Russian 6H30

Yes, the NOS American 6H6s are short, octal tubes.

sailor wrote:Hi Jim, interesting idea. Unfortunately they are mounted on a circuit board so adding the grid stopper would require cutting the circuit board trace for all 4 grids.
This is probably not the problem in this case as I had a total of 5 6H30 and they all sound the same. I will stick with the 6H6 and change them out with the 6h30 when I sell it. Thanks for the advise.

A couple things...

1. It's fact, it's been observed by a number of people. It's not just theory. I've actually seen them oscillate in my TV-7B Hickok tube tester!

2. It's NOT a defect in the tube, it's normal behavior under some circumstances. So the fact that you had 5 tubes sound the same way does NOT rule out the possibility of them oscillating.

3. It is a pain to cut traces and all, I agree. But I'd at least consider it.

Finally, with regard to the 6H30Pi-DR - many skilled listeners cannot tell any difference between the -DR version and the -EB version. As well, the most recent production Sovtek branded tubes have the best section-to-section match along with more consistent Gm and plate current measurements. They certainly seem to be better made than the earlier -EBs.

Again, thanks, Jim. My replacements are all -DR, so I feel good about them.

pmarcin wrote:Yes, the NOS American 6H6s are short, octal tubes.

The US 6H6 is a dual diode.

pmarcin wrote:Again, thanks, Jim. My replacements are all -DR, so I feel good about them.

My pleasure!

When you do run out of -DRs at least you know the -EB tubes being made now are comparable.

First the Chinese make a 6N6 which I think is a power tube that is not compatible. Like I said there are both 6N6 and 6H6 that are not the right tube.
Second Jim I am not disagreeing with you about the 6H30 but why bother cutting my board if the 6H6 works so well in my amp. The 6H30 and 6H6 are a far closer match than the 12AU7 and the 12BH7 which are routinely interchanged in amplifiers. All I am saying is for a few bucks you can tube roll to the 6H6 and see if you like it. If not put the old tubes back in and enjoy. The fact the the main difference between the 6 and the 30 is the fact that the 6H30 was designed for pulse work which I would guess is the reason it may oscillate, and probably why the 6H6 sounds so much better in most applications.
Again I'm sure you are right about the 6H30 that is a good reason to pull it and replace it with the 6H6.

sailor wrote:First the Chinese make  a 6N6 which I think is a power tube that is not compatible. Like I said there are both 6N6 and 6H6 that are not the right tube.
Second Jim I am not disagreeing with you about the 6H30 but why bother cutting my board if the 6H6 works so well in my amp. The 6H30 and 6H6 are a far closer match than the 12AU7 and the 12BH7 which are routinely interchanged in amplifiers. All I am saying is for a few bucks you can tube roll to the 6H6 and see if you like it. If not put the old tubes back in and enjoy. The fact the the main difference between the 6 and the 30 is the fact that the 6H30 was designed for pulse work which I would guess is the  reason it may oscillate, and probably why the 6H6 sounds so much better in most applications.
Again I'm sure you are right about the 6H30 that is a good reason to pull it and replace it with the 6H6.

I just wanted people to know why the tube acts the way it does. You do what you think is best for you - that's cool! But others might find a bit of background interesting, and I felt it was important that people realize that the oscilation that can occur is NOT because a tube is defective. It's a matter of layout and taking appropriate precautions. That's all I was trying to do - provide some useful background and context.

Jim, I understand where you are coming from and totally agree with what you have said. All I was interested in stating was that the 6H6/6N6 may be a viable and very low cost option.

I ordered the 6n6s; I will give my impressions next week.

==A cautionary tale==
This week, I noticed that my links were getting scrambled and sent to Yahoo search. So,
I searched Google for the 'Firefox link scrambler.' I found:
 
     1.A website with an English accented man exlaing how dire this virus was an how difficult
     it was to remove, implying there were many steps involed in its removal and referring
     the reader to another site. This site was tagged as a 'malware' site by my protection
     software.
     
     2. I went to another site which suggested that displaying the preferences in Firefox
     and looking for the most recently changed might indicate the problem. Voila!
     There was a link that referenced the Yahoo Search Engine. I reset Firefox and things work
     fine.
     
It's apparent that 1.) is a very sophisticated attempt at social engineering by having the
owner install a'trojan horse' virus. It would be almost impossible to uninstall the final
virus. Hackers are getting incrdibly sophistcated these days. Just view the Youtube videos; it's
very convincing. ( I couldn't locate the the bad site. P.S. It's not the DNS changer virus.)

**** 6n6p vs 6h30 ****
As has been mentioned, the bass is more robust and the high end is smoother. There is  no sibilance
and the soundstage is 3D. It is very much a triode' sound. That said, there is a loss of
detail with th 6n6, particularly associated with percussion instruments. Drumstick claps are
muted and  the sound of muted horns is soft. I prefer the UL sound over the 'triode', so I prefer the 6h30. slighty

The 6n6p will will remain in my system for further listening review. It is nice to have such
a reasonably priced alternative to the 6h30.

Pmarcin, Thanks for taking the time to write the review. I am glad you are going to give them a little time to see the long term affect. It will be interesting to read another review when you switch back. As I said before," you will love them or hate them but you sure can't say they sound the same." I have forgotten, did you install them in a preamp or the driver stage of an amp and what preamp and amp are you using?

I installed them in a preamp. I just played some Latin rhythms and the sound was exceptional. I only have about 20 hrs on them. I can't believe they cost $6 - $18 USD vs $30 - $210 for the 6h30s. Also, there's a lot of negative talk about the 6h30s on the net (even the Drs.) pCx has some DRS on sale for about $100, but their origin isn't verifiable.