Having built a number of vacuum tube output transformer-less (OTL) amplifiers in recent years, it seemed as though it might be a good idea to try combining older with newer technology and using both ...

The GA-10 is an audiophile-grade headphone amplifier that features the SEPP (single-ended push-pull) circuit with eight vacuum tubes, a linear transformer, and direct tube output. The vacuum tubes ...

Using a transformer coupled differential inverting amplifier stage can give a very low input referred noise voltage or Noise Figure (NF) with exceptional SFDR/mW. The NF equation needs to include ...