genek Posted March 13, 2008 Report Share Posted March 13, 2008 Some addiitional info on my previous question about putting 3a drivers in a 3...A friend of mine who is mostly computer-illiterate came home from a garage/moving sale with an "unfinished restoration project," which is turning out to be more of a "what were they thinking?" exercise. A pair of obviously AR3-series speakers with their grilles replaced by an ugly multicolored fabric that probably came from Radio Shack sometime in the 80's turned out to be a mismatched set consisting of an AR-3 with working but ratty-looking fabric woofer and blown mid and tweeter plus an AR-3a with rotted foam woofer and chewed-up crossover (I think the cabinet must have sat open in someone's garage long enough for some critter to get into it and try to eat the crossover) but working mid and tweeter, with a box of spare parts that yielded a full set of AR-3a drivers in decent shape. So once the rotted 3a woofer has been refoamed (my suggestion was to have both woofers refoamed so they match), my friend has all the parts to reconstruct a pair of 3a's...except for the crossovers.Last night he spent some time on my computer (dangerous thing, letting your computer-illiterate friends onto your computer), and he comes up with these:http://www.partsexpress.com/pe/showdetl.cf...tnumber=260-154300W rating, turnovers are 625Hz (vs AR-3a's 575Hz) and 5KHz (same as AR-3a's).Other than my initial "it's not original AR" reaction, can anyone think of a technical or sound quality reason why these would be a bad idea compared to the agony of reconstructing one original AR-3a crossover and completely rebuilding an AR-3 crossover to duplicate the AR-3a's? How much difference is raising the AR3a woofer's crossover point 50Hz likely to make? Link to comment Share on other sites More sharing options...
genek Posted March 13, 2008 Author Report Share Posted March 13, 2008 Nevermind, got answer from Parts Express, it won't work with 4 ohm mid and tweeter. Unless, of course, someone here smarter than me knows what to do to make it work. Link to comment Share on other sites More sharing options...
johnieo Posted March 13, 2008 Report Share Posted March 13, 2008 Some addiitional info on my previous question about putting 3a drivers in a 3...Other than my initial "it's not original AR" reaction, can anyone think of a technical or sound quality reason why these would be a bad idea compared to the agony of reconstructing one original AR-3a crossover and completely rebuilding an AR-3 crossover to duplicate the AR-3a's?The simple answer is: If your friend rebuilds the crossovers correctly, the result will be an excellent pair of AR-3a speakers! If the sound power ouput is to remain flat, one needs to use the original crossover as designed by AR. Yes, it is worth it -- VERY well worth it ... only way to go.Go to the library archives; locate and print the restoration document. There is one additional step not discussed that you may wish to consider. That is removal of the crossover boards so as to facilitate their rebuilding on your workbench. They were hot glued and stapled to the interior back of the cabinet, and may or may not come out easily. I have had some that would not budge, and others that after removing most of the staples, simply popped free with a twist of a screwdriver. The aging glue is rather dry and brittle. The staples can be removed from the inside with an awl and pliers - takes some time, work carefully and be patient. After rebuilding the crossover, it can be installed again. This time use gel contact cement; it makes the job much easier than hot glue. Before removing the boards, mark their location on interior of the cabinets with a sharpie so that you reinstall the boards in exactly the same place. New capacitors can be purchased from a number of sources. You will need matching inductors to replace those used in the AR-3 to build the second AR-3a crossover. If you cannot find the same value of #18 wire, air-core inductors from Parts Express, then someone on this board might have a spare to sell. All the other details including sources of grille cloth, and so on are in the document.Just ask for help if you become stuck -- there are many here who can and will offer help.Your friend will have restored a great sounding pair of speakers and in the long run, be quite pleased with the effort. Rather than agony, consider it a fun project!Cheers, Link to comment Share on other sites More sharing options...
genek Posted March 13, 2008 Author Report Share Posted March 13, 2008 The simple answer is: If your friend rebuilds the crossovers correctly, the result will be an excellent pair of AR-3a speakers! If the sound power ouput is to remain flat, one needs to use the original crossover as designed by AR. Yes, it is worth it -- VERY well worth it ... only way to go.That's what I was afraid of, or perhaps I should say what my friend was afraid of. He's all thumbs with electronics and dangerous to be around anything that generates heat. I'm a bit better than that (if I have one crossover in front of me I can copy it without setting my house on fire even if I don't understand the schematic), but there's no way I can generate the enthusiasm to take on a project like this if it isn't mine.My advice to him was to just refoam the woofers, put the 3a drivers into both cabs with their existing crossovers and make the best of them as they are while I set up an automatic ebay search for someone parting out some 3a crossovers we can fix up outside the boxes and then swap into them. Either that or sell the whole lot to me. Link to comment Share on other sites More sharing options...
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