I'm refreshing my electronics knowledge a bit (after 30+ years), and I'm trying to build an audio amplifier from scratch without integrated circuits (transistors, and mosfets only).
I'm trying to build the input stage, which is a differential amplifier using 2 transistors. I'm currently simulating it with LTSpice, but I seem to amplify only the positive part of my input signal. I guess it's because of the values of the emitter and collector resistors.
I understand the principle of a diff amplifier, but I'm struggling with the practical setup.
Can somebody explain to me (or point me to a site) how to calculate those resistors?
I guess there should be current flowing through R2 while out1 should be at ground level, if no signal is applied?
I included my schematic and the waveforms.
Thanks a lot!