7 pin X

Salas · 14th October 2007, 02:21 PM

Does anybody know the type of the 7 pin mini tube in the attached picture? I found 4. Maybe they are useful for audio. There is a screen with a stamped X rib between the 2 constructions in the tube.

JohnAtwood · 14th October 2007, 03:16 PM

This looks almost for sure a 6AL5 dual diode (or possibly a 12AL5, the 12V version). This is sometimes used as a bias supply rectifier, but is more often used as a detector in FM tubers and TVs. Many classic tube tuners from the 1950s and 60s used these.

- John Atwood

kevinkr · 14th October 2007, 04:01 PM

Looks like a 6AL5 dual diode to me as well. Sometimes used in FM ratio detectors or discriminators. Some people have also used them as bias and very low voltage/current full wave rectifiers.

Colt45 · 14th October 2007, 04:05 PM

I'm thirding 6AL5

gianis · 14th October 2007, 06:47 PM

may be 6al5 dedector

Salas · 14th October 2007, 09:33 PM

Thanks guys. Bias rectifier...hmmm, I got some 2A3 RCA by Volterex, and I think of making a PP 2A3 in the future. Should not be bad to use fix bias 2A3s driving a 6K6 PP OP, and use the mini rectifiers for a regulated bias circuit with a 12B4 pass and a 12AX7 controller. Maybe LTP input EF86 to 2A3 I am thinking. On the other hand...maybe too low 2nd harmonic vs 3rd, 5th etc. Have you listened to an excellent 2A3 PP circuit that you can recommend?

14th October 2007, 03:16 PM	#2
JohnAtwood diyAudio Member Join Date: May 2006 Location: Rural Nevada	7-pin tube This looks almost for sure a 6AL5 dual diode (or possibly a 12AL5, the 12V version). This is sometimes used as a bias supply rectifier, but is more often used as a detector in FM tubers and TVs. Many classic tube tuners from the 1950s and 60s used these. - John Atwood

14th October 2007, 04:01 PM	#3
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	Looks like a 6AL5 dual diode to me as well. Sometimes used in FM ratio detectors or discriminators. Some people have also used them as bias and very low voltage/current full wave rectifiers. __________________ "Extraordinary claims require extraordinary evidence." - Carl Sagan

14th October 2007, 06:47 PM	#5
gianis diyAudio Member Join Date: Jan 2004 Location: athens	6al5 may be 6al5 dedector

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14th October 2007, 04:05 PM	#4
Colt45 diyAudio Member Join Date: Feb 2002 Location: Canada	I'm thirding 6AL5

14th October 2007, 09:33 PM	#6
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Thanks guys. Bias rectifier...hmmm, I got some 2A3 RCA by Volterex, and I think of making a PP 2A3 in the future. Should not be bad to use fix bias 2A3s driving a 6K6 PP OP, and use the mini rectifiers for a regulated bias circuit with a 12B4 pass and a 12AX7 controller. Maybe LTP input EF86 to 2A3 I am thinking. On the other hand...maybe too low 2nd harmonic vs 3rd, 5th etc. Have you listened to an excellent 2A3 PP circuit that you can recommend?