This article is mainly about triodes. It is relatively easy to get large amplification of audio signals by using high μ valves, and thereby obtain large audio frequency voltages. But in these valves the internal resistance of the valve, ri, … Continue reading →
I recommend that the article impedance matching of loudspeakers to output valves is read first. It will give some useful basic knowledge about the subject. I also recommend to read the article: Difference between power valves and voltage amplifying valves … Continue reading →
When we want to design a valve stage, we normally use the characteristic curves to obtain the data we need, and then use some formulas to calculate the needed values. All formulas for valves are based on based on the … Continue reading →
This is a simplified approach, just to explain how it works. The principles and calculations are basically the same for a push pull stage as it is for an SE stage, so everything described in the Impedance matching of loudspeakers … Continue reading →
We all must be aware of what a capacitor is; it can be considered as two metal objects with an insulator between. It is actually as simple as that. Therefore, there will always be capacitance between the elements of a … Continue reading →
It is relatively easy to determine whether a transformer is defective or not, by using a multimeter. And if you are working with tube amps you may need to calculate the output transformer impedance especially when we have an old … Continue reading →
There are several ways to make the correct bias for a valve. We have fixed bias, where the grid is supplied with a constant negative voltage, and automatic, or cathode bias where we bias the valve by giving the cathode … Continue reading →
This is a simplified approach, just to explain how it works. A loudspeaker usually has an impedance of 4 – 8 ohms, and an output valve will usually demand a load of several k.ohms. To make this work we need … Continue reading →
Grid current are in most cases unwanted, but can in certain circuits be necessary to make the circuit function as wanted, that will be covered in a separate article later. Now I will look at the causes for unwanted grid … Continue reading →