Recording thunder.

Question

Hi all

Yesterday a massive (for Denmark atleast) thunderstorm was passing a great deal of the country. 40000 lightning strikes was recorded from midnight to noon. It was wild to say the least.

I was recording much of it. Having my 702 turned on the most of the day, with a 416, and AMbient Emesser in a Rycote zepp and fur. My pres was set to 45db on the 702. Apx. 12 min past 12 :) and the limiter was on.

Some of the close hits made my headphones crackle a bit, I thought it was just the headphones, since the 702 meter wasnt clipping, and only just making the limiter work on the closest ones.

Today I was very exited to go to the studio and have a listen....... Only to be very dissapointed. Most of the strucks were useless. The recordings were crakling alot.

I now have multiple hundreds of thunder strucks that are absolutely useless:(

I guess my question to you are, if you can see somewhere in the recording chain where I have gone wrong?

Thanks alot

Best wishes

Mikkel

PS: Here is a link to soundcloud with some samples of it all: http://soundcloud.com/gimaudio/thunder-recording-samples

Answer 1

Hi Mikkel, Not familiar with your particular microphone system, but I use the SD702 with different mics. However I tend to use a different rig for recording thunderstorms and know the problems caused by reasonably distant strikes let alone powerful close strikes. I would suggest you have two problems - Firstly your gain levels are set too high. EG: Today I have just recorded an 80 truck convoy passing by with their horns blasting away, but these are not as powerful as a close thunder strike. I just had the clip light show on one occasion with the following settings on the SD702 using a matched pair of Rode NT5s: 30dB gain (10 'O'clock), gain range 'normal', limiter 'on', but with a low-cut set at 40Hz, 12dB/Oct. This is possibly your second problem; I have noticed low frequency sound will swamp the input on the 702, by cutting these low frequencies you will reduce the tendency to overload and clip. Even though the limiter is set 'ON', it does not necessarily mean that it will prevent distortion! I love recording thunderstorms and can never seem to get enough of them, however recording them is one of the most difficult aspects of field recording, as you never know where, when, or how loud the next strike will be. Just think what it should be and take another 10dB gain off! - just a guess - Best of luck

Answer 2

Hi Mikkal,

It's curious that your meter wasn't clipping and you were still picking up the crackling. Perhaps you picked up some static discharge?

May be helpful to look into VLF phenomena: http://en.wikipedia.org/wiki/Radio_atmospheric

There is software to remove various levels of static and hiss. Waves Restoration plugins are fantastic.

Answer 3

I would suggested using an inline pad on the mic to knock back the levels.

I would also y split the signal and run one channel 10 dB quieter than the other. This is worth doing even if you are not worrying about distortion as you increase the recorded dynamic range. If I am really nervous I will use a 20 dB difference. Just be careful not to send phantom power down both channels.

The distortion might be due to the mic as well as the limiters not being fast enough, the attack time for the 702 is 5ms.

As a general rule if you hear distortion assume that it is being recorded, as meters can never be fast enough to catch everything. Typically the ballistics of a PPM meter are around 5 ms, so if the peak is shorter than that it might not show up on the meter.

Answer 4

Hi Mikkel I was actually on a boat in Tunø when the storm hit. It was quite an incredible storm to say the least. If you know anything about winds then we registered 44 knots, 22 meters/sec or Force 9 (storm force).

I had my recorder and mics with me but unfortunately as we were being rocked about dramatically, and the rain was horizontal I felt it was a bit to dangerous to go out and start recording. I regret not trying though as I'm sure I would have got some great stuff.

I have been recording other things during my sailing trip so hopefully there will be some other good stuff to make up for not recording the storm.

Answer 5

Hi,

There is a really nice article/vimeo on www.designingsound.org He has some interesting ideas about recording weather etc.

http://designingsound.org/2011/08/frank-bry-on-rain-recording-north-country-rain-hd-library-available/

Answer 6

Definitely sounds like the preamps overloading (input gain too high...someone suggested a pad on the input, that would likely help) or too high SPL for the 416 (possibly a dynamic mic like an SM57 would be better, or 421, but then you'd loose some of the detail).