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AR3a Midrange Help


tnatet
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Hello.  New member here, though I've been lurking for some time.  This site has been very helpful.  

By way of quick introduction...I have a pair of 3as that I bought in the early 90s from their original owner.  They sat in storage from around 2004 until this past summer when I decided to put them back in action.  Before they were stored, one of the tweeters had failed so I knew I needed to find a replacement.  Rather than try to find a match for the original, I replaced both with the HiVi Q1Rs.  Both woofer surrounds had started to deteriorate, so I replaced both with a kit from Vintage AR (eBay).  I also spent a lot of time refinishing the cabinets.

During the refinishing process, the glue on one of the midrange magnets gave up and the magnet separated from the driver.  There didn't seem to be a lot of options to fix this other than try to reglue it back in place.  My concern was that the voice coil would make contact, but after reconnecting it all seemed to be well.  For a time anyway.   I started to notice some slight distortion  - occasionally, not persistent in some frequencies and more noticeable in quieter moments than those with lots of content (same tracks or passages would replicate the issue, but other tracks or passages in similar frequency range would not).  The tone controls were quite scratchy and intermittent, so I replaced them with new ones (the ones that Vintage AR sells).  I didn't expect that to fix the issue but to my surprise after reconnecting, the problem vanished - tested with the same tracks/passages that were causing issues before.  That was a little over a week ago, and now I'm starting to hear the distortion again, though seemingly less than originally.   I should mention that the speakers sound fantastic otherwise.  Just to eliminate other possibilities, I've swapped channels, swapped amplifiers, swapped sources - so I'm fairly confident the issue is contained to the speaker.  

I guess this a long winded way of asking if the short answer is that I need a new midrange?  Could it be something else - capacitor or crossover issue?  I've been keeping my eye out for a replacement, but in the meantime figured it was worth coming here for other considerations.  The real head scratcher for me is that it completely disappeared for a period of time.  

Thanks for any help!

Nate

Obligatory pictures:

ar2.jpg

ar1.jpg

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Welcome to CSP, Nate.

The magnet problem with your mid could result in the intermittent type of distortion you describe. Another possibility is a loose crossover or level control connection. It is not likely to be a capacitor. I would start by pulling the offending mid and thoroughly test it out of the cabinet.

Roy

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18 hours ago, RoyC said:

Welcome to CSP, Nate.

The magnet problem with your mid could result in the intermittent type of distortion you describe. Another possibility is a loose crossover or level control connection. It is not likely to be a capacitor. I would start by pulling the offending mid and thoroughly test it out of the cabinet.

Roy

Thanks for the fast reply Roy.  It sounds like I need to research out how to thoroughly test the speaker and pull it out of the cabinet.  I didn't find anything here at classicspeakerpages doing a quick search, but I should do my due diligence and search more thoroughly.  One concern is if the cost of proper testing equipment starts to eclipse the cost of a new driver.  Generally I don't like throwing new parts at a problem, but that may be a logical choice.

Nate

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49 minutes ago, tnatet said:

Thanks for the fast reply Roy.  It sounds like I need to research out how to thoroughly test the speaker and pull it out of the cabinet.  I didn't find anything here at classicspeakerpages doing a quick search, but I should do my due diligence and search more thoroughly.  One concern is if the cost of proper testing equipment starts to eclipse the cost of a new driver.  Generally I don't like throwing new parts at a problem, but that may be a logical choice.

Nate

Testing equipment is not usually needed. Simply apply a musical signal directly to the mid and listen for clarity. In fact, you can do this via the front terminal connections...after disconnecting the woofer jumper, and turning the tweeter control all the way down. Do the same with the cabinet containing the good mid, and compare.

Roy

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On 2/17/2018 at 2:01 PM, RoyC said:

Testing equipment is not usually needed. Simply apply a musical signal directly to the mid and listen for clarity. In fact, you can do this via the front terminal connections...after disconnecting the woofer jumper, and turning the tweeter control all the way down. Do the same with the cabinet containing the good mid, and compare.

Roy

As follow up, I went ahead and tested the midrange as you suggested.  I feel a little stupid for not thinking of this method myself as a way of bypassing all of the other components and isolating the speaker.  I guess I was overcomplicating things.  The advice was much appreciated.  Unfortunately, there's definitely something slightly off with that speaker.  If I'm not mistaken, the correct replacement would be an A.12 midrange, part number 200010-1, with the front terminals.  Do you (or anybody else reading this) have any recommendations for where to find one of these?  I'm currently keeping an eye out on the obvious auction site, and regional audio marts.  

Thanks again for the help,

Nate 

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2 hours ago, tnatet said:

 Do you (or anybody else reading this) have any recommendations for where to find one of these?  I'm currently keeping an eye out on the obvious auction site, and regional audio marts.  

Thanks again for the help,

Nate 

I may be able to help you out, Nate. Send me a PM.

Roy

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