Audio Ducking Amp

[Robert Reed]

Also known as "supervisory control" and really doesn't require any amps. But your explanation does shed some light about its mysterious origin.

[Robert Reed]

Well I will certainly be "ducking" the reply above me.

[MrAl]

Hi Robert,

He he, it's now been officially 'ducked' ha ha.
His/her/it's other posts have been shot completely out of the water too

[Lenp]

OK duckies, here's some thought...

A 'ducking' amplifier appears to be an accross the pond term, and not too much used here.
I think it's root is from a duck's reaction to something in the water, a quick dip down, then back up, like we duck when someone throws something.

The ducking amplifier, for example, lowers, or eliminates the signal on the program channel when it sees a signal on the cue channel. It then returns to normal program channel when the signal on the cue channel is gone. The difference between this and a paging amplifier with voice priority is that a paging amplifier generally requires an exernal input, like a PTT switch on a microphone or a contact from a telephone dial-up page system to override the normal channel.

The ducking channel feature would be ideal for switching from a normal program buss to an emergency program buss whenver audio appeared on the emergency buss. For example, a firehouse system could allow the radio dispatch call to override any other program audio being sent to the house.

Similiarly I have modules that sense speaker level audio and operate a relay so speakers can be switched between two different systems. It is typically used in school auditorium sound systems to switch the auditorium speakers from the auditorium sound system to the main building sound system in the event of a building wide announcement. If a ducking amplifier was used in the auditorium it would have to be turned on all the time to allow the switch over.

If multiple 'ducking' channels were needed I suppose any method to amplify the input audio for each channel resulting in a logic output, fed into a processor with the pecking order programmed to operate analog switches in a matrix to do the switching. Any desired delays could be set in software. Now, for the caffeine addict, just go do it in 'solder logic' and discrete parts!

Len

[MrAl]

Sorry, i just could not resist...

"QUACK"

[Bakerbones]

Hi Bob,

I am an amateur radio operator and have been working on a priority mixer that can mute or duck lower priority signals. Can you describe your ham radio application in more detail or give examples of each input for a 4-channel version? I can't decide if the priority mixer should also automatically switch the microphone to the highest priority active radio.

Thanks,
Allen

[VernGraner]

like we duck when someone throws something.

Very close.

AFAIK, the term "Ducking" is a slang term used by radio station engineers to describe a setup where a compressor/limiter is configured to adjust the gain on a music "bed", in inverse proportion to an external audio signal. This external signal is typically from a microphone spoken into by the talent reading a script. A light mention of the topic of "ducking" is on wikipedia here.

Though "Ducking" is an apt name, the process is more accurately described as "Side Chain Compression" and is detailed well in this wikipedia article.

Here's an excerpt so you don't have to click the link

Side-chaining uses the signal level of another input or an equalized version of the original input to control the compression level of the original signal. For sidechains that key off of external inputs, when the external signal is stronger, the compressor acts more strongly to reduce output gain. This is used by disc jockeys to lower the music volume automatically when speaking; in this example

the DJ's microphone signal is converted to line level signal and routed to a stereo compressor's sidechain input. The music level is routed through the stereo compressor so that whenever the DJ speaks, the compressor reduces the volume of the music, a process called ducking. The sidechain of a compressor that has EQ controls can be used to reduce the volume of signals that have a strong spectral content within the frequency range of interest. Such a compressor can be used as a de-esser, reducing the level of annoying vocal sibilance in the range of 6–9 kHz. A frequency-specific compressor can be assembled from a standard compressor and an equalizer by feeding a 6–9 kHz-boosted copy of the original signal into the side-chain input of the compressor. A de-esser helps reduce high frequencies that tend to overdrive preemphasized media (such as phonograph records and FM radio). Another use of the side-chain in music production serves to maintain a loud bass track, while still keeping the bass out of the way of the drum when the drum hits.

A stereo compressor without a sidechain can be used as a mono compressor with a sidechain. The key or sidechain signal is sent to the first (main) input of the stereo compressor while the signal that is to be compressed is routed into and out of the second channel of the compressor.

Hope this helps clears up any confusion on the term "Ducking".

Vern
(the guy who used to work at a radio station many moons ago!)