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Question about 6DJ8 pin-out

99.250.113.150
Posted on May 2, 2012 at 17:26:44
bjh
Audiophile

Posts: 14232
Location: Toronto, Canada
Joined: November 22, 2003
 6DJ8

Can someone tell me what pin 9 is? It looks like a grid element!

If we compare with 12AX7 (I know they're not compatible!) 9 seems to be an alternate for filament/heater hook-up, presumably for when you want to use just one of the two triodes.





"Can you support that with measurements?"
"Yes, I sit 3m from my speakers and definately hear that there is more bass." - anonymous

 

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RE: Question about 6DJ8 pin-out, posted on May 3, 2012 at 06:47:01
truep
Audiophile

Posts: 289
Location: Texas
Joined: March 28, 2004
 The center tap on the 12AX7 is so you can tie pin 4 and 5 together and use 6.3v between the tie point and pin 9. On the 6DJ8 pin 9 is a shield.

 

RE: Question about 6DJ8 pin-out, posted on May 3, 2012 at 07:27:00
bjh
Audiophile

Posts: 14232
Location: Toronto, Canada
Joined: November 22, 2003
 "The center tap on the 12AX7 is so you can tie pin 4 and 5 together and use 6.3v between the tie point and pin 9"

That would be wiring each half of the filament in parallel, putting the full 6.3v volts across each half (or equivalently the heater circuit would "see" 1/2 the resistance of the full filament).

Can't imagine why that would be done, and I suspect the filament would have a *very* short life.










"Can you support that with measurements?"
"Yes, I sit 3m from my speakers and definately hear that there is more bass." - anonymous

 

RE: Question about 6DJ8 pin-out, posted on May 3, 2012 at 08:21:43
Tre'
Industry Professional

Posts: 7941
Location: So. Cal.
Joined: February 9, 2002
 A 12ax7 has a 12.6 volt, center tapped filament. Each half seeing 6.3 volts when 12.6 volts is applied.

Wiring the two halves in parallel and and applying 6.3 volts at double the current draw is done all the time. They are meant to be used either way.

The heater draw with 12.6 volt across the whole filament is 150ma and the heater draw with the filaments in parallel at 6.3 volts is 300ma.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

Ah right! ... I've got 6DJ8/6922 on the brain! LOL ... Thanks. nt, posted on May 3, 2012 at 08:46:20
bjh
Audiophile

Posts: 14232
Location: Toronto, Canada
Joined: November 22, 2003
 .


"Can you support that with measurements?"
"Yes, I sit 3m from my speakers and definately hear that there is more bass." - anonymous

 

RE: Question about 6DJ8 pin-out, posted on May 2, 2012 at 18:00:51
Eli Duttman
Audiophile

Posts: 7599
Location: Plainsboro, NJ
Joined: March 31, 2000
 It's an internal shield, which should be grounded. True 6CG7s have the same pinout, as does the 7058.

Russian types that have that arrangement include the 6Н1П (6n1p) and 6Н2П (6n2p).

Eli D.

 

Thanks! nt, posted on May 2, 2012 at 18:08:34
bjh
Audiophile

Posts: 14232
Location: Toronto, Canada
Joined: November 22, 2003
 .


"Can you support that with measurements?"
"Yes, I sit 3m from my speakers and definately hear that there is more bass." - anonymous

 

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