The Heritage Audio 73JR II is a single-slot 500 Series 73 mic preamp with the full three-gain-stage Class A circuit, Carnhill transformers, and up to 80 dB of gain. The 2021 update adds a sweepable 20-220 Hz high-pass filter while keeping through-hole discrete parts, Styroflex and tantalum capacitors, and an onboard +24 V supply.

Inputs

Inserting a mono 1/4" jack auto-switches into the Class A JFET DI ahead of the mic transformer. Line mode is there for reamping or adding 73 color to recorded tracks. Pad, polarity, and +48V are on the panel. EIN stays at -125 dBu across the gain range because the third gain stage is not omitted to save power.

Specifications

• Format: 500 Series, 1 slot
• Maximum gain: Greater than 80 dB
• Mic input: Transformer balanced, HI 1200 Ω / LO 300 Ω
• Line input: 10 kΩ, transformer balanced
• DI impedance: Greater than 2 MΩ
• Maximum output: Greater than +26 dBu into 600 Ω
• Noise: Less than -125 dBu EIN
• HPF: Sweepable 20-220 Hz, Class A
• Power: 86 mA per rail ±16 V, internal +24 V slow turn-on