Heritage Audio 73JR

Mic preamp – 500 series

The ´73JR is true 1073 style mic preamp in a single 500 series slot with some added features that will cover all the recording needs for engineers and musicians that don´t find the need to track with eq.

Employing only discrete circuitry and conventional components, the ’73 junior is a faithful 3 stage all class A 1073 preamp. Styroflex and tantalum capacitors have been used throughout. No corners were cut.

A useful all discrete class A hi pass filter has been added, essential for recording everything with the exception of probably kick drum and and bass.

The Line mode allows for reamping of prerecorded tracks and it´s perfect for adding some class A color to lifeless recordings.

The smart switched DI (automatically switches from MIC to DI mode when inserting a MONO ¼” jack) is an all discrete class A JFET circuit ahead of the MIC transformer, so all the juice is there. Since its introduction in 2013, it has become a classic DI for bass.

Finally, special care has been taken with power handling, implementing internal +24v slow turn on regulation (about 20 seconds to reach full voltage).This makes your 500 series enclosure´s power supply healthier and makes the ´73JR independent of the rest of the slots.

Specifications

• Microphone input impedance: HI, 1200 Ohm minimum, LO, 300 Ohm minimum. Higher gain positions gradually have greater impedances, optimum for lo gain ribbon mics. Input is transformer balanced and floating.
• Line input impedance: 10K Ohms bridging, transformer balanced and floating.
• DI input impedance: Greater than 2 Megohms, unbalanced.
• Output impedance: Less than 75 Ohms, transformer balanced and floating, to drive a load of 600 ohms (factory terminated).
• Maximum output: Greater than +26dBu into 600 ohms.
• THD: Less than 0.025% at 1 Khz, less than 0.05% at 100Hz.
• Frequency response: 20Hz ( +0.3dB ) to 20Khz (-0.2dB)
• Maximum gain: Slightly greater than 80dB
• Noise: Less than -100dBu.
• Power consumption: 88 mA per rail @+-16VDC.