Stella Phono Preamp Humming Noise

I purchased a brand new Stella phono preamp from PSAudio back in May of this year but it had audible humming noise from the listening position (around 7.5 ft) from the speakers. I was able to get a RMA returned that unit back to PSAudio and I received another unit in beginning of October. The second unit also has a humming issue but it is more noticeable from the left channel louder then first unit. I am not sure if this is just my bad luck or sometime from the AC is causing the humming. By the way the humming would present with or without the phono cable attached to the Stella phono preamp and the noise would go away when I muted the phono preamp. Previous to purchase the Stella, I use Project Phono Box RS and Musical Surrounding Phenomenal phono preamps without this humming noice issue. I am posting here in PSAudio Forum to see if other people has similar experience like mine and what solution help to resolve this humming issue.

My set is VPI Prime Scott with Hana SL cartridge, Transparent RCA cable with separate grounding wire. Stella phono preamp setting is, MC medium gain, load resistor at 200ohm. Stella output via Cardas Reflection XLR to Pass Lab X1 or Toppling Pre90, X1 or Pre90 to Krell KSA200S with Cardas Reflection XLR and Cardas Clear Sky X4 speaker cables to B&W 801N. Therefore I am not sure if the humming is from the phono cable EMI pick up from the turntable to Stella. I also does not have any ethernet switch in the same room and I have tried to move it away from other components but still had the humming.

When playing music the humming is not quite noticeable expect at the blank area between music. It just bothers me for a $2500 priced phono preamp would have this type of issue and my much less expensive preamp is more quiet.

By the way, Stella phono preamp sounds great with dynamic, bass impact, transient, musicality and etc., it is much much better than my other phono preamps.

I appreciate anyone can suggest any idea to get rid of this humming noise. Thanks in advance.

Tin Man

Hi @tin_man.wong,

Have you gone through these steps, including the link to the extended list of steps?

1 Like

I also had humming problems although I have a different phono preamp. I found it’s the phono cable from the turntable to the phono preamp. It was a Cardas Golden 5C RCA cable. When I grab the cable with my hands, the noise would change. I cure the hum with a WireWorld RCA interconnect. It had better shielding than the Cardas.

I don’t know it helps or not but let me tell you my case.
My Steller Phono picks up a local radio station at MC position. MM has no problem.
I don’t have this issue when nothing is connected to the MC input. Only when phono cables are connected. I also tried to disconnect the cartridge side. With or without cartridge, I still hear the radio station so the issue in my case is the phono cable (Cardas Clear Cygnus) acting like an antenna. GND cable is connected to the Stellar Phono’s GND post but it doesn’t help.
What I did is added an additional GND wire from the Steller phono to the other components GND post. This drastically dropped the noise level and I can no longer hear it from my listening position (around 7.5 feet from the speakers). Not perfect but it’s good enough for me.

It is possible that there is an AC polarity difference between your Phono and Preamp as they are both 3-prong grounded units and you are using XLRs. I would try the AC Cheater Plug test as well as compare inserting it in both directions to see if it diminishes. I would also try using the RCA unbalanced connections instead of the XLRs to see if that changes things.
Finally, I would test with shorting plugs into the input selected. This will help determine if it is induced hum. With those three test results the problem should be decipherable.

Thank you all for the feedbacks. I have tried without the cable connected to the Stella but the humming noise is still present (no change) and the noise would stop when I hit the Stella mute button. I have tried different cables between the preamp and power amp so I am pretty confident that I had rule out other elements.

Unfortunately, those tests are insufficient to pin down the source of the hum. Running without an input vs. using shorting plugs can yield different results. This is why SNR test are usually run with inputs shorted. The Mute button shorts the outputs which does not yield much information. Additional tests beyond the plugs would be to check whether the hum increases with the gain setting? Does it still exist if you select MM input? Finally, I would check if the hum is there when you use the RCA phono inputs between your Phono Preamp and Line Preamp? I have seen hum induced into the XLRs feedback into the output section of the source component.