I've noticed an issue in my system - buzzing noise from speakers. The system consists of BDA3, BP173, 4B3, Torus Power RM-8 and PMC OB1 speakers, I use Bryston XLR cables and set 23db gain on power amp. 4B3 and BP173 were installed 3 months ago, they replaced 4BSST and BP25/MPS1 - which were completely silent. BP173 and 4B3 are 220V units switched by local distributor to 230-240V, BDA3 is 220-230V unit. Here is what I found after some investigation:
- Noise comes from woofer and mid woofer - woofer is loudest, I can hear it in 10 cm near the speakers. It sounds like uniform buzz.
- Noise doesn’t depend on preamp volume level and I hear it with volume knob in zero position and without any source attached to dac.
- Noise is loudest in right channel with all units switched on, dac can be left on standby. Removing power from dac makes noise quieter and moves it to left channel, muting preamp makes noise much quiet, and disconnecting all inputs from power amp makes speakers silent.
- When dac is switched on swapping cables between DAC and preamp from left to right moves noise to left.
- Increasing gain on power amp makes noise louder.
- Noise is same with system switched either to Torus RM8 or wall outlet. Outlet is grounded and checked by electrician, input voltage is always 230V, switching system to other outlets makes same noise.
- Noise doesn’t depend on used cables - same with RCA, other XLR cables, other speaker cables, and any power cables.
- Noise doesn’t depend on placement of components.
- Switching off Wifi, moving away phones and switching off all other electric equipment at home makes no difference.
- BP25/MPS1 and 4BSST are completely silent with BDA3. I tried to identify faulty unit with switching BP25 to 4B3 and BP173 to 4BSST - without DAC at all. However every such combination has some noise. Only using BP25 and 4BSST together has no noise at all.
I tried to email Mike Pickett with this, but got no reply. Please help me to understand how defeat this noise - I don't think I should ignore it