1073/500 Preamp/EQ Specifications:

• 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.
• 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: 10KOhms bridging, transformer balanced and floating.
• Output impedance: Less than 75 Ohms, transformer balanced and floating, to drive a load of 600 Ohms.
• Maximum output: Greater than +26dBm into 600 Ohms, greater than +32dBu into 10KOhms.
• THD: Less than 0.025% at 1Khz, Less than 0.05% at 100Hz.
• Frequency response :20Hz (+0.3dB) to 20Khz (-0.2dB).