Heritage Audio 73 JR II

Description

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. 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 lunchbox PSU healthier and makes the 73JR independent of the rest of the slots. • 80dB Class A Microphone preamplifier, HI-LO selectable minimum input impedance, balanced and floating. High gain positions show a higher impedance, ideal for old ribbon mics. • 50Db Class A Line preamplifier, bridging input impedance, balanced and floating. • All discrete Class A Ultra High Impedance J-Fet Direct Input on a high quality Neutrik Jack. The DI circuit is ahead of the Mic Input transformer, so the transformer is ON when in DI mode. DI is automatically switched on when inserting a jack. • Class A single ended, 2N3055 driven, high headroom output stage. • PAD: 20dB Mic input attenuation ahead of the input transformer to avoid overloading it. • HI PASS FILTER: Active all discrete Class A 3rd order Bessel, 80Hz Hi Pass Filter. 18dB/octave slope. • OUTPUT control to allow overloading of the preamp. • Internal slow turn-on +24v power supply for lower inrush current, which improves your lunchbox performance. • Carnhill Input and Output transformers. • 3 gain stage, genuine modular card construction. All active circuitry is on pluggable cards for easier service. • Marconi style knobs and vintage style engraved pushbuttons. • 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 Carnhill transformer balanced and floating. • Line input impedance: 10K Ohms bridging, Carnhill transformer balanced and floating. • DI input impedance: Greater than 2 Megohms, unbalanced. • Output impedance: Less than 75 Ohms, Carnhill transformer balanced and floating, to drive a load of 600 ohms (factory terminated). • Maximum output: Greater than +26dBm 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 -100dBm. • Power consumption: 88 mA per rail @+-16VDC.

Additional information