The Reference 6SN7 Thread

[bcowen]

What is "tapping" ?

Just that -- lightly tapping the top of the tube with your fingertip. Operative word is lightly. I typically do this when testing a tube for shorts or interelement leakage just to be sure that there isn't some internal part that is loose and looks good initially, but even a slight vibration (like a tap) causes an issue to appear.

 

[Paladin79]

I've had a good number of tubes test as worn out immediately after receipt from some Ebay purchases ("worn out" meaning testing below minimum GM or emission levels). Can't say that I've ever worn out a pair of new-testing tubes from use, although I've had some that have developed noise or significant microphonics after a period of time. As far as life span on a 6SN7 (or any other tube for that matter), a lot depends on how it is run in the circuit. If it's run at conservative voltages, then a 6SN7 can probably last 5k hours, maybe more. If it's run at the upper end (or max) of its ratings, then 1k hours may be the max. I've seen stories of Western Electric 300B tubes still going strong after 20+ years of 24/7 operation in telephone equipment, although I would imagine they were run quite conservatively in that equipment. I have 9k hours (and counting) on the KR 300BXLS output tubes in my Jota amp. While they don't test at NOS levels, they are still well above minimum. My tester has settings for a regular 300B but it doesn't have specific settings for the higher-output XLS version (which were developed long after Hickok disappeared from the market), so I can only get an approximation on my tester. But I can't tell any sonic difference (yet) when swapping in a new pair that I have as backups, which is a more valid test.

I do push 6sn7's a bit but nowhere near their limits. Most of us change tubes so often it would be nearly impossible to calculate hours of usage. Or want to calculate it.

It was boring enough waiting for a Foton to cook for 100 hours back when that was a belief.

 

[Paladin79]

Just that -- lightly tapping the top of the tube with your fingertip. Operative word is lightly. I typically do this when testing a tube for shorts or interelement leakage just to be sure that there isn't some internal part that is loose and looks good initially, but even a slight vibration (like a tap) causes an issue to appear.

Back when I was more involved with large production electronics a small rubber ball on the end of a wooden dowel was used. An easy way to test for intermits throughout a sound or video circuit.

 

[tubebuyer2020]

Back when I was more involved with large production electronics a small rubber ball on the end of a wooden dowel was used. An easy way to test for intermits throughout a sound or video circuit.

I guess at some voltages it's better to not tap things with a finger.

 

[tubebuyer2020]

I also have managed to procure some of those Fotons @bcowen recommended so very frequently:

It sounds quite good.

 

[Paladin79]

I also have managed to procure some of those Fotons @bcowen recommended so very frequently:



It sounds quite good.

I hope you have re-soldered the pins, otherwise the sound can vary quite a bit. I might plug one in when I want more bass.

 

[tubebuyer2020]

I hope you have re-soldered the pins, otherwise the sound can vary quite a bit. I might plug one in when I want more bass.

No, I have not yet though I am aware of your recommendation from past posts.

 

[Paladin79]

No, I have not yet though I am aware of your recommendation from past posts.

Thanks, even reflowing the solder might help a bit if you bought some from the fifties.

 

[bcowen]

I also have managed to procure some of those Fotons @bcowen recommended so very frequently:



It sounds quite good.

I want to know where you got purple ones. All of mine are like kind of orange.

 

[tubebuyer2020]

I want to know where you got purple ones. All of mine are like kind of orange.

Don't starve the plate and put an honest 10'000 Megavolt on it!

In reality the LED does not look like a Razor gaming PC, it's quite subtle. That was a dark room HDR smartphone shot.

 

[mayurs]

My amp is a Feliks Euforia with stock psvane gold tubes that seem quite good but now I think its time to explore some more tubes.

I have decided to pick 2 sets out of the following tubes that one guy here has for sale. However comparing these to the first page of this thread has me more confused than ever. I am not sure which Sylvania Vt-231 is this, as I read that it has a silvered base to 1/3 length of the bottle and has rectangular mica plates while these seem circular. Same confusion with Raytheon VT-231, the pictures seems a little different from the description I read on the first page.

Then there is the Ken rad VT-231. This seems to be the clear glass and not black so is it worth buying at all? Then there is the Sylvania wgt brown base which I could not find much info on.

Thanks in advance.

 

[Tom-s]

Your first "Sylvania" is a Brimar; there's your "problem".

That's sure a nice Sylvania to score!

 

[bl4scott]

Do you know if 6SN7 tubes will work in a Lyr 2 - since I am using an adapter in my Freya 2 to use the 6SN7, would I be able to use the same for the Lyr 2? Any opinions on this older unit and would this be a good upgrade to the Freya 2. Do the inserted tubes need to be the same? Sorry for my ignorance.

Per the manual " Lyr 2 accomodates any 6DJ8, 6922, ECC88, 6N23P, 6BZ7, and 6N1P tube types, so feel free to swap the stock tubes"

 

[mayurs]

Thanks for the id of Brimar based Sylvania VT-231. I do not see any info or any thing anywhere about this tube.

Is the Ken Rad VT-231 a ribbed plate one or the staggered one and is the Raytheon VT-231 one with T-plates or flat plates?

Apologies in advance for such basic questions, but the photos on the first page of this thread which has descriptions of the various tubes do not open for me.

Thanks in advance.

 

[whirlwind]

That Ken Rad looks to have staggered plates.
Plop it in your amp and enjoy the bass...I have mine in at the moment and the fun factor is really high!