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? for MSL about PP "iron" for 12 W. pentodes.

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Posted on May 13, 2004 at 15:39:55
Eli Duttman
Audiophile

Posts: 10382
Location: Monroe Township, NJ
Joined: March 31, 2000
Down the road, I'm going to put the quad of NOS Mullard EL821s in my stash to work.

Would you be able to source "iron" on the lam stack used for Dyna A-410s with a 10 K CT primary, no UL taps, and 20% CFB tertiary windings?

Eli D.

 

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Re: ? for MSL about PP "iron" for 12 W. pentodes., posted on May 14, 2004 at 18:32:12
mqracing
Manufacturer

Posts: 4322
Joined: June 29, 2000
Hi Eli:

wow... I never even heard of a EL821...boards only been up a few days and I think this is the second tube type I mentioned that I have never seen....

re: custom output transformer... with our own in-house R&D and new product development I'm not accepting any custom output transformer design work or development at this time...

the only "custom" work I am doing at this time is for plate chokes and filter chokes.

sorry I could not offer more assistance,

Mike

 

Re: ? for MSL about PP "iron" for 12 W. pentodes., posted on May 15, 2004 at 00:46:35
Eli Duttman
Audiophile

Posts: 10382
Location: Monroe Township, NJ
Joined: March 31, 2000
EL821 = 6CH6 is a 12 W. pentode. The EL821 will work with EL84 "iron", but Ra is higher. The EL821 is more sensitive than the EL84 and max. Ua is 275 V.

What I've got in mind is PP "finals" employing Dennis Boyle's combination bias. The smallish unbypassed cathode resistor raises the O/P impedance. That's why I'm thinking in terms of a 10 KOhm CT primary.

BTW, a KEY virtue of the EL821 is price. A matched quad of NOS Mullard EL821s is about $100.

Eli D.

 

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