This tube amp with push-pull output uses KT88 valves that can provide up to 40 W audio power when supplied with a 520 V voltage. The circuit can be found in many devices from the years 50 and 60 with excellent sound quality when using an ultra-linear transformer output.
Critical components of this circuit, besides the valves are special transformers. The output transformer must be ultra-linear characteristics in accordance with the outputs of valves used.
We also have a filter shock that is bulky component, not very simple to obtain.
The circuit also has an output to feed an external preamp, which is common in this type of application. In Figure we have the device complete diagram employing two rectifier valves.
