shindyra Posted February 8, 2015 Share Posted February 8, 2015 Hey there,I have a Behringer B300 powered speaker, I have replaced both the main driver and the tweeter, however I still get massive thumps when switching on and off and also certain tones produce a crackle.Looking for an urgent fix for this and was hoping you could help.Thanks in advancedWill. Link to comment Share on other sites More sharing options...
Bobbsy Posted February 8, 2015 Share Posted February 8, 2015 Is your gain turned up too high or perhaps switched to the mic setting with a line input? Does the overload indicator flash? Link to comment Share on other sites More sharing options...
shindyra Posted February 8, 2015 Author Share Posted February 8, 2015 1423395488[/url]' post='516928']Is your gain turned up too high or perhaps switched to the mic setting with a line input? Does the overload indicator flash? I don't think so, I have the other speaker of the pair and works absolutely fine, I am just trying to get it fixed otherwise I've wasted a lot of money on spare parts and have lost a main pair of speakers. The speaker crackles at certain frequencies and has the dreaded thud on power up Link to comment Share on other sites More sharing options...
timsabre Posted February 8, 2015 Share Posted February 8, 2015 I would check that the pos/neg power supply rails on the main power amp are both good. Sounds like one of them may be at the wrong voltage or not there at all giving DC offsets. By using the working speaker to check against, you should be able to spot any problems. Link to comment Share on other sites More sharing options...
bruce Posted February 8, 2015 Share Posted February 8, 2015 If it’s any consolation, these speakers (which sound fine for what they are, but are stupidly heavy!) can be picked up for buttons on eBay - easiest way to get spares etc. Link to comment Share on other sites More sharing options...
shindyra Posted February 8, 2015 Author Share Posted February 8, 2015 I would check that the pos/neg power supply rails on the main power amp are both good. Sounds like one of them may be at the wrong voltage or not there at all giving DC offsets. By using the working speaker to check against, you should be able to spot any problems. How would I go about checking that? Link to comment Share on other sites More sharing options...
shindyra Posted February 8, 2015 Author Share Posted February 8, 2015 The top end is fine but as soon as I add any low it sounds l I've wet farts pretty much. Link to comment Share on other sites More sharing options...
timsabre Posted February 8, 2015 Share Posted February 8, 2015 I would check that the pos/neg power supply rails on the main power amp are both good. Sounds like one of them may be at the wrong voltage or not there at all giving DC offsets. By using the working speaker to check against, you should be able to spot any problems. How would I go about checking that? Poking about with a multimeter - sounds like you might need to get some assistance with this as there's potential to hurt yourself and/or blow things up if you don't know what you are doing. Link to comment Share on other sites More sharing options...
sam.spoons Posted February 8, 2015 Share Posted February 8, 2015 +1, you've done all the things a sensible non-amp-tech can reasonably do so take it to a pro, it'll be cheaper in the long run (and I speak from experience). Link to comment Share on other sites More sharing options...
shindyra Posted February 8, 2015 Author Share Posted February 8, 2015 I've checked all fuses, connections and other pcb components so I'm not sure what's going on really. Link to comment Share on other sites More sharing options...
sam.spoons Posted February 8, 2015 Share Posted February 8, 2015 As suggested above, if you don't know how to check the power rails take it to an amp tech. Link to comment Share on other sites More sharing options...
timsabre Posted February 9, 2015 Share Posted February 9, 2015 I would also suggest you don't use the speaker until you've got this fixed or you'll be replacing the drivers again... Link to comment Share on other sites More sharing options...
shindyra Posted February 9, 2015 Author Share Posted February 9, 2015 Could it be an issue with the crossover as the top ends are fine. Link to comment Share on other sites More sharing options...
warrenstuart Posted February 10, 2015 Share Posted February 10, 2015 In the nicest possible way it sounds like you are clutching at straws so just take it into a technician to fix for you to save further damage and/or injury :) Good luck Warren. Link to comment Share on other sites More sharing options...
DrV Posted February 11, 2015 Share Posted February 11, 2015 In the nicest possible way it sounds like you are clutching at straws so just take it into a technician to fix for you to save further damage and/or injury :) +1 to that. The most difficult faults to diagnose are the ones where someone has already had a go and failed. And in doing so they've unwittingly destroyed the 'forensic' evidence that helps the next guy trace the root cause of the fault. Dave Link to comment Share on other sites More sharing options...
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