The speaker is probably 15 years old. I have had it into the shop and have had all of the capacitors replaced. It worked well for a while after the capacitors were replaced, But now it is humming again. When it starts humming I can turn the volume all the way up and it will stop the home. I turn it back down to normal listening position things are fine, for a while. But the humm will start again. Any ideas or help will be appreciated.