Checked the quad cap temp after running the amp at low volume for an hour. I measured 120 an inch from the top and bottom of the cap and over 200 in the middle. (Room temperature is 75.) Just wondering if this is normal....
4 posters
Quad cap temperature
GreggW- Posts : 80
Join date : 2015-07-15
sKiZo- Posts : 1530
Join date : 2013-04-01
Location : Michigan USA
What amp?
The quad cap itself shouldn't generate much heat. It's proximity to the iron and tubes that does it. From there, it's all about ambient temperature and air circulation as to how hot it will actually get.
Bob posted up a pick somewhere around here with test temps of all the components.
Aha!
https://dynacotubeaudio.forumotion.com/t828-tube-amps-get-pretty-warm-especially-in-the-summer-photo?highlight=temp
Notice the difference between the front and rear tubes ... that's due to the rears being sandwiched between the front tube and iron. Not a lot of breathing space. And there's the quad cap, right next to it.
The quad cap itself shouldn't generate much heat. It's proximity to the iron and tubes that does it. From there, it's all about ambient temperature and air circulation as to how hot it will actually get.
Bob posted up a pick somewhere around here with test temps of all the components.
Aha!
https://dynacotubeaudio.forumotion.com/t828-tube-amps-get-pretty-warm-especially-in-the-summer-photo?highlight=temp
Notice the difference between the front and rear tubes ... that's due to the rears being sandwiched between the front tube and iron. Not a lot of breathing space. And there's the quad cap, right next to it.
GreggW- Posts : 80
Join date : 2015-07-15
I recall seeing this. The back KT88s run 330 or so, but tonight on a whim, I checked the quad cap a few times with similar results. The 5V3a is the rectifier of choice for now, and I wondered if it had an effect on the quad cap. The ST 120 is 3 ½ years old and has very little time on it. The amp's getting better the more it's used...
Bob Latino- Admin
- Posts : 3277
Join date : 2008-11-26
Location : Massachusetts
GreggW wrote:Checked the quad cap temp after running the amp at low volume for an hour. I measured 120 an inch from the top and bottom of the cap and over 200 in the middle. (Room temperature is 75.) Just wondering if this is normal....
Tube amps do run pretty warm .. The quad cap will give off a lot of heat when the amp is running. Your ambient temperature was also 6 degrees higher (75 F vs 69 F) than when I ran the heat test. It will be more difficult for the amp to give up heat when the ambient temperature is higher. As such, the amp will tend to run warmer. Photo below from the link that sKiZo posted ..
Bob
GreggW- Posts : 80
Join date : 2015-07-15
Didn't realize how warm the quad cap gets, but sitting right next to a 300+ degree tube makes sense. I was concerned because the amp was at a very low volume....
sKiZo- Posts : 1530
Join date : 2013-04-01
Location : Michigan USA
As I mentioned earlier, the quad cap doesn't so much generate heat, as absorbs it ...
Mine stays nice and cool mounted underneath.
Mine stays nice and cool mounted underneath.
GreggW- Posts : 80
Join date : 2015-07-15
You've got a great looking 120 with a little extra room. Have you ever checked the real power out with those KT120 glass pillars?
Tubes4ever- Posts : 167
Join date : 2015-07-14
Location : Star, Idaho
GreggW wrote:I recall seeing this. The back KT88s run 330 or so, but tonight on a whim, I checked the quad cap a few times with similar results. The 5V3a is the rectifier of choice for now, and I wondered if it had an effect on the quad cap. The ST 120 is 3 ½ years old and has very little time on it. The amp's getting better the more it's used...
No. The 5V3a is too far away to effect the quad cap to any great degree.