der Posted March 31, 2015 Report Share Posted March 31, 2015 I finished up recapping my 3a's this morning. I don't know why I didn't do this two years ago when I refurbished my pots. Actually, I didn't realize at the time that those 45 year plus caps could drift. (I had the big wax monstrosities) I did notice some harshness in the lower mid-range and some reduced treble. I put the treble off to my old ears. I simply hate dealing with the fiber fill but it has been worth it. Those old, original tweeters are back and apparently my ears have some life left in them. Played a favorite jazz vocal record that I had noticed some mid-range harshness and it now sounds sweet. It's likely that nothing more needs serviced on my 3as - at least in my lifetime. Just wanted to pass this on.der Link to comment Share on other sites More sharing options...
Carlspeak Posted March 31, 2015 Report Share Posted March 31, 2015 Enjoy the music! Link to comment Share on other sites More sharing options...
stan461 Posted March 31, 2015 Report Share Posted March 31, 2015 der,I will be recapping a pair of AR3a's very soon and would be interested in your parts list. Link to comment Share on other sites More sharing options...
stupidhead Posted March 31, 2015 Report Share Posted March 31, 2015 glad to hear it, enjoy! Link to comment Share on other sites More sharing options...
der Posted April 1, 2015 Author Report Share Posted April 1, 2015 der,I will be recapping a pair of AR3a's very soon and would be interested in your parts list.The big waxy dual caps in my 3a's were falling apart. They were literally disintegrating. This is the combo 50 and 150 microfarad cap, huge and heavy, held in with 3 metal straps. The 6 microfarad tweeter cap was in better shape physically but there was no comparison after installing the new poly caps. I had tweeters again and the midrange was just so much better. It actually was like getting new speakers. The caps I used are poly and were 6, 50 and 150 microfarad. Parts Express sells them among others.I actually bought mine from Carl's Custom Loudspeakers. You pay a bit more but get complete instructions with schematics and Carl's expertise. I like to support those small businesses that support the hobby, especially folks that deal with Acoustic Research. I have no affiliation with Carl's.Outside of the caps I bought duct seal at Lowes to reseal my woofers after pulling them. I used my wife's hot glue gun to glue the new caps into the speakers. Of course, there's a bit of soldering to do as well. The worst part for me is removing and replacing the fiber fill. I recommend rubber gloves and some type of mask for that work. Just give me a shout if I can be of any further help to you stan461.der Link to comment Share on other sites More sharing options...
DavidR Posted April 1, 2015 Report Share Posted April 1, 2015 Just kidding.Great job. Pictures are always appreciated.Enjoy the music. Link to comment Share on other sites More sharing options...
der Posted April 1, 2015 Author Report Share Posted April 1, 2015 worthless.gifJust kidding.Great job. Pictures are always appreciated.Enjoy the music.Sorry, I didn't take any pictures. Guess I should have. I was kind of rushing this morning to finish up. I started this yesterday and wanted to get it done. I had a doctor's appointment to make. I'm having cataract surgery soon.der Link to comment Share on other sites More sharing options...
DavidR Posted April 1, 2015 Report Share Posted April 1, 2015 Good luck with the surgery.I have serious eye issues but surgery is not an option. Link to comment Share on other sites More sharing options...
VintageMan Posted April 1, 2015 Report Share Posted April 1, 2015 der,I will be recapping a pair of AR3a's very soon and would be interested in your parts list.Me2! Link to comment Share on other sites More sharing options...
DavidDru Posted April 1, 2015 Report Share Posted April 1, 2015 Did they sound good right from the get go or did it seem the caps needed to settle in? Maybe Carl forms them prior? Link to comment Share on other sites More sharing options...
der Posted April 2, 2015 Author Report Share Posted April 2, 2015 Did they sound good right from the get go or did it seem the caps needed to settle in? Maybe Carl forms them prior?They sounded great from the first moment I listened. Well, sort of. After finishing the recapping and before hot gluing the new caps and before refilling the fiber fill I reconnected the woofers and put a couple of screws in and hooked each up to make sure everything worked. Didn't pay that much attention to the sound - just worked the pots to make sure everything was OK. Then I hot glued the caps in, re-stuffed the fill, duct sealed the woofers in and started listening. Massive improvement. The original 50/150uF combo caps were practically melting they were so bad. I have not noticed any further improvement. But, then again, I'm not sure I believe in "forming" or "burning" in capacitors. I'm still amazed that those old tweeters still work so well. All in all an amazing product. Imagine, a loudspeaker built in 1968 or 1969 still working so well! Of course, I am the original owning and they've suffered little abuse.der Link to comment Share on other sites More sharing options...
DavidR Posted April 2, 2015 Report Share Posted April 2, 2015 I can't say I've heard any change in the 91s I recapped. Good from the get go.Perhaps the bass has filled in some, if even that. Link to comment Share on other sites More sharing options...
DavidDru Posted April 2, 2015 Report Share Posted April 2, 2015 Yeah, just looking for field evidence and proofing. Congrats! Link to comment Share on other sites More sharing options...
JKent Posted April 2, 2015 Report Share Posted April 2, 2015 der,I will be recapping a pair of AR3a's very soon and would be interested in your parts list.Me2!Be sure to read the AR-3a restoration guide. All the information is there. Keep in mind there were a couple of different versions of the 3a crossover.The only real questions IMHO are whether to use (expensive) film caps for the big caps or go with NPEs, and whether to clean up the pots or use L-pads.I used Dayton Polys for the 150 and 50uF caps and a Clarity (only because I had it in my parts box) for the 6uF. Erse caps are a good choice if they have the needed sizes. So are Carli. And if I were doing it today I'd probably build up the 50uF using those cheap 10uF surplus caps.Don't overlook the 0.5 ohm Nichrome resistor--it just looks like a piece of wire. Since I was building my xo from scratch I used two 1 ohm 10w resistors in parallel.-Kent Link to comment Share on other sites More sharing options...
der Posted April 2, 2015 Author Report Share Posted April 2, 2015 I've got some time this morning for another listening session. I've been going through vinyl that I know very well to ascertain improvements. I've not been disappointed so far. Congrats to you as well DavidDru, I've never heard AR 91's myself but I'm sure they're sweet. I heard a pair of LST many years ago. Not many of those around but I loved the sound. I dream of finding a nice pair of those. I knew a guy in Columbus, Ohio at the time that actually owned 2 pair of LST. He drove them with about 500 pounds worth of McIntosh gear. Edit: If I ever got my hands on a pair of LST I'd want to swap out the woofers for the older cloth surround woofers like the ones I have in my 3a. I've heard both and prefer the cloth surround variety.der Link to comment Share on other sites More sharing options...
owlsplace Posted April 2, 2015 Report Share Posted April 2, 2015 ... I heard a pair of LST many years ago. Not many of those around but I loved the sound. I dream of finding a nice pair of those. I knew a guy in Columbus, Ohio at the time that actually owned 2 pair of LST. He drove them with about 500 pounds worth of McIntosh gear. Easier to find Allison One's these days than the LST models ... Link to comment Share on other sites More sharing options...
der Posted April 2, 2015 Author Report Share Posted April 2, 2015 I actually don't even bother looking anymore.der Link to comment Share on other sites More sharing options...
RoyC Posted April 2, 2015 Report Share Posted April 2, 2015 Don't overlook the 0.5 ohm Nichrome resistor--it just looks like a piece of wire. Since I was building my xo from scratch I used two 1 ohm 10w resistors in parallel.-KentVintage AR uses all Daytons (75's in parallel or 100 and a 50 in parallel, a 50, and a 6 for each cabinet. I often use Erse mylar and Madisound "surplus" film caps.We have never found a reason to replace the Nichrome resistor.Roy Link to comment Share on other sites More sharing options...
JKent Posted April 2, 2015 Report Share Posted April 2, 2015 Vintage AR uses all Daytons (75's in parallel or 100 and a 50 in parallel, a 50, and a 6 for each cabinet. I often use Erse mylar and Madisound "surplus" film caps.We have never found a reason to replace the Nichrome resistor.RoyWhat I meant was, don't remove it, thinking it's just a piece of wire (see Fig 3.7 in the restoration guide). I only used the resistors because I was converting AR-3s to 3a's.Kent Link to comment Share on other sites More sharing options...
RoyC Posted April 3, 2015 Report Share Posted April 3, 2015 What I meant was, don't remove it, thinking it's just a piece of wire (see Fig 3.7 in the restoration guide). I only used the resistors because I was converting AR-3s to 3a's.KentOh, ok Actually AR used a convential sand cast resistor instead of the wire near the end of 3a production. It isn't unusual to see it beginning with serial numbers around 90,000 and higher.Roy Link to comment Share on other sites More sharing options...
stan461 Posted April 3, 2015 Report Share Posted April 3, 2015 der and JKent,Thanks for the help on the AR3a recapping.I really appreciate it. Link to comment Share on other sites More sharing options...
der Posted April 3, 2015 Author Report Share Posted April 3, 2015 der and JKent,Thanks for the help on the AR3a recapping.I really appreciate it.Good luck with your project. If a half blind arthritic bumbler like myself can do it, you can do it and you'll be thrilled I'm sure. I'm hopefully fixing the half blind part soon. Getting cataract surgery on my left eye on April 15th, the right a month later.ps - You better take some pictures, these folks like pictures a lot.der Link to comment Share on other sites More sharing options...
JKent Posted April 3, 2015 Report Share Posted April 3, 2015 Oh, ok Actually AR used a convential sand cast resistor instead of the wire near the end of 3a production. It isn't unusual to see it beginning with serial numbers around 90,000 and higher.RoyWhere would one even get such a thing? The schematic in the AR-3a restoration booklet shows the value as 0.51 ohms, 20w. The closest at PartsExpress is 0.47 10w. I suppose 10w is enough for a speker xo but I don't like going down in power handling. Madisound has 0.47 ohm Mundorf M-Resist Supreme Resistors 20 watt for $14.15 each!! Mouser has some 0.5 ohm 25w wirewound resistors for $2.56 and 0.51 ohm 25w for $3.47.My point is; 0.51 ohm 20w wirewound does not seem like a common value. Some of the 3a schematics show 0.5 ohm and do not specify the wattage but even 0.5 ohm is pretty uncommon..When AR went to conventional sand-cast resistors what did they use?Anyway, my tow 1 ohm 10w resistors in parallel seem to work.-Kent Link to comment Share on other sites More sharing options...
iso Posted April 3, 2015 Report Share Posted April 3, 2015 KentLong time power handling of 4 ohm AR mid is likely 10-20 W... so 10 W power handling of 0,5 ohm resistor should be enough even stuffed in the fiberglass... note also that 16 ohm pots are only 25 W items and they have been stuffed also in the fiberglass. Best RegardsKimmo Link to comment Share on other sites More sharing options...
owlsplace Posted April 4, 2015 Report Share Posted April 4, 2015 Where would one even get such a thing? The schematic in the AR-3a restoration booklet shows the value as 0.51 ohms, 20w. The closest at PartsExpress is 0.47 10w. I suppose 10w is enough for a speker xo but I don't like going down in power handling. Madisound has 0.47 ohm Mundorf M-Resist Supreme Resistors 20 watt for $14.15 each!! Mouser has some 0.5 ohm 25w wirewound resistors for $2.56 and 0.51 ohm 25w for $3.47.My point is; 0.51 ohm 20w wirewound does not seem like a common value. Some of the 3a schematics show 0.5 ohm and do not specify the wattage but even 0.5 ohm is pretty uncommon..When AR went to conventional sand-cast resistors what did they use?Anyway, my tow 1 ohm 10w resistors in parallel seem to work.-KentHmmm, Mouser lists a 0.51 thick film rated 20w but they are not stocking. Several options for 0.5 ohm resistors at 20w in stock. Link to comment Share on other sites More sharing options...
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