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Hi   just checking in to see if anyone has answers to the question of repair or replacement of the 3 and 3a Midranges?

I have a couple of blown or low volume mids that need repair

I would also like suggestions on replacement as close as possible to originals.   I know this is a topic that has come up, but just wanted to see if there is any New  Ideas

thanks

Brian O

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2 hours ago, AR surround said:

surround

yes I know Larry and have purchased from him    just wondering if anyone had come up with any new ideas for implementing new drivers into the 3 or 3a

I will send one to Larry to see if he can get it going

Thanks for the resopnse

Brian O

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Brian,

Which type? With the exception of the very last AR-3's manufactured, the 3 and 3a mids are very different. Generally speaking, many AR-3 mids have output issues, but I've had some success repairing them for Vintage AR/Larry, as well as some forum members. On the other hand, 3a mids are very reliable, but are not usually repairable when they malfunction. There are no aftermarket drop-in replacements for either AR mid.

Roy

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1 hour ago, RoyC said:

There are no aftermarket drop-in replacements for either AR mid.

but.... There are other AR mids that can replace the 3a. I know this because Roy was kind enough to sell me a pair of 10pi mids for my 3a project. Actually, truth be told, it started as an AR-3 project but I had 2 dead tweets and 1 dead mid so decided to make some quasi-3a's with Hi-Vi tweeters and 10pi mids. Probably ruined any resale value but these are keepers!

So Roy, which mids are appropriate to use in the AR-3a?

-Kent

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2 hours ago, ra.ra said:

Any chance these mids might possibly work: p/n XXX028 (from AR-9 and 90); p/n XXX032 (from AR-91 and 92), or p/n XXX044 (from AR-58s)?

I believe Tom Tyson has mentioned that the 200028 driver isn't interchangeable with the one used in the AR-91, 92, or 58S, due to an inability to handle the lower cutoff frequency of these 3-way systems. The AR-3a should present the same sort of problem, I'd guess.

Using an AR-91 style crossover, I've been very pleased with the sound of the 200032 midrange in an AR-3a enclosure.

 

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3 hours ago, JKent said:

but.... There are other AR mids that can replace the 3a. I know this because Roy was kind enough to sell me a pair of 10pi mids for my 3a project. Actually, truth be told, it started as an AR-3 project but I had 2 dead tweets and 1 dead mid so decided to make some quasi-3a's with Hi-Vi tweeters and 10pi mids. Probably ruined any resale value but these are keepers!

So Roy, which mids are appropriate to use in the AR-3a?

-Kent

AR-10pi and AR-11 mids, regardless of color (like the later pink and black version), are functionally identical to the last back-wired mids used in the 3a. They are easily interchangeable.

There have been other discussions here regarding the use of ferro-fluid in later mids as it applies to the suitability of the AR-9xx series/AR-58 mids. I've tried them all in the 3a, and I have dissected a few. The only easily observable differences are varying amounts of fiberglass damping material under the dome (the only one with no material under the dome is the AR-58 mid). Fortunately, they all drop into the 3a cabinet hole, and with the exception of the AR-5/LST2 version, they all have a dcr of 3 to 4 ohms (the earliest 3a mids were just under 3 ohms)...and they all have the same magnet size. Any of them are certainly much better than any non-AR mid. To be clear, mids after the AR-11/10pi era are not a perfect match to the AR-3a mid, but they can keep a 3a alive, and work reasonably well under typical conditions of use.

Roy

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After reading these latest comments here, I was reminded of the last time this discussion came up. As outlined in this excerpt from Tim Holl's paper on the AR-9 series, ar_pro is correct to note that the 028 and 032 mid drivers did have one original difference that was engineered specifically for their intended speaker models, and this difference was the amount of ferro-fluid used in the gap which affected the lower frequency output. The 028 mid (AR-9 and 90, four-ways) with a fully filled gap, extends down to 1200 Hz; while the 032 mid (AR-91 and 92, three-ways) with a partially filled gap, extends further down to 700 Hz.

But, as we concluded in the prior thread and RoyC seems to be stating here again, any of these drivers could be suitable replacements for these restoration projects, and we need to be reminded that many of these aged drivers are most likely not performing precisely as they did when they left the factory decades ago. 

AR-9 series midrange.jpg

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