Passive audio compressor..

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Everyone should wire various lightbulbs in series with a guitar amp cabinet at least once. 
 
That´s an old trick that has been used since the early days of PA systems to protect HF drivers. There´s even a 500 product out which uses a bulb: https://www.anamodaudio.com/tlcompressorbr.html
 
I had to watch the video before posting.  :-\

I am not sure that lamps are completely passive, but they have long been used for level control (inside sine wave oscillators like that classic old HP) but more widely as protection for loudspeakers (tweeters).

JR
 
jensenmann said:
That´s an old trick that has been used since the early days of PA systems to protect HF drivers.

I learned that SWR 4*10" bass cabs use this method for horn-protection as well,
when band members alerted me on 4 illuminated circles per cab behind me: the cone edges of the 10" speakers  :eek: :D

A simple auto-lightbulb, effective.
 
JohnRoberts said:
I had to watch the video before posting.  :-\

I am not sure that lamps are completely passive, but they have long been used for level control (inside sine wave oscillators like that classic old HP) but more widely as protection for loudspeakers (tweeters).

JR

I wonder about the linearity of the bulbs when not compressing.
 
user 37518 said:
I wonder about the linearity of the bulbs when not compressing.
Not very linear...  Peavey designed an improved version where a PTC fuse shorted across the lamp when cold, so clean when not limiting. After it heats up and starts limiting distortion is relative....

JR
 
JohnRoberts said:
Not very linear...  Peavey designed an improved version where a PTC fuse shorted across the lamp when cold, so clean when not limiting. After it heats up and starts limiting distortion is relative....

JR

Nice idea!
 
user 37518 said:
Nice idea!
Not my idea, one of the lads working in transducer engineering came up with it.

I used some PTC fuses in my 1980s boosted rail power amp (PMA70+) to limit the recharge rate for the boost capacitors.  60W rms when cold, falling back to 35W continuous when slammed. Playing typical music it didn't fold back. It put out more than 60W for transient peaks.

JR
 
Back
Top