DIY Audio Projects Forum

Hi all! My name is Greg, located in St. Louis MO- USA. I am a Security and Fire Alarm / Low voltage technician, and have been for nearly 20 years. I am trying to find a circuit to build that could best be described as an automatic volume control, or maybe a small, simple version of a compressor/expander used in pro PA systems to control/even out levels from microphones.
What I want it to do is control volume levels from my entertainment system to put a stop to the annoying practice of cranking up the audio levels of commercials that blow people out of their chairs. I would like it to boost the output level slightly to match levels from other components in my system. (the output of the cable box is lower than cd player, hd radio tuner, computer input, etc.) I have to remember to decrease volume on amp before switching to radio tuner during a commercial, or I blow myself out of the chair.
Apparently, there is legislation before our government to outlaw this practice, but I'm not holding my breath on this! Does anyone have any ideas, as I'm sure someone smarter than me as built one!

Hi Greg and welcome to the forum.

In the US a law just passed on this, the Commercial Advertisement Loudness Mitigation (CALM) Act .
http://arstechnica.com/tech-policy/news ... a-year.ars

Sorry, no suggestion for an automatic volume control.

Cheers

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[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]

Most modern TVs already supposedly have this technology. Magnavox ran a series of commercial spots touting the technology (Smart, Very Smart" campaign). From my experience having 3 different (RCA, Magnavox and Sylvania) sets that supposedly have this technology, it doesn't work very well. Since the best effort that can happen is volume averaging, if you have alot of very loud commercials you just wind up with a "nominal" reduction in volume. It's aggravating. Why commercials are driven so loud is really beyond me. Don't look for this new law to have any meaningful affect either. If it's anything like most laws that already exist, there are so many loopholes and ambiguities that it will be rendered unenforceable.

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The key to a successful build is to keep the smoke IN the circuit.
-Les

We cannot solve our problems with the same thinking we used when we created them. - Albert Einstien
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LM380 Bridged Guitar Amp, Oatley K301 Phono Pre-amp, Oatley K272 Headphone Amp, Tube proto-board