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.
 
 

SAFETY WARNING:

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 page.
 
 

***********************************************************************************************

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" values.
 

1.    OUTPUT TUBES for B+ to 250V DC

6AQ5A
6AS7G
6DS5
6J6 (150v)
1626
5763
5998 (similar to 6AS7G)
6005 (=6AQ5W)
6080
6082
6094 (=6AQ5W)
6095 (=6AQ5W)
6520 (=HQ version of 6AS7G)
6870
7558
EC90

2.    OUTPUT TUBES for B+ to 300V DC

2A3
42
47
6A3
6B4G
6BM8
6BQ5/EL84
6C4
6CM5
6CM6
6CZ5
6EM5
6K6GT
6M5
6N7GT
6V6GT
4074A
5618
5763
6417
7189  (HQ form of 6BQ5/EL84)
7408  (HQ form of 6V6GT)
7868

6F6GT
6L6GB
1613
5556
6293 (similar to 6146)
7581A (similar to 6L6GC)
KT81

2E24
2E26
6AR5 (similar to 5881)
6AR6 (similar to 5881)
1610
1614 (375v)  (HQ form of 6L6G)
1619 (HQ form of 6L6G)
1622 (HQ form of 6L6G)
4300A
5881 (HQ form of 6L6G)
5932 (HQ form of 6L6WGA)
6098 (similar to 5881)
6973 (HQ form of 6CZ5)
EL37
KT61

6L6GC
6L6GCW
10-Y
841
842 (425v)
843
1608 (425v)
1632  (HQ form of 12L6GT)
5894
6550
7027A  (HQ form of 6L6GCWA)

802
837
4061A
6524
6850
KT66

7.    OUTPUT TUBES for B+ to 600V DC

5B/254M (= 807)
6AR6/6098
6BG6GA
6BQ6GTB/6CU6
6DQ6A
801A
802
807 (= QV05/25, QE06/50, 5B/254M, ATS25)
832A   (600v)
1624 (similar to 807)
1625 (similar to 807)
4033L
4043C
5894/QQE06-40
5933 (=807W)
6098/6AR6
6146
6159 (similar to 6146)
6293
6550
6883B (similar to 6146)
8032A
8298 (similar to 6146B)
8417
8552
ATS25 (= 807)
KT77
KT88
P17X
QE06/50 (=807)
QQE06-40/5894
QV05-25 (=807)
QV06-20 (=6146)
5B/251M
5B/252M
5B/254M
5B/255M
5B/256M
5B/257M
5S1-B

809
829B
865
1623 (similar to 809)
6384 (similar to 6AR6)
KT90 (Absolute)

6CA7/EL34
12E1
826
EL34/6CA7
KT94
KT100

KT120

203A
211
800
804
811A
812A
814
830B (1000v)
832 (1000v)
834
835
838
845
850
4304CB (1000v)
5588 (1000v)
8005 (similar to 203A)
4X150A
4X150D
4CX150A
4CX150D

           805
           808
 

12.    OUTPUT TUBES for B+ to 2000v DC

           803
           810
           828 (1750v)
           7203/4CX250B
           7580W/4CX250R
           8001/4E27
           8957/4CX250B
           4CX250B/7203/8957
           4CX250R/7580W
           4E27/8001
           4X250B
 

13.    OUTPUT TUBES for B+ to 2500v DC

204A
4CX350A/8321
4CX350F/8322
4CX350FJ/8904
813 (= QB2/250)
849
5866
7986
8000 (similar to 810)
8321/4CX350A
8322/4CX350F
8904/4CX350FJ
QB2/250 (= 813)

        3-500Z/8802
        4-65A/8165
        4-125A/4D21/6155
        4CX1000A/8168
        6C24
        806
        6155/4-125A/4D21
        8165/4-65A
        8168/4CX1000A
        8802/3-500Z
 

15.    OUTPUT TUBES for B+ to 4000v DC

        4-250A/5D22
        4-1000A (6000VDC)
        4E27/8001
        4E27A/5-125B
        4X500A
        250TH/454H/RK63A
        454H/250TH/RK63A
        8001/4E27
 
 
 

REMEMBER - ALWAYS TAKE CARE WHEN WORKING WITH HIGH-VOLTAGE - DEATH IS PERMANENT!!
 

Contact:
 

Email:    contact
 
 

Home Page
 
 

This page last modified 05 January 2015