Recording the sound of lightbulbs... (yes!)

[MattReceiving]

Hi,

 

My first post, so hello to one and all.

 

I'm recording various wildtracks in order to produce a set of FX for a theatre show. One effect currently has me stumped, so I'm after some wisdom.

 

I need to capture (or simulate) the ringing sound of a lightbulb filament as it glows. Failing this, the rather sharper buzz of a flourescent fixture will do.

 

The principal problem I've had so far is that the ringing is extremely quiet. Too much gain and I lose the signal in the preamp hiss. Too close with the mic and I just pickup RF mains interference from the filament itself. Equipment used so far is an MKH416 mic through either a Portadisc (far too noisy) or a MOTU828 MkII (less noisy, but still too noisy) into Logic.

 

I've tried using a domestic dimmerswitch to exaggerate the ringing, but without success. I've also tried the general hum off noisy mains transformers; same problem (too quiet, or too much RF).

 

Ultra-quiet mic pre? Simulation by synthesis?

 

Thanks for any wisdom,

Matt

[Bobbsy]

My initial instinct on this is that it's one to solve by synthesis.

 

The actually sound you want (apart from a failing filament) is at such a low level as to be inaudible at normal listening levels. Therefore, even if you manage to get a good recording, as soon as you amplify it enough to be audible in a theatre setting (above rattling sweet wrappers, the ventilation system, the coughing audience, colour scrollers, etc. etc.) it simply won't sound natural anyway.

 

For that reason, I'd try to decide in my own mind what I wanted the effect to sound like and create something totally synthetic to create the atmosphere I decided on. This might end up being very different to the actual sound...but might end up seeming more realistic to the audience.

 

Bob

[godoflight]

Have you tried recording a 1K Par 64 on 25-50%?

I find that some can be particularly noisy, also if you have the dimmer close by that will provide some extra noise.

 

I'm also surprised that a portadisc is picking up so much mains hum and other noise, is the mic lead dodgy, or poor screening on the mic?

 

If I remember Ill bring a portadisc home tomorrow and see what I can get from the above setup.

 

I do think that Bobbsy as a valid point about it not sounding realistic when amplified though and you may be best to trawl the net and effects CD's for something, try looking for things relating to high voltages etc - that usually involves a buzz.

[MattReceiving]

Thanks for the advice, Bobbsy and God (!)

 

I take your point; it's a good excuse to dig out a monosynth and invent.

 

The effect I'm after is less outright buzzing, and more the effect of an anaemic 40W bulb / dimly-lit hotel corridor sort of angle.

 

I don't think there's anything wrong with the Portadisc I'm using, just the amount of gain. I'm at nearly maximum gain on the recording level to get anything meaningful (and even then it's quiet). I'd expect any pre to get hissy at full tilt, unless maybe it has Focusrite or GML written on the front...

 

Matt

[Bobbsy]

Creating effects like that is one of my favourite parts of the job. I agree that I'd probably start with a synth on this one, probably playing with a pure tone mixed with a bit of square wave or sawtooth to add a bit of edge--or maybe a real electrical hum...but I'd have to play.

 

Maybe you should add the odd moth inside the fixture, if only to drive LX mad when they have to create a matching shadow! :(

 

Bob

[Tomo]

So the sound you want is less of a filament "ring", more a general filament mains hum?

 

Or to put it another way, you want the sound of a lamp being driven by a sinewave rather than the chopped sine given by SCR-based dimmers (the origin of parcan ringing).

 

If you're still trying to record it, I'd suggest finding a lamp with the longest filament possible - the large globe lamps in the really old floods would probably be the best bet.

You'd probably get the loudest sound near the lamp base, but the RF would be loudest there as well.

 

The sound is low at best though, so it's probably easiest trying to generate it yourself - a 50Hz sine would be the obvious starting point.

My gut instinct would be adding a little bit of 5th and onwards harmonics to that, but I could be utterly wrong!

[Seano]

You'd probably get the loudest sound near the lamp base, but the RF would be loudest there as well.

 

How about improvising a stethoscope to move the mic itself back away from the RF/induction problems?

Maybe it'd be worth experimenting with tubing, you could also try a light solid rod between the mic and the lamp (something non-conductive might be smart), or even a piece of thread under tension (like a bean-can telephone).

[MattReceiving]

Problem solved. Following a friend's suggestion of an electric razor, I used a set of Wahl hair clippers!

 

They give off a very healthy hum when they're running which sounds spot on. The added advantage is that you can adjust the degree to which the mic picks up additional RF by waving the clippers around the mic capsule; good for 'on' and 'off' changes in tone. Works a treat.

 

Thanks for all the advice

Matt

[Bobbsy]

The best effects always come from the strangest direction! I actually had a haircut a couple of days ago so know exactly what you mean. FYI, the Wahl clippers we have (at least) have an adjusment screw on the side that allows for subtle variations in the sound too...though ours are very old!

 

Bob