[mordy]

All right - more observations re how hot the 6AS7 tubes run. My preconceived idea was that since these tubes are larger and have more surface area than the 6080 tubes, they would run cooler.
Not so.
I again let a pair sit for an hour playing music and then took the measurements:
Svetlana 6H13C (which I thought run hot) measured 104/104C for the pair.
Tung Sol 5998 measured 104/106C for the pair.

What conclusion(s) can you draw? Soliciting your opinions...

 

[Dogmatrix]

All right - more observations re how hot the 6AS7 tubes run. My preconceived idea was that since these tubes are larger and have more surface area than the 6080 tubes, they would run cooler.
Not so.
I again let a pair sit for an hour playing music and then took the measurements:
Svetlana 6H13C (which I thought run hot) measured 104/104C for the pair.
Tung Sol 5998 measured 104/106C for the pair.

What conclusion(s) can you draw? Soliciting your opinions...

I think your preconception is likely still correct since the lower half of the 6AS7G is almost certainly cooler , because you are looking for the hottest area to measure and the construction of the upper sections of the two tubes are very similar the results are likewise

 

[bcowen]

All right - more observations re how hot the 6AS7 tubes run. My preconceived idea was that since these tubes are larger and have more surface area than the 6080 tubes, they would run cooler.
Not so.
I again let a pair sit for an hour playing music and then took the measurements:
Svetlana 6H13C (which I thought run hot) measured 104/104C for the pair.
Tung Sol 5998 measured 104/106C for the pair.

What conclusion(s) can you draw? Soliciting your opinions...

I can't offer any conclusions, and I don't mean to send this subject sideways (as I find it very interesting), but how accurate is the thermometer you're using? Infrared I presume? We went through probably 10 different brands and cost points at work trying to get something reliable for taking employee temps (Covid), and they were all over the map with readings, varying (seriously) 15+ degrees (F) between the highest reading one and the lowest. I could guarantee safe passage to all my employees with a couple of them, but of course they would also be dead if that was their true body temp.

I have a contact thermometer at home that reads exactly 212 (F) in boiling water and 34 F in a cup of ice water, so seems to be pretty spot on. I can try it when I get home this weekend, but then how meaningful is taking the temperature of the glass? That I don't know either...

 

[Galapac]

I can't offer any conclusions, and I don't mean to send this subject sideways (as I find it very interesting), but how accurate is the thermometer you're using? Infrared I presume? We went through probably 10 different brands and cost points at work trying to get something reliable for taking employee temps (Covid), and they were all over the map with readings, varying (seriously) 15+ degrees (F) between the highest reading one and the lowest. I could guarantee safe passage to all my employees with a couple of them, but of course they would also be dead if that was their true body temp.

I have a contact thermometer at home that reads exactly 212 (F) in boiling water and 34 F in a cup of ice water, so seems to be pretty spot on. I can try it when I get home this weekend, but then how meaningful is taking the temperature of the glass? That I don't know either...

if you use the same thermometer for every reading, regardless if it is off, then wouldn’t it be off the same amount for each reading or is it that you could take five readings and they would vary?
The latter would be more problematic.

 

[mordy]

I think your preconception is likely still correct since the lower half of the 6AS7G is almost certainly cooler , because you are looking for the hottest area to measure and the construction of the upper sections of the two tubes are very similar the results are likewise

All the tubes exhibit different temperatures in different parts of the tube - something of a 10 - 15C difference depending where you aim the infrared beam. The further the measurements are from the heaters, the cooler.

I can't offer any conclusions, and I don't mean to send this subject sideways (as I find it very interesting), but how accurate is the thermometer you're using? Infrared I presume? We went through probably 10 different brands and cost points at work trying to get something reliable for taking employee temps (Covid), and they were all over the map with readings, varying (seriously) 15+ degrees (F) between the highest reading one and the lowest. I could guarantee safe passage to all my employees with a couple of them, but of course they would also be dead if that was their true body temp.

I have a contact thermometer at home that reads exactly 212 (F) in boiling water and 34 F in a cup of ice water, so seems to be pretty spot on. I can try it when I get home this weekend, but then how meaningful is taking the temperature of the glass? That I don't know either...

Good points! The infrared thermometer I have cost around $13 on Amazon on sale and is not supposed to be used clinically.
For me, doing this is a hobby and for these purposes I am not going to invest in laboratory grade equipment. Still, I think that this little experiment shows that the 6080/6AS7 tubes run hot and that the larger tubes heat up similarly to the smaller ones.
We all knew they run hot (hopefully not from painful experiences), but I was surprised that the larger ST type tubes did not run cooler.
Again, if I were to measure the temperatures at the base of the tubes maybe the results would be different.
Anyhow, in this experiment, using NEC 6SN7GTB tubes (labeled Channel Master) in combination with the Tung Sol 5998 tubes sounded the best, (compared to 6080 Bendix and Sylvania, and 6AS7G / 6H13C Svetlana), and THAT is important.

 

[Galapac]

Nice way to bring it home and back on topic @mordy!

 

[mordy]

if you use the same thermometer for every reading, regardless if it is off, then wouldn’t it be off the same amount for each reading or is it that you could take five readings and they would vary?
The latter would be more problematic.

The thermometer has a trigger and projects a little red dot on the object and you get an instant reading on a little screen. The screen has two lines -the top one instantly reads where you project the red dot, and the second line locks into the highest reading.
I found it to be consistent in the readouts, but I am well aware that the readings may not be 100% accurate.
Still, I find it very useful, and it tells me when to turn on the fans if the chassis or the transformer housing start to get hot.
The distance also alters the readings; closer = hotter, so I try to do all readings at 1m or roughly 3 feet.

 

[bcowen]

if you use the same thermometer for every reading, regardless if it is off, then wouldn’t it be off the same amount for each reading or is it that you could take five readings and they would vary?
The latter would be more problematic.

Theoretically, yes. Depends on the quality of the thermometer I suppose. Not trying to invalidate anything here, mostly just wondering based on my recent experiences with IR thermometers. As well, the demand for them went ballistic with Covid, and it's very possible that quality went downhill as panic buying led to panic manufacturing. Perhaps older ones are better? Kind of like tubes?

 

[bcowen]

All the tubes exhibit different temperatures in different parts of the tube - something of a 10 - 15C difference depending where you aim the infrared beam. The further the measurements are from the heaters, the cooler.

Good points! The infrared thermometer I have cost around $13 on Amazon on sale and is not supposed to be used clinically.
For me, doing this is a hobby and for these purposes I am not going to invest in laboratory grade equipment. Still, I think that this little experiment shows that the 6080/6AS7 tubes run hot and that the larger tubes heat up similarly to the smaller ones.
We all knew they run hot (hopefully not from painful experiences), but I was surprised that the larger ST type tubes did not run cooler.
Again, if I were to measure the temperatures at the base of the tubes maybe the results would be different.
Anyhow, in this experiment, using NEC 6SN7GTB tubes (labeled Channel Master) in combination with the Tung Sol 5998 tubes sounded the best, (compared to 6080 Bendix and Sylvania, and 6AS7G / 6H13C Svetlana), and THAT is important.

Oh, I agree. I went off on an unnecessary tangent (apologies), and even well-calibrated, lab grade equipment might not tell us anything different.

 

[mordy]

Oh, I agree. I went off on an unnecessary tangent (apologies), and even well-calibrated, lab grade equipment might not tell us anything different.

Nothing to apologize for - the thread becomes more interesting with more tangents!

 

[HTSkywalker]

I am not sure if this is the case, but the 6080 is supposed to be a 6AS7G in a smaller envelope.
There were only two manufacturers of the 6AS7G in the US - RCA and Tung Sol / Chatham. Especially the RCA appears under many different labels.
There are numerous different 6080 makes and IMHO some of them may sound better than the ST types. —As always, the pairing and synergy with other tubes is the key.
It appears that the Russian Svetlana 6H13C and equivalents was modeled on the RCA version. It was made for both civilian and military use and in very large quantities.
This Russian tube is being sold under many fake names today at high prices, but is always easily identified by the double inverted saucer getters.
As far as I can remember, there are only US, Russian, British and Japanese 6AS7G tubes.

Good to know

 

[HTSkywalker]

I can't offer any conclusions, and I don't mean to send this subject sideways (as I find it very interesting), but how accurate is the thermometer you're using? Infrared I presume? We went through probably 10 different brands and cost points at work trying to get something reliable for taking employee temps (Covid), and they were all over the map with readings, varying (seriously) 15+ degrees (F) between the highest reading one and the lowest. I could guarantee safe passage to all my employees with a couple of them, but of course they would also be dead if that was their true body temp.

I have a contact thermometer at home that reads exactly 212 (F) in boiling water and 34 F in a cup of ice water, so seems to be pretty spot on. I can try it when I get home this weekend, but then how meaningful is taking the temperature of the glass? That I don't know either...

The safest and most accurate way was to use the A$$ Thermometer to have a COVID free work environment but of course with a "bit" of inconvenience
For home and hobby use am using this one with good results
https://www.amazon.com/dp/B00IT0ODPQ/?tag=ybdirth-20&geniuslink=true&th=1

 

[mordy]

The safest and most accurate way was to use the A$$ Thermometer to have a COVID free work environment but of course with a "bit" of inconvenience
For home and hobby use am using this one with good results
https://www.amazon.com/dp/B00IT0ODPQ/?tag=ybdirth-20&geniuslink=true&th=1

What I have looks like this but in red:
https://www.amazon.com/dp/B00DMI632...k6o&ref_=sbx_be_s_sparkle_mcd_asin_0_img&th=1

 

[HTSkywalker]

What I have looks like this but in red:
https://www.amazon.com/dp/B00DMI632...k6o&ref_=sbx_be_s_sparkle_mcd_asin_0_img&th=1

With 33K+ of reviews and a 4.5 Star rating, am sure it's excellent

 

[toddc2]

Treat yourself with those Mullards and also pick up the GEC 6080s from the same seller for a great contrast to your Tungsols. Both are on the warmer side of things.

Sylvania 6080 would be my least recommendation to be honest. Pick them up if you get them dirty cheap.

Low/high gain doesn't make a big difference on my Euphoria amp.

Just picked up a pair of the GEC 6080 from this seller, thanks for this post.