Sent this in error, just to Chris so re-sending to the list.
Have just tried it unplugged and while it isn't perfect, it is better.
Bev
On 04/07/2020 17:36, Bev Nicolson wrote:
<snip>
Also, is there anything else plugged in to the laptop, USB devices or whatever, if so try disconnecting them as well.
By the way - by 'hum' you do mean mains hum do you? I.e. a very low
frequency hum of fixed frequency.
Hopefully this short audio clip will explain the hum. I don't hear it as I record anything, but only on play back.
I have headphones and a mouse plugged in, to answer your other query, but if anything it's worse without the headphones.
Bev
On Sat, Jul 04, 2020 at 07:13:15PM +0100, Bev Nicolson wrote:
By the way - by 'hum' you do mean mains hum do you? I.e. a very low
frequency hum of fixed frequency.
Hopefully this short audio clip will explain the hum. I don't hear it as I record anything, but only on play back.
That's mains hum. Because of the way it sounds, not a 50Hz sine wave, rather a 100Hz 'buzz', its source is probably imperfect smoothing (as in electrical smoothing) on a power supply somewhere.
I have headphones and a mouse plugged in, to answer your other query, but if anything it's worse without the headphones.
OK, it probably just sounds worse without the headphones because you can hear it 'better' on the laptop's speakers.
Have you made a recording with everything unplugged? If you go out in the garden (well, away from anything electrical anyway) and make a recording using the internal microphone and play it back out there too do you *still* get the hum? I'd be surprised if you do.
Having got a 'clean' recording you should then be able to workout exactly what stage is adding the mains hum.
Have you made a recording with everything unplugged? If you go out in the garden (well, away from anything electrical anyway) and make a recording using the internal microphone and play it back out there too do you *still* get the hum? I'd be surprised if you do.
This is what it sounds like unplugged, though not in a garden away from any other electrical gubbins. (Laptop is heavy, garden non-existent etc.)
Not perfect, but as you can tell, better.
This is it unplugged, using the internal microphone. Not pretty. (The very brief noise at the very start is me, sighing.)
This probably confirms your diagnosis.
Bev.
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Bev Nicolson -
Chris Green