quebecois59 Posted January 18, 2013 Report Share Posted January 18, 2013 Hey there!My restored 2ax speakers had performed well for a few months. I was pretty happy with the way they performed until last week.First, the right side (in my office room) started acting up: the woofer started going off and on, and one day it seemed to definitely quit, but if I put my hand directly on it, I can feel the woofer weak vibrations. Then the left one did exactly the same two days later! Tweeters and mids are still doing OK.Do you have any ideas what can cause this? I changed both surrounds at the same time and according to my observations, the glue is still holding good.I replaced the caps and the pots inside one speaker but left the original components in the other one, but both experimented the same bass loss.I obviously had to do some new soldering of my own on both woofers, but I doubt they would have gone south in two months.I am a little bit puzzled and would appreciate advices before I opened them. You guys were very helpful during the restoration process.Thanks in advanceFrancois Link to comment Share on other sites More sharing options...
RoyC Posted January 18, 2013 Report Share Posted January 18, 2013 Hey there!My restored 2ax speakers had performed well for a few months. I was pretty happy with the way they performed until last week.First, the right side (in my office room) started acting up: the woofer started going off and on, and one day it seemed to definitely quit, but if I put my hand directly on it, I can feel the woofer weak vibrations. Then the left one did exactly the same two days later! Tweeters and mids are still doing OK.Do you have any ideas what can cause this? I changed both surrounds at the same time and according to my observations, the glue is still holding good.I replaced the caps and the pots inside one speaker but left the original components in the other one, but both experimented the same bass loss.I obviously had to do some new soldering of my own on both woofers, but I doubt they would have gone south in two months.I am a little bit puzzled and would appreciate advices before I opened them. You guys were very helpful during the restoration process.Thanks in advanceFrancoisAssuming your amp is working properly, pull the woofers and test them directly.Roy Link to comment Share on other sites More sharing options...
quebecois59 Posted January 18, 2013 Author Report Share Posted January 18, 2013 Assuming your amp is working properly, pull the woofers and test them directly.RoyHey RoyI forgot to mention that I tested the speakers with my other amp in the living room with the same result.What do you mean by "test them directly"?FP Link to comment Share on other sites More sharing options...
RoyC Posted January 18, 2013 Report Share Posted January 18, 2013 Hey RoyI forgot to mention that I tested the speakers with my other amp in the living room with the same result.What do you mean by "test them directly"?FPRemove the woofers from the cabinets and touch your amp's speaker wires directly to their terminals. If they work satisfactorily, you will know the problem is in the cabinet. If they don't, it is the woofers. If that turns out to be the case, it wouldn't have anything to do with the new surrounds. Most likely it would be voice coil issues.Roy Link to comment Share on other sites More sharing options...
rrcrain Posted January 18, 2013 Report Share Posted January 18, 2013 Before you do anything else. Check the resistance between a terminal and the speaker frame. If it's anything other than completely open, the voice coil is rubbing on the frame and you run the risk of blowing your amp. Link to comment Share on other sites More sharing options...
soundminded Posted January 18, 2013 Report Share Posted January 18, 2013 Check the links between terminals on the back. Check your solder connections. A cold solder joint may not show up right away. It sounds odd that this happened to both speakers at about the same time. It almost sounds like the receiver somehow damanged both of them, possibly with DC. Link to comment Share on other sites More sharing options...
RoyC Posted January 18, 2013 Report Share Posted January 18, 2013 Check the links between terminals on the back. Check your solder connections. A cold solder joint may not show up right away. It sounds odd that this happened to both speakers at about the same time. It almost sounds like the receiver somehow damaged both of them, possibly with DC.Agreed... Link to comment Share on other sites More sharing options...
quebecois59 Posted January 19, 2013 Author Report Share Posted January 19, 2013 I won't have too much time to work on them tonight, would you suggest that I don't use them until I fix them? Link to comment Share on other sites More sharing options...
RoyC Posted January 19, 2013 Report Share Posted January 19, 2013 I won't have too much time to work on them tonight, would you suggest that I don't use them until I fix them?Why would you want to use them if the woofers aren't working? Link to comment Share on other sites More sharing options...
quebecois59 Posted January 19, 2013 Author Report Share Posted January 19, 2013 Why would you want to use them if the woofers aren't working? They still work, but very far from usual and hey, this is a small room, I don't need that much of the woofers most of the time! But I'd want them to perform at best when I do turn the volume up! Link to comment Share on other sites More sharing options...
HarryM Posted January 19, 2013 Report Share Posted January 19, 2013 It might be a little late now but I would check the amp to see if it's putting out DC before you run it with speakers hooked up. Link to comment Share on other sites More sharing options...
dynaco_dan Posted January 19, 2013 Report Share Posted January 19, 2013 Hi thereDisconnect the speakers from the amp.Place a d-cell battery across the terminals.Depending on polarity the woofer only will move in or out.Because of the caps there will be no highs. Link to comment Share on other sites More sharing options...
quebecois59 Posted January 20, 2013 Author Report Share Posted January 20, 2013 Hi thereDisconnect the speakers from the amp.Place a d-cell battery across the terminals.Depending on polarity the woofer only will move in or out.Because of the caps there will be no highs.Ok I just did it and both woofers did move in and out at least one quarter of an inch while testing with this method.What does that mean?FP Link to comment Share on other sites More sharing options...
quebecois59 Posted January 20, 2013 Author Report Share Posted January 20, 2013 It might be a little late now but I would check the amp to see if it's putting out DC before you run it with speakers hooked up.How would I test that? Link to comment Share on other sites More sharing options...
HarryM Posted January 20, 2013 Report Share Posted January 20, 2013 How would I test that?With a meter. Set the meter on the lowest DC level and check the speaker outputs on the amp with the amp turned on. Hook the neg from the meter to the neg speaker output and the pos from the meter to the pos from the speaker output. If everything is perfect you should have no reading. You can have a very very low reading or even a very low negative reading but they should be equal from one side to the other. Any high readings or differences between sides means DO NOT USE THE AMP. Send it out for repair and you quite possibly shorted the voice coils in your woofers. Link to comment Share on other sites More sharing options...
quebecois59 Posted January 20, 2013 Author Report Share Posted January 20, 2013 With a meter. Set the meter on the lowest DC level and check the speaker outputs on the amp with the amp turned on. Hook the neg from the meter to the neg speaker output and the pos from the meter to the pos from the speaker output. If everything is perfect you should have no reading. You can have a very very low reading or even a very low negative reading but they should be equal from one side to the other. Any high readings or differences between sides means DO NOT USE THE AMP. Send it out for repair and you quite possibly shorted the voice coils in your woofers.Just tested it the way you said. No DC at all!What do I do from here? Link to comment Share on other sites More sharing options...
HarryM Posted January 20, 2013 Report Share Posted January 20, 2013 Open up the speakers, test the woofers as per Roy's suggestion, if the woofers are working good, check connections, wiggle stuff around until you find what is loose, resolder any connections. Link to comment Share on other sites More sharing options...
quebecois59 Posted January 20, 2013 Author Report Share Posted January 20, 2013 I just opened one speaker, pulled the woofer out (leads still connected, though), put the amp on, played a CD, and then connect the amp wires directly to the woofer terminals. I had the same poor performance. I can hear music and feel the vibes with my fingers on the cone, but the sound is very weak.Then I tested the other woofer, with the same result.What is the diagnosis and then what would be the cure? Link to comment Share on other sites More sharing options...
RoyC Posted January 20, 2013 Report Share Posted January 20, 2013 I just opened one speaker, pulled the woofer out (leads still connected, though), put the amp on, played a CD, and then connect the amp wires directly to the woofer terminals. I had the same poor performance. I can hear music and feel the vibes with my fingers on the cone, but the sound is very weak.Then I tested the other woofer, with the same result.What is the diagnosis and then what would be the cure?It sounds to me like a voice coil issue, possibly due to rubbing after re-foaming. The voice coil windings gradually wear and weaken, and will eventually stop working.Another possibility is heat damage to the voice coils caused by the amp, or overdriving.Unless you know a very good re-builder, you probably need to begin shopping for woofers.Roy Link to comment Share on other sites More sharing options...
quebecois59 Posted January 20, 2013 Author Report Share Posted January 20, 2013 It sounds to me like a voice coil issue, possibly due to rubbing after re-foaming. The voice coil windings gradually wear and weaken, and will eventually stop working at all. Unless you know a very good re-builder, you need to begin shopping for woofers.RoyIf you're right, I'm stumped! I carefully followed all of the steps when refoaming, I used the shims provided with the kit. I can't see what I could have done wrong... Link to comment Share on other sites More sharing options...
RoyC Posted January 20, 2013 Report Share Posted January 20, 2013 If you're right, I'm stumped! I carefully followed all of the steps when refoaming, I used the shims provided with the kit. I can't see what I could have done wrong...You posted while I was editing. :-)It can also be caused by excessive heat due to an amp issue or overdriving. The result is the same. You will need new voice coils if it is the type of damage I suspect it is.Roy Link to comment Share on other sites More sharing options...
rrcrain Posted January 21, 2013 Report Share Posted January 21, 2013 Did you bother to check the resistance between a terminal ans speaker frame? GENTLY move the cone while measuring this and listen for anything resembling a rubbing noise while moving the cone. Link to comment Share on other sites More sharing options...
quebecois59 Posted January 21, 2013 Author Report Share Posted January 21, 2013 Did you bother to check the resistance between a terminal ans speaker frame? GENTLY move the cone while measuring this and listen for anything resembling a rubbing noise while moving the cone.Forgot it...just did it: result is open circuit on both speakers, no rubbing noise, cones move freely.According to that test, coils are not rubbing at all.What's next step now? Link to comment Share on other sites More sharing options...
RoyC Posted January 21, 2013 Report Share Posted January 21, 2013 That test is not a reliable indicator of a rubbing voice coil. You are still looking at new voice coils or woofers if your impressions of the severely reduced output are correct. Link to comment Share on other sites More sharing options...
quebecois59 Posted January 21, 2013 Author Report Share Posted January 21, 2013 That test is not a reliable indicator of a rubbing voice coil. You are still looking at new voice coils or woofers if your impressions of the severely reduced output are correct.Well, I'd like to replace the voice coils or the woofers whatever is the best solution but I wouldn't like them to fail again within two months. Is there any chance my amp is the source of the problem? This is a Sansui TA-300 (110 watts per channel). It is written speaker impedance: 8 ohms and more on the back.I haven't played the music very loud because my room is small, never more than 4 on a 10 scale,My brother has used it for 25 years and he's never bursted a speaker. Link to comment Share on other sites More sharing options...
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