Building Blocks of an Amplifier


Guitarist's Tech Workshop


Lesson Info

Building Blocks of an Amplifier

I was going to talk more about the design side of two of amplifiers s so it's less about the upkeep and whatnot but actually breaking down each major part of a tube amp and how it works and what it does and how to make it do how to make it fail the way you might want to make it failed to sound the way you wanted tio because kind of general topic to keep in mind about guitar amplifier specifically is that they're not they're not there to be perfect and not there to accurately reproduce the stuff you're putting into them they're adding color they're part of your instrument and so it's worth kind of keeping in mind the ways that they fail throughout the air single path to sound cool and make a what you get it at the output be what you wanted to be so anybody who's thinking about doing a little bit designed this should be hopefully helpful so I guess just kind of overview what we'll talk about we'll go through all the major building blocks of of a tube amplifier and then we'll talk about w...

hat are the major questions to be asked when you're trying to design something from the ground up and figure out where to start and then we'll go through each of those building blocks the pre amplifier, the power amplifier, the power supply and then we'll kind of go through distortion different kinds of distortion, how to get those different kinds of distortion, how to do tone shaping with passive circuitry to make the thing uh, kind of trim and taylor those distorted sounds that you've been creating and then ah, some other tricks using what's called negative feedback and then we'll talk about some of the practical concerns faras grounding and noise issues and ways to avoid those sort of bad failures. So looking at the schematic that I had it before, which is again a good basic schematic example to talk talk about using because it it pretty clearly adheres to the er left to right signal path flow top to bottom dc current flow, which kind of helps simplify the description of thes things. So starting at the input kind of put this guitar single into the thing and what's the first thing that happens, we hit the pre amplifier of the amp and the pre empt is there to do a few different things. Um, on the ideal and correct amplifier tip, the job of the pre amplifier is to take years very, very small signal that's created by ah metal string and a magnet that comes out of your guitar and that little signal needs to find its way up to be what's called a line level signal and a line level signal is large enough to feed a power amplifier power and fires job is to make that pre amplified signal legal speaker so the pre amplifier it's kind of all this stuff on the left hand side and the basic gist is that single comes in it works its way through these gains stages and these passive circuits and honest way to feed the power amplifier and then moving through the signal path get to the power amplifier kind of all this business over here on the right hand side so you've taken your little signal you've amplified it you've tone shaped it and then you go into this whole section of the circuit whose job it is to make that signal make your speaker wiggle and annoy your neighbors uh and in a power supply is sort of the part of the circuit that it kind of infiltrates all of it and so it's it's it's you taking thea the power coming out of the wall and creating the different supply voltage is that you need to make all these different parts of the amplifier do their job there's plenty of places and there where you can insert intentional failures to make it fail well and sound cool um somebody exactly so if you were going to design an amplifier this few questions to kind of start with that will sort of give you a general idea of where to begin the first one really general what kind of sound I want so that could be do I want this thing to be a really clean clear chinese bhumi I could use a bunch of stupid words war are meeting with word or do you want to be really distorted? What kind of distortion do I want? I want really thick fuzzy uh uh you know, kind of woolly overdrive do I want a really tight articulate um you know don't want it to be really touch sensitive distortion where you can clean up with your hand or do you want it to be all go crazy distortion? That sort of thing? Those just the main kind just the general character of the sound of the amp and then a really fundamental one that needs to be talked about early on is how much power do I need? How loud do I need this thing to be and that's going to dictate a lot of the different component choices and the wadleigh out the circuit and then the third major one is what controls do I need? What kinds of speakers do I imagine I'm gonna drive with it to have one particular speaker load in mine on that one, eh? You know mt put er do you need to drive many speakers? Do you need to have control over the issue of the amp? Do you need to have control over how distorted it can get in the preempts a versus how loud. You want to send a signal off to the power amplifier? You could do any number of different things. And some of us were joking earlier between thes talks about how it could get really bad. If you want to have too many controls, you can really design yourself into a corner of having way too many things to worry about and way too many places for failure to so worth, considering. Early on, how much of that a adjustability really need before you, uh, throw yourself into that whole mess.

Class Description

Performing a proper setup for your guitar can seem like a dark art requiring a copper chalice filled with incense. Reading a schematic of a tube amplifier can seem like you’re staring at ancient Sanskrit. Guitar and tube amp masters Kurt Bloch and Ben Verellen are here to help.

In this two-part workshop, Kurt and Ben will show you exactly how to get the best sound out of your gear.

In part-one Kurt will teach the basics of setting up your guitar – you’ll learn about:

  • Truss rod adjustment
  • Bridge and nut adjustment
  • String gauge and playing style
  • Guitar maintenance and upkeep
  • Guitar electronics and pickups

Part-two is your primer on tube amplifiers. Kurt and Ben will explain how they work and show you how to keep them sounding great. You’ll learn:

  • Tube biasing
  • Block diagrams and understanding schematics
  • Basic amplifier maintenance
  • Capacitor, resistor, and transformer replacement
  • Speaker repair and power-matching

Kurt Bloch is not only Gibson Guitar’s in-house guitar guru, he’s a legend in the Seattle music scene. He plays in The Fastbacks and Young Fresh Fellows and has a producer credits for his work with The Presidents of the United States of America and Tokyo Dragons. Ben Verellen started Verellen Amplifiers in 2000 and now has a full-time staff churning out hand made custom tube amplifiers for some of the most respected artists in rock and metal. He also fronts Helms Alee, a rock band based in Seattle.

Don’t get caught with crappy tone and blown out speaker – let these two masters show how to take care of your gear and get the best possible sound.


Andrew Synowiec

I bought this course for the amplifier section and skipped straight there. It's fantastic. Right at the perfect level for me, a newbie DIY-er with a few pedals, a kit amp and an Electronics 101 course under my belt. Well done! I'll update my review if I have time to watch the guitar section.