Feelgood Posted February 28, 2011 Report Share Posted February 28, 2011 Hi, folks!I'm new here and first of all want to thank everybody for deep enthusiasm regarding AR speakers.My first pair was AR-6's in 1976, European model. They were very good sounding little bookshelf speakers which I had for many years.Last week I bought a nice pair of AR-5's from their original owner (delivered -75, European model). No serial numbers on the back of the cabinets, but original receipt was included.Now I'm starting to get these beauties restored and first checked all the elements. I was very upset to discover a huge mismatch in the DC resistance between the woofers after disconnecting them from the XO's. One gives me 8.6 Ohms (model number 3903-3), the other 6.2 Ohm (two stickers: 3903-1 and 3903-3). Magnets are visually identical but the cone is darker and stiffer to my fingers on the second one. The cabinet DC-resistance for the first one is 7.6 Ohms and 7.2 Ohms for the second one. Sound was ok on both woofers.Should I be worried? Link to comment Share on other sites More sharing options...
RoyC Posted March 1, 2011 Report Share Posted March 1, 2011 Hi, folks!I'm new here and first of all want to thank everybody for deep enthusiasm regarding AR speakers.My first pair was AR-6's in 1976, European model. They were very good sounding little bookshelf speakers which I had for many years.Last week I bought a nice pair of AR-5's from their original owner (delivered -75, European model). No serial numbers on the back of the cabinets, but original receipt was included.Now I'm starting to get these beauties restored and first checked all the elements. I was very upset to discover a huge mismatch in the DC resistance between the woofers after disconnecting them from the XO's. One gives me 8.6 Ohms (model number 3903-3), the other 6.2 Ohm (two stickers: 3903-1 and 3903-3). Magnets are visually identical but the cone is darker and stiffer to my fingers on the second one. The cabinet DC-resistance for the first one is 7.6 Ohms and 7.2 Ohms for the second one. Sound was ok on both woofers.Should I be worried?Welcome to CSP! All of the AR-5 (and 2ax) woofers I have measured are around your 6.2 ohm woofer. If everything else seems OK, I wouldn't worry about the 8.6 ohm woofer, but it is not typical.Post photos of the front and back of each woofer if you can.Roy Link to comment Share on other sites More sharing options...
Feelgood Posted March 1, 2011 Author Report Share Posted March 1, 2011 Thanks, Roy!Please, see photos enclosed.I've already pulled off some rotten surrounding foam of the woofer that has high impedance. I also re-measured it and got 8.2 Ohms after some proper cleaning of the contacts. The difference is still 2 Ohms!Unfortunately the woofer with a correct value of 6.2 Ohms has been refoamed with an incorrect rubber surrounding. I'm going to order the Boston 'Filled Fillet' 10 kit from M-Sound, as you have recommended.The tweeters are Seas H2o2's from the early 80's with a measured impedance of 7.5 Ohms. I also got one working original hi-driver that measures 6.1 Ohms. Maybe it'd be a good idea to order a pair of replacements from AB Tech Services?Hannu Link to comment Share on other sites More sharing options...
RoyC Posted March 1, 2011 Report Share Posted March 1, 2011 I've already pulled off some rotten surrounding foam of the woofer that has high impedance. I also re-measured it and got 8.2 Ohms after some proper cleaning of the contacts. The difference is still 2 Ohms!Unfortunately the woofer with a correct value of 6.2 Ohms has been refoamed with an incorrect rubber surrounding. I'm going to order the Boston 'Filled Fillet' 10 kit from M-Sound, as you have recommended.The tweeters are Seas H2o2's from the early 80's with a measured impedance of 7.5 Ohms. I also got one working original hi-driver that measures 6.1 Ohms. Maybe it'd be a good idea to order a pair of replacements from AB Tech Services?Your woofers are the later mid 70's version with ceramic magnets. The one with 8+ ohm dcr is a puzzle, and you certainly have some re-foaming to do.As for the tweeters, I doubt the AB Tech tweeter will work any better than your Seas tweeters. Any replacement tweeter (including AB Tech's) will require a small inductor in parallel with it if you want it to sound close to the original. The HiVi tweeter (with inductor) mentioned in this thread is another possibility:http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=6108Roy Link to comment Share on other sites More sharing options...
KlausDK Posted March 2, 2011 Report Share Posted March 2, 2011 Now I'm starting to get these beauties restored and first checked all the elements. I was very upset to discover a huge mismatch in the DC resistance between the woofers after disconnecting them from the XO's. One gives me 8.6 Ohms (model number 3903-3), the other 6.2 Ohm (two stickers: 3903-1 and 3903-3). Magnets are visually identical but the cone is darker and stiffer to my fingers on the second one. The cabinet DC-resistance for the first one is 7.6 Ohms and 7.2 Ohms for the second one. Sound was ok on both woofers.Should I be worried?I have had similar experience with 10" woofers, although not to the same magnitude:http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=6060&st=0&p=85657entry85657Still wonder what speaker the 3903-1 was intended for, can you see what model is printed on the 3903-1 label?BRgds Klaus Link to comment Share on other sites More sharing options...
Feelgood Posted March 2, 2011 Author Report Share Posted March 2, 2011 As for the tweeters, I doubt the AB Tech tweeter will work any better than your Seas tweeters. Any replacement tweeter (including AB Tech's) will require a small inductor in parallel with it if you want it to sound close to the original. The HiVi tweeter (with inductor) mentioned in this thread is another possibility:Thank you for you instant reply!Off-topic, but I just wonder if there exists any real alternative to Seas or HiVi? What would be your ultimate tweeter replacement including the most modern designs? Link to comment Share on other sites More sharing options...
Feelgood Posted March 2, 2011 Author Report Share Posted March 2, 2011 Still wonder what speaker the 3903-1 was intended for, can you see what model is printed on the 3903-1 label?AR-8 Link to comment Share on other sites More sharing options...
dynaco_dan Posted March 3, 2011 Report Share Posted March 3, 2011 Thank you for you instant reply!Off-topic, but I just wonder if there exists any real alternative to Seas or HiVi? What would be your ultimate tweeter replacement including the most modern designs?Hi thereNothing is ever off topic here, we all learn from others, all the time.I had written a few months ago regarding a magazine suggesting that the old Philips dome tweeter would be a great 8 ohm replacement tweeter.Not just for AR speakers but for use in several others as well.The magazine was, The Audio Alternative, J. Gordon Holt had contributed an undisclosed amount of writing to it.About 1" thick and about 12" x 18" with lot's of pages, some reviews have photos, some just commentary.You could say the book was, like a bit of, The original Stereophile, The Absolute Sound, Stereo Review and Audio magazine.The Dahlquist DQ-10 speaker appeared to be the best of the best.It was there that I read about the Philips tweeter and how good they felt it was and that it could be used as a suitable tweeter replacement for several brands.It would not necessarily be a drop-in replacement, but may require a masonite adaptor ring to fit existing tweeter holes.My own opinion is, using an older 8 ohm Dynaco, Advent, AR, Allison and or KLH, etc, tweeters, which are about the same efficiency and qualityand generally are available in quantity on ebuy all the time.Dispersion may not be the exact same, nor power handling capabilities, but they also do not have the AR 3/4" dome foam deterioration issue.They have already been proven by time and performance, cone or domes. Just a thought for today. Link to comment Share on other sites More sharing options...
RoyC Posted March 3, 2011 Report Share Posted March 3, 2011 Off-topic, but I just wonder if there exists any real alternative to Seas or HiVi? What would be your ultimate tweeter replacement including the most modern designs?This has been discussed many times. If by "real alternative" you mean a tweeter that can be dropped into the cabinet hole (with or without an adapter) and be a sonic match to the original tweeter, the answer is no. Quality is not the issue. There are many fine tweeters available, but ALL of them require changes to the original crossover to have the same effect as the original tweeters...and the vast majority will require cabinet hole modifications or adapters for installation. The crossover points of the original AR dome tweeters were very high, and the tweeters were constructed accordingly with built-in steep lower frequency roll-off properties. This mechanical feature is simply not available in other tweeters regardless of quality or era, and is why such things as small parallel inductors are necessary. ...and then there is the debatable dispersion issue. I personally do not think it is as much of an issue as some other forum members believe it to be, but it is still a consideration.AR used small inductors in parallel with the company's next generation of 3/4" dome tweeters, used in the AR-11, 10pi, and 12. The best alternatives are probably these tweeters, when they can be found, implemented with an appropriate inductor. They fit the older cabinet holes perfectly, and have good dispersion.Roy Link to comment Share on other sites More sharing options...
nosex Posted March 10, 2011 Report Share Posted March 10, 2011 Thank you ^^" :D ________________________________การที่เราชนะใน บาคาร่าออนไลน์ ไม่ได้หมายความว่าเราเป็นผู้ชนะและการที่เราแพ้ใน บาคาร่าออนไลน์ ก็ไม่ได้หมายว่าเราแพ้เช่นกัน Link to comment Share on other sites More sharing options...
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