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Amplifier Input Topology

Posted by Triode_Kingdom (A) on July 7, 2017 at 12:27:57

I'm designing a vacuum tube preamp with a direct-coupled output circuit. When first powered on, it will output -30V through a 2.3K resistor (approximate). Once the output stage warms up, the DC will go to zero. This won't present a problem driving a tube power amp. Worst case, the temporary negative voltage will cut off conduction of the first tube until the preamp stabilizes. However, I'm concerned about what might happen if this is connected to a solid state amp. Do I need to install a delay circuit to prevent this from happening, or will all solid state amp survive -30V DC on their input? Again, this is through a 2.3k resistor, so current is limited to roughly 13 mA.

FWIW, I've worked on thousands of solid state amps. However, the last one was more than 25 years ago, and I've forgotten all the various iterations of input circuits. Maybe someone who's more current on this can help me think through all the "what-ifs."

Thanks!

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