Guest leopoldstotch Posted June 7, 2007 Report Share Posted June 7, 2007 I would like to replace the caps in my pair of AR-3's and upon checking the wiring schematic in the library I see that there is one cap with both a 6 & 24 mfd and then a 6 mfd cap by itself. I also see that there is a turn choke going to the mid pot. My AR-3's only have the one 6 & 24 mfd cap there is no single 6 mfd cap, there is no turn choke going to the mid pot. I have recently purchased a two sets of caps which consist of two 6 mfd caps and one 24 mfd caps per speaker and I would like to know how to properly install these caps since my pair of speakers vary from the schematic. I tried installing the caps according to Layne Audio's schematic and it sounded as though there was a hole in the music. The midrange volume was low almost non exsistant compared to my AR-3a's. Any help is appreciated. Thanks! Link to comment Share on other sites More sharing options...
johnieo Posted June 7, 2007 Report Share Posted June 7, 2007 Leopold:I just tried to post but it didnot work. Hope this is not a duplicate!AR modified the x-o in the AR-3a on13 May 1970. The midrange capacitance was increased from 24- to 30-uF, and a 0.42 mH coil was added to the midrange crossover. (This is the "143 turn coil shown in the AR-3 crossover drawing Archived in the CSP library.)If you choose to add that modification, consider using that AR factory wiring diagram and not the one from Layne Audio. Layne Audio likes to reverse the midrange driver polarity and it likely results in the "hole" you hear. (They show this same reversal on their AR-3a upgrade, but that is not the way Roy Allison designed the 3a!)Cheers, Link to comment Share on other sites More sharing options...
Guest leopoldstotch Posted June 7, 2007 Report Share Posted June 7, 2007 Thanks for the reply Johnieo. Now my next question is is where do I find the coil for the midrange? I know parts express sells coils but I do not know if any of these are the correct one: http://www.partsexpress.com/webpage.cfm?WebPage_ID=310 Link to comment Share on other sites More sharing options...
RoyC Posted June 7, 2007 Report Share Posted June 7, 2007 Parts Express #'s 255-224 or 255-226 (.40mh or .44mh) will work fine.If you want to get fancy, you can easily de-wind a .44 coil one turn, if you don't have a meter to measure it. You will not hear the difference between any of these values.Roy Link to comment Share on other sites More sharing options...
Guest leopoldstotch Posted June 7, 2007 Report Share Posted June 7, 2007 RoyC Thanks for the reply. I'll be ordering those coils and 30 mfd caps today. I'll post in time when I finish the upgrade. Again thanks for helping me out! Bruce Link to comment Share on other sites More sharing options...
johnieo Posted June 7, 2007 Report Share Posted June 7, 2007 Bruce:If you already purchased new 24-uF capacitors, simply order 6-uF caps and connect them in parallel. Cheers, Link to comment Share on other sites More sharing options...
Guest leopoldstotch Posted June 8, 2007 Report Share Posted June 8, 2007 >Bruce:>If you already purchased new 24-uF capacitors, simply order>6-uF caps and connect them in parallel. >>Cheers,>Yes I already have the 24-uF caps. The set came with one 24-uF cap and two 6-uF caps per speaker. Which schematic should I follow? Thanks for all your help I truly appreciate it! Link to comment Share on other sites More sharing options...
johnieo Posted June 11, 2007 Report Share Posted June 11, 2007 Hi Leopold:The schematic shows only one engineering change on that date: the addition of a capacitor and coil. It does not show any other changes. Perhaps we might ask Tom Tyson if there were any other ones. Otherwise it looks like AR shifted the lower mid crossover down a bit and sharpened the rolloff. Assuming no other changes, then one might try the newer crossover. Let's check with Tom in case there was something not described on the engineering drawing.Cheers, Link to comment Share on other sites More sharing options...
Guest MarkAnderson Posted June 12, 2007 Report Share Posted June 12, 2007 So we're talking about "upgrading" the original AR-3 crossover to match that of a 1970 AR-3a? Why? It's two different speakers...OP - I recapped my '67 (IIRC) AR-3's, which have just the 6 & 24uF caps, per Layne Audio's schematic and mine sound just peachy. Maybe you've missed something? Link to comment Share on other sites More sharing options...
tysontom Posted June 12, 2007 Report Share Posted June 12, 2007 Hi Leopold:The schematic shows only one engineering change on that date: the addition of a capacitor and coil. It does not show any other changes. Perhaps we might ask Tom Tyson if there were any other ones. Otherwise it looks like AR shifted the lower mid crossover down a bit and sharpened the rolloff. Assuming no other changes, then one might try the newer crossover. Let's check with Tom in case there was something not described on the engineering drawing.Cheers,John O'HanlonJohn,The changes in the AR-3 crossover occurred first at SN C 1414. At this point the midrange and tweeter phase was reversed with respect to the woofer. On AR-3 C 1414 through C 19467, the crossover had a 6 mfd capacitor on the tweeter and a 24 mfd cap and .06 mH coil on the midrange, as well as the 0.4 mH coil on the woofer. From C 19468 onward, the .06 mH coil was eliminated in the midrange circuit. After SN C 70228, AR was no longer able to supply the original 2-inch midrange unit, and these units came supplied with a modified AR-3a 1-1/2-inch midrange unit along with a slightly modified crossover to reduce the energy output of the 3a midrange.--Tom Tyson Link to comment Share on other sites More sharing options...
tysontom Posted June 12, 2007 Report Share Posted June 12, 2007 >I would like to replace the caps in my pair of AR-3's and>upon checking the wiring schematic in the library I see that>there is one cap with both a 6 & 24 mfd and then a 6 mfd>cap by itself. I also see that there is a turn choke going to>the mid pot. My AR-3's only have the one 6 & 24 mfd cap>there is no single 6 mfd cap, there is no turn choke going to>the mid pot. I have recently purchased a two sets of caps>which consist of two 6 mfd caps and one 24 mfd caps per>speaker and I would like to know how to properly install these>caps since my pair of speakers vary from the schematic. I>tried installing the caps according to Layne Audio's schematic>and it sounded as though there was a hole in the music. The>midrange volume was low almost non exsistant compared to my>AR-3a's. Any help is appreciated. Thanks!If you look at that schematic, which is confusing, it appears that there is a separate 6 & 24 mfd cap and a stand-alone 6 mfd cap. What the schematic was trying to show, I believe, is that the configuration could be either a single-unit cap with three wires (6 & 24) and a singe-unit (24) and a single-unit (6 mfd). The crossover always had the two values, not three.What was different was the elimination of the .06 mH coil from the midrange circuit, which was wired in series with the 24 mfd capacitor value. Effective with serial number C 19468, this capacitor was eliminated from the circuit. Also, somewhere around serial number C 30500 the midrange magnet was changed from the huge, way-over-kill 9-lb structure to a slightly smaller magnet structure.--Tom Tyson Link to comment Share on other sites More sharing options...
tysontom Posted June 12, 2007 Report Share Posted June 12, 2007 >>What was different was the elimination of the .06 mH coil from>the midrange circuit, which was wired in series with the 24>mfd capacitor value. Effective with serial number C 19468,>this *capacitor* was eliminated from the circuit. Also,>somewhere around serial number C 30500 the midrange magnet was>changed from the huge, way-over-kill 9-lb structure to a>slightly smaller magnet structure.>>--Tom Tyson "Capacitor" was meant to be read as "coil."--Tom Tyson Link to comment Share on other sites More sharing options...
johnieo Posted June 12, 2007 Report Share Posted June 12, 2007 >So we're talking about "upgrading" the original>AR-3 crossover to match that of a 1970 AR-3a? Why? It's two>different speakers...My apology--the 'a' was a mistake. AR modified the AR-THREE crossover on 13 May 1970. See circuit in CSP AR-Archives.Cheers Link to comment Share on other sites More sharing options...
johnieo Posted June 12, 2007 Report Share Posted June 12, 2007 >If you look at that schematic, which is confusing, it appears>that there is a separate 6 & 24 mfd cap and a stand-alone>6 mfd cap. What the schematic was trying to show, I believe,>is that the configuration could be either a single-unit cap>with three wires (6 & 24) and a singe-unit (24) and a>single-unit (6 mfd). The crossover always had the two values,>not three.>>What was different was the elimination of the .06 mH coil from>the midrange circuit, which was wired in series with the 24>mfd capacitor value. Effective with serial number C 19468,>this capacitor was eliminated from the circuit. Also,>somewhere around serial number C 30500 the midrange magnet was>changed from the huge, way-over-kill 9-lb structure to a>slightly smaller magnet structure.>>--Tom Tyson Tom, this is indeed confusing!RE: AR-3 Engineering drawing in the CSP Archives-- It shows one change dated 1965 in which a 51 turn midrange coil was removed. I presume that is the 0.06 mH coil to which you refer.Next, the 13 May 1970 date entry shows clearly the addition of a 143-turn choke (0.4 mH) to the midrange. It IMPLIES that a 6-uF capacitor was added in parallel with the 24-uF capactitor making the midrange cap = 30 uF. However, it makes no note of the change in driver. Was that the date at which the midrange was changed? This is why I suggested that you comment before anyone changes the crossover.Cheers, Link to comment Share on other sites More sharing options...
johnieo Posted June 17, 2007 Report Share Posted June 17, 2007 Greetings:Tom Tyson and I discussed the engineering change dated 19 May 1970. It appears that this is the date the old midrange was replaced by the AR-3a midrange driver, as the original midrange became unavailable. As Tom explained to me-- All AR-3s after C 70228 already had this modification to the crossover and already had the new AR-3a-style midrange.So my current understanding is that if your cabinets have serial numbers lower than that, and their midranges still operate, then no change in the existing crossover network is desirable.I would not follow Layne Audio's suggestion of changing driver polarity.Cheers, Link to comment Share on other sites More sharing options...
Guest leopoldstotch Posted June 17, 2007 Report Share Posted June 17, 2007 >Greetings:>>Tom Tyson and I discussed the engineering change dated 19 May>1970. It appears that this is the date the old midrange was>replaced by the AR-3a midrange driver, as the original>midrange became unavailable. As Tom explained to me-- All>AR-3s after C 70228 already had this modification to the>crossover and already had the new AR-3a-style midrange.>>So my current understanding is that if your cabinets have>serial numbers lower than that, and their midranges still>operate, then no change in the existing crossover network is>desirable.>>I would not follow Layne Audio's suggestion of changing driver>polarity.>>Cheers,>Ok so as I now understand it I should be following the original schematic and not Layne Audio's since my AR-3's are in the 29000 range. Thank You! Link to comment Share on other sites More sharing options...
johnieo Posted June 17, 2007 Report Share Posted June 17, 2007 >Ok so as I now understand it I should be following the>original schematic and not Layne Audio's since my AR-3's are>in the 29000 range. Thank You!Hi again: I would phrase it somewhat differently: "I should be following the original schematic since my AR-3s are in the 29000 range." I would ignore Layne Audio circuits regardless of serial number. But I am sure that is what you meant to say!Cheers,John Link to comment Share on other sites More sharing options...
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