Help request for noise induced into microphones from Dyson Airblade hand dryer

[Big Valley Audio]

Hi DIYers,

I’m looking for some help with an issue I’m having at one of the studios I maintain.
They have a Dyson airblade hand dryer in the washroom and when using any tube mic the studio owns ( two Manley mics and two CU29 Telefunkens) you can hear a high pitched whine at very low level whenever someone uses the hand dryer.
-All other mics are quiet, only mics that require an AC power source have the issue ( the SSL 4K power supply is filtering it all out)
-Ground lifts on the mic power supplies make no difference
-I’ve checked the building ground system pretty extensively and it is providing a very low impedance path to the main ground point from all circuits.
-All other audio functions in the building do not have ground issues (3 control rooms, one live room, a sound stage as well as offices for a record label
-The studio was a ground up build and is approximately 10 years old

Anyone have any issues with studios that have Dyson hand dryers?
I imagine any fan that operates at that high an RPM may induce noise into the power grid.

I’m going to forward to the owner numerous reports of how these hand dryers create a “germ bomb” when they are operated in any bathroom they exist in due to the amount of air flow they create so maybe they will decide to switch to paper towels

In the meantime any thoughts or suggestions would be appreciated!

Thank you

 

[NOON]

More likely coming in on the active than ground. Do you have a power filter you can plug in between the wall and the mic psu? Adding some filtering internally to the power supplies is likely the answer, although getting rid of the dyson is a great idea too.

 

[Big Valley Audio]

Thanks for the reply NOON,

I agree it definitely does seem to be coming down the hot or neutral line and not the ground.
Do you have any recommendations for inline power filters?
I looked at a bunch of them online but they all seemed very short on any kind of specs.

Thanks again

 

[Ike Zimbel]

I just dealt with a noise issue in a Manley mic, which I'm pretty sure was the cellular issue that we've discussed before. Something that helped a lot was adding a couple of ferrite clamps around the mic cable, one at the mic end and one at the PS end. Might not apply in this situation...but it might. Maybe adding those to the AC wiring for the Dyson might help too.

 

[Big Valley Audio]

I just dealt with a noise issue in a Manley mic, which I'm pretty sure was the cellular issue that we've discussed before. Something that helped a lot was adding a couple of ferrite clamps around the mic cable, one at the mic end and one at the PS end. Might not apply in this situation...but it might. Maybe adding those to the AC wiring for the Dyson might help too.

Yes the cellular issue! It’s now even affecting our C band satellite feeds. The government just keeps reallocating bandwidth to the cell companies.

I will definitely give it a try next time I’m there. It can’t hurt.

Thanks Ike!