HUG - here for all audio enthusiasts

At its inception ten years ago, the Harbeth User Group's ambition was to create a lasting knowledge archive. Knowledge is based on facts and observations. Knowledge is timeless, independent of the observer and can be replicated. However, we live in new world in which objective facts have become flexible, personal and debatable. HUG operates in that real world, and that has now been reflected in the structure of HUG.

HUG has two approaches to contributor's Posts. If you, like us, have a scientific mind and are curious about how the ear works, how it can lead us to make the right - and wrong - decisions, and about the technical ins and outs of audio equipment, how it's designed and what choices the designer makes, then the factual Science of Audio sub-forum area of HUG is your place. The objective methods of comparing audio equipment under controlled conditions has been thoroughly examined here on HUG and elsewhere and can be readily understood by non-experts and tried-out at home without deep technical knowledge.

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{Updated Jan. 2017}
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Slight hum like sound

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  • #16
    Low frequencies from your Air Conditioner!

    Originally posted by STHLS5 View Post
    I removed the interconnects, played with the mono bridge switch and balanced/regular switch and now the speakers are noiseless.
    I am wrong again. The noise is still there but the good news is I managed to identify the culprit. The hum like sound is actually heard at certain locations in my room even with my system turned off. It only audible when the air cond is turned on. The strongest is at the room boundaries, especially near the rear right corner and from the speakers.

    Interestingly, my air cond is usually set in Ultra Silence mode and you can only hear the sound of air rushing out from the air cond which somehow changes to low frequencies sound and get reinforced at the room boundaries.

    What I don't understand is why I get the sound near or from the SHL5? Could it be the port tunes the low frequencies and output them through the woofers? It is bit difficult to pin point the exact location. Anyone, please?



    • #17
      Hi STHLS5

      Perhaps there is some sinusoidal effect kicking in and your speakers so happen to be at the peak of it. It could even be as simple as not pointing the louvres of your air conditioner towards your speaker but down towards the floor.

      I do encounter a hum in one of our rooms caused by building services, a pump perhaps, and if I draw an imaginary line (or even a chess grid) and move along it, the hum actually phases in and out (as little as 15cm) as I move in one dimension (and the other dimension as well). You can perhaps find a point where the hum decreases to a level where you can no longer perceive it. Trial and error (moving speaker and listening position) might get rid of it.

      And the last point about the sound changing, reminds me as a child sitting in front of a table fan and making sounds into it. They sound will indeed come out sounding odd.

      If all this doesn’t work, perhaps its time to ditch the cooler and start listening to music in the lightest clothing you have.


      • #18
        Originally posted by kittykat View Post
        .. the hum actually phases in and out (as little as 15cm) as I move in one dimension...
        It looks like a 1150Hz wavelength. That must be really annoying :))



        • #19
          Recently my "king" hum too when i accidently switch over my preamp selector switch to an unused (rca) output. No hum before. Switch back to connected (XLR) output the hum is gone.