Push Pull Amplifier Using Vacuum Tube

The amplifier project utilizes vacuum tubes on the preamplifier section to produce a push pull output stage while using point-to-point connections.

Each of the tubes are consuming 940 mA of current and the total consumption reaches 3.76 A. With 6.3 V winding, the transformer used is only rated for 3 A. The type of tubes used was 12AX7A where a separate transformer powers its heaters. The probable occurrence of hum in the preamp stages may be reduced by filtering and rectifying the heater supply.

Most of the components used in this project are taken from old equipments just like the dual potentiometers from an old Allen Bradley and has a short shaft with screwdriver adjustment. The end of the shaft is drilled and a 4-40 screw hole is tapped which caters a ¼ diameter spacer for bolting. This makes the potentiometers more useful during the operation.

The chassis is made of brass and wood combination. The speakers used are 8 inch in size from the early 70’s with features such as 8 Ohms, 15 W, and ceramic magnet. The speaker’s output is very impressive due to the deep bass that they produce.

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