Zähl EQ1 Stereo Equalizer

Development - 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.

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.

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 setting

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
- 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

HI EQ
- 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

HI MID EQ
- 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 EQ
- 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

LO 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

LO CUT
- Frequency adjustable 25 Hz to 250 Hz
- Individual ON/OFF switch