Excuse if this is irrelevant, but my system (amp and pre) developed a sudden transformer hum a few months ago. It was fine, then I shut it down to swap power cords. When I brought it back up, fairly loud tranformer hum from the amp and the preamp. Well, it was more of a transformer squeal from the preamp. It actually took a few days to sort. I was telling my wife about it and she mentioned she had plugged in our humidifier about the same time. I unplugged the humidifier, and the hums were gone.
Krell FPB300 - mechanical transformer noise.
I have an FPB300 that does not have the pinging issue discussed on another thread - my problem is a noisy transformer. I have measured approximately .75 volts of DC on my incoming line (dedicated 30A) and plan to try a DC trap such as PS Audio's UPC200HB.
The unit makes the most noise and is most noticable when the music stops or when the music transitions from loud to very soft - unit almost growls for several seconds and then fades away. I am assuming that this is related to the class A biasing scheme. Krell had no suggestions even after I asked if DC could be saturating the transformer - they acted like they never heard of toroids and DC issues. I am feeding the amp directly with a Wadia 850 (balanced) and it is driving Apogee Duetta Signatures (Audioquest Midnight Cables) Anyone experience this or have ideas? I am very happy with the combo except for the noise. Thanks in advance for any help.
The unit makes the most noise and is most noticable when the music stops or when the music transitions from loud to very soft - unit almost growls for several seconds and then fades away. I am assuming that this is related to the class A biasing scheme. Krell had no suggestions even after I asked if DC could be saturating the transformer - they acted like they never heard of toroids and DC issues. I am feeding the amp directly with a Wadia 850 (balanced) and it is driving Apogee Duetta Signatures (Audioquest Midnight Cables) Anyone experience this or have ideas? I am very happy with the combo except for the noise. Thanks in advance for any help.