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6H30 VA stage?

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Does anyone have a link to a 6H30 as a VA stage? I am working on an amp, and I have 184V on the plates with a 28.8K anode resistor, and 11.7V on the cathode. Just wondering what is "normal" for this tube. I have a 1.5K cathode resistor.

Thanks for any information!

Blair
 
Hi,

Thank you! I can find the tube data, but I wanted to see if anyone had a working schematic of this tube as the VA stage of their or a commercial amplifier. In my amp, I have:

Using a 28.8K plate resistor and 1.5K cathode resistor:

184V on the plate, and 11.7V on my cathodes.

I have never seen cathode voltage that high in a VA stage and wondered if it looked OK to run like this.

Thank you!

Blair
 
You are running 7.8mA for cathode current, which is well within the spec of the tube.

However, this is a low for best performance for this tube. Also your anode voltage is a too high. The two together will put you out of the most linear bias region.

I would suggest decreasing your cathode resistor significantly, to increase anode current and lower anode voltage.
 
Thanks!

Looking at the tube specs, it looks like I need to also decrease the plate resistor from almost 30k to around 6-10K and change my dropping resistor in my PS to lower the plate voltage.

You think 250-560 ohms for the cathode resistor?

Ill tinker with it and post some voltages if you don't mind.

Thanks again!

Blair
 
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My suggestion.
 

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It was a single side. I ditched the 6H30. It acted very unstable and both that I have are fairly noisy. I had some wicked 120hz artifacts.

I swapped plate resistors, changed my cathode resistor, dropped a 6CG7 in and away went the noise and wobbly sine waves.

I got the 6H30s from a buddy, so god knows what they went through.

Thanks!
 
Did you build anything like post #8. Yeah, 38mA, with a 3k plate resistor would be ok. That would keep the output impedance nice and low.

I think the reason your 6N30P was behaving badly was that it's running with such low plate current. I really think it sounds best with at least 15mA plate current, per triode section. That gets it out of the "knee" in the plate curves.
 
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Well, that is surprising, because I've used quite a few of them and had completely the opposite experience. Just the basic Electro-Harmonix, normal ones you get for way too much money. All have been very well behaved. I guess it's just one of those crazy things.
 
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