6.3V AC supply for heaters

Discussion in 'The Projects Forum' started by sikter, Apr 8, 2015.

  1. sikter

    Thread Starter New Member

    Jan 25, 2012
    This is about preamp section of an 50W guitar amplifier (all tube).
    I read 4,1V AC here and I wonder how does this affect preamp tubes, sound, etc...
    I don't hear any difference but while I'm trying to find out the cause of this voltage drop, someone could clear this up for me.
    How bad is it?
    Will it just take more time to preheat the tubes or there are bigger issue because of low voltage?
  2. JDT

    Well-Known Member

    Feb 12, 2009
    Are you sure your meter is correct?

    There will be an issue because if the cathode is running at a lower temperature the electron emission will be much lower. The fact that you don't hear any difference makes me question your measurement.
    sikter likes this.
  3. #12


    Nov 30, 2010
    Your centering resistors might be lopsided, but we can't tell if you even have centering resistors on your 12.6 volt winding that we don't know if you have. Can you tell a model number, name, schematic...anything?
    sikter likes this.
  4. sikter

    Thread Starter New Member

    Jan 25, 2012
    Oh grrrrrrrrrr
    My meter was correct but I was wrong, or my eyes. I didn't wear my glasses and menaged to read at wrong pin.
    I'm sorry for this thread but I'm glad I started it.
    Thank you very much