How silent should the 300 mono’s be? I can hear a hum from each unit that is audible to me from my listening seat 3m away. It is low level but always there - I may just happen to be susceptible to this frequency range.
The 1st thought was DC induced hum (even though my other amplifier which has a larger transformer than each mono unit that amp doesn’t hum) so I purchased a DC Blocker, no change.
Cable dressing hum is not an issue as the speakers are quiet.
The set-up is as follows;
3 Dedicated AC lines for hifi.
PS Audio P10 (either direct from wall socket or with DC Blocker from wall socket and P10 plugged in to that) feeding the S300’s (and also the Quad2905’s).
Separate AC cct powering;
PS Audio BHK Pre, DS-DAC, PWT. All interconnects are XLR-XLR.
Ambient noise level at listening seat is 35dB (using Iphone Decibel 10th app)
Iphone at rear of S300 (1cm away from access/vent grill for tubes);
No power to amp = app reading is 35/6dB
Power via P10, S300 power switch on (I) = app reading is 41/42dB
Power via P10, S300 power switch on (I) + initialised (S300 front blue light continuously on) = app reading is 41/42dB
Result is exactly same if P10 power is supplied via DC Blocker.
Result is same if speakers connected or not and if signal leads are connected or not.
Any thoughts? I don’t like hearing a continuous, low level hum when the room is quiet so I’d like to eliminate this if at all possible…