Guest SamS Posted July 19, 2006 Report Share Posted July 19, 2006 Something must be wrong with my browser IE6. nada. Link to comment Share on other sites More sharing options...
Guest SamS Posted July 30, 2006 Report Share Posted July 30, 2006 Okey.. finally got around to taking apart my speakers.However, my rheostats don't look like all the other pics I've seen on the net. They don't look that corroded. Can someone suggest just how to clean these up?1463.txt Link to comment Share on other sites More sharing options...
Guest SamS Posted July 30, 2006 Report Share Posted July 30, 2006 Repair is done!There is no scratchiness in the mids or treble. Still, there doesn't seem to be a whole lot of treble coming out, even at max setting. It's there, and you can here it reduced over the full range of the pot, but there's no way these speakers will ever be 'bright' sounding IMO. Link to comment Share on other sites More sharing options...
johnieo Posted July 30, 2006 Report Share Posted July 30, 2006 Sam:The "potentiometers" that you show are obviously not AR Pollack 15-Ohm pots. It is possible that they are L-pads, which are wired incorrectly. Many of us do not feel that L-pads produce the best balance, but they should operate. The issue here is not whether L-pads are best, but if they are they wired properly. So, what have you?Potentiometers?---------------Try disconnecting two of the three leads to the tweeter level control. Measure the resistance between terminals 1 and 3. It should be about 15 Ohms if it is a potentiometer of the correct value. Also, the sum of the resistances between 1-2 and 2-3 should equal 15 Ohms, at any angle of rotation.L-pads?-------If L-pads, the resistance between 2-3 will be 0 Ohms at one end of the shaft's rotation, while the resistance between 1-2 will be 120 Ohms. At the other end of the shaft rotation, 2-3 will measure 8 Oms and 1-2 will measure 0 Ohms. If you have L-pads, check to see that they are wired properly, the 0-to-8-Ohm section, should be in series with the tweeter; the 120 Ohm section should be in parallel with the tweeter. If they are reversed, the level of the tweeter's output will be reduced. Perhaps that is what you are experiencing? Ditto for midrange. Link to comment Share on other sites More sharing options...
JoeB Posted July 31, 2006 Report Share Posted July 31, 2006 >Sam:>>The "potentiometers" that you show are obviously not>AR Pollack 15-Ohm pots. It is possible that they are L-pads,>which are wired incorrectly. Many of us do not feel that>L-pads produce the best balance, but they should operate. The>issue here is not whether L-pads are best, but if they are>they wired properly. So, what have you?--snip--John,I agree that those aren’t Aetna-Pollak pots – and I don’t know what they are. But you (and others) refer to “15-Ohm pots” but the actual AR parts list in the library shows AR Part Number 2750A as a 16 Ohm 25 W pot. This isn’t much of a difference (actually if the pot is +/- 10% it is within spec), but I wonder if the value was always supposed to be 16 Ohms, or was changed somewhere during production and after the parts list was made, or is incorrect in the parts list. BTW, the value should probably be measured with the pot at one extreme or the other since the wiper contacts more than one turn of the nichrome coil and may vary as the pot is adjusted. I just measured the Pollak pot sitting on my desk and it measured 15.8 Ohms – but with a meter I don’t entirely trust.Joe Link to comment Share on other sites More sharing options...
johnieo Posted July 31, 2006 Report Share Posted July 31, 2006 Sorry Joe: I belive you are correct -- 16 Ohms. Sorry for taking artistic license with an Ohm! Link to comment Share on other sites More sharing options...
dynaco_dan Posted July 31, 2006 Report Share Posted July 31, 2006 Hi John;Excellent advice and information, as always, thank you. Link to comment Share on other sites More sharing options...
Guest SamS Posted July 31, 2006 Report Share Posted July 31, 2006 >Sam:>>The "potentiometers" that you show are obviously not>AR Pollack 15-Ohm pots. It is possible that they are L-pads,>which are wired incorrectly. Many of us do not feel that>L-pads produce the best balance, but they should operate. The>issue here is not whether L-pads are best, but if they are>they wired properly. So, what have you?>>Potentiometers?>--------------->Try disconnecting two of the three leads to the tweeter level>control. Measure the resistance between terminals 1 and 3. It>should be about 15 Ohms if it is a potentiometer of the>correct value. Also, the sum of the resistances between 1-2>and 2-3 should equal 15 Ohms, at any angle of rotation.>>L-pads?>------->If L-pads, the resistance between 2-3 will be 0 Ohms at one>end of the shaft's rotation, while the resistance between 1-2>will be 120 Ohms. At the other end of the shaft rotation, 2-3>will measure 8 Oms and 1-2 will measure 0 Ohms. >>If you have L-pads, check to see that they are wired properly,>the 0-to-8-Ohm section, should be in series with the tweeter;>the 120 Ohm section should be in parallel with the tweeter. If>they are reversed, the level of the tweeter's output will be>reduced. Perhaps that is what you are experiencing? Ditto for>midrange.Hi Joe,Rats! I've already buttoned these babies up. The photo shows the pots w/o the covers on them. I coulda sworn they said AR 15 Ohms on there stamped in the metal covers. Should have taken another pic!Now, don't L-pads not have any adjustment range? Just a fixed resistance, right? My pots (whatever the heck they are!) definitely have full range of adjustment, and look like what the originals should have.. except more 'coils'. Hard to see from the picture, but they appear to operate like the ones seen in Post #9, just diffent coils and contact. Link to comment Share on other sites More sharing options...
johnieo Posted July 31, 2006 Report Share Posted July 31, 2006 >Now, don't L-pads not have any adjustment range? Just a fixed>resistance, right? Sam: Hold on a minute... L-pads are not fixed resistors! Please see:http://www.classicspeakerpages.net/dc/dcbo...ing_type=searchthen look at the jpg picture in reply #4It describes the diference between a potentiometer and an L-pad. When you say it has "extra coils" then you are telling me it is an L-pad (two coils inside each case but only three external leads).Best open the cabinet again, dig out your ohmmeter, unsolder two of the three leads, and check it carefully. Might just be installed backward. (e.g., The two end terminals *may* be reversed.)The devices you picture are for sure not Pollak (16) Ohm potentiometers -- the devices you show were never factory installed in an AR-3a! Link to comment Share on other sites More sharing options...
Guest SamS Posted July 31, 2006 Report Share Posted July 31, 2006 Hi John,I didn't word my last post properly.My pots look similar to the originals. I said more coils, but really meant they are more densely spaced than orginals. They have a single coil, and a wiper that works like the standard set of pots. After looking at the link/pic, I realized what l-pads look like, and how they work. What's in my speakers is not l-pads IMO. Just pots that are close, but not identical to originals.That being said, I've very happy with the sound. The tweeters are turned up all they way, the midranges about 90%. I should have done some measuring/experimenting with my volt meter, but I was so eager to get them back up and running, I closed them all up in a hurry. Link to comment Share on other sites More sharing options...
Guest SamS Posted August 2, 2006 Report Share Posted August 2, 2006 Browsing on ebay, I see a guy selling the exact same pots as what's in my speakers!http://cgi.ebay.com/AR-ACOUSTIC-RESEARCH-A...1QQcmdZViewItem Much better pics than mine... maybe this will clear things up. So what do I have exactly? Link to comment Share on other sites More sharing options...
RoyC Posted August 2, 2006 Report Share Posted August 2, 2006 They appear to be 8 ohm/15 watt l-pads...Roy Link to comment Share on other sites More sharing options...
johnieo Posted August 2, 2006 Report Share Posted August 2, 2006 As Roy observed, these sure are L-pads. The 8-Ohm version is very common and its diameter is considerably larger than that of a pot. Next time you open the cabinets, you might wish to check to see if they (or one of them) is wired in reverse. The second coil is hidden under the first so it would not have been easily visible to you. You can decipher their connections with the previously posted sketch and an ohmmeter.Good luck. Link to comment Share on other sites More sharing options...
mluong303 Posted August 2, 2006 Report Share Posted August 2, 2006 They are Culver 8 Ohms 15 watts L-Pad that were made in Japan. Very well built and better quality compare to the made in Taiwan L-Pads now available in the market. Minh Luong Link to comment Share on other sites More sharing options...
Guest SamS Posted August 2, 2006 Report Share Posted August 2, 2006 Great information guys! Link to comment Share on other sites More sharing options...
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