Audacity Forum

kozikowski wrote:What kind of answering machine do you have and how do you have it connected to your computer? Is the computer a laptop? Can you record a short piece on laptop batteries only, no wall power, and see if the hum goes away?

GE with built in phone (old fashioned large handset). It's a digital recorder. Laptop on battery power with the hum. Netbook, actually, to be technically correct.

Koz

kozikowski wrote:What kind of answering machine do you have and how do you have it connected to your computer? Is the computer a laptop? Can you record a short piece on laptop batteries only, no wall power, and see if the hum goes away?

Koz

kozikowski wrote:Let's assume a Magnetic Pickup since that's how most of these machines work. The earpiece in a telephone handset is highly magnetic and it throws off serious sound magnetic fields while it's working.

However, magnetic pickups like this also love to pick up Everything Else. Do you have fluorescent lamps in the room? How about compact fluorescent bulbs? Does it change if you turn all the lights off?

Does the hum change if you move the answering machine and and computer to another part of the room?

Get Audacity to monitor the pickup out loud and wave it around the room to see where the worst hum is. I live under city power lines and there are parts of the house I can't use for recording because of the buzz.

First Aid for this problem might be cleaning the connectors. If you have a mini stereo audio cable like this (top one)...

http://www.kozco.com/tech/audioconnecto ... ctors.html

Pull it out and clean it with alcohol-based glass cleaner, dry it and plug it back in again.

Do you have a model number for the pickup so I can look it up?

Koz

ktot wrote:Totally rural, off the grid,

stevethefiddle wrote:

ktot wrote:Totally rural, off the grid,

So where does your power come from?

Since you are using a Netbook, could you try making a recording with the pickup somewhere outside of your home (or wherever it is that you are using this). No need to use a telephone, we just want to see if the source of the hum is localised or if it is picking up the global "mains hum".

stevethefiddle wrote:It's not irrelevant if you're sitting on top of/under a generator. Neither is it irrelevant if the power is significantly non-sinusoidal as this would produce significantly greater EMI. If you can test the equipment at a totally different location then we can rule out localised EMI effects. Until we rule out that possibility there is little point looking elsewhere. If the effect IS caused by EMI and you can't get away from it when making your recordings then we need to look at managing the symptoms rather than finding a cure. If the effect is not caused by excessive EMI then it looks like you may have some faulty equipment (most likely but not definitely the pickup).