Vacuum Tube Amplifiers

"they sound good and keep you warm at night"

Vacuum Tube Amplifier Basics

There is a growing number of audio enthusiasts and hobbyist interested in creating their own vacuum tube amplifiers. If one has the necessary technical information, high quality tube amplifiers can be assembled using point-to-point hand wiring.

For the novice not versed in electronics several sections of the book cover electronic basics. Includes how capacitors work, voltage, current, ohms law, reading circuit drawings plus other related information.

Principles of vacuum tube operation includes function of grids, effect of tube capacitance, tube resistance, heat dissipation and voltage gain. A table of component values for the popular 12AX7 in various operating parameters simplifies pre-amplifier stage design. Power supply sections cover vacuum tube and solid state rectifier conversion of AC to DC and DC filtering. A sample power supply is used to explain calculating loads, determining required transformer ratings and component values. Includes high voltage, bias and filament supplies.

Vacuum Tube Amplifier Basics Book
Projects have layout drawings

Working with electronics and vacuum tube circuits requires some math. Circuit calculations in this book use various forms of addition, subtraction, multiplication and division. Formulas are all solvable using a standard 12 digit calculator. Calculations are presented with examples.

Projects include a line amplifier with 25db gain, triode balanced-unbalanced input stage, tone control stage, turntable pre-amplifier, 6V6SE Class A stereo amplifier, 6V6SE Class A monoblock amplifier, 30 watt monoblock amplifier and a 5 watt guitar amplifier with adjustable overdrive. The 30 watt monoblock amplifier is designed for tube rolling using various type output tubes. Projects include parts list and component layout drawings.

This book is occasionally checked for corrections or outdated information and revised. When shopping around be sure you are buying a current version with the latest revisions. The latest revision for this book is dated Dec, 2018. A revision date is printed in the book after the title page. Third party sellers may list the book as new, but it may be an older printing without current revisions or corrections. If you purchase through the links below, you will have the most current revision.

The printed book has the advantage of being able to quickly thumb through and bookmark pages. A printed book is readily available without the need for a viewing device. To keep the print book affordable it is printed black and white.

Vacuum Tube Amplifier Basics

8½ X 11 inch paperback book

List Price - $15.00

Retail - $14.25




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A Brief Bio of EJ Jurich
EJ Jurich

Originally From Chicago
Current Age -
Radio Broadcast Engineer, retired

Started tinkering with electronics in 1955 at the age of ten. I had a table in my room where I started experimenting with tube amplifiers. The tubes I used were 35W4 rectifier, 12AX7 and 50C5 output tubes. These were mostly tubes used in AC/DC radios of the time. Filaments were wired in series and connected directly across the 115VAC power main. The 35W4 rectified AC directly from the 115VAC power main, there was no power transformer. This would mean working with a chassis where ground circuits connected directly to the AC power main. AC plug prongs were the same size allowing a plug to be plugged into an AC outlet either way. Depending which way the amplifier was plugged in circuit grounds might actually be on the hot AC main. Click here to read rest of the Bio

The Allure of Vacuum Tube Amplifiers

There are a few possible reason for the allure of vacuum tube amplifiers. Perhaps it is nostalgic, status symbol of owning a vacuum tube amplifier or possibly because of the way audio sounds amplified through vacuum tubes. If you ask audio enthusiasts who prefer vacuum tube amplifiers, more than likely they will say it's the sound. The opinion of a few audio enthusiasts may not mean much. How about the opinion of a few thousand ordinary people. Click here to read rest of the article

Importance of Filament Voltage

Tubes have an optimal filament voltage, most common is 6.3 volts. Although a voltage range below and above the optimal voltage is specified in datasheets there is good reason to not apply more than the optimal value. Click here to read rest of the article

6SN7 Headphone Amplifier

This is an experimental headphone amplifier using one section of a 6SN7 as the output tube. Power output at 1KHZ is ½ watt sufficient to drive headphones loud and speakers in a small room to a moderate listening level. With the tone control set in middle rotation frequency response measured 40HZ to 18KHZ -3db points.

6SN7 Amplifier

Speaker Binding Post
Speaker Binding Post
Speaker Binding Post

Gold Plated
Speaker Connect Posts
4 for $11.48

free shipping

Custom Panel Engraving
Custom Panel Engraving
Custom Panel Engraving

Single Panels
Production Runs

Tube amp transformers
Tube amp transformers
Tube Amp Transformers

Power Transformers
Output Transformers
Custom Wound Transformers
Made In U.S.A.

Vacuum Tube Amplifier Basics

Vacuum Tube Amplifier Basics
8½ X 11 Paperback
LULU Bookstore

Principles of vacuum tube operation includes function of grids, effect of tube capacitance, tube resistance, heat dissipation and voltage gain. Projects include a 30 watt monoblock amplifier designed for tube rolling.

Acrosound Amplifier Circuits

These are circuits from the 1955 Acrosound transformer catalog. The circuits are updated using current available transformers, component values and have a parts list. Building using only a circuit drawing as guide requires some amplifier building experience.


6L6 Push-Pull
Center-Tap Output Transformer
6SL7 Driver/Phase Inverter


Williamson Type Circuit
Pentode or Triode Output Option
6SN7 Driver/Phase Inverter


6V6 Push-Pull
Ultra-Linear or Tetrode Option
12AX7 Driver/Phase Inverter

The Rejuvenation of Vacuum Tubes
Lane S. Upton

This is a good reference source for those who wish to try bringing weak tubes back to life. It does require the use of a tube tester.

Rejuvenation of Vacuum Tubes PDF

Secrets of Output Transformers
Menno van der Veen

A lot of good information about output transformers, amplifier performance and selecting an optimal output transformer for a special application.

Secrets of Output Transformers PDF

RoHS beware the Grim Reaper
, beware the Grim Reaper of electronics

vacuum tube amplifiers
High Voltage Audio
New to electronics or experienced, when working with vacuum tube equipment be careful where you put your hands.

DISCLAIMER assumes no responsibility for damage, injury or otherwise related to any use of information on this site or given by other means. Many electronic circuits, in particular vacuum tube circuits, operate with dangerous voltage and current. Always excercise care when working with electronic circuits.

EJ Jurich has no association with sites offering free downloads of my book. A site that offers free downloads or wants you to register beware. If the download is free, then why would they require you to register? Free download or torrent sites are notorious for passing malware on to you. Be very careful.

For those wondering what happened to the resource links at the bottom of the page. Those links needed to be verified every few weeks. In an effort to reduce web site maintenance and have more time to work on circuit design the site was reduced to primarily my own material. EJ Jurich

copyright 2014 -