Do they make a hissing noise when the NC is activated but they are not plugged?
1783230
Yes, that is an integral part of NC on all NC headphones. However, it is not loud, and it really is easy to not notice. It's the NC hiss that actually cancels out the outside noises. Therefore, these headphones are GREAT for airplanes and other noisy transportation. If you use them on an airplane you will notice that the engine noise almost disappears, and you will be able to hear the overhead announcements very clearly as a result.
533485
If you use the sleep mode it is a low hum but I usually can't tell it's on. On regular mode just sounds like a fan.
253873
I have two of these, and one emits a high frequency sound, but it is slight. I believe I've only noticed the sound when the transformer was on, not when it's just plugged in and off.
897406
No. I've owned two of these and they do not make noises unless you touch them while on.
1596300
Your source is doing that. Try plugging it in a different device. Hiss gone, guaranteed. (Late answer, but might help future inquirers).
1688167
Yes I have the same hissing sound on my unit too. Not too excited about it either. I am from Canada, and shipping it back and forth to the USA will be too much of a hassle and too expensive to do, so I'll just keep it as is. :-(
1633717
No noise or hum - I forget it's even there unless it's doing it's self test (about 5 seconds) then it's quiet again. South Florida.. we have lots of power interruptions and it's been a blessing.. I know it has saved my computer time and again.
1861239
Never have heard anything , but hums or noises could be resistance... either from outlet or heater unit itself.... but noise shouldn't happen.... prob wanna get that checked
1864332
no it is not normal. I get the hissing sound until i turn off the puck(i.e. I touch it). The hissing with power on appears to happen with most computers and speakers, until the speakers are turned off.
823639
I'm not having grounding noise issues. Are you sure the feeding devices are properly grounded?
1463100
I had this happen to me whenever the speakers were on, charging, and the headphone jack plugged in to the computer. If it is off and only charging, there is no noise emitted at all.
769811
This is not normal. I have the speakers and they do not buzz when there is no sound output.
2144740
I never unplug any of mine. They have been plugged in since I installed the unit.
1633716
I don't hear any noise or hum from any fan. The only thing that i didn't like is that when unplugged or the power goes out for any length of time there is a loud alarm until the power comes back on. Kinda annoying! but that is the only problem i have with it. Otherwise it is a great backup battery for my TV and cable box.
2201777
I have noticed this behavior before, it is entirely normal for any (if not all) headphones that use active noise cancellation. Generally, the cancellation sound is unnoticeable or very faint (and goes away with music, speaking, etc...). I have noticed that while rare (for me) the low-grade noise that you hear from the NC is turned on can raise in pitch slightly. Moving to a different part of the building or even room can help if this occurs.
878946
Yes, very quiet. Maybe a very slight click when the turn on, but when they are just plugged in there is no sound at all.
2231420
They're not noisy for me. Is it the lights themselves, or the power supply you're using?