18Watt.com

Hi,
just finished and tested my Ceriatone kit 18w TMB with some
much appreciated transformer help from Bieworm.
Everything appears to be working well which I am really pleased about.
Sounds great and is very quiet - no static or buzz.
Only problem, one of the EL84 power tubes was not silver but cloudy at the end
when I installed it.
This tube is not glowing when the amp is working.
I swapped the two power tubes around and the non cloudy valve glows OK
in both positions.
I assume I have a damaged tube with leaking vacuum.
Not sure why the amp still appears to work well.
I will order another matched pair of power tubes.
Is it OK for me to run it like this in the mean time?

Thanks

The voltages will reveil any issues. Take the voltages and report back please

Jomarkredfern wrote: ↑

Fri 02/16/24 1:14 am

I assume I have a damaged tube with leaking vacuum.
Not sure why the amp still appears to work well.

You assume correctly, and should replace the tube. It may work well until it doesn't. Don't risk it.

Hi everyone,
apologies for the late reply as I have been away for a few days.
I have replaced the power tubes with a new matched pair.
Everything is working really well now.
Must have just been a damaged tube.
I did take some voltages during power up (although this is not something I’m confident with). The values matched those supplied by Ceriatone.
Very happy with this build now. Thanks for your input.