THE BASICS OF VACUUM TUBE AMPLIFIERS
We all love the sound of Vacuum tubes for guitars, bass, electric piano, vocals, stereo, etc.
The technology is both old and new. A lot of the things we will look at are old technology, dating back to the 1930’s.
But people like you and me are always working on new approaches to Vacuum tube amplifiers.
There isn’t a day when something new isn’t dreamed up or some old idea isn’t unearthed from the musty corners of ancient books, magazines, and minds.
We’ll study both new and old to gain a good working knowledge of tube technology and allow everyone to dream up their own new amplifiers and ideas.
This book is written for musicians, not technicians.
I provide math and formulas, but there are complete examples to keep anyone from being frustrated or confused.
Technology. What is right? What is wrong? Why not just tell you how to make the perfect amp and be done with it?
This is why I’m writing this book – frustration with getting answers.
Music technology can never be completely classified as “right, wrong, good, bad, or perfect.”
Technicians say: “My design is perfect – all others are bad.” But YOU do not hear it as being all that “perfect.”
Good sound, Bad sound is a relative thing. We are conditioned to believe something is good by what we hear and what we like – but in any society those preferences are socially based.
If we grew up hearing rock music, then guitars through limited frequency response, high distortion tube amps is what we like. That doesn’t mean the gods like it, just that we do.
The sound we like is “colored” – it is not technically perfect. There are peaks and valleys in the frequency response, and even at the cleanest there is a good degree of distortion (a Gibson Type Humbucking pickup can never be 100% clean – phase distortion is built in, and can’t be removed.)
If you want to hear technically perfect, plug into a solid-state sound reproduction power amp. You won’t like the sound.
So we can’t determine a set of perfect specs and work towards them. It is a personal/societal preference.
This book will help you to get your personal sonic signature, and give you the knowledge to change it when your tastes change. Just pull the old chassis out and rebuild it!
Musicians will like the dozens of possible designs here. You can make whatever you want. Some approaches are new and experimental, some are old, some are very old. We look at “standard practices” and some tricks and techniques are outside the “perfect specs” scope jockey’s vocabulary.
It’s all there to learn from. If you do not like something, or find it does not suit your needs, move on. There will be something else on the next page.
I write it all in layman’s language and you can skip the formulas if you want.
What’s It All About?
Tube amplifiers are relatively simple devices. Everything is built upon only three basic assemblies.
#1. The Preamp. Takes the signal from your source, a guitar or bass, and amplifies it enough to run the driver and power tubes.
#2. The Output Section. The driver tube(s) run the power tubes. The power tubes deliver the amplified signal to the speakers.
#3. Power Supply. Gets the power from the wall plug into the amplifier, converts to DC to run the tubes, boosts to high voltages and distributes to the amp circuit.
Our interest starts with the tone producing sections of the amp.
If you are a player, you could care less about a power supply – just extra wasted bucks. But the power supply is important to the sound of the amp and must be carefully designed.
Final Note. There are opinions of the author here. You may disagree and that’s fine.
There are technologies and ideas here. Others may approach these things differently and express different answers. Again, that’s fine. Since tube technology is so flexible, there are bound to be more than one answer to any given problem.
I encourage you to gather your own information and produce your own