The Reference 6SN7 Thread

[Ranger Ron]

It depends upon how it was used. I have 3 Raytheon 6SN7 that are fine on one triode, and completely dead on the other triode. Not unusual at all. And yes, I have tried resoldering the pins.

I had one similar, soldered still tested dead one side. I put it in the freezer for a few days, it worked again and still going strong.

 

[Mr Trev]

**** did you put them on simultaneously and think that you had stereo (1+1 = )?

Didn't The Flaming Lips release an album that had 4 discs meant to be played simultaneously on 4 different stereos?

 

[genefruit]

Didn't The Flaming Lips release an album that had 4 discs meant to be played simultaneously on 4 different stereos?

Zaireeka - https://en.wikipedia.org/wiki/Zaireeka

 

[Somatic]

What are the consensus on the TS 6SN7GT? Are they a bit darker sounding than the Melz 1578? So far they sound darker and less extended to me on the treble. I am testing them out today on the MOs and nothing pops out at me. Thoughts?

Edit: Will let them burn in and see if it changes. Thanks.

 

[JeffMann]

I have a question about the 6sn7 driver tubes used in a Cayin HA300MK2 headphone amplifier.

How does one know when the tubes need to be replaced presuming that they are still actually working? Is it based on a significant deterioration of the sound quality of one's headphone's musical sound output or is it based on using a tube tester? If it is based on using a tube tester, what should one do if one does not own a tube tester?

Jeff.

 

[JTbbb]

I have a question about the 6sn7 driver tubes used in a Cayin HA300MK2 headphone amplifier.

How does one know when the tubes need to be replaced presuming that they are still actually working? Is it based on a significant deterioration of the sound quality of one's headphone's musical sound output or is it based on using a tube tester? If it is based on using a tube tester, what should one do if one does not own a tube tester?

Jeff.

I’ve posted this a few times, which will go a fair way to answering your query. It’s from a professional tube amp and tube tester builder, who knows his stuff. This particularly relates to the 5998/WE421a tubes, but the conclusions can relate to any audio tube.

“The PC/TC figures are pretty much a standard that people use to buy / sell valves to give an idea of their ‘goodness’, but in reality the 421A / 5998s are very high power triodes used mainly in Military applications back in the day, so to be honest for the purposes of matching the valves for your preamp, the PC score is really irrelevant, whether a valve can drive 90mA or 40mA is of no consequence when it is in circuit driving 5/6mA, they will pretty much all work until they become noisy or completely exhausted. A more useful parameter to match against is the TC (transconductance, loosely described as the gain of the valve), so use that as a basis for matching, but again don’t worry unduly, because I think you would be hard pushed to hear the difference between a valve with a TC of 9 or 14, but always good practice to get as close as possible. The main criteria with your amp I would suggest is how noisy they are, as that directly affects the listening experience, old valves can become noisy and microphonic, as you know.”

 

[JeffMann]

I’ve posted this a few times, which will go a fair way to answering your query. It’s from a professional tube amp and tube tester builder, who knows his stuff. This particularly relates to the 5998/WE421a tubes, but the conclusions can relate to any audio tube.

“The PC/TC figures are pretty much a standard that people use to buy / sell valves to give an idea of their ‘goodness’, but in reality the 421A / 5998s are very high power triodes used mainly in Military applications back in the day, so to be honest for the purposes of matching the valves for your preamp, the PC score is really irrelevant, whether a valve can drive 90mA or 40mA is of no consequence when it is in circuit driving 5/6mA, they will pretty much all work until they become noisy or completely exhausted. A more useful parameter to match against is the TC (transconductance, loosely described as the gain of the valve), so use that as a basis for matching, but again don’t worry unduly, because I think you would be hard pushed to hear the difference between a valve with a TC of 9 or 14, but always good practice to get as close as possible. The main criteria with your amp I would suggest is how noisy they are, as that directly affects the listening experience, old valves can become noisy and microphonic, as you know.”

Thank you for answering.

I am not sure that I have the capacity to understand your answer as I am a neophyte tube amplifier owner who has no previous experience with tubes.

I purchased my first tube amplifier - Cayin HA300MK2 headphone amplifier - 3 months ago to drive my Susvara headphones (see attached jpg to view my audio system).

I am 74 year-old retiree so I have plenty of time to listen to classical music and opera. I usually turn-on my audio equipment at 2pm and shut it down at 12pm and of the 10 hours of daily "equipment-on" use I only listen to music for about 4 hours per day. If my tube amplifier is "on" for 10 hours per day, that works out to >3,500 hours per year. My amplifier uses two types of tubes - 6sn7 driver tubes and 300B power tubes. I can only presume that with >3,500 hours of use per year that the tubes may deteriorate later in the year to make it either noisy, or unbalanced or too inefficient. I can use my ears to recognise a noisy tube, but how do I recognise when a tube becomes too worn-out (inefficient) or too unbalanced (unmatched)? Do tube amplifier owners, who own a tube tester, periodically test their tubes every few months for parameters like transductance to ensure that the tubes are functioning well. In the absence of a tube tester and with no previous experience with tube amplifiers, should I just empirically buy new (unused) NOS 6sn7 and 300B tubes every 6 - 12 months to be 100% certain that my tube amplifier is always functioning at its best?

Jeff.

 

[JTbbb]

Hi there Jeff,

There are many more people on this site far more experienced with tubes than I. Figures for the life expectancy of a tube I have seen on this site seem to be in the range of 6000-10,000 hrs, but in truth a fairly new or NOS tube could fail early, whilst a well used tube could give you years of service.

My best advice for your tube usage would be to have a spare pair of your favourite tubes, ready to go if and when you have a tube failure. As mentioned by the professional in my previous post, I believe a tube will sound as good as a NOS tube till it’s at death’s door! Then as mentioned previously it will get noisy. I have a Tungsol 6sn7gt black glass that tests very low, yet sounds just the same as a NOS example I have.

Hope this helps.

 

[leftside]

I have quite a few tubes, but I tend to prefer to use tubes that test 70 - 80% Gm on my tube tester. I have tubes that also test very low, and unless they are gassy, my own personal opinion is that these sound better than the new NOS 100% testing tubes.

I don't bother testing the tubes again after I've tested them, unless I start to notice a noisy channel (which fortunately has been a very rare experience).

The good tube testers will test for Gm (kind of like the strength of the tube and how long it will last), shorts (if your tube tester detects this then bin the tube), leakages, emissions and gas.

Agreed with the above - if you're not a tube collector, just get a spare pair of your favorite tubes and don't worry about it too much. Also remember, these are headphone amps - not main speaker amps, so I think the tubes should last much longer in these amps (someone please feel free to correct me if I'm wrong).

 

[mordy]

Thank you for answering.

I am not sure that I have the capacity to understand your answer as I am a neophyte tube amplifier owner who has no previous experience with tubes.

I purchased my first tube amplifier - Cayin HA300MK2 headphone amplifier - 3 months ago to drive my Susvara headphones (see attached jpg to view my audio system).

I am 74 year-old retiree so I have plenty of time to listen to classical music and opera. I usually turn-on my audio equipment at 2pm and shut it down at 12pm and of the 10 hours of daily "equipment-on" use I only listen to music for about 4 hours per day. If my tube amplifier is "on" for 10 hours per day, that works out to >3,500 hours per year. My amplifier uses two types of tubes - 6sn7 driver tubes and 300B power tubes. I can only presume that with >3,500 hours of use per year that the tubes may deteriorate later in the year to make it either noisy, or unbalanced or too inefficient. I can use my ears to recognise a noisy tube, but how do I recognise when a tube becomes too worn-out (inefficient) or too unbalanced (unmatched)? Do tube amplifier owners, who own a tube tester, periodically test their tubes every few months for parameters like transductance to ensure that the tubes are functioning well. In the absence of a tube tester and with no previous experience with tube amplifiers, should I just empirically buy new (unused) NOS 6sn7 and 300B tubes every 6 - 12 months to be 100% certain that my tube amplifier is always functioning at its best?

Jeff.

IMHO just enjoy your amp and don't worry! There is no need to spend money on a good tube tester which can be quite pricey.
Let your ears guide you. Despite what some sellers claim, tubes can last a very long time.

 

[JeffMann]

I have quite a few tubes, but I tend to prefer to use tubes that test 70 - 80% Gm on my tube tester. I have tubes that also test very low, and unless they are gassy, my own personal opinion is that these sound better than the new NOS 100% testing tubes.

I don't bother testing the tubes again after I've tested them, unless I start to notice a noisy channel (which fortunately has been a very rare experience).

The good tube testers will test for Gm (kind of like the strength of the tube and how long it will last), shorts (if your tube tester detects this then bin the tube), leakages, emissions and gas.

Agreed with the above - if you're not a tube collector, just get a spare pair of your favorite tubes and don't worry about it too much. Also remember, these are headphone amps - not main speaker amps, so I think the tubes should last much longer in these amps (someone please feel free to correct me if I'm wrong).

Thank you for expressing your opinion.

I get the impression that I should just wait for a tube to fail or become noisy and that there would be no benefit by testing the tube periodically.

Being intellectually curious, if I just happened to own an Amplitrex AX100 tube tester (that was recommended in this thread), how would I use it to check on my Cayin HA300MK2 tubes' health? What specific measurement would I be testing for with respect to the 6sn7 and 300B tubes and how often would it make sense to perform that test?

Jeff.

 

[JeffMann]

I have quite a few tubes, but I tend to prefer to use tubes that test 70 - 80% Gm on my tube tester. I have tubes that also test very low, and unless they are gassy, my own personal opinion is that these sound better than the new NOS 100% testing tubes.

I don't bother testing the tubes again after I've tested them, unless I start to notice a noisy channel (which fortunately has been a very rare experience).

The good tube testers will test for Gm (kind of like the strength of the tube and how long it will last), shorts (if your tube tester detects this then bin the tube), leakages, emissions and gas.

Agreed with the above - if you're not a tube collector, just get a spare pair of your favorite tubes and don't worry about it too much. Also remember, these are headphone amps - not main speaker amps, so I think the tubes should last much longer in these amps (someone please feel free to correct me if I'm wrong).

As a neophyte tube amplifier owner, I have another question.

I noted that you stated that you have older tubes that test low, but sound better than new NOS 100% testing tubes.

That made me wonder about decision-making choices when buying tubes from an e-bay seller.

For example, let's presume that I decided to purchase a pair of Sylvania V231 6sn7GT tubes for my Cayin HA300MK2 headphone amplifier.

Here is a listing for an used set for $174 for a matched pair - https://www.ebay.com/itm/225287178877?epid=1729696074&hash=item3474298a7d:g:oAwAAOSwQ2djkXny

I noted that the seller had another set that was labelled brand new, that was selling for $358 for a matched pair.

What are the pros and cons of buying the used set versus the brand new (unused) set?

Jeff.

 

[mordy]

As a neophyte tube amplifier owner, I have another question.

I noted that you stated that you have older tubes that test low, but sound better than new NOS 100% testing tubes.

That made me wonder about decision-making choices when buying tubes from an e-bay seller.

For example, let's presume that I decided to purchase a pair of Sylvania V231 6sn7GT tubes for my Cayin HA300MK2 headphone amplifier.

Here is a listing for an used set for $174 for a matched pair - https://www.ebay.com/itm/225287178877?epid=1729696074&hash=item3474298a7d:g:oAwAAOSwQ2djkXny

I noted that the seller had another set that was labelled brand new, that was selling for $358 for a matched pair.

What are the pros and cons of buying the used set versus the brand new (unused) set?

Jeff.

Wow, if you have that tube tester you would have to read the manual and figure out how to use it...
Regarding the question of new versus used: Some people will only buy NOS, but personally, if I come across something that looks promising, I would try to buy less expensive tubes of that kind to see if I like them.
Once you find something that you like, it may be the time to look for new backups etc.
One advantage of used tubes is that they don't need time to burn in to sound their best. This may be the reason why a used tube could sound better than a new one since the sound usually changes for the better when the tube has seen at least 30-50 hours of use (and in some cases the burn-in takes much longer).

 

[raindownthunda]

Wow, if you have that tube tester you would have to read the manual and figure out how to use it...
Regarding the question of new versus used: Some people will only buy NOS, but personally, if I come across something that looks promising, I would try to buy less expensive tubes of that kind to see if I like them.
Once you find something that you like, it may be the time to look for new backups etc.
One advantage of used tubes is that they don't need time to burn in to sound their best. This may be the reason why a used tube could sound better than a new one since the sound usually changes for the better when the tube has seen at least 30-50 hours of use (and in some cases the burn-in takes much longer).

New generally in better physical condition, but not always (depend on how they were stored). New more likely to come with original boxes, but not always. If they are sealed and unopened there’s a certain pleasure in unboxing something for the first time packaged so many years ago…

If sealed/unopened, that means untested. If so, although unlikely, they may be noisy or defective.

In general absolutely nothing wrong with going used/tested especially if it’s significantly cheaper and it’s your first set.

 

[Sean H]

What are the consensus on the TS 6SN7GT? Are they a bit darker sounding than the Melz 1578? So far they sound darker and less extended to me on the treble. I am testing them out today on the MOs and nothing pops out at me. Thoughts?

Edit: Will let them burn in and see if it changes. Thanks.

Hmm, I have never found them to be dark at all but in terms of being darker than the Melz unfortunately I have never heard the Melz. I think these particular Tung Sol’s are excellent and to my ears are very neutral and detailed with lots of spatial qualities and excellent bass. They don’t have the rich tonality as many other tubes but they are not dry and cold like later tubes. Their sibling, the mouse ears version of this tube, is even a tad more detailed but to me but just a hair brighter as well and huge spatial qualities.