24 Hour Outdoor Recording
 

I need to record two channels of audio, continuously, for up to 24 hours.

We may start with just an 8 to 10 hour shoot, but we want to also do the full 24 hours.

My Sound Devices 744t has been upgraded to 160GB so storage is not a problem.

I will need to power the 744t with a larger battery than normal.

My challenge is that I want to protect my microphones from dew.

The recording will be started at 10 pm, in rural South Carolina, so I can expect high humidity, and some dew by morning.

At the very minimum, I will have some protection, such as an umbrella above the microphones. But, I would think that dew could still form on the microphones.

I have the following mics available:

Two Neumann U87 ai's
Scheops CMC-641 with full Rycote
Sennheiser MKH-60 with full Rycote
Sennheiser MKH-70 with full Rycote
Neumann KMS-105
4 Tram TR-50's

I feel that the Sennheiser MKH-60 would be immune to humidity effects (as advertised), but they will not capture any very low frequency sounds.

The Neumann's would be excellent for these recordings, but I do not know how to protect them from the elements.

Our goal is to capture the sounds of nature, uninterrupted.

I am open to any suggestions that will protect the microphones and still allow good audio to be recorded.

Dan:

I assume that you will have a zeppelin on the mic? Realistically, any dew will form on the zeppelin and not on the mic element itself. You could always for for the hogs hair cover used for shooting in rain and downpour but you will sacrifice some highs.

If it were me, I would not use a Neumann, I would use the Sennheiser. The MKH-60 is a pretty rugged beast, mine has been to hell and back and is still going strong.

Dan

Dear Dan,

Thank you for your thoughts.

I agree. I do not have adequate protection for the Neumann's.

I have found that the MKH-60 and MKH-70 work well in high humidity conditions and they have never failed me.

Ideally, I would like to record low frequencies, such as deep sounds from big frogs, but this is not the highest priority.

Since I do have the full Rycote (Blimp with Windjammer) setup for each of the Sennheiser's, I think this is the best overall choice.

During the night the Windjammer may get wet from falling dew, but I will try to protect it with an umbrella.

Would it be practical to wrap a mic with heat tape to keep its temperature above the dewpoint such as is commonly done with telescope objectives? One simple implementation is a number of resistors connected in series (sealed in heat shrink tubing) and connected to a large battery. Perhaps something around 5W.

Dear Jim,

That is a very interesting idea.

I will be "off the grid", but will have a big battery so that I can power the 744t for 24 hours.

I think the full Rycote plus an umbrella will work.

I am expecting the umbrella to prevent falling dew to reach the microphone.

Then I am not expecting the windjammer to collect much dew, since it is not metallic.

The 744t will be in a tent, and thus protected somewhat.

Of course, I could be completely wrong. We will be running a test this Saturday.