KLD amp kit building primer

"The basics"of electronics comes down to: Having a good understanding of current, voltage and resistance: Not the definition of them. But the understanding of how they work. You should be able to look at a simple circuit, "see" how the current flows and what the voltages are (or how to find them) at key points around the circuit.
​ Knowing how the basic components work: Resistors, capacitors, LED and transistors. You don’t need to learn every detail about them. But get a good understanding of what they do and how to use them.
​ Knowing how to build simple circuits: You'll get a much better understanding from building (even simple) circuits that you'll never learn by just reading. But even more - you'll build

Amps have both power and output transformers. Both have a "primary coil" and a "secondary coil." Both have laminated cores and both handle high voltage.
Power transformer primary and secondary coils are generally as follows:
Primary coil: This is the power coming in from the wall. Power transformers have multiple primaries ports that can take different wall voltages like 100v, 120v, 230v and 240v.
Secondary coil: high voltage secondary for the rectifier, 6.3v secondary for filaments and 5v for rectifier filaments (if the circuit has a tube rectifier).

Power transformer 110V Power transformer

Output transformer primary and secondary coils are as follows:
Primary coil: can be 2 or 3 wires. These feed B+ to the plate of the output tubes and carry high voltage.
Secondary coil: This is the speaker output section. These can have 2 or more wires, usually 3 or 4 wires for a push-pull, and 2 wires for a single ended amp.

Output transformer 6L6 x2
This can be solid state or tube. Either way, this takes high AC voltage and turns it into DC voltage. Tube rectifiers will need the 5v or 6v filament winding on the power transformer.
Power supply
This is important! Every amp has a power supply. This involves the power transformer, filter caps, rectifier and other components, depending on the amp. This supplies voltage to different parts of the amp for the different circuits. What the voltage is depends on the type of amp it is. Is it a cathode bias or fixed bias amp? Does it have 2,3, or 4 stages of filtering? Does it have a reverb driver? Etc. You'll need to know this information for ease of troubleshooting and keeping yourself safe
Preamp section:
This is where your signal is amplified and sent to the various stages for amplification as well as modifying the tone via various potentiometers.
Phase Inverter
Some amps have them and some don’t. There are also different types of phase inverter circuits. It may be best to research phase inverters separately as this is a topic that encompasses a ton of information.
Output section:
This is what does the heavy lifting for the amp. It takes the preamp signal and boosts it via the output transformer, tube plates, negative feedback loop, etc.
Bias circuits
This is what regulates the idle of the output tubes so the amp can run efficiently. This voltage is negative on fixed-bias amps. There are fixed-bias amps, cathode-biased amps and fixed-bias amps with a bias balance. Know what all three are and note the differences.
Preamp tubes
these are most commonly 9 pin (noval) tubes that can have 2 triodes in the same glass envelope. Examples are 12AY7, 12AT7, 12AX7, 7025, 5751, etc.
Output or power tubes These are larger than preamp tubes and have various methods of operation. They are commonly 8 pin (octal) pentodes, power beam tubes, and tetrodes. These are limited to one amplification circuit per tube. Examples are 6V6, 6L6, EL34, EL84, KT88's etc.
Tube anatomy
Tubes can be called a diode, a triode, a pentode, or a tetrode, depending on the construction of the tube itself. Even though they may have the same base that fits your socket, this doesn't mean it will work. All tubes will have a cathode and a plate. This makes up a diode. When you add components like a control grid, screen and suppressor, the tube type changes.
Filament wiring:
This is usually to pins 2 and 7 on the octals and 4+5 and 9 on 9-pin sockets and 2 and 8 on common rectifiers.
These have many different values and do various things. Think of them as variable resistors. Tone and volume controls are usually pots. Bias supplies also have these, but they are not the same as regular signal/tone pots.
These also have different value and voltage ratings in addition to different types of construction. These include polyester film , and electrolytic polarized , ceramic disk, film and foil and Mica type caps. These tend to look very different by design. A polarized cap means it needs to go into the circuit in a particular orientation, usually denoted by a'+' or a '–'on the side of the cap in most cases.Detail about capacitor , please watch Capacitors used in tube guitar amp
Like capacitors, these have different values, types, and voltage ratings. Different types are carbon comp, metal oxide, metal film, and carbon film. Carbon comps usually look different than carbon film and metal film. Also, generally speaking, the larger the resistor, the greater the power it can tolerate. Common values in tube amps are 220k, 1Meg, 68K, 100K etc. These can be anywhere from 1/2w to 10w, depending on the application. Carbon comps are generally used in Fender amps and Carbon film are used in British style amps historically.