Good news but maybe one of you clever chaps can help me understand. Upgraded an old tx 210 a while ago and at the time added tweeter protection similar to the ampeg circuit to cover the tweeter for the additional power. Not a huge tweeter fan but these cabs need a smidge imo as the crossover point is quite low and there a bit muddy without. All was well add a high pass filter and the 210 is getting pretty much all the playtime. Until the tweeter started acting up funnily enough on the low notes sound through other speakers was fine. High end was still all there. So now my tweeter is a crisp packet emulator. Bloody annoying. With another amp less of an issue but still present, speaker cables changed still present.... Err. Switched out the cab same noise on my 410. They can't both be buggered can they? Turned out to be an instrument cable. High quality but well used, soldering intact, No other noise you usually get with a bad cables but that was the issue. Good news. But help me understand this embarrassing phenomenon........