A2 Driver

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ACPEN
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Joined: Thu Jul 08, 2010 11:29 am
Location: South Tankerton.

A2 Driver

Post by ACPEN » Mon Apr 24, 2017 6:51 pm

Hello! Its been sometime since I've posted here, but thought someone may find this useful - I've built several Amps using TZ40, 811A, 812A etc in class A2 - usually with a triode strapped pentode as driver - I've also tried several true triodes (usually of the B9A base variety) but not found anything exceptional - until, the P61 came to my notice - I won't go into detail (you can look it up) but its a very cheap, very suitable triode as an A2 driver. There is also a P41 (4v htrs) version. Only slight drawback is the British Octal (Mazda) base - readily available thouh, so no real problem. If you haven't tried the P61 its worth a go!

Regards,

David.

P.S - Its entirely possible that you all know about these anyway - if so, well done!

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pre65
Amstrad Tower of Power
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Location: North Essex

Re: A2 Driver

Post by pre65 » Mon Apr 24, 2017 7:11 pm

Hi David, nice to hear from you again. :)

I'm due to re-visit 811a in A2 in the future, so I'd be interested to see the circuit you used.
Life is what happens to you while you're busy making other plans. John Lennon

G-Popz THE easy listening connoisseur. (Philip)

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pre65
Amstrad Tower of Power
Posts: 17604
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex

Re: A2 Driver

Post by pre65 » Mon Apr 24, 2017 10:12 pm

There is an 811a thread in "projects".

viewtopic.php?f=11&t=3696
Life is what happens to you while you're busy making other plans. John Lennon

G-Popz THE easy listening connoisseur. (Philip)

steve s
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Re: A2 Driver

Post by steve s » Tue Apr 25, 2017 6:51 am

Those Mazda valves are good, but still not quite up to the early large anode equiverlants, early ml4 and the like take some beating, but the Mazda does beat most 50's valves
They are on the lines of an early L63
I have to be careful what I say after a few years of using a 1930's cosser triode at the wigwam show the prices have more than tripled on ebay

I have a nice collection of early acpen valves now with a view to building something with them after your comments on them
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number

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