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Here are some typical valve guitar amplifiers ...
Life is too short for bad tone. Modern amplifier, speaker, effects and guitar production is more consistent than it has ever been. There is also more information on how to use these tools today, so it's easier to get good tone than ever before. There is also more choice and options than ever before, so it's also easier to get bad tone than ever. I hope you will find enough information on my site to make some informed decisions about which path will take you to your own signature ultimate tone.
Guitar amplification is a specialised field, where much commonly understood theory does not apply, and little theory is published. Technically speaking, a guitar amplifier has a specific type of non-linear gain at its signal extremes, and a specialised type of limited frequency response. Most published theory and learning is aimed at maximising linearity and avoiding any type of clipping or distortion, with the intention to preserve signal quality.
I have around 30 years experience of playing electric guitar, and watching the industry react to changing styles. I have some observations which reveal an entirely different approach to amplifier design. Some concepts will appear foreign or even unbelievable to those with experience in hi-fi amplifiers, however, what I have written is well recognised by those within the industry.
Guitarists are often regarded as living in the past by favouring guitars and amplifiers designed in the 1950s. I think it is quite simple: When a new design becomes available that sounds better than a good guitar plugged direct into a good valve amplifier, guitarists will buy it and move on.
So how it that a 1950's design got it so right that it is still relevant today? Was it luck? Or were they designed by geniuses of the day? I like to think it's a bit of both. Either way, I hope you find enough information on these pages to help you make up your own mind. Bear in mind also that many great instruments such as grand pianos & concert violins have their own heritage many hundreds of years ago, with little technological change, and old instruments highly regarded.
Guitars have evolved to some extent; current Gibsons and Fenders include playability, technical and consistency improvements over their original 1950's releases, although finding good wood is becoming difficult today. And several manufacturers (such as Paul Reed Smith and Parker) have successfully competed with their own new designs and technology.
However, valve guitar amplifiers have evolved very little beyond early designs, despite some difficulties with the supply of quality valves. Even though there are a small number of subtle variations, the vast majority of players prefer valve designs for their guitar amplifiers, and there are some good reasons for this.
Not surprisingly, current solid state circuits and digital "emulation" designs are as good as they ever have been. Indeed, solid state amplifiers are now more popular in every other type of live musical amplification, such as bass guitar, piano and other keyboard instruments, and public address systems. And yet guitarists consistently describe valve amplifies as having a set of attributes not obtainable with any other technology. Common descriptions include "warmth", "richness", "feel" (which I take to mean an interactivity), "organic" and "sustain".
The following pages focus on amplification used for popular electric guitar styles. There are schematics for the standard guitar amplifier tone controls, and a generic overdrive/distortion circuit.
Click the related menu topics at the left for the rest of the story. I hope that I have been able to convey the unusual design goals of a guitar amplification system. These concepts do not change any existing principles for good amplifier design, its just a highly specialised application where the "rules" of linear amplification are only a small part of the overall picture.