EQ1 - Stereo Equalizer

The legendary ZÄHL EQ from the state-of-the-art mixing console AM1 in the API 500 format

EQ1 Stereo Equalizer


Taking the next step

It all came into place when Michael Zähl, former engineer and designer of the main custom made mixing console at the legendary Conny's Studio and Mark Ernestus, long time producer known from projects like Basic Channel and Rhythm & Sound had a special encounter. This led to the collaborative development of AM1 - the state-of-the-art pure analog mixing console.

Given the excellent response to the AM1 mixing console with famous users such as Ricardo Villalobos or Tobi Neumann, it was time for the consistent next step - the EQ1 Stereo Equalizer. The legendary Zähl EQ is now also available in the API 500 format.

Michael Zähl and Mark Ernestus EQ1


Zähl EQ1 Guide by Chris Allen

Special Features

Twin Contest

HI with BELL/SHELF and MID with fully parametric BELL – same quality standard, but different circuit technologies and sound character. For optimum versatility MID frequency range switchable to HI range, HI frequency applicable at HI MID band. Similar: LO and LO MID.

Twin Contest
Single Band Switching

Single band switching

Individual ON/OFF switching

  • direct comparison each band ON/OFF while leaving GAIN pot in position
  • minimizing noise/preserving signal integrity by switching OFF unused bands

For sensitive use

Global EQ GAIN setting 5dB or 15dB

  • GAIN resolution enhancement
  • easier restoration of GAIN setting
  • direct comparison of different GAIN settings

Sensitive Use EQ1
EQ1 Manual Download PDF

"I never realised how depressing a bypass button could be."

Darren White aka dBridge

Photo: Khali Ackford

dBridge Darren White

Details EQ1

Design Features

  • stereo design for mix & mastering as well as voices & instruments
  • highly musical design
  • intuitive, user-friendly, self-explaining layout
  • lowest noise and distortion signal paths built with highest quality components
  • audio switching on EQ gain potentiometer zero position for bypassing unused stages
  • no microprocessor, no clock pulses, sequential logic only
  • individual power stabilization on each module, no switched power circuitry
  • fully compatible with API 500 module series specs, occupying two slots

I/O Stage

I/O Stage
  • electronically balanced, max. level > +26dBu
  • true overall hard bypass (relais), disconnecting I/Os
  • gain stage switchable to input or output, thus optimizing headroom vs. noise
  • gain range +/- 15 dB or +/-5dB, trimmed zero gain at mid position
  • SIGNAL LED (green) level present
  • O/L LED (red) overload warning driven by 10 checkpoints throughout signal chain


  • gain range +/- 15 dB or +/-5dB, bypass in mid position
  • individual ON/OFF switch
  • frequency 2 kHz to 20 kHz
  • BELL/SHELF characteristic switchable for effective treatment or sensitive adjustment with very soft slope and ‘airy’ character


  • gain range +/- 15 dB or +/-5dB, bypass in mid position
  • frequency 600 Hz to 6 kHz
  • frequency range switchable to 1.8 kHz to 18 kHz (x3)
  • adjustable Q-factor


Lo Mid
  • gain range +/- 15 dB or +/-5dB, bypass in mid position
  • frequency 200 Hz to 2 kHz
  • frequency range switchable to 40 Hz to 400 Hz (/5)
  • adjustable Q-factor


Low EQ
  • gain range +/- 15 dB or +/-5dB, bypass in mid position
  • frequency 30 Hz to 300 Hz
  • BELL/SHELF characteristic switchable with slight sub frequency roll-off at high gain shelf


  • frequency adjustable 25 Hz to 250 Hz
  • individual ON/OFF switch


To buy a eq1 or ask a question please contact Chris Parkinson below.


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