LCTLight said:
I working on a show that calls for a LOT of thunder and lightning on
stage. We currently have a "Thunder board" (a piece of metal attached to the wall with a rope to move it) that is made of 1/8" galvanized metal that is 3' X 9'. However, the director does not think it is big enough or the correct material to create a long rumbling thunder. We are trying to create thunder that is LOUD, it's a box set, and continues to rumble for several seconds afterwards.
Does anybody have any suggestions on accomplishing this? We're really trying to avoid recorded efx as we would rather have something live. What size is normally a good size for a thunder board? Is there any particular material that works better than any other? Your help, thoughts, and suggestions would be most appreciated.
Hiya,
wow been a long while since I had to make one of those...but from your description the sheet metal you have seems to me to be too thick and is not flexible. You want it thinner and very flexible. The size is about right--the bigger the sheet the larger resonances you can get from it. I don't remember using galvanized sheet metal--but I do recall I have used aluminum sheeting I got from a hardware store that is used in duct work--its thin and flexible. You can also use a pre-rolled and cut square for duct work--something in the 3' x 3' size. The box, if closed on one end or padded, can help make it seem lower, and the thunder is created by flexing the top or sides of the box...but thats another method. Typically tho for one of these you will screw a wood slat in the top and bottom as it free-hangs, but leave the sides open so it can flex when you shake it or slightly curve it when you hit it with a padded beater. Its like playing a saw--the angle you curve it and where you hit it changes the resonance.
Ideally you will also, for the best results, wish to mic this item, EQ it a
bit to thicken it, and pipe it
thru your sound
system. When doing that I would suggest you use a large diaphram mic that is good for low frequency's--like an RE 20 or
Sennheiser 421. To add to this--when you do this it would also be a good idea to insert a
compressor and slow
gate on the
channel so you don't overdrive/clip your input pre-amp, and don't blow people out of their seats or burst your speakers. My suggestion--use a hard knee compression
threshold, and set the ratio to infinity or at least 10:1, and a VERY SLOW
release so you get the "breathe" type
effect from the
compressor to thicken this. Works great. Best EQ for this type of thing--use a Low Pass Filter cut off around 800hz-1khz. This will allow the low frequency's only and not the higher metallic frequency's to go
thru. Give a boost in the 60hz-120hz range, and cut out some of the nasty 250 and 400 hz range that will make it sound fake. If you can route this signal to your subs and mids only--more the better. While not needing to record FX to do this effect--what you CAN do if you want to add more things to this, is also route the signal of this
thru a
reverb or delay
unit...something to give it some more
thickness in verb, or a 300-400ms delay to "double" the sound so it sounds like its echoing in the distances. You can even try a
pitch shifter dropped about 8-10 octaves. Its fun to
play around with. "Flexing" and shaking the thunder board will give you one type of sound, hitting on it with a padded beater (like the kind used for Timpani's) will give you another....again you have to
play around with it to get the sounds you want. If you use the "box" idea, just pressing into it or beating the outside works great. Also, for psychoacoustic orientation since the audience WILL hear you doing this
effect, is it helps to have this very much off-stage, or in another area, and most important--higher up--like on the lock
rail or in the catwalks since thunder comes from the sky. Know what I mean?
Any other info I can share to help you with this effect--just post back. I'm sure others will have some great input and views too that they will share.
best of luck...
-wolf