Guest hawkman199 Posted March 26, 2006 Report Share Posted March 26, 2006 I have just acquired a pair of 3a speakers in excellent condition. As expected, the woofer surrounds need to be replaced.The mid-range and tweeters seem to be just fine.I cleaned the pots and they work OK.Looking at the crossover schematic there appears to be a 0.47 ohm power resistor after the 50 mfd cap. However, there is no resistor of any kind in the crossover circuit in my speakers.The serial number for the speakers is 68215.There is a date on the woofer magnets of November 1972.Can anyone help me with this discrepancy?Cheers to all. Link to comment Share on other sites More sharing options...
dynaco_dan Posted March 27, 2006 Report Share Posted March 27, 2006 Hi there;A great speaker system, congratulations.Help will be along shortly from the experts. Link to comment Share on other sites More sharing options...
johnieo Posted March 27, 2006 Report Share Posted March 27, 2006 In some AR-3a cabinets, the 0.51-Ohm resistor was a short length of resistance wire--perhaps Nichrome. Look again and see if you can spot two tie points with a short loop of wire between. If so, you're in fine shape. Not much inductance in that resistor!cheers, Link to comment Share on other sites More sharing options...
RoyC Posted March 27, 2006 Report Share Posted March 27, 2006 Here is a picture of the critter!Royhttp://www.classicspeakerpages.net/dc/user_files/1177.jpg Link to comment Share on other sites More sharing options...
dynaco_dan Posted March 27, 2006 Report Share Posted March 27, 2006 >In some AR-3a cabinets, the 0.51-Ohm resistor was a short>length of resistance wire--perhaps Nichrome. Look again and>see if you can spot two tie points with a short loop of wire>between. If so, you're in fine shape. Not much inductance in>that resistor!>>cheers, Hi John;Great advice from you as always.I do find it interesting, that such a small change between .47 and .51 ohms in resistance value, would alter the speakers enough for AR to have done that.I don't know why there was a resistance used.My only written experience with a piece of Nichrome wire was in a single AR-4X.It was by mistake, used as a soldered jumper at the factory.It looks for all intents and purpose to be a piece of tinned bare wire.Unfortunately it won't solder, it will be surrounded by solder but solder will not adhere to it.If any member should experience a dead driver and this Nichrome resistor has been used, check out continuity first, there may be a bad riveted connection.Any bad connection with Nichrome will be an open circuit, hense no sound. Link to comment Share on other sites More sharing options...
Guest hawkman199 Posted March 27, 2006 Report Share Posted March 27, 2006 Well, huge thanx for the help!Sure enough the 'resistor' wire is there and measures .8 ohms on my meter. I guess I was loooking for a ceramic resistor. It just goes to show, you can learn something new every day!Any recommendations on replacement caps?The 6 mfd is quite interesting in that it is housed in a waxed cardboard box and was made by the 'Industrial Cond. Corp.' of Chicago.The 50 mfd and 150 mfd are from 'Sprague'.Thanx again! Link to comment Share on other sites More sharing options...
stan461 Posted March 27, 2006 Report Share Posted March 27, 2006 I bought my caps for my AR3a speakers from Madisound. At first, they seemed a little bright but not any more and I am very, very happy with them. For the pair I bought:Quantity Item # Desc 2 CP6 6.0mfd Polypropylene Capacitor2 CP50 50mfd " " 2 M140 140MFD Electrolytic " As I recall, they are all Solen.The total bill was a little over $40.00 and I bought them about 2 years ago. Link to comment Share on other sites More sharing options...
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