The driver stage is an SRPP circuit with ECC802S tubes, while ultra linear operation is used for the output stage with Sovtek EL84 tubes. LM317 Regulators are used to produce a constant current source (CCS) to set the bias of the output stage. The power and output transformers are from Edcor. 12VDC from a SMPS is used for the tube heater supply.
Bruce reports that performance from this amplifier is excellent. The low end extension is clean but not excessive. As expected, it has the characteristic tube warmth and is very easy to listen to.
For additional information, pictures and schematics, see the complete page of Bruce's EL84 Push-Pull Tube Amplifier Project.
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- Bruce's KT88 Push-Pull DIY Tube Amplifier Project