Abstract: An oscillator circuit comprises a push-push oscillator and a differential output, comprising a first and a second output circuit. The push-push oscillator has a first and a second branch. Each of the first and second branch comprises an own voltage divider branch of a common bridge circuit. Each of the first and second voltage divider branches comprises an own pair of micro-strip lines connected in series. Each of the first and second voltage divider branches has an own tap. Both taps are connected to each other by at least one of a first capacity and a micro-strip line. The differential output comprises a first and a second output terminal. The first output terminal is connected via the first output circuit to a first node. The second output terminal is connected via the second output circuit to a second node. Each of the first and second nodes of the push-push oscillator is a common node of both of the first and the second branches.

Abstract: A balanced voltage amplifier is disclosed as comprising a single stage containing three pairs of vacuum tube triodes configured to amplify two input signals (+INPUT, ?INPUT) and to generate two output signals (+OUTPUT, ?OUTPUT). The balanced voltage amplifier offers high voltage gain, wide bandwidth and low output impedance. Local feedback may be applied between the outputs and the second pair of triodes. Overall feedback may be applied between the outputs and the first pair of triodes. If local or overall feedback is used, it will further broaden the bandwidth, lower the output impedance and improve the overall balancing.

Abstract: A vacuum tube amplifying apparatus provides predetermined varying dynamic response characteristics in order to enhance the playing characteristics of musical instruments, especially guitar.

Abstract: An audio amplifier in which an output stage is coupled by a driver stage to an input stage which includes two antiphased sources of alternating current. The output stage includes two pentode vacuum tubes each having a cathode, a plate and a screen grid located between the cathode and the plate. Each tube has a control grid connected between the cathode and the screen grid and a suppressor grid connected between the screen grid and the plate, with the control grid and the suppressor grid being shunted to their respective cathodes. The driver stage includes a pair of transistors connected in a push-pull configuration with their emitters connected to the screen grids of said tubes to supply a relatively high value of alternating current to the screen grids which function as control grids for their respective tubes.