Categories: Technical

Interesting Passive EQ circa 1961

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?

chris

View Comments

  • 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

  • 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

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