Warmer than usual top plate and power tube...

[liamstrain]

I don't recall the Crack I had been borrowing getting quite so warm as the one I just completed does. The top plate and power tube base, especially. The top plate I can continue to touch with mild discomfort, but the Stock 6080 tube base gets hot enough to burn - probably ~200 deg (not that I make a habit of touching that).

All the resistance and voltage checks out, though some of the voltage readings did trend high. 1/5/7/9 were all about 20% high. Everything else was dead on or less than 10-15% high.

Sounds great with only a slight background hiss (assuming tube rush). Just double checking to make sure nothing is wonky.

 

[Doc B]

the Stock 6080 tube base gets hot enough to burn - probably ~200 deg (not that I make a habit of touching that).

Yup, that's the way a 6080 is supposed to be.

 

[liamstrain]

Well that's comforting.

I'll keep listening and worrying less. It's fantastic with the Beyer 880/600's - those have enough resistance to mask the hiss. With some luck this power tube will burn in and quiet down to where it is less noticeable with the HD600s.

Now to start saving for the speedball.

Thanks for a great product and kit, Doc. Was a great build.

 

[Grainger49]

That is FAQ #4.

 

[liamstrain]

*thumbsup*

Thanks! I did a quick search, but that didn't come up. (And unfortunately, a lot of undesirable results return for "hot crack."

 

[Laudanum]

As mentioned by the others, it appears normal and there have been numerous posts about it.  Mine just never gets that hot but I didnt run the straight glass tubes for long,  just the ST shaped 6AS7's and Tung-sol 5998.  More glass with those tubes may have something to do with it.  So would other factors I would think such as where the amp is placed and ambient temperature and air movement.  My Crack sits on top of a stand in a room with a lot of air movement so maybe that accounts for mine running pretty warm but not hot.  Im referring to the top plate here, I dont think I would want to touch the tube glass or base 

 

[Doc B]

The 6080 has a metal base.

 

[Paul Joppa]

Because it's direct coupled, the driver plate voltage controls the output cathode. If the driver plate voltage is high, then the output load (big resistor or Speedball) dissipates more heat under the plate, and less in the output tube envelope. Low driver plate voltage reverses that. It could be an explanation.