How hot should this preamp get? Also purple dot in center of tube

[Sonido]

I finished building one last night and it sounds fine (as in it sounds like it's working properly). I noticed the transformer itself doesn't get as hot as the Crack transformer, but the center tube gets pretty hot. The center tube is suppose to be a cold cathode right? Well it's not very "cold". It's just as hot as the other two tubes. Perhaps it's heat radiated from the other tubes, but I just want to make sure this is working as intended.

One other thing I noticed is there's a bright purple dot that's in the middle of the center tube on the central metal rod when powered on.

 

[Paul Birkeland]

Yes, the Smash doesn't draw nearly as much high voltage or heater current as the Crack, so the transformer will run cooler.

The 0D3 uses a cold cathode, but cold in this case refers simply to not being heated.  The tube still draws current, and dissipates a few watts in the process.

The bright purple dot inside the 0D3 is quite normal.

-PB

 

[Sonido]

Also I have noticed some distortions when the volume knob is turned past 12 o'clock (with 6 o'clock being the starting point and 4 o'clock being max volume). It seems noticeable for only some lower frequencies. Is this normal?

 

[Paul Birkeland]

Yes, you can overdrive the input of the Smash, which will be most immediately apparent with low frequency content.

-PB

 

[randy@matrixq.com]

I'm a big fan of the purple glow.  It's a mini electron accelerator.  Awesome.  See my profile pic.