finished my build! a few questions

[R-Oak]

i just wanted to say, thanks to people who answered a few of my easy questions
soldering for a first time is quite threatening

i attached 2 pictures for eyecandy (verry bad camera)

i still had a few questions, i'm wondering if it's normal.

during the voltage test, all my test's where perfecly in the middle of the range given exept one
- my red RCA voltage was 110 (perfectly normal)
- my back RCA voltage was 89.9 (a little low, even more so compared to the 110)
is that normal ? should i try to resolder/reflow that joint ?

i did try the amp whit music, and it sounds amazing, i'm really happy
- but i'm just wondering why the power tube (Big one) goes realy really really hot (burn level)
- and the input tube (small one) only middly hot, is that normal ?

 

[Jameson]

Tubes will operate at different temps. On the Quickie, for instance, the temp of the glass is hardly above room temperature while the tubes on my SEX 3.0 amp get into the 250s (Fahrenheit). Similarly the 12AU7 on my crack is in the 120s and while the 6080 is much hotter. All good.

 

[Paul Birkeland]

during the voltage test, all my test's where perfecly in the middle of the range given exept one
- my red RCA voltage was 110 (perfectly normal)
- my back RCA voltage was 89.9 (a little low, even more so compared to the 110)
is that normal ? should i try to resolder/reflow that joint ?

The resistance tolerance of carbon pots is pretty broad; it isn't unusual to see +/-10%, which is what you're noticing.  Thankfully this doesn't create problems unless you have ridiculously high source impedance (roughly 20-100 times what we are accustomed to seeing)

- but i'm just wondering why the power tube (Big one) goes realy really really hot (burn level)
- and the input tube (small one) only middly hot, is that normal ?

The 6080 requires 15.75W of heat just to glow while the 12AU7 only needs 3.6W.  During operation, the parts aside from the heaters in the 6080 produce about another 7.5W worth of heat, while the 12AU7 makes about another 0.5W. 

 

[R-Oak]

thank you for the answers,

i'm still a little sceptic,
the power tube glass goes boiling hot when warmed up (after 5min), i cant touch it for 1 second

 

[Paul Birkeland]

This is completely normal.  You are not supposed to touch the tubes while the amp is running, especially the 6080.

 

[Doc B]

It points out in the manual more than once that vacuum tubes get too hot to touch. I really want to emphasize here that you should not touch hot vacuum tubes. They are intended to run very hot and they will burn you. Let a tube cool for at least five minutes after you turn off the amp before touching it.

Us old timers grew up around incandescent light bulbs, so we have a learned caution around glowing bulbs. So many LED lights run cool these days (though not all of them) that it is easy to forget that bulbs can get very hot.