When we came with the idea of making our 1073 version in an API VPR series 500 module, first thing we noticed was how many compromises our competitors had to assume to fit their repros in such a small package.
We decided to make exactly zero compromises on ours. This meant making a 3u wide module capable of holding all three vintage accurate transformers, dual concentric switches , pushbuttons and same exact PCB cards. Exactly what the name says. No downsized knobs. No transformers left out. No ICs in place of discrete class A circuitry. Just what the faceplate says: a 1073 in a 500 series format.
• 70dB 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.
• 10dB Class A Line Amplifier, Bridging input impedance, balanced and floating.
• Class A, single ended, 2N3055 driven high headroom output stage.
• High Frequency: +/-16dB shelving at 12 kHz, Baxandall type.
• Low Frequency: +/-16dB with selectable frequency shelving of 35Hz, 60Hz, 110Hz & 220Hz, Baxandall type.
• Mid Frequency: +/-18dB peaking, fixed 'Q' , selectable center frequencies of 0.36kHz, 0.7kHz, 1.6kHz, 3.2kHz, 4.8kHz , and 7.2kHz , dual inductor based.
• High Pass Filter: 18dB per octave slope, switchable between 50Hz, 80Hz , 160 Hz & 300Hz, inductor based.
• EQ Button: Switches the equalizer on or off.
• Phase Button: Flips phase 180º.