Hello. I have a brand new NPC that produces an audible buzz when the volume is turned up to 50% or more. Couple things to note:
a. It’s not the NPC. This is the second brand new unit supplied by the nice folks at PSA. Both units buzz/hum in exactly the same way.
b. My previous GCPH had the same buzz.
c. The buzz goes up and down with volume.
d. I’ve spend hours tracking down a possible ground loop–no success. Took everything out of the system and started from scratch. Buzz starts when I add the NPC. Even tried a cheater plug. Tried grounding the chassis to other components. Tried running a ground from the NPC to a ground by wiring a plug with just the ground wire connected to the ground pole. No change.
e. The unit still buzzes with the LP12 and Lingo 3 power supply taken completely out of the system.
f. No buzz from cd player or DAC.
g. Tried numerous cables from cheapos to Chord interconnects.
h. Analog system is Linn LP12/lingo3;Rega RB300/Clearaudio Concept LOMC. Impedance is set at 100 on the npc.
i. Rest of system is Naim Nac 42 modified with Teddy regulators/Naim Hi-Cap/Naim 110 monos modified with Les Avondale type Minccap6. Naim Nac A5 speaker cable and old Aegis 3 speakers.
Everyone is stumped, including my dealer who has 40 plus years dealing with Naim, Linn and other analog systems.
Here’s what I’m thinking–could my gain be way too high? I initially tried it 57db. I recently read an article suggesting that the NPC’s gain values are set up way too high–meaning that it has so much gain authority, it can be noisy if now moderated. Who knows, maybe the guy is a wack but I’ve lowered the gain to 47db and the buzz is less pronounced but still there. Can anyone give me some insight on the gain settings? Any other thoughts on the buzz/hum?