Mesa/Boogie graphic equalizer
Jump to navigation
Jump to search
Analysis of a Mesa/Boogie Mark IV schematic revealed the following settings for recreating the famous amp's graphic EQ.
Frequencies:
- 87.61 Hz
- 371.74 Hz
- 723.43 Hz
- 1575.87 Hz
- 4822.88 Hz
Q:
- 1.414 (ideal for octave equalizer)
- 1.3 (actual, due to component values used)
There's about 18dB of cut and 17dB of boost. This is in the ideal world, so +/- 15dB was probably the design goal. The pot response is logarithmic – i.e. most of the cut/boost is near the end of the pot travel. Also, this is not a constant Q design, so the Q decreases (or bandwidth increases) with less boost or cut. I don't know if Cliff's graphic is constant Q, but the parametric should be constant Q, given you have a Q setting.
