17-Dec-2016, 11:11
This is quite a useful resource - https://en.wikipedia.org/wiki/Mains_hum - largely as it has sound samples of 50/60Hz hum (depending which country you're in - 50Hz in UK. 60Hz in US) to compare with what you're hearing, if it is a fixed-frequency hum.
I think I'd start by disconnecting any wires apart from the mains and see if it still hums. That might narrow it down though obviously it might not be that easy to fix..
A reasonably common source of hum is a DC offset component to the AC mains ( see http://www.isol-8.co.uk/dc_on_the_mains.html for some info) , which requires a filtering device to fix. It's a very simple circuit and costs pennies in components but naturally in the world of hi-fi solutions for DC offset are usually rather expensive!
Also check out any other devices on the mains and perhaps selectively turn things off to see if they're affecting the Phantoms. Even airborne interference could do it but it would have to be something fairly close by.
I think I'd start by disconnecting any wires apart from the mains and see if it still hums. That might narrow it down though obviously it might not be that easy to fix..
A reasonably common source of hum is a DC offset component to the AC mains ( see http://www.isol-8.co.uk/dc_on_the_mains.html for some info) , which requires a filtering device to fix. It's a very simple circuit and costs pennies in components but naturally in the world of hi-fi solutions for DC offset are usually rather expensive!
Also check out any other devices on the mains and perhaps selectively turn things off to see if they're affecting the Phantoms. Even airborne interference could do it but it would have to be something fairly close by.
