dBx 303 A Schematic

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mediatechnology
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dBx 303 A Schematic

Post by mediatechnology » Sun Feb 12, 2017 9:02 am

This is the dBx 303A schematic showing the discrete transistor Blackmer® VCA and RMS detector based on a CA3083 array.

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dBx 303A Schematic

Large format: http://www.proaudiodesignforum.com/imag ... Actual.jpg
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JR.
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Re: dBx 303 A Schematic

Post by JR. » Fri Feb 17, 2017 10:56 am

Old school logger... 1974 so early days.

JR

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mediatechnology
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Re: dBx 303 A Schematic

Post by mediatechnology » Fri Feb 17, 2017 11:05 am

Someone may need to repair one.
"There does seem to be a pattern where, the more difficult a truth is to stomach, the higher the hysteria levels go internally at Google."
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JR.
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Re: dBx 303 A Schematic

Post by JR. » Fri Feb 17, 2017 11:41 am

Back in the day I would devour schematics like this to learn circuit design. While I do not recall seeing these particular ones. I saw some similar tricks in Buff (Alice/Valley people) schematics. Not many designers were fluent in logging circuits (while the Nat Semi app notes did have generic designs to help sell their precision transistors (LM300?) for logging application.

Back in 1989 I got a patent for a variant class A VCA(US04818951 Roberts), this stuff by Blackmer was way ahead (Class AB) even back in the '70s, but that was before dbx/THAT corp decided to share technology.

JR

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