IGS Audio NE573

The NE573 is a single-channel Class A microphone preamplifier in API 500 format, built by IGS Audio as a faithful circuit recreation of the Neve 1073 first revision. The design focus is on the authenticity of the internal circuit rather than the appearance – which separates the NE573 from cosmetic clones: a Motorola transistor on the output stage, Grayhill switches, IGS Custom transformers (Carnhill in some versions) on input and output, and operation at 24 V rather than the standard 16 V of the 500-series power rail. That last point is critical – the original Neve 1073 ran on higher supply voltage, which directly affects the transistor operating point, headroom, and saturation character at higher input levels. Three-year manufacturer warranty.

24 V instead of 16 V – why supply voltage matters here

Standard 500-series modules run on ±16 V rails. The NE573 operates at 24 V – requiring a 500-series rack that supports higher voltage or an onboard voltage conversion stage. This is not a marketing decision: higher supply voltage directly shifts the Motorola output transistor's operating point closer to the conditions under which the original 1073 worked. At 16 V, the same circuit behaves differently – lower dynamic headroom before saturation, different harmonic distortion characteristics when the input is driven hard. The choice of 24 V is a design decision in service of tonal authenticity, not installation convenience. Switchable input impedance at 300/1200 Ω (via Grayhill switch) changes the loading behaviour on the microphone: 300 Ω gives a more aggressive, closer-to-original 1073 character; 1200 Ω offers more headroom and a gentler tonal interaction with the source.

Front-panel combo jack and stepped gain

A combo XLR/TS jack on the front panel handles both microphones and Hi-Z instruments without rerouting cables to the rear XLR when switching between a mic and a direct guitar or bass. The stepped Gain control provides session recall across its range of up to approximately 70 dB, with a separate Output trimmer for fine level adjustment after the gain stage. Phantom power +48V and a phase reverse switch complete the controls. The combination of switchable impedance, front-panel Hi-Z, and full gain range means the NE573 handles virtually any source type in a tracking session without reorganising the signal chain between takes.

KEY FEATURES

• Class A Mic/Hi-Z preamplifier, API 500 format, mono (Neve 1073-style)
• Motorola transistor on the output stage – as in the original Neve 1073 Rev 1
• IGS Custom / Carnhill transformers on input and output
• Grayhill switches throughout
• Operates at 24 V instead of standard 16 V
• Switchable input impedance: 300 / 1200 Ω
• Front-panel combo XLR/TS jack (Mic + Hi-Z)
• Stepped Gain (up to ~70 dB) + Output trimmer
• Phantom power +48V
• Phase reverse switch
• 3-year manufacturer warranty

TECHNICAL SPECIFICATIONS

• Type: transformer mic/Hi-Z preamplifier, Class A, API 500, mono
• Topology: Neve 1073 Rev 1-style
• Output transistor: Motorola (original type)
• Transformers: IGS Custom / Carnhill (input and output)
• Switches: Grayhill
• Supply voltage: 24 V (above standard API 500 ±16 V)
• Input impedance (balanced): 300 / 1200 Ω (switchable)
• Gain: up to ~70 dB (stepped) + Output trimmer
• Inputs: XLR (rear) + combo XLR/TS jack (front, Hi-Z)
• Phantom power: +48V (switchable)
• Phase reverse: yes
• Format: API 500, single slot