This 6W amplifier with 4 tubes was indicated in an American documentation from 1947 to operate with recorders. The circuit uses a source with a transformer.
This circuit is from an American magazine that no longer exists, Modern Electronics, in a February...
March 2017 - The new Texas Instruments TPA3244 class D amplifiers with power ratings from 60 to...
This preamplifier is intended for the use with magnetic pick-ups. Power supply must have voltages...