This page is presented for your information and guidance.
To assist you make a more informed choice I have listed commonly available tubes that are known to perform well in their respective classes of service in audio output and transmitter RF modulator applications.
Please refer to the manufacturer's catalogue for full ratings and applications for tube types in which you are interested.
Some tube types are available only from one manufacturer however most are available in more than one brand name.
There are many, many, more possible inclusions but this list is intended to be a ready reference - not an encyclopedia.
It is not intended to be a definitive guide to all available types of tubes but if you know of any other types that are worth including please let me know their details.
I hope it is of help to you in selecting the best audio output tube for your needs.
THE AUTHOR MAKES NO CLAIM WHATSOEVER AS TO THE VALIDITY OR ACCURACY OF ANY STATEMENT, INFORMATION OR OPINION CONTAINED IN THESE PAGES AND NO LIABILITY WILL BE ACCEPTED FOR ANY ERROR OR OMISSION OF ANY KIND WHATSOEVER.
NO WARRANTY IS EXPRESSED OR IMPLIED AS TO THE
WORKABILITY OR PERFORMANCE OF DESIGNS DESCRIBED HEREIN.
VACUUM TUBES AND CIRCUIT COMPONENTS OPERATE AT HIGH VOLTAGES OF BOTH ALTERNATING CURRENT AND DIRECT CURRENT THAT CAN BE FATAL.
VACUUM TUBES OPERATE AT HIGH VOLTAGES AND TEMPERATURES THAT CAN CAUSE PERMANENT INJURY, DISFUNCTION OR DISABILITY - TO YOU OR SOMEONE ELSE.
DO NOT ATTEMPT TO CONSTRUCT, TEST, WORK ON, OR COME INTO PHYSICAL CONTACT WITH, LIVE ELECTRONIC EQUIPMENT UNLESS YOU ARE TRAINED OR OTHERWISE QUALIFIED TO DO SO.
NEVER REMOVE A PROTECTIVE COVER FROM ELECTRONIC EQUIPMENT UNLESS YOU ARE TRAINED OR OTHERWISE QUALIFIED TO DO SO, BECAUSE LETHAL MAINS AND HIGHER VOLTAGES ARE PRESENT INSIDE.
Extra care should be taken with circuit designs using the B+ voltages listed in this guide.
Safety is of extreme importance and live wiring should be fully insulated to prevent electrocution of yourself and/or users.
Tubes for use at B+ voltages over 450v DC require sockets made from materials that can withstand high voltages. Inferior materials may cause flashover or arcing, leading to burning, short-circuits and/or tube damage.
Many tube types listed require a top cap plate connection and such tubes must be carefully mounted to minimise wire length, proximity to other components and risk of accidental contact. Insulated caps are recommended. Do not solder directly to tube caps.
Most vacuum tubes are glass encased devices that have been evacuated of air - ie they contain a vacuum atmosphere. If dropped or impacted they are likely to implode, shattering glass in any direction. Handle with care and respect. Do not drop or impact. Always pack and store in padded wrapping or the manufacturer's carton.
When inserting into a tube into its socket always take care to align all the tube pins correctly with the matching socket. Incorrectly aligned tubes may result in high voltages being applied to low voltage circuit compomnents or systems, and may result in short-circuit fault currents being applied with resultant expensive damage to tubes and equipment.
To avoid serious and permanent tube damage when constructing an amplifier, always ensure the grid bias voltage is present at grids 1, 2 and 3 before applying B+ high voltages to the circuit. In this regard, cathode bias and back bias configurations are safer and more reliable designs than fixed bias.
Always ensure large HV electrolytic capacitors
are fitted with suitable bleeder resistors to automatically discharge them
after the amplifier is switched off - otherwise you may expose yourself
to lethal current if you accidentally touch a live conductor.
1. SCREEN GRID (GRID # 2) SUPPLY
The Screen Grid should always be supplied by a suitable low voltage supply, having a low-impedance path to ground - ie effectively AC earthed.
See Screen-Grids page for full details.
2. "ULTRA-LINEAR" OPERATION
An alternative to normal tetrode, pentode or beam power tube configurations is the Ultra-linear circuit.
Ultra-linear configuration avoids the need for a separate screen grid supply.
"ULTRA-LINEAR" is a term when applied to audio amplifiers, describes that output stage configuration whereby the screen grids (Grid 2) of tetrodes or pentodes are fed from a tapping on the primary of the output transformer, typically 43% turns or 19% impedance, instead of from a separate DC supply.
Ultra-linear is also known as distributed load operation.
Full details are provided in my separate ULTRA-LINEAR
Now that you have been suitably prepared, feast yourself upon this glorious selection of magnificent TRIODE, TETRODE, PENTODE and BEAM POWER audio output tubes from manufacturers dedicated to excellence in performance and reliability.
Except where otherwise noted, classifications are based on "Design Centre"
1. OUTPUT TUBES for B+ to 250V DC
5998 (similar to 6AS7G)
6520 (=HQ version of 6AS7G)
2. OUTPUT TUBES for B+ to 300V DC
2A33. OUTPUT TUBES for B+ to 350V DC
7189 (HQ form of 6BQ5/EL84)
7408 (HQ form of 6V6GT)
6F6GT4. OUTPUT TUBES for B+ to 400V DC
6293 (similar to 6146)
7581A (similar to 6L6GC)
2E245. OUTPUT TUBES for B+ to 450V DC
6AR5 (similar to 5881)
6AR6 (similar to 5881)
1614 (375v) (HQ form of 6L6G)
1619 (HQ form of 6L6G)
1622 (HQ form of 6L6G)
5881 (HQ form of 6L6G)
5932 (HQ form of 6L6WGA)
6098 (similar to 5881)
6973 (HQ form of 6CZ5)
6L6GC6. OUTPUT TUBES for B+ to 500V DC
1632 (HQ form of 12L6GT)
7027A (HQ form of 6L6GCWA)
7. OUTPUT TUBES for B+ to 600V DC
5B/254M (= 807)8. OUTPUT TUBES for B+ to 750V DC
807 (= QV05/25, QE06/50, 5B/254M, ATS25)
1624 (similar to 807)
1625 (similar to 807)
6159 (similar to 6146)
6883B (similar to 6146)
8298 (similar to 6146B)
ATS25 (= 807)
8099. OUTPUT TUBES for B+ to 800V DC
1623 (similar to 809)
6384 (similar to 6AR6)
6CA7/EL3410. OUTPUT TUBES for B+ to 850 V DC (Absolute)
KT12011. OUTPUT TUBES for B+ to 1250V DC
203A11. OUTPUT TUBES for B+ to 1500v DC
8005 (similar to 203A)
12. OUTPUT TUBES for B+ to 2000v DC
13. OUTPUT TUBES for B+ to 2500v DC
204A14. OUTPUT TUBES for B+ to 3000v DC
813 (= QB2/250)
8000 (similar to 810)
QB2/250 (= 813)
15. OUTPUT TUBES for B+ to 4000v DC
REMEMBER - ALWAYS TAKE CARE WHEN WORKING WITH HIGH-VOLTAGE - DEATH IS
This page last modified 05 January 2015