Hum fun (trouble with amp hum and buzz)

Hi-Fi Corner
1

I may be stepping down a rathole here, but here goes…

When turned up about half way on volume (12 o’clock) there is very audible low frequency hum through my speakers from the NAC202:

  • from the AUX 1 input both channels - stops when cable removed from DIN
  • from the CD input, remains on left channel when CD switched off, but stops when the cable removed from DIN
  • loudish hiss from AUX 2
    All other inputs are fine

Is this normal? Is there much can be done?

2

We need to know what your system is:

All components connected to the system, what is connected to what, and what are the settings on the preamp (e.g. use of the AV setting).

3

No, it’s not normal - you probably have an earth loop that is broken when you plug your DIN lead.

4

Apart from the CD you haven’t clarified what is connected if anything to the other cables. Nor have you clarified whether the CD player is a Naim or other make. If the cables hun with nothing connected then it may be that the cables themselves are the problem, not adequately shielded. On the other hand if they are connected to something it could be either a ground loop or a fault with the source, or the cable (disconnect the cable from the source to identify whether it’s the cable). Regarding ground loops, have you tried changing the settings of ground lift switches on whatever items have them?

5

What source and speakers do you have? 12o’clock is way louder than you could actually play music at with a typical modern source component and speakers, at least for most systems, rooms and ears. So maybe it’s nothing to worry about at normal listening levels? Having said that, if I turn my preamp up to 12 o’clock the speakers remain silent, with only a faint hiss if I turn it to max volume, so maybe there is something worth investigating.

6

Thank you. Sorry for the vagueness, my technical knowledge isn’t great, but here goes…

Inputs into 202 are:

  • CD5x
  • Apple airport express (output 2.5mm jack) connected to tuner DIN input for some streaming
  • tape input unused
  • av input unused
  • TV set top box (twin phono output) to DIN aux 1 input
  • turntable to Naim stageline to aux2 DIN input
  • Flatcap2 powers 202 and CD5x
  • original Naim power and SNAIC cables, power cables are bundled into one single power plug (3 pin square)
  • Naim Allae speakers and NACA cables

Xanthe, thanks for the question, can you explain more on what you mean on the 202 settings?

Chris, completely agree that 12 o’clock is way higher than I’d ever attempt, so perhaps the buzz is a non-issue and I should be getting concerned, but I wonder if it would improve the overall sound if I identified the source of the buzz and removed it.

As a reminder, here’s where the noise is found when 202 volume is up high (with nothing playing):

  • from the AUX 1 input both channels - stops when cable removed from DIN
  • from the CD input, remains on left channel when CD switched off, but stops when the cable removed from DIN
  • loudish hiss from AUX 2
    All other inputs are fine

Thanks again all

7

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