Solid state emulation of vacuum tube audio power amplifiers

A solid state amplifier for emulating the character of a vacuum tube amplifier having a power supply, said power supply having a response to said vacuum tube amplifier, said solid state amplifier comprising:

• an input and an output;
• means for operating in three regions;
• a) an unclipped region;
• b) a first clipped region at a first level;
• and c) a second clipped region at a second level greater than said first level;
• and
• wherein said first clipped region and first level vary in response to the emulation of said power supply response to said vacuum tube amplifier.

A low power solid state amplifier for the vacuum tube audio power amplifiers driving a speaker load and having a power supply which has a response to said vacuum tube amplifier, said solid state amplifier having an input and an output and comprising:

• input means for receiving an input signal;
• a controlled amplifier means responsive to said input means and a gain control signal for producing a controlled output signal;
• an output means responsive to said controlled output signal for producing an output signal at said output, for emulating said speaker load, and for producing a load signal indicative of said response of said power supply of said vacuum tube amplifier under load of said speaker;
• and
• gain control means responsive to said load signal for producing said gain control signal.

A semiconductor output amplifier having an input, and output, and a power supply for emulating a push-pull pentode vacuum tube amplifier comprising:

• a phase splitter for receiving said input and producing first and second grid signals;
• a first non-linear amplifier including grid conduction emulation means for receiving said first grid signal for producing a first drive signal;
• a second non-linear amplifier including grid conduction emulation means for receiving said second grid signal for producing a second drive signal;
• means for operating in three regions;
• a) an unclipped region;
• b) a first clipped region at a first level;
• and c) a second clipped region at a second level greater than said first level;
• and wherein said first clipped region and first level vary in response to the emulation of the response of said power supply of said vacuum tube amplifier to said vacuum tube amplifier;
• and
• an output amplifier means for receiving said first and second drive signals and producing said output signals.