Alan Brown UK Posted January 7, 2009 Report Share Posted January 7, 2009 Hello all - first a thank you for a wonderful resource. I have 'wasted' many an hour searching & lurking through the collective wisdom in these hallowed pages, much to my wife's chagrin! I have some 1974 AR-4xa's that I will be restoring - first operationally then cosmetically - as my first ever DIY project. The capacitors are on order, I am practising with the soldering iron and I'm full of anticipation. I already love the way they sound, but one tweeter is not giving much output. I hope it is the capacitors, though the tweeter in question has a small tear in its (rather tall) dust cap. I hope this is OK as I think it is a cone tweeter - the same unit as the AR6? The switch (no pot like the 4x) doesn't make much difference that I can hear. I disconnected the woofer to listen to it 'a cappella' and it seemed good. I also did this for the other speaker and they both seemed to be about the same - we'll see after the new capacitor goes in. Any thoughts on this? If the tweeter is gone completely, I may take the advise I saw elsewhere on this board to change the capacitors and tweeters to AR-4x spec, as that was probably as good - or even better than the xa, according to what I read. Below is a link to a photo of an identical speaker without the torn tweeter dust cap, from a current ebay listing:AR_4ax_drivers.pdfI also want to know what to use for re-sealing the cloth surrounds here in the UK - the permatex product is unavailable here (and permatex UK don't seem to have a computer for reading and replying to emails) and I wondered what any other UK-Europe based AR lovers had used? Any suggestions at all from anyone, anywhere would be welcome.Also, the cabinet stuffing is the blue/grey wool substance used in the European production AR speakers - I know state side you had fibreglass. Would it be a good move to swap this over? The wool I have is dense, weighs just over 8oz per speaker. If I were to exchange the stuffing, what weight would be right for the 4xa?Below is a drawing of the crossover I did after a good look. The crossover point is 1600 according to the library here. I think it is all original, but If you spot differently, please advise me.AR4xa_original_crossover.PDFThank you in advance for your time in reading this, and any advise you give. I'll check in when I can (when my wife isn't around!?) to see your pearls of wisdom, but please bear in mind the time difference also if I seem tardy in replying or thanking you. Link to comment Share on other sites More sharing options...
Carlspeak Posted January 7, 2009 Report Share Posted January 7, 2009 Welcome aboard Alan!With regard to your surround sealer issue, there must be some auto parts supply stores nearby? The should have something on the shelves that is akin to liquid tacky gasket sealer. Try canvassing a few if you haven't already.The switch in your schematic is a bit puzzling. Most xover circuits with a switch have one or two resistors tied into them so the signal is passed thru the resistor to attenuate the tweeter if desired. Check out some of the schematics in the Advent library area. I don't see how a plain switch will do anything significant to the audio signal.The US version AR4x schematic has a #4 coil and a 20 uF cap. This means there is something different about your 4xa's from the US version. I would suggest you reuse the same stuffing. Just be sure to put the same amount back in that you took out. Link to comment Share on other sites More sharing options...
Alan Brown UK Posted January 7, 2009 Author Report Share Posted January 7, 2009 Thanks Carl, I appreciate your thoughts & expertise;There may well see a resistor in there somewhere, but I've yet to find it. If there is one it is hiding around the switch, though I've removed one from its glob of hot glue, still can't see it. Perhaps it is integrated into the switch somehow. Or buried in the glue...Would a resistor such as you mention drift away from its original value, or can I forget about it? Link to comment Share on other sites More sharing options...
Carlspeak Posted January 7, 2009 Report Share Posted January 7, 2009 I'd say for now don't worry about it. Change out the cap, test the speaker BEFORE you re-install the woofer. Flip the switch around a bit to see if you hear anything different without the woofer playing. That's the best way to test the new cap and see if the switch does anything for your tweeter's output. Link to comment Share on other sites More sharing options...
Alan Brown UK Posted January 7, 2009 Author Report Share Posted January 7, 2009 I'd say for now don't worry about it. Change out the cap, test the speaker BEFORE you re-install the woofer. Flip the switch around a bit to see if you hear anything different without the woofer playing. That's the best way to test the new cap and see if the switch does anything for your tweeter's output.This I will do. I reassembled the speakers tonight - the capacitors may take a few weeks to arrive, hey ho - and had a good listen. I interestingly the problematic tweeter seemed way better today. I suspect some oxidation of the spade connector or tweeter tag; the speakers really sounded quite good. The switch seems to give some variation now, as it always has in the other speaker.As an aside, it's amazing how a slightly recessed tweeter output on one side can remove 20% or more of the effectiveness of the pair, especially WRT imaging. So much better today. I am in eager anticipation of hearing them properly fettled. Link to comment Share on other sites More sharing options...
Guest norman verona Posted January 20, 2009 Report Share Posted January 20, 2009 Sorry to go slightly off topic.I need some speaker mounting diaphragms for a pair of AR44 BX speakers. The woofer is 10" and the midrange 6.5".Is there somewhere in the UK that I can order these?many thanksNorman@FrenchBlat.com Link to comment Share on other sites More sharing options...
Alan Brown UK Posted January 20, 2009 Author Report Share Posted January 20, 2009 Sorry to go slightly off topic.I need some speaker mounting diaphragms for a pair of AR44 BX speakers. The woofer is 10" and the midrange 6.5".Is there somewhere in the UK that I can order these?many thanksNorman@FrenchBlat.comHi Norman,I've yet to find a specialist over here, but with light weight items you can usually get these things sent over from the States. A 1st port of call would be Larry at his ebay shop (http://search.stores.ebay.co.uk/VINTAGE-AR-PARTS-AND-SERVICE_acoustic-research_W0QQ_trksidZp3286Q2ec0Q2em57QQftsZ1QQsaselZ65919614QQsofpZ0You could ask this chaps advice, he seems to be based in the UK. (I've not used him): http://stores.ebay.co.uk/onlydiesel058Best of luck, Regards, Alan Link to comment Share on other sites More sharing options...
Guest norman verona Posted January 20, 2009 Report Share Posted January 20, 2009 Hi Norman,I've yet to find a specialist over here, but with light weight items you can usually get these things sent over from the States. A 1st port of call would be Larry at his ebay shop (http://search.stores.ebay.co.uk/VINTAGE-AR-PARTS-AND-SERVICE_acoustic-research_W0QQ_trksidZp3286Q2ec0Q2em57QQftsZ1QQsaselZ65919614QQsofpZ0You could ask this chaps advice, he seems to be based in the UK. (I've not used him): http://stores.ebay.co.uk/onlydiesel058Best of luck, Regards, Alan Thanks Alan, I'll try them. Link to comment Share on other sites More sharing options...
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