Abstract: A tonal altering feature for a tube type guitar audio amplifier provides apparatus enabling selection of the type of phase inverter utilized.

Abstract: An inverter stage includes a supply voltage terminal and a reference potential terminal. An npn transistor has a base terminal for receiving an input signal, a collector terminal for supplying an output signal, and an emitter terminal. A controllable current source is connected between the emitter terminal of the transistor and the reference potential terminal. A series circuit of at least two diodes is connected between the supply voltage terminal and the collector terminal of the transistor. A symmetrical inverter stage assembly includes two of the inverter stages being connected in parallel with the emitters of the transistors of each of the inverter stages being connected to one another. A ring oscillator includes n (n.gtoreq.1) of the inverter stages connected in series. The inverter stages include first and last inverter stages, each of the inverter stages has an output and an input, and the output of the last inverter stage is connected to the input of the first inverter stage.

Abstract: In this invention, in arranging a balance type input terminal group or output terminal group in an integrated circuit, the formation is provided with one terminal for grounding and two signal terminals adjacent to this grounding terminal on both sides. In connecting the output terminal group of the first integrated circuit and the input terminal group of the second integrated circuit with each other in such formation, the grounding terminals themselves and signal terminals themselves are respectively connected in one to one. Further, in the integrated circuit formed as mentioned above, among the bonding wires connecting the balance type input terminal group or output terminal group with an electrode group of an inner chip, the two bonding wires connecting the chip with the signal terminals are wired symmetrically with the bonding wire connecting the chip with the grounding terminal as a center.

Abstract: A rectangular-to-sine wave converter circuit (10) is provided that comprises a flip-flop (12) that provides for a square wave and an inverse square wave circuit with fifty percent duty cycles. Each of the square wave signals is passed through a multi-stage low pass filter. The stages of the low pass filters are separated by buffers (26) and (32). The common mode voltage of the output signals at output nodes (40) and (44) are adjusted with respect to an arbitrary bias voltage V.sub.bias by using bias resistors (42) and (68).