Multiple example valve amplifiers are provided. A first example valve amplifier is provided which comprises (i) a valve power amplifier switchable between a high-power mode and a low-power mode and (ii) a loudspeaker simulator circuit, the valve amplifier being configured such that the valve power amplifier drives the loudspeaker simulator circuit in the low-power mode. A second example valve amplifier is provided which comprises a switched-mode power supply, SMPS, system), the SMPS system comprising (i) an SMPS and (ii) circuitry configured to enable an output impedance of the SMPS to be switched between first and second output impedances, the first output impedance being lower than the second output impedance.

Disclosed is an amplifier for incremental wattage reduction. The amplifier comprises a first pair of pentode vacuum tubes and a second pair of pentode vacuum tubes arranged in a push-pull-parallel power configuration. Each pentode vacuum tube from the first pair of pentode vacuum tubes and the second pair of pentode vacuum tubes includes a plate element, a screen grid element and a cathode element. The amplifier further comprises a single multi-position user switch to configure the first pair of pentode vacuum tubes and the second pair of pentode vacuum tubes to achieve varying wattage outputs of the amplifier by deactivating at least one of the first pair of pentode vacuum tubes or the second pair of vacuum tubes, and causing at least one of the first pair of pentode vacuum tubes or the second pair of vacuum tubes to operate as triodes.

Disclosed is an amplifier for incremental wattage reduction. The amplifier comprises a first pair of pentode vacuum tubes and a second pair of pentode vacuum tubes arranged in a push-pull-parallel power configuration. Each pentode vacuum tube from the first pair of pentode vacuum tubes and the second pair of pentode vacuum tubes includes a plate element, a screen grid element and a cathode element. The amplifier further comprises a single multi-position user switch to configure the first pair of pentode vacuum tubes and the second pair of pentode vacuum tubes to achieve varying wattage outputs of the amplifier by deactivating at least one of the first pair of pentode vacuum tubes or the second pair of vacuum tubes, and causing at least one of the first pair of pentode vacuum tubes or the second pair of vacuum tubes to operate as triodes.

An amplifier circuit including a first stage, second stage and output stage. The first stage includes a cathode biased triode. The amplifier circuit includes a second stage having two long tailed pair triodes, each of the second stage tubes output signals inverted from each other wherein the long-tailed pair triodes are direct current coupled to the output tube's grids, Each cathode biased triode section is direct current coupled to one of the two long tailed pair triodes. The output stage includes two output tubes are in a Circlotron configuration with each output tube's cathode connected to the loudspeaker terminals. Each Bluetooth receiver's ground is connected to the ground of the first stage and the output of each Bluetooth is connected to the grid of the first stage.

An amplifier circuit including a first stage, second stage and output stage. The first stage includes a cathode biased triode. The amplifier circuit includes a second stage having two long tailed pair triodes, each of the second stage tubes output signals inverted from each other wherein the long-tailed pair triodes are direct current coupled to the output tube's grids, Each cathode biased triode section is direct current coupled to one of the two long tailed pair triodes. The output stage includes two output tubes are in a Circlotron configuration with each output tube's cathode connected to the loudspeaker terminals. Each Bluetooth receiver's ground is connected to the ground of the first stage and the output of each Bluetooth is connected to the grid of the first stage.