Pleiades 2N3055 single ended power amplifier revisited

 At your risk.

This is on one transistor only single ended audio power amplifiers with no negative feedback.

Using Italian Transeria Ligure E,I laminations a new lower ratio output transformer was made that the used for the Pleiades 2N3053 operated at 24V, 10mA.

This transformer was made by winding 64 turns of 0.55mm wire, then 270 turns of 0.25mm wire, then 64 turns of 0.55mm, then again 270 turns of 0.25mm,  then 60 turns of 0.55mm.

Inductance ratio with no air gap is 340mH to 47mH.

This sounded very nice with Pleiades BD139 at Vb=6V, Ic=25mA.

Signal path: Flashdance soundtrack on CD - Sony CD Walkman line out - Pleiades power amplifier - Marantz Imperial speakers

Then air gap was introduced by attaching a layer of 3M scotch invisible tape across the open end of stacked Es. Inductance ratio became 227mH to 33mH.

Sound is still very nice with amazing bass, mid, treble.

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Then Vb was changed to 12V and Ic to 60mA for louder sound but 2N3055 sounded better at 12V and Ic=80mA.

Then transformer was opened up again and airgap was increased by putting all Is in a small transparent plastic bag and placing them by hand on top of the Es while music is playing.

Now inductance ratio is 173mH to 26mH.

Sound is very nice and loud .