API Audio THE BOX User Manual
Page 22
API “The BOX”
Operator’s Manual
22
The combination of Walker's incomparable 2520 op-amp, and his "Proportional Q"
circuitry gives the 550A user an uncomplicated way to generate acoustically superior
equalization.
With the long-awaited reissue of this unit, an EQ that has had such a part in the
history of recording is continuing to make history in today's music.
Equalizer Controls:
550A EQ Curves