A mono microphone, line and keyboard pre-amplifier, with outstanding sonic qualities and features.
The device has balanced and floating inputs and output. The entire audio chain employs symmetric circuitry, and the headroom level from input to output is +30dBu.
The balanced and floating inputs are equipped with oversized torodial transformers. The common mode rejection ratio of the microphone input amounts to > 76dB @ 15kHz. A stepped switch with calibrated positions provides coarse gain adjustment. Below 22dB the switch changes the pad, so that in every setting an optimal gain is maintained. Another control witth a range from 0dB to +10dB is used for the fine gain adjustment. The maximum gain of the unit is 80dB. A passive subsonic filter with the edge frequencies 20, 40 and 80 hertz can be activated directly in the input. The LC filter uses the primary winding of the input transformer and prevents low frequency disturbances and step sound in the amplifier that can cause inter-modulation effects. Two knobs adjust input impedance for microphone load matching. For the ohm load, 200 ohms, 300 ohms or 600 ohms values can be selected. For the capacitive load, the values 0.33, 0.68 and 1.5nF can be selected.
The instrument input is balanced electronically and a high impedance value. The UNBAL and GND LIFT switches are used for un-balanced and high-Z signals. UNBAL switches the usually symmetrical input between both legs of the circuit with the b leg to the Sleeve of the jack socket. The GND LIFT switches off the connection between the ground of the V776 and the sleeve of the jack socket. The symmetric input takes the ground potential of the connected device. This circuit is meaningful when keyboards or amplifiers are connected which are already grounded. The gain has a range between 0dB and 36 dB and is infinitely variable. The electronically balanced input has an input resistance of > 200kOhm. Special filter circuits care without influence on the frequency and phase way for an effective oppression of HF disturbances. The Instrument input circuit of the amplifier is optimized on the lowest rushing for medium to high impedance signal sources. The selection of the instrument input takes place by the switch INSTR IN.
The line input is implemented balanced and floating and is equipped with an oversized torodial transformer. The gain range is ± 20 dB. The switch LINE switches over to this input.
The high-pass filter has a slope of 24dB/octave and a range of <20Hz to 300Hz. The low-pass filter has a range of >20kHz to 2kHz and a slope of 12dB/octave.
A peak meter indicates the output level. The Ø switch rotates the input phase.
The V776 is a standard V700 module and fits into standard mounting frames.
