[Early B.]

I have a dedicated line for my audio system. However, whenever I turn the space heater on in the bedroom on the second level directly above the audio system, the preamp starts to hum.  Why?

(NOTE: my preamp has a separate power supply and it doesn't have an off switch, just a mute button, if that matters.)

Thanks.

 

[nature boy]

Your preamp hums because it hasn't learned all the words to the song yet😁.

NB

[RichPark]

Beat me to it

[RichPark]

Is the him mechanical? Or does it come through the speakers?

[twitch54]

Is the him mechanical? Or does it come through the speakers?

thinking the same thing. Even tho you have a dedicated line for your audio is it on the same down leg in your breaker box as the bedroom outlets above ?

[Early B.]

Is the him mechanical? Or does it come through the speakers?

No, it's not coming through the speakers.

[Early B.]

Even tho you have a dedicated line for your audio is it on the same down leg in your breaker box as the bedroom outlets above ?

I have no idea. I have a sub-panel in the basement for the dedicated line, but I don't know how that panel is hooked up to the main panel. 

[richidoo]

Electric resistive element Heaters emit EMF. Not surprising since they are a long wire with 120V  60Hz signal on it.

Preamps are very sensitive to EMF. You could try metal tube shields.

[Early B.]

Electric resistive element Heaters emit EMF. Not surprising since they are a long wire with 120V  60Hz signal on it.

Preamps are very sensitive to EMF. You could try metal tube shields.

It's a solid state preamp.

[zimpah]

your hum is probably due to a bad ground, or a grounding problem.  Which could be caused by a million things.  Make sure your analog terminals are clean (use alcohol), make sure your cables are reasonable quality and are well insulated, try to keep power cables away from analog audio/video cables, and make sure your ground cables are connected nice and tight.

[dB Cooper]

https://avahifi.com/products/humdinger-dc-line-blocker

[Early B.]

Found out the problem:

DC on the line is caused by things like an electric heater that is only running at half power and so only using half of the AC waveform. That causes that half to be lower amplitude- thus the DC on the line.

When I turned my space heater on full blast, the hum disappeared.

[avta]

Good catch. You might see if you can plug the heater into a different plug ie line or do that with your audio equipment. It’s trial and error but you might be surprised.

[jjss49]

https://avahifi.com/products/humdinger-dc-line-blocker

^^^ this ^^^ 

[Early B.]

https://avahifi.com/products/humdinger-dc-line-blocker

I'm looking for a DC blocker that doesn't require plugging any of my gear into it. Maybe something that plugs into the same outlet that redirects DC from my power conditioner, if such a thing exists.   

[Craig B]

From the avahifi website:

"What the HumDinger will not do: Reduce the hum you hear out of the speakers." They make the point very early in the product description that it's intended to reduce mechanical hum, and not electronic like the OP's problem, now apparently resolved.

[charmerci]

Found out the problem:

DC on the line is caused by things like an electric heater that is only running at half power and so only using half of the AC waveform. That causes that half to be lower amplitude- thus the DC on the line.

When I turned my space heater on full blast, the hum disappeared.

Is this the same reason why I hear buzzing on those (old?) rotating light dimmers placed where room light switches are?

[twitch54]

turn your thermostat in the house up so you don't need the space heater !   

[richidoo]

https://www.amazon.com/dp/B002G51BZU/

Keep the window open a crack

[twitch54]

https://www.amazon.com/dp/B002G51BZU/

Keep the window open a crack

LOL, just what you don't want to trust, some Chinese made POS !