A vacuum tube amplification system includes: a first power circuit electrically connected to utility power alternating voltage to transform it into a first DC voltage; a first vacuum tube amplification load circuit having a first grounding end, the first vacuum tube amplification load circuit using the first DC voltage as operating voltage; a second power circuit electrically connected to the utility power alternating voltage to transform it into a second DC voltage and output the second DC voltage; and a second vacuum tube amplification load circuit having a second grounding end, the second vacuum tube amplification load circuit using the second DC voltage as operating voltage. The first grounding end is not directly electrically connected to the second grounding end, the first grounding end and the second grounding end are each electrically connected to a compliance ground of the utility power alternating voltage through a jumper-wire zero-ohm resistor.

A vacuum tube amplification system includes: a first power circuit electrically connected to utility power alternating voltage to transform it into a first DC voltage; a first vacuum tube amplification load circuit having a first grounding end, the first vacuum tube amplification load circuit using the first DC voltage as operating voltage; a second power circuit electrically connected to the utility power alternating voltage to transform it into a second DC voltage and output the second DC voltage; and a second vacuum tube amplification load circuit having a second grounding end, the second vacuum tube amplification load circuit using the second DC voltage as operating voltage. The first grounding end is not directly electrically connected to the second grounding end, the first grounding end and the second grounding end are each electrically connected to a compliance ground of the utility power alternating voltage through a jumper-wire zero-ohm resistor.

The present invention provides a device with rear-mounted vacuum tubes, comprising a protective cover with a plurality of heat dissipating holes, a rear panel with a panel opening, and at least one vacuum tube, wherein the vacuum tubes are arranged in a containing space of the protective cover through the panel opening and inserted to a connection circuit board for coupling to a printed circuit board. In addition, the protective cover, the rear panel, and the vacuum tubes are placed in parallel with the printed circuit board, so that heat dissipation for the device is improved and replacement and maintenance of the vacuum tubes are easier. In particular, a vacuum tube audio amplifier apparatus having the device with rear-mounted vacuum tubes as disclosed herein can be stacked.

The present invention provides a device with rear-mounted vacuum tubes, comprising a protective cover with a plurality of heat dissipating holes, a rear panel with a panel opening, and at least one vacuum tube, wherein the vacuum tubes are arranged in a containing space of the protective cover through the panel opening and inserted to a connection circuit board for coupling to a printed circuit board. In addition, the protective cover, the rear panel, and the vacuum tubes are placed in parallel with the printed circuit board, so that heat dissipation for the device is improved and replacement and maintenance of the vacuum tubes are easier. In particular, a vacuum tube audio amplifier apparatus having the device with rear-mounted vacuum tubes as disclosed herein can be stacked.

The present invention provides a device with rear-mounted vacuum tubes, comprising a protective cover with a plurality of heat dissipating holes, a rear panel with a panel opening, and at least one vacuum tube, wherein the vacuum tubes are arranged in a containing space of the protective cover through the panel opening and inserted to a connection circuit board for coupling to a printed circuit board. In addition, the protective cover, the rear panel, and the vacuum tubes are placed in parallel with the printed circuit board, so that heat dissipation for the device is improved and replacement and maintenance of the vacuum tubes are easier. In particular, a vacuum tube audio amplifier apparatus having the device with rear-mounted vacuum tubes as disclosed herein can be stacked.

The present invention provides a device with rear-mounted vacuum tubes, comprising a protective cover with a plurality of heat dissipating holes, a rear panel with a panel opening, and at least one vacuum tube, wherein the vacuum tubes are arranged in a containing space of the protective cover through the panel opening and inserted to a connection circuit board for coupling to a printed circuit board. In addition, the protective cover, the rear panel, and the vacuum tubes are placed in parallel with the printed circuit board, so that heat dissipation for the device is improved and replacement and maintenance of the vacuum tubes are easier. In particular, a vacuum tube audio amplifier apparatus having the device with rear-mounted vacuum tubes as disclosed herein can be stacked.

A number of low voltage vacuum tube circuits include using supply voltages well below the manufacturer's recommended voltages applied to the plate or screen grid. Some of the tube circuits operate at near zero plate and or screen grid voltages. Other low voltage circuits have forward biasing on one or more grids that are normally biased at a non positive voltage or a grid that is normally connected a cathode. Substantially lower supply voltages allow for example, the filament supply to also supply voltage to the plate and or grid for providing an output signal at a grid and or a plate. Also one or more voltage controlled resistors circuits are shown that include near zero plate (e.g., supply) voltage.

A number of low voltage vacuum tube circuits include using supply voltages well below the manufacturer's recommended voltages applied to the plate or screen grid. Some of the tube circuits operate at near zero plate and or screen grid voltages. Other low voltage circuits have forward biasing on one or more grids that are normally biased at a non positive voltage or a grid that is normally connected a cathode. Substantially lower supply voltages allow for example, the filament supply to also supply voltage to the plate and or grid for providing an output signal at a grid and or a plate. Also one or more voltage controlled resistors circuits are shown that include near zero plate (e.g., supply) voltage.

The invention provides a grounding structure and a grounding method for a vacuum tube audio amplifier, the grounding structure and the grounding method including: with respect to a power source, utilizing a power circuit without a choke, an anti-coupling circuit, and a filament voltage regulator circuit; and with respect to the grounding method, utilizing an negative output terminal of an audio output transforming circuit or a negative terminal of a filter capacitor in the power circuit as a single ground terminal of the vacuum tube audio amplifier, and not arranging a grounding metal bottom plate therein, in order to achieve a compact, lightweight desktop model of a vacuum tube audio amplifier.

The invention provides a grounding structure and a grounding method for a vacuum tube audio amplifier, the grounding structure and the grounding method including: with respect to a power source, utilizing a power circuit without a choke, an anti-coupling circuit, and a filament voltage regulator circuit; and with respect to the grounding method, utilizing an negative output terminal of an audio output transforming circuit or a negative terminal of a filter capacitor in the power circuit as a single ground terminal of the vacuum tube audio amplifier, and not arranging a grounding metal bottom plate therein, in order to achieve a compact, lightweight desktop model of a vacuum tube audio amplifier.