Tube Audio Basics

Although there are hundreds of tube amps out there in the market with all kinds of exotic tubes, for the "never-been-tube’d" before, there are 3 basic types of 'power tube' amps you can start with:

EL-34 tubes are widely used by in guitar amplifiers because it is characterized by a greater amount of distortion at lower power than other octal type of tubes. You can be assured that EL34 tube sound is highly desirable by the music pros. EL34 is a vacuum tube of the pentode type. It has an octal base (indicated by the '3' in the part number) and is found mainly in the final output stages of amplification circuits. In common with all 'E' prefix tubes, using the Mullard-Philips tube designation, the EL34 has a heater voltage of 6.3V. It is capable, when used at its plate rating of 800 volts maximum, of producing 90 watts output in Class AB1 in push-pull configuration, but they won't last very long at that kind of voltage. Typically you will find 40 to 50 watts plenty of EL34 power, with decent life expectancy. The EL34 was introduced in 1953 by Mullard and its parent company Philips, and although no longer made by them, is still in production by many and readily sold at very affordable prices.
 
KT-88 tubes are used in the power sections of tube amplifiers. The KT-88 is a beam (kinkless) tetrode tube, fitting a standard eight-pin (or Octal) socket, with similar pin out and functions as EL34. The KT88 was introduced by GEC in 1956 and was specifically designed for audio amplification. Being one of the largest tubes in its class, KT-88 can handle significantly higher plate voltages than similar tubes, up to 800 volts. There are only a handful of manufacturers who produce KT-88 tubes.  NOS examples in good condition are extremely rare and quite expensive. Given its limited availability, the KT-88 is rarely used in guitar amplification. Historically it has always been far more popular with hi-fi manufacturers than guitar amplifier builders given its high-power, low-distortion characteristics.
 
300B tubes produce the ultimate high fidelity sounds. The 300B is a directly heated power triode using a four pin base, introduced by Western Electric in 1937 to amplify telephone signals. It measures 6.4 inches high and 2.4 inches wide. It has a 40 watt anode dissipation. In the 1980s the 300B was rediscovered by audiophiles for use in home audio equipment and is known for its high fidelity, low noise and reliability. It is frequently used in single-ended triode (SET) audio amplifiers but unfortunately they are lack of the power that EL-34 and KT-88 tubes can produce. If a single ended 300B tube amp can punch out the power matching EL34 and KT-88, there probably will be no need to have tube amps types other than 300B. That speaks how desirable 300B tube sounds are for audiophiles and music lovers. Due to their rarity and high demand, new old stock (NOS) 300B tubes made by Western Electric from the 1940s–1960s have become collectible items among audio enthusiasts.
 
The above 3 basic power tubes types are sufficient for you to experience and appreciate tube amps, before you head onto the venture of tube rolling, which will request substantial knowledge of tubes and well trained ears.
Grant Fidelity currently only provide the above 3 types of tubes amps, because of the tubes’ availability and affordability. After all, we want you to be able to afford hi-fidelity audio without being too much wrapped in the gear itself. It is the music really matters, isn’t it?
 
Which one is right for me?

 

Amps with Tube Type
Availability
(how easy is it to purchase)
Affordability
(does it hurt your wallet?)
Appearance
(do they look good?)
Maintenance
(can they survive tough usage)
Sonic quality
(how does it sound?)
EL-34
Abundant options
Most Affordable
standard
Low
Powerful & musical
KT-88
Sufficient options
Moderate
Attractive
Low
Lush & musical
300B
Limited options
Slightly pricy
Sexy
Medium
I am in heaven but may just need a bit more punch 

 

 
Pre-amp tubes are typically the smaller tubes that feed the power tubes circuits on integrated tube amplifiers, popular production types are the 12AX7, 12AX7, and 6N1P. These tubes provide the sound character definintion the power tube circuits amplify. Rolling these tubes is relatively inexpensive and can create the most 'bang for the buck' change to your system.
 
Vacuum tube manufacturers: Most current mass-production vacuum tubes are made by former and current socialist countries such as China and Russia. China accounts the world's 30-40% vacuum tube production in today's market and many of their tubes are sold under western OEM brands with the origin undisclosed. Most developed countries stopped making vacuum tubes in the 1970's and today even if they want to resume production for the lucrative profit in hi-fi tubes, the production equipment cannot be restored anymore. China has never stopped making vacuum tubes in the past 50 years since the country was closed to outside world until late 1970s and early 1980s. There are two vacuum tube manufacturers in China - Shuguang (meaning 'dawn' in English) and TJ Full Music. Shuguang is one of the oldest tube manufacturer in China with over 50 years of history and it is about 10 times the size of TJ Full Music. TJ Full Music has been in business for over 15 years and is privately owned. 
 
To take a look of how tubes are made at Shuguang - please see Enjoy the Music.com factory tour in Dec 2009: 
 
To take a look of how tubes are made at TJ Full Music - please see Enjoy the Music.com factory tour in Dec 2009: