Pop sound from speakers

[aHaidc]

Hello, my current system is NUC > Topping E30 > Pass Labs XA25 > Klipsch Heresy 4. I can hear a pop sound from my speakers whenever I adjust the step dimmer of my ceiling fan. If I adjust to higher number (the fan will rotate faster), there will be NO pop sound. But it will pop whenever I reduce the fan speed to lower number (for example. from 3 to 2), or go from 0 to 5 (off to 5), the speakers will pop. What can I do to solve the problem? Should I add Voltage stabilizer/voltage regulator/noise filter or anything else to get risk of it? Thank you.

 

[wwenze]

Find out which circuit breaker the fan is connected to and avoid using the same circuit breaker.

Having your audio equipment close together electrically i.e. sharing the same power strip is a generally good practice for avoiding common-mode noise.

If still fails, install a bunch of line filters between the fan and your audio stuff.

 

[aHaidc]

Find out which circuit breaker the fan is connected to and avoid using the same circuit breaker.

Having your audio equipment close together electrically i.e. sharing the same power strip is a generally good practice for avoiding common-mode noise.

If still fails, install a bunch of line filters between the fan and your audio stuff.

It is impossible to change to change to other line because the ceiling fans share the main power cord with the whole room. Look like I have to add something to get risk of the pop.

 

[RayDunzl]

What can I do to solve the problem?

How much of a problem is it?

 

[jasonhanjk]

Add aluminum foil around your fan box. See does that improve.

 

[Vini darko]

Try borrowing a amplifier thats double insulated with E core transformer (I'm assuming the pass is single insulated and torroid). That should solve the issue.

 

[AnalogSteph]

Try borrowing a amplifier thats double insulated with E core transformer (I'm assuming the pass is single insulated and torroid). That should solve the issue.

Indeed, the XA25 sports a 3-pin IEC and seems to be Class I with an earthed chassis. On an amplifier with only unbalanced inputs, that is inviting ground loop issues. The NUC may have a power supply with either a hard PE connection or a good bit of mains filter capacitance; shielded network cables may also carry a ground connection.

As indicated, this is going to require galvanic isolation somewhere.

1. The E30 does not come with galvanically isolated USB but some more expensive DACs do. USB isolators for 1.1 level data rates are quite common, 2.0 (480 Mbit/s) is far more tricky and expensive.
2. Galvanic line-level isolators tend to vary in quality and can degrade audio quality substantially if the transformers aren't good or if they are used incorrectly (anything with a real 10k:10k transformer must be plugged pretty much directly into the input, and even that may not be enough to keep capacitive loading low enough). I like the little Behringer HD400, which is perfectly adequate for consumer line level but does need an output that has lowish output impedance (no idea where the E30 ranks here) and is not particularly bothered by driving ~600 ohm loads (probably not a major hurdle for something relatively high-performance like the E30).
3. An IEC Class II amplifier as suggested (employing a transformer with shield winding for minimal mains coupling) would be the third option. Usually that's how the big Japanese manufacturers make theirs. I understand that finding something of moderate gain (XA25 was measured at 20.4 dB) with low enough intrinsic noise for the relatively high-sensitivity (~94 dB) Heresy is not necessarily trivial. You want output noise levels of ideally -85 dBV max, for a 2 Vrms DAC that means a required dynamic range of 111 dB @ 20 dB power amp gain, 117 dB @ 26 dB or 120.5 dB @ 29.5 dB... or you could use the 29.5 dB amp preceded by a 10-12 dB line-level attenuator, dropping requirements to 110.5-108.5 dB again.

 

[raindance]

Run an extension cord to another room to see if a different circuit helps.