Heritage Audio DMA-73 Dual Microphone Preamp and DI
• 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.
• Class A single ended, 2N3055 driven, high headroom output stage.
• Individual Neutrik gold plated XLR connectors for microphone and line inputs.
• Gold Plated Neutrik XLR output.
• 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.
• External linear PSU to avoid electromagnetic radiation into the audio transformers ( a.k.a. hum ).
• Carnhill Input and Output transformers.
• 3 gain stage, genuine B283 gain card modular construction.
• 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: Less than 200 mA @24VDC