Two chip VCA

[Freq Band]

This short Analog Devices app. note gives a circuit for a video VCA and "video keyer" (crossfades, etc.).
I'm wondering if it can be applied to audio signals ?

http://www.analog.com/UploadedFiles/Application_Notes/369680044AN-216.pdf

I have both of these chips.

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[JohnRoberts]

[quote author="Freq Band"]This short Analog Devices app. note gives a circuit for a video VCA and "video keyer" (crossfades, etc.).
I'm wondering if it can be applied to audio signals ?

http://www.analog.com/UploadedFiles/Application_Notes/369680044AN-216.pdf

I have both of these chips.

=FB=[/quote]

The -60dB noise floor doesn't look too audio friendly... perhaps a consequence of running at high current density to get good video bandwidth. THAT corp chip sets are more commonly used for GP audio VCA these days.

 

[Freq Band]

Thanks.
I'm thinking of trying this circuit anyway, to use in a modular synth. I still need to get a 1.2v reference part.....I do have some LM385 1.2v (old, nasty 'pulls'), although the AD circuit calls for a AD589.

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[Sleeper]

Hi Freq Band,
What if you pile up a couple of old television sets and get some dancing girls to swing magnets across the top of them- you need a pretty bumpin output PA to get the girls moving appropriately. this would be your sidechain.
Put a video camera in front of the tv's and rig the brightness control to compress your levels. I'll bet it would sound like a sexier version of a T4B.

Of course you might have to feed the dancing girls hamburgers and champagne now and again. this would qualify as makeup gain.

this might take up a bit of space, but there seem to be some fairchild clones on the list that aren't much more compact.

nice icon. :grin:
Kelly

 

[beatpoet]

[quote author="Sleeper"]Hi Freq Band,
What if you pile up a couple of old television sets and get some dancing girls to swing magnets across the top of them- you need a pretty bumpin output PA to get the girls moving appropriately. this would be your sidechain.
Put a video camera in front of the tv's and rig the brightness control to compress your levels. I'll bet it would sound like a sexier version of a T4B.

Of course you might have to feed the dancing girls hamburgers and champagne now and again. this would qualify as makeup gain.
Kelly[/quote]

I prefer a voltage amplifier in the signal chain wired to a cattle prod that's connected to my genitals. When I'm electrocuted, I automatically reflexively turn down the volume pot.

In al seriousness, has anyone done anything to modulate audio from video signals?

 

[King_Cruiser]

"The -60dB noise floor doesn't look too audio friendly"

Bandwidth Up>Noise Up

Bandwidth Down>Noise Down

Sample

 

[Freq Band]

.....this would qualify as makeup gain.

I always understood that "makeup gain" was what average looking women applied to their faces, resulting in "compensation".


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[StephenGiles]

It's one of the female activities usually prefaced with the word "just", like "I'm just going to the duty free"!!