This is the official site of EJ Jurich author of Vacuum Tube Amplifier Basics. Written for hobbyist interested in building high-fidelity vacuum tube audio systems, the book is concise with illustrations and examples.
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.
In 1955 started tinkering with vacuum tube electronics at the age of ten. My father worked for Western Electric
and was well versed in electronics. As I experimented with circuits I would consult my father. Between 1955 and
into the mid 1970s built several kits both Knight and Heath Kits. In 1969 passed exams obtaining an FCC First
Class License, then started a career in radio broadcast engineering.
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.
Vacuum tube audio processor for maintaining an average level while preserving dynamics using an all triode vacuum tube design built around the 12AX7 dual triode. This is the gain controlled amplifier mentioned in The Allure of Vacuum Tube Amplifiers.
A gain controlled amplifier (also called a compressor) is an amplifier that maintains an average output level over
a larger input level range. This type of amplifier is used to prevent over-driving audio systems and keep levels in
a more comfortable listening range.
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.
Building a vacuum tube amplifier can be expensive, transformers and power output tubes can be especially pricey.
If you are working with a tight budget, there are options available to help reduce costs. Backing off on amplifier
power and referring to sound pressure levels for loudness can save you money and save your hearing.
Tubes have an optimal filament voltage, for example 6.3 volts, 12.6 volts, etc. Although a voltage range above and
below the optimal voltage is specified in datasheets there is good reason to not apply more than the optimal value.
ejjurich.com 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 exercise care when working with electronic circuits.
EJ Jurich has no association with sites offering free downloads of my book. Beware of sites that offers free downloads or want you to register. 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.