This stuff can be a bit much to the uninitiated.
I’ll try to break it down quickly. I’m not a professional or an electronics major, but I’ll do my best to explain it in layman terms.
Electric guitar tone needs to be amplified via a speaker to sound good; those little magnetic pickups have a weak signal by themselves. So you need an amplifier that will boost the signal to push some air in your speaker. The speaker is an integral part of converting that signal to a fuller sound. Guitar Speaker Cabinets have guitar specific speakers that are not “full range, full frequency” (FRFR) transducers. These guitar speakers colour the sound. An electric guitar would sound shrill via FRFR speakers.
A typical guitar tube amplifier has a preamp followed by a power amp. The preamp boosts and colours the sound which feeds the power amp to feed/drive the speakers eventually.
The preamp usually has a “Gain” control, sometimes called a “Drive”, “Overdrive”, “Distortion”, “Volume” etc.
Between the preamp and the power amp, often the amplifier will have a send and return loop, this is used to add time-based effects like reverb and delay ( more on this later) .
The other thing a guitar amplifier does is have an equaliser to shape the guitar signal, typically treble, middle and bass. These equaliser settings usually affect the preamp.
There are more tone shaping possibilities with some amps that work with the power amps section, things like presence ( hi frequency cut), thump ( bass).
The amplifier may or may not have a master volume. The non-master volume amps are typically controlled via the preamp drive control.
Master volume amps have a master volume (duh) and control the power amp output.
The power amp section can also compress ( more on this later) and introduce its own distortion depending on the design and how much you’re pushing it.
British amps typically ( Marshal ) have higher gain preamps where the valves are driven into distortion. The earlier amps didn’t have master volumes and needed to be played very loud to get the desired gain tone from the amplifier.
Fender amps ( the amps Jim Marshall cloned and modified initially ) have cleaner sounding preamps for the most part.
Guitar cabinets and speakers are of various types too. I will just say here that guitar speakers can have their own sound signatures, some boost the mids, some are scooped ( that is highs and lows are more pronounced) etc. A good match with an overdriven amplifier is when the guitar speaker is also sufficiently pushed into compression, and it’s own musical distortion. The guitar speaker is where it all comes together if you hear the signal via an FRFR speaker the driven amp will sound horrendous and broken. The guitar speaker is where the horrible sound is smoothed out into the musical sounds we all know and love.
Some amplifiers have effects built in. The basic signal from the amp is considered “dry”, the minute you add time-based and other effects you have a “wet” signal mixed with dry signal.
Typical effects categories:
Reverb: simulates the short echo of a room/hall etc.
Delay: simulates longer echos with repeats, length and eq.
Compressor: Makes the softer signals go loud, makes the louder signals go softer. This results in a lower dynamic range for the single strength.
Chorus: Fattens the sound by pitch shifting the note with a delay and then mixing the sound back with the dry signal.
Tremolo: An effect that oscillates raising and lowering the pitch of the note. Much like how you play a note with “vibrato”, bend up and down, or wiggle your tremolo arm on the bridge of a guitar.
Vibrato: An effect that oscillates raising and lowering the volume of the guitar.
Honestly, Vibrato means Tremolo and Tremolo means Vibrato, can’t imagine why this was done to confuse everybody further.
Boost, Drive, Overdrive, and Distortion are just words that express the stages of signal degradation while amplifying the guitar signal.
Boost: used to describe a preamp that boosts the signal without any clipping( another word for distortion). They are designed to retain the original signal, but just make it louder.
Drive/Overdrive: boost with moderate distortion.
Distortion: heavy distortion.
Simulations/modelling of guitar signal chains.
The only thing that can be confusing is the speaker cabinet modelling. They are know as IR for Impulse Response, basically are snapshots of a guitar cabinet, loaded with a specific speaker and a microphone set at a particular orientation.
All electric guitar you hear is a cabinet being miced up for the reasons I said earlier; the speaker is very important.
Recording/tracking sessions can use one or more mics at specific places and phases in the room to get the desired sound.
The reson guitar amplifiers have effects loops, one of them atleast is to use time based effects like delay after the preamp and before the poweramp, using delay in most cases before a heavily driven preamp will result in mush unless it’s something specific you want to do like EVH on his first album.
So typical chain to sum it up follows as such:
–> speaker cabinet
–> microphone preamp
–> mixing desk etc.
Nowadays folks often use pedals and other more practical devices to enhance, substitute part or all of bulky and loud amplifiers/cabinets for taste and practicallity.
A lot of folks prefer to use a clean amp ( sans/ distortion) and use pedals to get the drive they need.
my signal chain for a bedroom guitar enthusiast:
Guitar: Fender Yngwie J Malmsteen signature Stratocaster
–> Vemuram Budi ( a boost pedal to get the single coil pickups that have a low output to drive the next pedal in the chain to a higher degree of dirstortion )
–> Vemuram Karen ( simulates a Marshal super lead type amp. These two pedals act as my preamp. )
–> RME Babyface pro ( Computer Audio Interface with low latency A/D & D/A converters, allows me to use my computer to simulate the guitar amplifier power amp, delay effect and speaker modeling to get a realistic sound )
->> Logic X DAW ( Digital Audio Workstation Client) This hosts my session where I can manipulate the virtual stack of software based effects to simulate the rest of my chain, monitor, mix, record etc.
–> TPA-1 (plugin simulating a power amp)
–> S-Gear2 ( plusing simulating effects like delay and the IR cabinet loader)
Phew… hope that helps