Crazy compressor idea?

Hey all.

I was sort of daydreaming the other day, and a weird idea came into my head... (I'll avoid the obvious pun)

Could a light bulb be used in a sort of compressor? ie, the signal is amplified and then passed through the bulb. The louder the average signal, the hotter the bulb, which increases the resistance of the bulb's element, which would reduce the signal.

I realise that you could not control the attack / release / ratio / anything... but... would it work?

I'm a bit of a noob, so don't crucify me.. just thinking aloud.

Kind regards
Mike

not crazy--do some poking around, it has been done before--like LA2A but light bulb will have a slower attack and release. type of bulb (incandescent, neon, led...) will determine what is needed to drive it.
see 'current' thread
http://www.groupdiy.com/index.php?topic=22083.0
edit:
dod nit read closley. sorry.
I don't think there would be much useful range. lamps are probably not very close tolerance. maybe useful as part of a sidechain/detector

This has been used successfully on some loudspeakers, to protect the drivers. The UREI 809/815 come to mind. As you say the attk/rel/ratio are somewhat impredictable.

http://www.roger-russell.com/compressor/compressor.htm
The point 2 point drawing in the linked PDF from that page is worth a look imho
[edit]
I realize the circuit use a LDR, so not really the same thing though

Gates 17 / 27 / 28 limiters from 1937-46 used lightbulb bridge along with minimal vari-mu approach. 

This will "limit".



It has been used by E-V to protect tweeters.

It needs BIG input power.

It gives very mild and slow limiting.

I do remember now that one studio I worked at had VW indicator lamps in the Tannoy monitors for protection..

So do you think the attack be too slow for something like vocals?

Regards
Mike

Urei 815's used auto bulbs IIRC. Pain in the ass to find 2 the same!

It was the lowly light bulb that made the product that launched the Hewlett-Packard company possible - the 200A audio oscillator. The varying resistance of the light bulb was used to keep the output level constant.

http://www.hp.com/hpinfo/abouthp/histnfacts/timeline/hist_30s.html

---Joe