Heritage Audio 73JR 500 Series Microphone Preamp

The Heritage Audio 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 who require EQ. Employing only discrete circuitry and conventional components, the 73JR 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 high-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 +24 V 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 from 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: 10 kOhms 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 +26 dBu into 600 ohms
• THD: Less than 0.025% at 1 kHz, less than 0.05% at 100 Hz
• Frequency response: 20 Hz (+0.3 dB) to 20 kHz (-0.2 dB)
• Maximum gain: Slightly greater than 80 dB
• Noise: Less than -100 dBu
• Power consumption: 88 mA per rail @±16 VDC