The 573EQ is an inductor-based equalizer in 500-series format, built by IGS Audio as a development of the classic British Neve 1073-style EQ topology. All four rotary switches on the front panel are ELMA units manufactured in Switzerland – the same switch quality found in mastering-grade hardware at significantly higher price points. The key addition over standard 1073-style 500-series clones is a seventh control: a highpass filter covering six selectable frequencies. A pair of 573EQs on the mix bus with no EQ moves applied introduces analog coherence and colour that is difficult to replicate by other means – a property of the inductor-based circuit interacting with the transformer-balanced signal path.
Seven controls where competitors offer six
Most 1073-format 500-series modules ship with six controls covering low shelf, mid bell, high shelf, and band selectors. The 573EQ adds a highpass filter with steps at OFF, 25, 45, 70, 160, and 360 Hz – the single most-used corrective tool on individual tracks in most sessions. It removes low-end clutter from instrument and vocal channels without engaging the main EQ bands and without reaching for a separate HPF module or a DAW plugin. Low shelf covers OFF through 220 Hz in six steps. The midrange band provides 12 selectable frequencies from 250 Hz to 10 kHz. High shelf runs across 8, 10, 12, 16, and 20 kHz. Every position is a switched step via ELMA rotary, meaning recall is exact and repeatable without photographing the panel.
Inductor topology – where the character actually comes from
Inductor-based EQ circuits produce asymmetric curves with a behaviour at the band edges that capacitor-based or digital implementations do not replicate at equivalent gain settings. That is why low-shelf boost on a 1073-style unit sounds dense without becoming slow, and high-shelf boost opens the material without adding the hardness common in active EQs. IGS Audio uses modern transparent op-amps rather than discrete amplifier stages, which keeps the noise floor low and makes the 573EQ integrate cleanly with transformer-balanced preamps or compressors in the same 500-series rack. The module carries a three-year manufacturer warranty.
KEY FEATURES
- 3-band inductor EQ plus highpass filter, 500-series format, mono
- 7 front-panel controls – one more than standard 1073-style clones
- All four rotary switches ELMA (Switzerland) – fully recallable settings
- Highpass filter: OFF, 25, 45, 70, 160, 360 Hz
- Low shelf: OFF, 20, 35, 60, 110, 220 Hz
- Mid band: 12 steps, 250 Hz – 10 kHz
- High shelf: 8, 10, 12, 16, 20 kHz
- Modern transparent op-amps
- Compatible with transformer-balanced preamps and compressors in the same rack
- 3-year manufacturer warranty
TECHNICAL SPECIFICATIONS
- Type: inductor band equalizer (Neve 1073-style)
- Format: 500-series, single slot, mono
- Controls: 7
- HP filter: OFF / 25 / 45 / 70 / 160 / 360 Hz
- Low shelf: OFF / 20 / 35 / 60 / 110 / 220 Hz
- Mid band: OFF / 0.25 / 0.36 / 0.5 / 0.7 / 1.1 / 1.6 / 2.3 / 3.2 / 4.8 / 7.2 / 10 kHz
- High shelf: 8 / 10 / 12 / 16 / 20 kHz
- Switches: ELMA (Switzerland), all four bands
- Amplifiers: modern op-amps, transparent signal path
- Warranty: 3 years
