Quanta Mechanic wrote:I got a pair of Dave Clarke H10 30 off eBay.

Everything is ok on the ground, but when in the air a loud white noise creeps in .

It gets better when the window ports are shut, but then slowly creeps in again.

You can hear the air /engine and I have to keep putting my hand over the mic.

Anyone know why this is happening and how to fix it?

Sounds like the mic is maybe hot all the time, can you adjust the squelch anywhere?

Ian

One other thing to maybe check is that the hole at the back of the mike isn't blocked as this is what provides the passive noise cancelling. If it is blocked, all the engine/air noise is through the front (mouth facing) holes and would require a high squelch setting.

FlyingBoot wrote:... the hole at the back of the mike isn't blocked as this is what provides the passive noise cancelling.

How's that work?

Rob P V2.0

Rob P V2.0 wrote:

FlyingBoot wrote:... the hole at the back of the mike isn't blocked as this is what provides the passive noise cancelling.

How's that work?

Sound = pressure variations. The hole ensures that ambient pressure (including background noise) is the same both sides of the mic element (a metal or ceramic disc) and cancels out, but the voice is only one side, hence only the voice is detected.

Simples.

I had exactly the same problem as the OP about 20 years ago and clearing out the accumulated gunk from the mic (both sides) fixed it.

As well as all the and above, check that the mic sock is in good condition - it makes a massive difference to the amount of wind noise picked up by the microphone.

Also that the mic element inside the sock is correctly aligned - it can rotate without you noticing. The side with mic element needs to be very close to your mouth and pointing at it. A few millimetres wrong can make all the difference.
I just checked a pic of the model in question and it doesn't look as if rotation of the element should be a problem as it's held at the base where it connects to the arm. OTOH this sort can easily allow the Mike to fall away from the correct position. The way the problem is described suggests that it might be moving about. Time to tighten up a few screws and nuts maybe?
I'm a bit confused by the OP. Is it white noise or engine/airflow noise? If the first then you're maybe looking for something wrong with the electronics, if the latter then more likely mechanical as discussed above.

For a moment, I thought this was about the voices I occasionally hear in my headset!!

What’s that all about?

There is a replacement available:

https://store.davidclark.com/dc-1a-micr ... -12948g-14

Spec says that it is a dynamic mic - modern mics are typically electret. If the radio / intercom is set up for an electret mic then it may not work properly.

Looking at the spec it does seem to suggest adjusting the mic gain to suit your installation.

What radio / intercom are you using?

Yes, you could change the mic. Might be worth getting in touch with Flackwell Electronics - its exactly the sort of thing they do.

That said, I would probably fiddle with the gain first.

This reminds me (a bit) of a guy who ran the previous airstrip I was based at.

He had a whole drawer full of ‘cheap’ headsets purchased off eBay and similar places. When the time came to go flying, likely as not the chosen headset would not perform as expected. There would be some wiggling of wires, changing microphones etc. and maybe it would work, maybe not.

If ‘not’, another headset from the collection would be put into service, with variable success and so on. Perhaps 20% of flights were cancelled due to headset unservicability.

From time to time, additional ‘bargain’ headsets were added to the collection, with, unsurprisingly, no significant impact on overall servicability.

I took my cue from this and purchased two brand new Bose headsets. I updated these 15 years later and I’m sure my overall cost of ownership has been significantly lower than the ‘budget’ option.

And, I get to fly in relative peace and quiet with great audio quality.

P

Honestly - with all of this chat, knowing this is your second flight, I'd chat it though with your instructor. The white noise is the squelch being lifted on the intercom. A slowly increasing white noise could be the squelch being lifted slowly by the intercom as much as your microphone producing increased noise. You also wont be able to test anything without being within the aircraft.
All that might be required is to slightly tweak the squelch knob on the intercom.