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Rebuilding my second set of AR 9's


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Four and a half years ago I was lucky to find a nice set of AR9's in Springfield IL.  I re-capped them and put new foams on the woofers and lower midranges. I have been enjoying them ever since. Fast forward to April 23, 2022 when my nieces husband and I attended AXPONA in Chicago. There was a gentleman there with a AR hat on so I had to strike up a conversation with him.  We talked about which AR models we had and I told him I was looking for a set of AR9LS or 9LSi speakers.  He told me he knew someone with a nice set of AR9's in storage and wanted to get rid of them. He called his buddy and when he told me what he wanted for them I was shocked. Half what I paid for my set. Two week later I made the 2 hour drive to Ft. Wayne and brought them home. Every bit as nice as my originals and untouched except for the tweeters, but I had a set of originals waiting.

My AR9,s went on temporary loan to Micha (my nieces husband) and I decided to rebuild the new set, but take my time and do with patience and forethought.  I finished the first one today and my nephew helped me move it down off the saw horses and put the second one in its place.  Here are some pictures. I am working in the air conditioning and not in the garage.

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I re-foamed the lower midrange and woofers. Replaced the AR11 tweeter.

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Removed the lower and upper boards.

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Lower and upper board rebuilt.

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More details coming tomorrow. 

 

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Nice.  I'd love to find a pair one day too...!

Also, just curious.  I believe you used Dayton poly caps on the upper board, except for the UMR.  There, it looks like you used Mundorf E-Caps.  Was that to keep the UMR dome in check?  Not too bright or harsh?  Plus, I like that you rotated inductors as well.  That's supposed to cut down on cross talk distortion.  

Well done.  :D

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Here are the caps I used. Mostly Dayton precision poly caps. Bennic non polar electrolytes, Jansen 82uf Cross Cap for the 80uf. Yes I used Mundorf E-Caps for the 24uf value. I used two 12uf Dayton's on my first pair, but that was before I read AR Surrounds recommendations for the upper mid ranges. I like the Dayton precision caps because there is no need to match values. Even the 10% Bennic's were about 5% once paralleled. You may of noticed all the Dayton film and foil bypass caps. Here is what I have to say about that. While I will drink the Kool-Aid I am not completely sure why.  

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Who is selling the Bennics now days?   The leads on the MDL brand are quite thin.

 

Some say using a bypass cap will help the larger caps discharge faster and thus a cleaner sound. Also using a film bypass on NPE bundle/base cap will enhance the SQ.

What brand of surround is this and where can we get them?

 

AR 8in LMR.jpg

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When I rebuilt my first set four and a half years ago I bought the Bennic's from Madisound. I bought extras thinking I would have a better chance matching them. Subsequently when Madisound discontinued them I bought more. They did not have everything so I found some at Meniscus Audio. I think they still have a couple listed. I keep a collection of different Electrolytes and Film caps. It takes me a hour to go thru and organize them. I had my choice between the MDL and Bennic caps. Comparing the leads they seem about the same. The Jantzen and Mundorf leads are defiantly nicer. 

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The surrounds for the lower midrange are the filled-fillet Boston type supplied by our friend Rick Cobb. I don't look anywhere else unless he doesn't  have what I need.

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Don't overlook the Black Beauty NPE from suppliers like Parts Express. (made by Solen if I'm not mistaken, just like the Dayton film caps). Several restores like these. I'll mix and match just so I can get the values I need.

The large MDL I have the leads are thinner than that on the Bennic and BB.

Thanks for the info on the surrounds. My memory is not what id used to be. They looked so familiar. I went to my workshop and had a set in a shipping box from Rick. At least I won't miss my memory much. IIRC the 10 inch will fit the AR90 woofers.

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Just got back from running around Ireland and saw your post.  Nice job!   I must admit that those caps do look vaguely familiar.   LOL

Also, it pleases me no end to see that you did the work in your living room rather than being banished to the cold, damp basement like @DavidR.

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Its currently 95 outside now and I just finished the bottom board on the second speaker. Now to remove the upper board. 

I wanted to talk about some of the mods I am doing on this set. I decided to replace all the internal wiring with 16 GA Marine Grade tinned OFC copper.  I ordered a box with all the correct colors from Remington Wire.  The original wiring must be either 20 or 22 GA.   

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Defiantly a big difference. I resoldered the spade connectors onto the new wire for the three upper drivers and the resister board. Pulling the new wire through the  cabinets one at a time. I had to reseal the wire hole in the lower midrange basket with silicone. When it came to the woofers I took my que from KLH and soldered pigtails onto the woofer terminals and used wire nuts. 

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Plan on getting started on the upper board right now. First remove the staples and apply heat to the back baffle and gently pry out without buggering anything up.

Glad the forum is up and running again. 

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9 hours ago, AR surround said:

Just got back from running around Ireland and saw your post.  Nice job!   I must admit that those caps do look vaguely familiar.   LOL

Also, it pleases me no end to see that you did the work in your living room rather than being banished to the cold, damp basement like @DavidR.

Its not damp as I run a dehumidifier and it was cold this winter (and de-humidifier is not needed in winter). The cold now bothers my hands that are riddled with Viking disease.

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Nice work! I must confess that I have never heard a set or AR-9's.

Curious, what amp are you using to drive them?

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The 9's are finished and I have been listening to them off and on for four days now. The new caps and surrounds are starting to relax and the sound is on par with my first set. I have swapped in two different preamps, two DAC's and tomorrow I will try another power amp.  They are up off the floor about 5 inches on small furniture dolly's which subdues the base a bit. The midrange is impressive. 

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The finish on these I would rate 9 out of 10. The only imperfection is one of the speakers must of sat in the sunlight with the woofer cover installed. When it is on it is not noticeable. 

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They have a switch installed where I can run the woofers with a 2 ohm load. I will soon be trying this.

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I am still looking for a set of AR9Ls or 9Lsi.

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You say "They have a switch installed where I can run the woofers with a 2 ohm load. I will soon be trying this."

Please explain, and why?  Thanks.

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On 7/16/2022 at 10:06 PM, lARrybody said:

They have a switch installed where I can run the woofers with a 2 ohm load. I will soon be trying this.

I believe they need to be bi-amped to accomplish this as the LMR/UMR and tweeter would still present a 4 ohm load. IIRC, Roy addressed this with a member (Valkyrie) and did not recommend it. If you do try it make sure your amp is stable in the 1 ohm range to handle the dip.

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Is the function of the switch the elimination of the series LC components often characterized as an "electronic automatic transmission" which raise the impedance on either side of the resonance peak of the woofers?  Does it just disconnect the 2500uF/10MH part of the circuit, leaving the feed to the 470uF through the remaining 10MH inductor?

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12 hours ago, johnfalc said:

Is the function of the switch the elimination of the series LC components often characterized as an "electronic automatic transmission" which raise the impedance on either side of the resonance peak of the woofers?  Does it just disconnect the 2500uF/10MH part of the circuit, leaving the feed to the 470uF through the remaining 10MH inductor?

It eliminates the 2500uF cap in the woofer circuit that keeps the impedance from dipping below 3.2 ohms. It does not affect the LMR/UMR and tweeter impedance.

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2 hours ago, Stimpy said:

This thread had discussions about eliminating the 2500uF cap.  Personally, I wouldn't, but an owner can experiment...!  :D

Yes ... I recall that.  I was just asking if the switch the OP added did as I suggested, cutting the LC series circuit out or if he'd made some other modification.  I agree that just defeating that leg would be a mistake unless one wanted to completely revise the circuit for the woofers - not to be done without proper equipment and knowledge.  My 9's and 90's sound just fine.

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Now you have me thinking if I added the switch correctly. I based my decision mostly on this thread by leesonic.

https://www.audiokarma.org/forums/index.php?threads/ar9-restoration-with-pics.673117/#post-8980683

The idea of eliminating the 2500 cap and letting the two woofers wired in parallel run at their natural impedance sounded interesting. Especially since I have this Crown XLS 2502 which is rated down to one ohm. I did install a safety cover so the switch could not be activated accidently.  I have not tested it yet because I am currently using a Adcom GFA555II. Now I am not sure if I wired it correctly. It really doesn't matter as long as the circuit is connected in the on position.  I will have to do more research. Maybe I will just go back in and solder a jumper between the two connection lugs.  I am not sure if the white wire that returns to the woofer positive post should be before or after the circuit interruption.  

Here are the sketches I made of the lower and upper boards. The numbers are the readings of the existing components, not the new capacitors. 

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If wired as shown in your drawings then I'd say you met your intent ... whether that is a good idea or not is a different issue.

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