Before we introduce you to the Onyx mixers' Perkins EQ section, we should probably introduce you to its designer, Cal Perkins. Along with Greg Mackie, Cal has been the driving force behind Mackie innovations like XDR mic preamps, HR Series monitors and more... not to mention his 30-plus years of experience designing classic audio gear for other folks.

The goal of Perkins EQ was to bring the classic EQ sound of British mixing consoles of the '60s and '70s and put it into a small-format mixer, for the first time ever. So Cal started with the Wien Bridge circuit topology--a very musical design made popular by mixing consoles from the hallowed "British Invasion."* This design basically trades boost/cut capability for a wider, highly musical Q filter. So you get a very sweet sound, but less control than you might find on modern mixers.

That's where Cal decided that you deserve something better.

To get past the tradeoffs of the Wien Bridge, he wrote 20 pages of equations describing the seemingly simple Wein Bridge circuit in complete detail. After solving the equations with calculus, Cal was able to specify capacitor and resistor values that would give Onyx mixers an extra 6dB of control (±15 dB) without excessively narrowing the "Q" or bandwidth of the filters. Next, Cal employed combining filters for minimum phase shift, making the entire EQ section as musical as possible. Finally, he added an individual hardware bypass on every channel that completely removes the EQ circuitry from the signal path... And on the seventh day, he rested.

What this all means for the Onyx Series is that you have four bands of superb, musically useful EQ at your command — ready to massage the most messed-up singers and musicians... or just make a snare drum really "crack."

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EQ - Mono Channels   EQ -Stereo Channels:
High ±15 dB @ 12 kHz
  High ±15 dB @ 12 kHz
High Mid ±15 dB, sweepable from 400 Hz to 8 kHz   High Mid ±15 dB @ 2.5 kHz
Low Mid ±15 dB, sweepable from 100 Hz to 2 kHz   Low Mid ±15 dB @ 400 Hz
Low ±15 dB @ 80 Hz   Low ±15 dB @ 80 Hz
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* The truth is that there were almost as many different types of "British EQ" circuitry as there were British mixing console designers in the 1960's and 1970's. But the Wein Bridge topology Cal used for Perkins EQ is generally considered to be among the sweetest. (You can now pick the "Debunking Audio Myths" category on Audio Jeopardy.)