I was having dinner tonight with some good friends, who'd recently bought a new system consisting of a Cambridge Audio 540A amp and 540C cdplayer connected to a set of Kef Q4's. The problem is: It has a noise (I wouldn't describe it as hum but rather a ripple, it could well be 50Hz). The pitch never varied, but the level did depending on the volume level setting. It's quite audible at seven o clock and gets less (sic) when you turn up the volume to barely audible at ten o clock and then rises again to quite loud when you turn the level up beyond that.
This is with no music playing. With music playing it was clearly audible on the quiet passages of, for instance, Janis Joplins Mercedes Benz or Faure's Requiem.
The amp is earthed/connected to ground I first disconnected the cdplayer, which made no difference. I then fooled around with the speaker cables, getting them as far away as possible from the mains cables, to no avail. Right about then dinner was served and anti-social geek behavior no longer tolerated, so I did no more messing about, but left them after a good meal and great talk with a hint to try an AC socket in another part of the house, to see if it was mains related.
Any ideas what else could be checked or tested? They already phoned the store (but probably not with this elaborate a description), who said this was normal. No way!
Take
This is with no music playing. With music playing it was clearly audible on the quiet passages of, for instance, Janis Joplins Mercedes Benz or Faure's Requiem.
The amp is earthed/connected to ground I first disconnected the cdplayer, which made no difference. I then fooled around with the speaker cables, getting them as far away as possible from the mains cables, to no avail. Right about then dinner was served and anti-social geek behavior no longer tolerated, so I did no more messing about, but left them after a good meal and great talk with a hint to try an AC socket in another part of the house, to see if it was mains related.
Any ideas what else could be checked or tested? They already phoned the store (but probably not with this elaborate a description), who said this was normal. No way!
Take