With the speaker disconnected, short the speaker terminals. Does the problem magically go away??
Focal Kanta No. 2 Speakers hum with speaker with speaker cable disconnected
Hi folks,
I'm a new member, and I couldn't find a solution for the specific issue I'm having on google. I'm thinking maybe someone here has any ideas on this weird issue.
As the title states I've stated noticing a hum emanating from the speaker's mid range woofer, specifically the left speaker. I only noticed it after upgrading my phono stage, which had a hum issue from the get go (not a ground loop or line hum evidently). Took about 2 months for my dealer and Pass Labs to send me a replacement unit. Long story short, same hum is still there, so it obviously wasn't the phono, though rotating the phono 90 degrees relative to the speaker reduced the hum. Did a bit of cleaning last week and noticed that the left speaker was humming at a very low volume, only noticeable when your ear is close to the woofer. The preamp, phono, power amp, and turntable are all turned off, yet I'm getting a hum that's unexplainable.
I disconnected almost all of my components' power and interconnect cables (Pre/Pro, Phono, DAC/Streamer, Turntable power supply) one by one hoping that any source of interference/hum could be identified. I also disconnected a separate power strip that powers the Router, TV, Philips Lights, and Apple TV with no change in the hum. For reference, my audio gear is fed by a Puritan Audio PSM 1512 mains purifier, pretty clean power.
For some reason I decided to disconnect the speaker cables to switch them around and there I noticed that the speaker is still humming very faintly with no speaker cable connected. My thinking at that stage that it might be some sort of wireless interference, so I unplugged anything that has bluetooth/wireless functionality. All of the audio components were disconnected from power as well. I noticed then that it's the exact same hum that the phono has been plagued wit all this time, but amplified at a much higher level. Maybe the phono cart is picking up this minute hum and sending it to the phono. I left the speaker for an hour to see if it discharged any of the crossover components that might be causing this, nope, still humming. 6 month old speakers so I'm thinking it's unlikely a bad cap, although possible.
I'm really out of ideas on how to sort this out. I did experiment with grounding wire paths, and ground lift adapters/DC blocking adapters when I thought the issue was with the phono stage, was not successful. Anyway any thoughts or ideas would be greatly appreciated.
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- 27 posts total
Swap the speaker positions (place the right speaker in the exact same spot to the half inch). Does the right speaker now hum and the left stay quiet? If so, then there is something inductively coupled to the speaker. Is there a basement underneath? There may be an alarm panel under that location. Or a loose wire connection in an electrical junction box (especially a 240V feed) under the speaker or in a wall near the left speaker. There is no way -- other than inductive coupling -- a speaker cone can move if nothing is connected to the terminals. If the left speaker continuous to hum after swapping places then call an exorcist. |
@mofojo the hum is independent of the phono. I did unplug the phono’s power and umbilical cord, so zero power. I think this hum is what’s causing the phono to hum in the first place. @erik_squires Thanks Erik! I give it a try. @gs5556 You might be onto something, the electrical wiring is indeed 240v and running through the wall approximately the same height same as the speaker terminals. Maybe the power line is emitting RFI/EMI in this instance, and the speaker is picking it up. Left speaker is around 3ft. off the back wall and 2.5ft off the side wall. |
In the Stereophile review of the Wilson SabrinaX, JA noted that they hum even when not connected to anything. I was stunned that such an incompetent design would be released. Even if it were masked while playing music, it’s still noise. your speaker is apparently picking up an external field. I suppose you could cover the speaker with mu-metal, but… |
Yeah it's troubling to hear that even speakers at Wilson's price point can have design flaws that cause it to pickup interference.
I think @erik_squires nailed it. I shorted the speaker terminals and indeed the hum dissipates completely. I'm not knowledgeable enough to make a diagnosis, but this kind of points to an internal issue, possibly a leaky/noisy cap? By shorting it, I guess it's being discharged, so no humming. The phono hum is hopefully going to be resolved if this is sorted. Right speaker is silent, so it's just limited to a single speaker.
Thank you all for the suggestions and help. It wouldn't have occurred to me to try out some of proposed tests. I'll reach out to my dealer and update him on this, hopefully he can source a new crossover and install it.
Regards, Faisal |
- 27 posts total