The 710 Twin-Finity from Universal Audio is a single channel, dual path microphone preamplifier that includes an instrument direct inject (DI) input. The dual path design combines the "warmth" of a high-voltage vacuum tube design with the clarity of a solid-state circuit. A blend control allows the dialing-in of either circuit or a combination of both in varying degrees.
The tube circuit utilizes a 310V single ended, Class-A triode tube stage, which is phased aligned with a solid-state gain stage. Both stages are fed from a variable gain solid-state transimpedance input amplifier, and are summed to a single output according to the setting of the blend knob. Along with the variable input and output controls, this design allows for an almost infinite range of tones to be dialed-in.
The discrete JFET DI input circuit can handle virtually any electric instrument, including guitars and basses with both active and passive pickups. The VU meter can switch between displaying standard output levels and a "Drive" mode that allows for seeing how hard the input stage is being driven. Phantom power, low pass filter and a polarity flip switch add full functionality to a versatile preamplifier.