Questions tagged [hum]
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33 questions
4 votes
5 answers
1k views
Why does grounding eliminate mains hum but not radio signals?
I'm a mechanical engineer, so my electrical knowledge is limited, but I still don't understand the grounding of antennas. The strings of a guitar will produce interference with the music signal ...
- 127
0 votes
1 answer
170 views
Mains hum in TDA7265-based active loudspeaker
The old pair of M-Audio Studiophile AV40 active speakers (one box containing all the amplifier parts and the second is just a passive box) I have have developed a clear low-frequency hum. This hum is ...
- 1
2 votes
0 answers
43 views
Why the induced noise is sometimes additive but sometimes works as a constant?
Why sometimes the noise (e.g., induced 50hz hum) is added to a useful signal (thus increasing its 50hz value), but sometimes it works as a noise floor - has a static value and can be overpowered by a ...
1 vote
0 answers
57 views
Alternate values of high pass filter isn't working, even though gain, phase & transient response is almost same
I'm trying to design a high pass filter to remove the humming noise (around 50-60Hz.) If I use alternate values, it's not working. It's the recommended value from a YouTube video (470pF, 5.6Mohm.). ...
2 votes
2 answers
140 views
Hum without ground loop
I have an audio measurement system. The system is connected to and powered by a laptop. The system has no other connection to the AC grid. Now, if the laptop is connected to the AC grid and i measure ...
- 151
0 votes
1 answer
150 views
Locating the source of a persistent 120 Hz hum in amplifier
I'm working on rebuilding a subwoofer amplifier. The caps have been replaced, the corroded press-on tabs for transformer and speaker connections have been replaced. Upon reassembly, the amplifier ...
0 votes
2 answers
557 views
Loud hum when input is connected to amp
I've just built a JLH 1969 amplifier kit that I bought online. When connected to the stereo output of my phone (isolating one channel at a time) the amp works fine one channel at a time but when I ...
- 143
0 votes
1 answer
645 views
Grounding Li-ion battery pack to stop amplifier hum
I'm trying to connect a tube guitar amplifier to the Delta 1300 W battery pack by Echo Flo. The pack is not grounded, so I get a hum. Echo Flo suggested connecting the amp to a power strip, then ...
- 9
3 votes
2 answers
880 views
Can appliances or wiring hum at frequencies of 500Hz and above?
I've been hearing this strange continuous hum in my apartment for a while now. It is a small apartment and the hum is present all throughout with varying intensities, so I can't really infer from ...
0 votes
2 answers
360 views
Subwoofer hums when no audio source is connected [closed]
The hum stops as soon as an audio source is connected or any metal part of the subwoofer is connected to the ground of a socket. Does anyone have any idea what the problem is?
- 1
1 vote
0 answers
52 views
Connected my audio input to two music systems by splitting the input, but the one with subwoofer produces continuous 100Hz hum
I have 10 year old Creative 2.1 audio system that has fairly capable subwoofer, and combined its input with a TPA3110 2x15W stereo amplifier module (for better treble). When both systems are powered ...
- 11
1 vote
1 answer
1k views
why does my USB 5V power supply not need a mains ground?
Every small 5VDC power supply (wall wart style) I see has the standard 2-prong Europlug, i.e. no ground. Even those with a British 3-prong plug just use a plastic prong for ground. Background - I am ...
- 11
0 votes
1 answer
812 views
I have a single phase induction motor, with no capacitor, and can't see the shaded pole. Can you help me understand how it starts or should start?
I have a small single phase, induction motor with no capacitor. It's not missing, so this has got me thinking it should be a shaded pole. However, I don't see the shaded pole and my motor is just ...
- 103
0 votes
1 answer
878 views
why does household ceiling fan electric motor hum?
I'm interested in the technical reasons behind why an inexpensive ceiling fan in a home would hum, such that when in your bedroom above your bed on low speed is annoying. Is there a better type of ...
- 151
6 votes
2 answers
2k views
Troubleshooting Hum in a Tube Guitar Amp
I have a Fender Deluxe Reverb Reissue guitar amplifier that hums whenever I turn on the reverb. It sounds like loud 60 cycle hum. The reverb effect is still applied, but is accompanied by the hum. ...
- 511