Part 2: Introduction into the Universal System

of The Vanderveen Project


All tubes in valve amplifiers have in common that the cathode is hot, emitting free electrons which are collected by the positive anode. The amount of electrons going from cathode to anode is determined by the negative voltage at the control grid.
While running from the cathode to the anode the free electrons hardly hit the control grid, therefore the current in the control grid is negligible.

The actual current in a power tube is small, about 100 mA, while the voltage variation is large, several hundreds of volts. However, loudspeakers need several amperes plus tens of volts. Therefore an output transformer is placed between the power tube and the loudspeaker to transform the current into larger values and the voltages into smaller values. The tube is connected to the primary side of the OPT with Np turns and the loudspeaker is connected to the secondary winding with Ns turns. Because Np is larger than Ns, the secondary current Is = Ip · Np / Ns is transformed into larger values while at the same time the secondary voltage Vs = Vp · Ns / Np is transformed into smaller values.

Every vacuum tube amplifier has its own specific manner in which the power tubes and OPT are connected to each other. However, it is possible to recognize a system in all these variations. This system will be discussed in the next two parts to come.


More news to follow soon!