Schematics for the dBx 3BX dynamic range expander. One of the first applications I saw using the non-linear capacitor.
dBx 3BX Schematic
Large format: https://www.proaudiodesignforum.com/Images/jpg/3BX.JPG (4.4 MB)
When I had a 3BX I had thought about modifying it to be a feed-forward three band compressor. Check out the derived filters and FET switching inside the OA feedback loops as well.
Wayne
EDIT: 1979 patent for 3Bx showing the non-linear capacitor: https://proaudiodesignforum.com/images/ ... 177356.pdf
dBx 3BX Three Band Dynamic Range Expander
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Re: dBx 3BX Three Band Dynamic Range Expander
That looks a little bit crazy. Probably just that they put it all in one drawing! What era is this device?
Best,
Doug Williams
Electromagnetic Radiation Recorders
Doug Williams
Electromagnetic Radiation Recorders
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Re: dBx 3BX Three Band Dynamic Range Expander
There is a second page I need to post with PSU and metering I had forgotten about.
It was early 1970's era.
It was early 1970's era.
Re: dBx 3BX Three Band Dynamic Range Expander
Interesting the ancients are stealing our ideas again...
Those active cap multipliers with diode clamps to make it fast for large changes and slow for small changes is very similar to a circuit I did in the '80s for a NR... While I added a few other tricks too, it was the same general concept.
JR
Those active cap multipliers with diode clamps to make it fast for large changes and slow for small changes is very similar to a circuit I did in the '80s for a NR... While I added a few other tricks too, it was the same general concept.
JR
Cancel the "cancel culture", do not support mob hatred.
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Re: dBx 3BX Three Band Dynamic Range Expander
Still found as the NLC in the Pico and THAT DN-114: http://www.thatcorp.com/datashts/dn114.pdfJR. wrote:Those active cap multipliers with diode clamps to make it fast for large changes and slow for small changes is very similar to a circuit I did in the '80s for a NR... While I added a few other tricks too, it was the same general concept.
Was yours in the NE570 compander we posted here?
On that note I'm tempted to start a thread on the "superbal" cirrca 1982.JR. wrote:Interesting the ancients are stealing our ideas again...
Re: dBx 3BX Three Band Dynamic Range Expander
viewtopic.php?f=6&t=252
here it is, a NE572 based tape NR
I did a bunch more than just the dual time constant C... I give a full description at the above link.
enjoy,
JR
here it is, a NE572 based tape NR
I did a bunch more than just the dual time constant C... I give a full description at the above link.
enjoy,
JR
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Re: dBx 3BX Three Band Dynamic Range Expander
That's the one I remember. Very clever.
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Non Linear Capacitor in 1979 Patent 4177356
1979 patent for 3Bx showing the non-linear capacitor: http://www.waynekirkwood.com/images/pdf ... 177356.pdf
Re: dBx 3BX Three Band Dynamic Range Expander
I grovel at your feet in awe, Oh Guru JRJR. wrote:viewtopic.php?f=6&t=252
here it is, a NE572 based tape NR
I did a bunch more than just the dual time constant C... I give a full description at the above link.