The iQ505 is a fully parametric five-band equalizer in API 500 format, built by IGS Audio in the style of the Sontec MEP-250A – one of the most sought-after analog EQs in the history of mastering and recording engineering. Five bands with overlapping frequency ranges and individual Q control per band (0.5–10) are packed into a single 500-series slot, making the iQ505 one of the very few modules of this type in this format. The signal path uses electronically balanced input and output via THAT chips – integrated circuits designed exclusively for audio applications, chosen for their exceptionally low THD and self-noise. Frequency range: from sub-bass (10 Hz) to 24 kHz. Correction range: ±12 dB per band. Hard-wire bypass. Current draw: 100 mA. Three-year warranty.
Five overlapping bands – what that means for corrective and creative work
In conventional parametric equalizers the bands occupy fixed, non-overlapping ranges – the Low band ends where Low-Mid begins. In the iQ505 the bands overlap: band 1 (sub-bass) and band 2 (bass) cover part of the same frequency territory, as do the mid and high bands. This means two bands can be set to the same frequency region with different Q values and different gain amounts – one broad, one narrow – producing curve shapes that are impossible to replicate on an EQ with mutually exclusive bands. Q range from 0.5 (very broad, several octaves) to 10 (narrow notch below one-third octave wide) in each of the five bands delivers surgical precision and broad tonal shaping in the same device without switching tools.
THAT chips and signal transparency – where the iQ505 differs from other IGS modules
Most IGS Audio modules build their character around transformers and the colour of tube or FET circuitry. The iQ505 is a deliberate exception: THAT chips are specialised analog integrated circuits designed exclusively for audio – VCAs, differential amplifiers, RMS detectors. In the iQ505 they handle gain and balancing without introducing the tonal character of a Carnhill or Edcor transformer. The result is one of the most transparent EQs in the IGS catalogue – there is no warmth or colouration added by the signal path, only the correction chosen by the engineer. This gives the iQ505 two distinct use cases: precise corrective work including notching and room resonance elimination, and subtle broad-band tonal shaping on tracks and groups where transformer character would compete with the source rather than serve it.
KEY FEATURES
- 5-band fully parametric equalizer, API 500 format, mono (Sontec MEP-250A style)
- Overlapping frequency bands – two bands can operate in the same frequency region simultaneously
- Individual Q control per band: 0.5–10
- Correction range: ±12 dB per band
- Frequency range: 10 Hz – 24 kHz
- THAT chips – electronically balanced I/O, low THD and self-noise
- No transformers – transparent, tonally neutral signal path
- Hard-wire bypass
- 3-year manufacturer warranty
TECHNICAL SPECIFICATIONS
- Type: fully parametric 5-band equalizer, API 500, mono
- Topology: Sontec MEP-250A style
- Number of bands: 5 (overlapping frequency ranges)
- Correction range: ±12 dB
- Q: 0.5–10 (each band independently)
- Frequency range: 10 Hz – 24 kHz
- Active components: THAT chips
- Input/output: electronically balanced
- Hard-wire bypass: yes
- Current consumption: 100 mA
- Warranty: 3 years
