6H30 VA stage?

[deicide67]

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

 

[Charm]

http://klausmobile.narod.ru/testerfiles/6n30p.htm

''Èñòîê2''. Ðàäèîëàìïû - ïî÷òîé. Ïàðàìåòðû è õàðàêòåðèñòèêè 6Í30Ï-ÄÐ êëàññèêà

Next-Tube. Ñïðàâî÷íûå äàííûå ïî ëàìïàì è òðàíñôîðìàòîðíûì ñåðäå÷íèêàì.

http://www.tubes.ru/techinfo/HiFiAudio/6n30pdr.html

http://www.tubeampdoctor.com/images/File/Specifications 6N30P.pdf

Google steers!

 

[deicide67]

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

 

[TheGimp]

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.

 

[deicide67]

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

 

[12B4A]

pRC put some 6H30Pi experimentation up on his website. AudioVidioPhilia: Mambo Foreplay

 

[deicide67]

I tinkered with it a bit by changing the dropping resistor, plate and cathode resistor.

Now, I have a B+ of around 150V

72V on the plates, and 3.45V on the cathodes.

Look better?

Thanks?

Blair

 

[euro21]

My suggestion.

 

[12B4A]

Is that for both sections in parallel?

 

[deicide67]

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!

 

[12B4A]

When I was using this tube I had to use little ferrite beads wrapped around the wires directly connected to the grid pins along with a 1k grid stopper before things settled down.

 

[deicide67]

Yeah,

It is probably very workable, but one was noticeable noisier than the other and the 6CG7 is very quiet. I'd be happy at this point with no more tweaks.

Thanks!

Blair

 

[rongon]

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.

 

[deicide67]

Hi Ron,

Yes, regardless of how I swapped things according to various schematics for the tube, they were noticeably noisier than the 6CG7.

 

[rongon]

Did you try a different 6N30P tube? Or you only have that one?

 

[deicide67]

I have two, and one was worse than the other for noise. I really only used them because they were here. I'm not bent on using them really.

 

[rongon]

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.