Above, a ‘distortionless’ equalizer circuit circa 1961 as designed by one Carlos Moura. Separate bass and treble boost functions (2 frequencies each) and bass and treble loss cut. I do not know the range, frequencies, or insertion loss. Can anyone tell me if/when this was manufactured, and by whom?
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5 replies on “Interesting Passive EQ circa 1961”
I’d plug it into a Spice program and see what it does. You’re running with the big dogs when you get into filter design, which is what this is.
Gravodisc is a record studio in São Paulo – Brazil and still exists.
This unit seams to be maded for use in this studio and not comercialized I think.
Rgs
Filipe Zanella
Well sourcing those pots might be tricky…
Do anyone knows how this equalizer works?, are this equalizer balanced equalizer? this look like one balanced unit because we have two lines with passive components and one ground line too.
I have done a more clear schematic of the original schematic and if anyone want to check it, please contact to me to:
opacheco_hn@yahoo.com
I would like to analysis this schematic in order to get its transfer function and if someone want to join to this tasks, please let me to know too.
Thanks a lot anticipated
opacheco