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AR-11s gave birth to AR-LSTs


Earthnz
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5 weeks ago I stumbled across a pair of AR-11s at my favorite second hand HiFi shop here in New Zealand (huge respect to the owner of this shop. So helpful and a great man). I had never heard vintage ARs before but had read only good reviews on them so gladly handed over the $$, took them home (My beautiful wife is used to me bringing home stray speakers now), cleaned a decade of dust and cobwebs off them, sat down and had a listen...Blown away! Even with one tweeter caput and a midrange on its way out. I jumped straight into researching AR speakers and classicspeakerpages was the logical place to start. All the information was here that I need to restore these AR-11s...Brilliant (and thankyou!)....so Midwest tweeters and replacement caps are on the way along with a midrange brought from a very cool guy in Australia (you know who you are and thanks again mate)

Onto the AR-LSTs.....

They had been sitting idle for around 10 years. When I went to view them at the home of the seller (and owner of the shop I originally brought the AR-11s from. These were from his personal collection) he plugged them in and we checked all the drivers (low volume). From what I could hear, only one tweeter and one midrange is out. Cabinets are in pretty good condition. Few deep scratches and stains on the top, but sides and edges are in good condition. Two of the grills are broken but easily fixed. Original cloth needs to be replaced (replacement cloth was thrown in with the deal)...All in all, a beautiful pair of early AR-LSTs.

I had heard of the AR LST speakers in the past while researching online vintage speakers. Never in a million years did I EVER think I would hear a pair, let alone own a pair, but here I am, after only 5 weeks of AR infatuation, with a pair of all original AR-LSTs. Even the wife loves them and she, like me, hasnt even heard what they are capable of "yet".

First task is to restore the AR-11s then onto the AR-LSTs. I will try and document the process (along with plenty of questions I'm sure) and record it here. Hopefully it will be useful for other people, like myself, learning to restore these works of art.

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I'm tackling the recap of the AR-11's today. Looks like Acoustic Research had a new shipment of glue arrive that day. 

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Will it be worth my while to try and remove the excess glue?? The switches are compleatly covered in it along with 3 resistors. 

Also when I ordered the caps, I ordered a 100uf and a 22uf as shown in the schematic I downloaded, but this speaker has a 120uf cap, which tells me this is a AR-11 B speaker... Doh! Will replacing this cap with a slightly higher value make a huge difference in sound? 

Thanks in advance 👍

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  • 6 months later...

Update time....

Finally finished the AR-11s. Looking and sounding spectacular! They have come a long way since I first brought them last July. 

New caps, new surrounds, midwest tweeters, repair of smashed baffle, replacement of one mid and a spit and polish.

Time for a beer then onto the LSTs.

Cheers one and all who helped me along the way🍻

 

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Finding anything AR related in NZ is quite a chore, to say the least. 

Those stands do look dam nice though. Is there any measurements in the library of these stands?? Looks like it could be an easy build. 

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  • 2 weeks later...

Question time....I'm going through the LST schematic in preparation of ordering new NPE capacitors and I see that the tweeters use a single 6mfd capacitor but on my crossover it has 2 wax capacitors. One says 6mfd, the other says 4mfd and 6mfd. Can someone explain what is going on here please and let me know what value capacitors I will need to buy....Cheers!

 

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The 4 and 6uf caps were just a way for AR to use up old capacitors. They were wired in parallel with the 30uf silver capacitor in your photo to make the required 40uf capacitor. You can see the 4/6uf leads converge to the 30uf cap. Eliminate the 4/6/30 combination and replace the whole arrangement with a single 40...and replace the single 6uf block cap with a new 6uf cap per usual.

Attached is a photo of a slightly later LST board showing a single 40uf cap in the same location as your silver 30uf cap. This is what your board should look like when you finish your work.

 

LST Early Crossover .JPG

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