Humming Sound I'm facing difficulty with one (left) of my Tannoy mx4 speaker. The lower most driver (bass) is giving out cracking/humming sound. It is very apparent when you increase the volume. I'm using Marantz amplifier. I tried switching the Left and Right speaker connection to the amplifier to isolate the problem and make sure it is not related with the amplifier. The sound came from the same speaker irrespective whether it was connected to the left or right terminals of the amplifier. Physical inspection shows that the driver is fine and nothing wrong with it. Can you suggest what should I check and how to solve this issue?

1. Check the cable of speaker which gives out the hum/cracking sound.Interchange the cables with the one that is working okay and find out if the hum still persists on the relevant Speaker. If the hum has gone, then replace cables ( to be on the safe side replace both right and left channel) to the speaker.If the Hum still persists, check the input female plug of the defective speaker and check if it is not lose or the solder has not gone wet. If so resolder both the wires of the connector by removing it with a soldering iron and scrapping the points of solder with a blade. If the problem still persists. Open both the cabinets. Mark the defective driver with a marker pen. Remove the non problemative driver and replace in it's place the Humming driver and check the configuration on both channels. If there is is problem then it has to do with driver and has to be recoiled and reconed ( ofcourse with a little quality lost) which could be done by any Speaker repair shop as per the manufacturers specifications. If the speaker works fine then the problem has to be either of the crossover network or tweeter. So remove the cross-over network from the defective speaker setup after marking it again for identification, and replace it in the good working speaker, where you now connected the humming speaker. If there is a hum, then the problem is the cross-over network, which should be replaced. If the hum is not there, again try similarly with the tweeter and I am sure you will get the Hum, and you may get a new one of similar specification from the market or get it repaired by a speaker shop. Replace the original configurations as was before. Woofer to its original places and similarly cross-over and tweeter ( as was before you opened the cabinets). Now you have identified the problem, solve the problem by repairing or replacing the culprit device. I am sure you may not have to go to all these. Perhaps it might be a loose connection or cable problem or even earthing problem. If you do not want to go through all these. Show it to a specialist with reputation ot take it to the company's service centres whose address in your area or nearby area you could get from their official site. Please note I have given my guidance on the premise that the amplifier if fine and has no problem.