31-08-2016, 01:45 PM
Hi Trevor I like the symmetrical appearance of the amplifier, above and below the chassis.
My experiences of power amplifiers is not all that great. We can take it as read that the output transformer is the most important component in an amplifier, also the phase splitter and output drivers of a push-pull amplifier must receive attention. The RGD 1046 amplifier I'm presently servicing has a simple phase splitter consisting of a low impedance triode which has equal value anode and cathode load resistors. Grid drive to the PX4 triodes is via 0.1mfd capacitors. Is this a satisfactory arrangement? The Williamson amplifier employs a similar phase splitter but signals developed across the two load resistors do not drive the output valves directly, but instead triode buffer amplifiers are interposed between the phase splitter and the grids of the output triodes.
The Mullard 5-20 amplifier employs an ECC83 as the phase splitter which has equal value anode load resistors. The Mullard description of the amplifier informs us that by using a high mu triodes the high value anode load resistors can be the same value, the balanced outputs across the load resistor should be within 3%.
There are other phase splitter and driver circuits which we can discuss later.
Geordie McBoyne.
My experiences of power amplifiers is not all that great. We can take it as read that the output transformer is the most important component in an amplifier, also the phase splitter and output drivers of a push-pull amplifier must receive attention. The RGD 1046 amplifier I'm presently servicing has a simple phase splitter consisting of a low impedance triode which has equal value anode and cathode load resistors. Grid drive to the PX4 triodes is via 0.1mfd capacitors. Is this a satisfactory arrangement? The Williamson amplifier employs a similar phase splitter but signals developed across the two load resistors do not drive the output valves directly, but instead triode buffer amplifiers are interposed between the phase splitter and the grids of the output triodes.
The Mullard 5-20 amplifier employs an ECC83 as the phase splitter which has equal value anode load resistors. The Mullard description of the amplifier informs us that by using a high mu triodes the high value anode load resistors can be the same value, the balanced outputs across the load resistor should be within 3%.
There are other phase splitter and driver circuits which we can discuss later.
Geordie McBoyne.
