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6SN7 Tube Addicts - Page 190

post #2836 of 4150
Quote:
Originally Posted by StalkerAssassin View Post

Found the net for information on the date code of British tubes:
. . .
Whether it is correct information?

 

This was the CV date code until they switched to numbers. The second letter indicates the month: A = Jan, etc. Apparently MOV used this for their non-CV production as well.

 

post #2837 of 4150
Thread Starter 

Hello Oskari,

 

Thanks for the valuable info, nice to hear from you.

 

You always have a very informative answer when I am struggling with these MOV tubes.

 

Edit:MOV


Edited by rosgr63 - 11/6/12 at 9:58am
post #2838 of 4150
Quote:
Originally Posted by Oskari View Post

This was the CV date code until they switched to numbers. The second letter indicates the month: A = Jan, etc. Apparently MOV used this for their non-CV production as well.
Cool, thank you very much for the information.
post #2839 of 4150

Sylvania green labeled 6sn7 gta - 3 holes in plates, parallel plates, splash of chrome on the top of the glass.  That is not the same as a "bad boy" right?  I like the 3-hole parallel plate GTA more than the offset plate version of the 6sn7 gta.  I now have 4 of them!

post #2840 of 4150
Quote:
Originally Posted by Mr.Sneis View Post

Sylvania green labeled 6sn7 gta - 3 holes in plates, parallel plates, splash of chrome on the top of the glass.  That is not the same as a "bad boy" right?
Yes, it's a different tube.
post #2841 of 4150

Arg my Ken Rad came in and shipping did what shipping does... claimed another NOS tube :(  Tested for noise and balance before shipping, arrived noisy and way out of balance.

 

I'll burn it in tonight but don't expect miracles.

post #2842 of 4150
Thread Starter 

Sorry to hear this but I don't think shipping could make the sections go out of balance.

It can cause shorts/ leakages but would not make the sections go out of balance.

post #2843 of 4150

No change after a night of burn in.  Sigh, oh well.  It was his only phono grade Ken Rad so no replacement either.  That said, since the PWD2 has warmed up, I've come to love the Bad Boy again so meh.  

 

Would also add, this Ken Rad is super bright.  You can hear the added bottom, but it has even more added top.   Like a super V EQ.  Not listenable even at modest volume.

post #2844 of 4150

Odd story.  I have an old Cossor 6sl7gt tube that tested fine on my local shop's Seco 1100 and when I used it in 3 different amps it had the same problem where one channel would get very very noisy after a little use.  I just about threw this tube away but sometimes tapping the tube would help bring it back of course it would then come back shortly thereafter.  Recently I picked up a "socket saver" and noticing that its gripping force was extremely tight, I tried it with the old Cossor.  Fingers crossed but so far it seems to be working fine, I guess the real test will be leaving it on for 5 or 6 hours to see.

post #2845 of 4150

That's what my guy said as well..

 

Try tapping the tube firmly on a table top, and snapping the glass with your fingernail.  The trick is to knock any possible cathode material that may be caught in the grid, to the bottom of the tube.

post #2846 of 4150
Quote:
Originally Posted by Solude View Post

That's what my guy said as well..

 

Try tapping the tube firmly on a table top, and snapping the glass with your fingernail.  The trick is to knock any possible cathode material that may be caught in the grid, to the bottom of the tube.

 

The past few weeks I have learned that just because a tube tests good doesn't mean all that much without having actually auditioned the tube for an extended period of time.  I have maybe 3 or 4 of these tubes that test in the good range on the Seco but I never use them because of stupid issues that pop up in use.  I figure I'd rather prefer to purchase from a seller who states something along the lines of having used the tube and it worked flawlessly rather than some guy with a tester saying his tube tests good!  I'm still a tube n00b though.

post #2847 of 4150
Thread Starter 
Quote:
Originally Posted by Solude View Post

That's what my guy said as well..

 

Try tapping the tube firmly on a table top, and snapping the glass with your fingernail.  The trick is to knock any possible cathode material that may be caught in the grid, to the bottom of the tube.

 

Loose material during transit can cause problems, even shorts and leakages so tapping the tube might cure the problem.

 

I usually amp test newly acquired tubes for a couple of hours to make sure there are no noise or other issues.

post #2848 of 4150
Quote:
Originally Posted by Mr.Sneis View Post

 

The past few weeks I have learned that just because a tube tests good doesn't mean all that much without having actually auditioned the tube for an extended period of time.  I have maybe 3 or 4 of these tubes that test in the good range on the Seco but I never use them because of stupid issues that pop up in use.  I figure I'd rather prefer to purchase from a seller who states something along the lines of having used the tube and it worked flawlessly rather than some guy with a tester saying his tube tests good!  I'm still a tube n00b though.

 

Bob Putnak, the guru of tubes and testers has said this to me time and time again.  Testing information is just one data point.  It doesn't mean everything by a long shot.

post #2849 of 4150
The main purpose of using a tube tester for me is to eliminate tubes that are for sure bad before sticking them in an amp where REALLY bad things could happen.
post #2850 of 4150

To be fair, noise testing from my seller is done in a phono pre-amp out to speakers, ie super high gain to spot light any noise.

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