[jonathan c]

I can't remember what my memory used to be.

I can’t remember what I forgot……

 

[DivinesGaming]

RME-ADI-2-Dac to Bottlehead Crack as a line-out, which device is better off having the volume on it lower than the other? I.e. Do you want to have your Amp turned down the most or the Dac/pre-amp turned down the most? Specifically when feeding to an OTL tube amp. I wonder if I'll get more tubeyness -at the same volume-, when the amp is turned down, and the dac is turned up, or vise versa?

 

[Galapac]

RME-ADI-2-Dac to Bottlehead Crack as a line-out, which device is better off having the volume on it lower than the other? I.e. Do you want to have your Amp turned down the most or the Dac/pre-amp turned down the most? Specifically when feeding to an OTL tube amp. I wonder if I'll get more tubeyness -at the same volume-, when the amp is turned down, and the dac is turned up, or vise versa?

Rule of thumb is DAC/DAP all the way up, controlling your volume with the amp.
I however have always kept my amp about half way and control my volume with my DAC as it is more convenient given my setup.
To my ears I never noticed a difference either way.

 

[Shane D]

Any idea if these tubes run cooler than the 6080's?

 

[Dogmatrix]

RME-ADI-2-Dac to Bottlehead Crack as a line-out, which device is better off having the volume on it lower than the other? I.e. Do you want to have your Amp turned down the most or the Dac/pre-amp turned down the most? Specifically when feeding to an OTL tube amp. I wonder if I'll get more tubeyness -at the same volume-, when the amp is turned down, and the dac is turned up, or vise versa?

The RME can output 4.6v at rca , that is way too hot for a Bottlehead
For the Bottlehead around 2v is ideal
So Ref lev of +7 Dbu and volume +1 , will give 1.9v

 

[hmscott]

Any idea if these tubes run cooler than the 6080's?

Which tubes vs the 6080?

I've observed that as long as your ambient "wind" is low or nil I've observed that the large envelope 6AS7G step-sided tubes reach the same average temperature as the straight-sided 6AS7G, along with equivalent tubes with the same heater current.

Early on I measured the tube envelope temperatures on my TA-26 - step-sided 6AS7G vs straight-sided 6AS7G and both measured about the same after about an hour - I think it was 150F - the TA-26 is off and I am leaving for a while - I'll test the 6080 temperature later and update.

I would have expected the larger envelope to be cooler, but after warm up they both heat up to about the same temperature due to low air currents at ambient in my room. If there were a steady breeze I would think the larger cooling area of the full sized envelope would help it dissipate the same heat load quicker.

They all have about 2.5A Heater Current warming them up, and I think the internals are about the same sized, but less compact in the full sized envelope.

The Xduoo TA-26's transformer has a maximum rating of 5A for the whole system, so I cannot run those 5A Heater tubes like the 6336/6528, and I would assume those 5A heater current tubes would run a lot hotter with double the heater current!

In comparison the Xduoo TA-20 can run the higher current 0.3A E80CC/E180CC vs .150A 12xx7/ECCxx tubes, and the higher 300mA current heater E80CC/E180CC do run hotter than the "stock" 150mA 12AU7's.

 

[Shane D]

Which tubes vs the 6080?

I've observed that as long as your ambient "wind" is low or nil I've observed that the large envelope 6AS7G step-sided tubes reach the same average temperature as the straight-sided 6AS7G, along with equivalent tubes with the same heater current.

Early on I measured the tube envelope temperatures on my TA-26 - step-sided 6AS7G vs straight-sided 6AS7G and both measured about the same after about an hour - I think it was 150F - the TA-26 is off and I am leaving for a while - I'll test the 6080 temperature later and update.

Excellent. Thank you.

 

[mordy]

...

Which tubes vs the 6080?

I've observed that as long as your ambient "wind" is low or nil I've observed that the large envelope 6AS7G step-sided tubes reach the same average temperature as the straight-sided 6AS7G, along with equivalent tubes with the same heater current.

Early on I measured the tube envelope temperatures on my TA-26 - step-sided 6AS7G vs straight-sided 6AS7G and both measured about the same after about an hour - I think it was 150F - the TA-26 is off and I am leaving for a while - I'll test the 6080 temperature later and update.

I would have expected the larger envelope to be cooler, but after warm up they both heat up to about the same temperature due to low air currents at ambient in my room. If there were a steady breeze I would think the larger cooling area of the full sized envelope would help it dissipate the same heat load quicker.

They all have about 2.5A Heater Current warming them up, and I think the internals are about the same sized, but less compact in the full sized envelope.

The Xduoo TA-26's transformer has a maximum rating of 5A for the whole system, so I don't think I can run those 5A Heater tubes like the 6336/6528, and I would assume those 5A heater current tubes would run a lot hotter with double the heater current!

In comparison the Xduoo TA-20 can run the higher current 0.3A E80CC/E180CC vs .150A 12xx7/ECCxx tubes, and the higher 300mA current heater E80CC/E180CC do run hotter than the "stock" 150mA 12AU7's.

I haven't compared how hot different 6080 tubes get, but I can tell that the 5A 6336/6528 tubes get really hot and you have to be very careful not to burn your fingers. However, I would not be surprised if different 6080/6AS7 tubes differ in how hot they run.
Another observation of mine that I have not had corroborated by others (yet): Very often a tube runs hotter when new and burning in, compared to after say 50-100 hours.

 

[hmscott]

Excellent. Thank you.

The FAA-6080WA/TA-26 was on while I was gone, no music was playing, and the FAA-6080WA measured 126F when I got back (and turned off the high airflow filter behind the amp), increasing to 137.5F after 5 minutes of listening to music... 10 minutes - 140.3F... @ 30 minutes back down to 130F-136F....temperature is varying with the music.

132.9F before, 138.2F right after - It's Only Rock 'N' Roll But I Like It by The Rolling Stones on TIDAL

139.6F during MONEY by The Warning on TIDAL

Rock Gods - playlist by Tidal

Rock - Tidal Masters playlist

A Levoit LV-H134 is set up on the backside of the equipment - designed with 360' intakes, and it was on the highest fan/filter setting while I was gone, so the constant wind flow generated was high enough to keep the tubes running cooler than normal. The Levoit LV-H134 is on the lowest/idle setting now, and runs that way 24/7. Normally there is a constant airflow over the tubes.

I'll swap in the 6AS7G straight-sided tube, and a couple of the RCA/Svetlana 6AS7G's to get another reading with the normal airflow. I think I had the Levoit off while those were measured originally.

If you don't have constant airflow over your tubes the temperatures might be higher...YMMV

Update: Swapped in the Cetron 7236 - 145F, 144F, 142F - ZZ Top + Jeff Beck - Video + CBS-Hytron 5296 @ 131.9F on Mix

 

[cddc]

There is no need to compare temperature on two tubes with the same specs. Both 6080 and 6AS7G draw 2.5A heater current, and they also have the same plate/grid voltage/current, so they must generate the same amount of heat from a scientific perspective.

If you measure some small difference, it must be caused by some other factors, such as kind of music that is playing (bass heavy music normally consumes more energy), individual tube variations (e.g. small variation in heater resistance), environmental, etc. But in general 6080 and 6AS7G should generate the same amount of heat.

5998/421A is a different story, as they have different specs than 6080/6AS7G.

6336/6528 are too hot to use with their 5A heater, you can imagine how hot they will be in summer...you definitely need to consider whether you can stand a furnace on your desk in summer...lol

 

[mordy]

There is no need to compare temperature on two tubes with the same specs. Both 6080 and 6AS7G draw 2.5A heater current, and they also have the same plate/grid voltage/current, so they must generate the same amount of heat from a scientific perspective.

If you measure some small difference, it must be caused by some other factors, such as kind of music that is playing (bass heavy music normally consumes more energy), individual tube variations (e.g. small variation in heater resistance), environmental, etc. But in general 6080 and 6AS7G should generate the same amount of heat.

5998/421A is a different story, as they have different specs than 6080/6AS7G.

6336/6528 are too hot to use with their 5A heater, you can imagine how hot they will be in summer...you definitely need to consider whether you can stand a furnace on your desk in summer...lol

My amp can take up to four 6080/6AS7 or two 6336 tubes. In the summer I have no problems using such tubes with the A/C on.
I have an infrared thermometer so I could measure the temperature of different tubes. My gut feeling is that a graphite plate tube which is much heavier than a regular plate tube, is going to run at a different temperature than a regular plate tube of the same kind.
Took a look at the spec sheets now - A 6080 RCA has a maximum bulb temperature rating of 200C - see page 2:
https://frank.pocnet.net/sheets/049/6/6080.pdf
A Raytheon graphite plate 6080 has a maximum bulb temperature of 300C:
https://frank.pocnet.net/sheets/138/6/6080WB.pdf

 

[mordy]

Sent an updated post with spec sheets

 

[cddc]

My amp can take up to four 6080/6AS7 or two 6336 tubes. In the summer I have no problems using such tubes with the A/C on.
I have an infrared thermometer so I could measure the temperature of different tubes. My gut feeling is that a graphite plate tube which is much heavier than a regular plate tube, is going to run at a different temperature than a regular plate tube of the same kind.
Took a look at the spec sheets now - A 6080 RCA has a maximum bulb temperature rating of 200C - see page 2:
https://frank.pocnet.net/sheets/049/6/6080.pdf
A Raytheon graphite plate 6080 has a maximum bulb temperature of 300C:
https://frank.pocnet.net/sheets/138/6/6080WB.pdf

Max temperature only means the said tube can stand such temperature, so yeah, with stronger graphite plates Raytheon graphite plate 6080 can stand 100c more than RCA 6080 regular plates. But in actual circuits RCA regular plate 6080 and Raytheon graphite plate 6080 will consume the same amount of heater current (2.5A), and the same amount plate/grid current in the same circuit/amp, hence they will generate the same amount of heat. Max temp on the tube data sheet is only the max rating, it has nothing to do with actual/working heat generated.

I don't put my faith on feeling or guts, I put my faith on science and data...

 

[hmscott]

I don't put my faith on feeling or guts, I put my faith on science and data...AND... **Measurements**

FTFY -

 

[mordy]

Max temperature only means the said tube can stand such temperature, so yeah, with stronger graphite plates Raytheon graphite plate 6080 can stand 100c more than RCA 6080 regular plates. But in actual circuits RCA regular plate 6080 and Raytheon graphite plate 6080 will consume the same amount of heater current (2.5A), and the same amount plate/grid current in the same circuit/amp, hence they will generate the same amount of heat. Max temp on the tube data sheet is only the max rating, it has nothing to do with actual/working heat generated.

I don't put my faith on feeling or guts, I put my faith on science and data...

Let’s do a scientific test, but I need your help to set up the parameters. Burned in tubes, leave them on for one hour, playing music, no fans on, temperature measured at hottest spot in tube. OK? I can use one pair of Bendix graphite plate and a pair of Sylvania regular plates.