• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Summing at the LTPI


Paid Member
I used to build all of my bigger (>60W) PP amplifiers using global feedback fed to the inverting input of an LTP input stage.. Worked just fine.

Designed a 0 global feedback PP 300B amplifier that was published in VTV with an LTP as input stage with a balanced input option. Built a similar stereo 300B PP amplifier commercially, no global feedback with an LTP input normally configured for a single ended input, a balanced option was available, but no one requested it.

All worked just fine.

The VTV article is available on my site.