DHT question.

pre65 · Post by **pre65** » Sat Dec 15, 2012 8:31 pm

On a DHT (like 2a3 or 6B4-g) when heated with DC, what terminal would you take the cathode resistor & cap from , plus or minus ?

According to one data sheet I was reading, on the 6B4-g filament plus is pin 2, and filament minus pin 7. Does it matter ?

Paul Barker · Post by **Paul Barker** » Sat Dec 15, 2012 9:24 pm

It doesn't make a blind bit of difference which pin is which, but general rule is ground whichever one you decide is minus and allow for the fact that 0.5 X filament voltage makes up some of your negative bias.

OR ground through a resistor devider network and you have made zero contribution to bias.

I always ground though the minus.

Mike H · Post by **Mike H** » Sun Dec 16, 2012 5:12 pm

So do I.

If it helps

IslandPink · Post by **IslandPink** » Sun Dec 16, 2012 5:23 pm

I would agree with Paul too, but there is one odd ( related ) comment I'm aware of - in his article about the 'Katelelo' 300B amp , Ciro Marzio complains that one of the new manufacturers of premium 300B's had got pin 1 and pin 4 the wrong way round - which he described as 'an elementary mistake' . I never got to the bottom of what he meant by this though .

pre65 · Post by **pre65** » Sun Dec 16, 2012 5:31 pm

Strange ? Depends on whether USA electrons are left hand drive.

Mike H · Post by **Mike H** » Mon Dec 17, 2012 12:20 pm

Did he mean on the pin-out diagram? Maybe?

IslandPink · Post by **IslandPink** » Mon Dec 17, 2012 6:27 pm

I can't find the full article on the web ( the circuit is however out there ) but his comment confused a couple of the best people in the DHT game, as you can see here :

http://www.audioasylum.com/cgi/t.mpl?f=tubediy&m=38634

Mike H · Post by **Mike H** » Tue Dec 18, 2012 3:57 pm

LOL as if we need more confusion

audio-talk

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