Dual Triode TubesThere are a number of dual triodes found in guitar and PA amps, all slightly different. Many of them are currently still in production, some are available in NOS (New, Old Stock), some are almost impossible to find.
In the chart below, the 12A? tubes are generally still available in some form, whereas the 12B?7 tubes are not in current production, and less commonly available as NOS.
(Click on column headings to sort by that field.)
100 330 V 40 mA 1.2 W 300 mA JAN 5751 70 330 V 40 mA 1.2 W 350 mA 12AY7
40 300 V 10 mA 1.5 W 300 mA 12BZ7 100 300 V ? 1.5 W 600 mA 12AT7
60 300 V ? 2.5 W 300 mA 12AZ7 60 330 V ? 2.5 W 450 mA 12AV7
41 300 V 18 mA 2.7 W 450 mA 12AU7
19.5 330 V 22 mA 2.75 W 600 mA 12BH7 16.5 300 V 20 mA 3.5 W 600 mA
(Where several tube numbers are given for one tube, the 5xxx is normally the industrial version and the 7xxx is normally a premium version with lower hum and noise, and sometimes matched triodes.)
Then there are the oddball cousins; I list them with only their gain factors. (Who cares? Just weirdos like me.)12DT8 - 60 (12V only - no pin 9 connection) 12AE7 - 13 and 6.4 (yes, each triode is different) 12DW7 - 100 and 20 (ditto) 12AH7 - 16 (but it's octal)(The 12DW7 is essentially one triode from a 12AX7 and one triode from a 12AU7.)
All the tubes except the 12AH7 share a common, nine-pin base. Heater currents vary. All the nine pin tubes except the 12AE7 can handle at least 150V at the plate, most 250 or more. The 12AE7 can handle only 12.6V at the plate. It was made to drive output transistors in hybrid car radios. 8^)
There are others, too, but I won't bore you. If you're really interested, or just wondering about some oddball dual triode you have, get an RCA tube manual or check one of the online tube data banks (Duncan, Triode Elec, etc).
All values from RCA Receiving Tube Manual (RC-22, 1963) or The Radio Amateur's Handbook (Fifty-fifth edition, 1978)) . JAN tube numbers from Lord Valve's preamp tube email list (http://www.freeyellow.com/members2/lord-valve/) or the Triode Electronics tube page (http://www.triodeel.com/) .
Copyright Y2K Miles O'Neal, Austin, TX. All rights reserved.