Ribbon mics, more so than condenser or dynamic mics, need to be properly impedance matched to the mic pre-amplifier. Ribbon mics use transformers and every ribbon mic's output impedance is different, ranging anywhere from 50 to over 600 Ohms. The problem is that most mic pre-amplifiers come with a transformer set to one specific input impedance. If the input impedance of the mic pre is dramatically less than the output impedance of the ribbon mic, this can result in what is referred to as "undershoot" and the mic will sound dull. That is because the mic pre is unable to properly manage the high end frequencies picked up by the mic and the result is a 3-6 dB attenuation of signal in the frequencies over 10 kHz. If the input impedance of the mic pre is dramatically more than the output impedance of the ribbon mic, this can result in "overshoot" and the mic will sound harsh or brittle as the high end frequencies are over-exaggerated.
We designed the V77M to solve this issue.
Using the same switching system as our V78M, the Input Sensitivity switch taps directly into the Input Transformer and changes the Input Impedance of the transformer. While the Input Sensitivity switch has six positions to choose from, the V77M comes equipped with an Input Sensitivity range selector switch that allows you to switch between two ranges of impedance; 12 to 200 Ohms and 200 to 1000 Ohms effectively providing 12 different impedance selections to best match your particular ribbon microphone. We also coupled the circuit with the AMI version of the V76 input transformer increasing the overall gain of the unit from 60 dB (V78M) to 76 dB. Finally, we also restructured the Make-up Gain settings so that there is more resolution at the top end of the gain structure to provide increased control where ribbon microphones most need it.
- Schematic based on historic V72s
- Transformers constructed faithfully to the historic V76 specs
- NOS tubes (Telefunken, Valvo, Philips)
- 76 dB of gain
- Split Input Sensitivity with Make-up Gain switches
- Input Sensitivity Range selector, allows 12 positions
- Phase Reverse
- 120 Hz Shelf EQ
- 100 Ohm Resistive Ground Buffer
- 5-year Warranty