Heater Artificial Center Tap & Voltage Reducer

[goangling]

I have an old PT that I'm using on a build (Multivox Premier 50) (6X4, 6L6, 12AX7).  Measuring non-center tapped heater voltage I get 7.3 V   So I need an artificial center tap, and would also like to reduce the voltage about 1 V.  I was playing around with DIYLC and came up with a small turrret board solution. My heater wires are very short, I have plenty of room to add this, and like making lugged turret boards.

1.) Does this make sense?  2.) Would I ground this to the pre-amp ground?


Thanks!

[kagliostro]

Did you measured the voltage with load or without ? It make difference

About the artificial CT if you want "The Best" use a 500R pot with wiper connected to Ground or, better, connect it to a DC Elevated Ground Reference point (a simple voltage divider formed using a pair of resistors and an e-cap)

One other option to have the Elevated Heater is to connect the Ground of the artificial CT to the cathode of the Power Tube (old scool Trick)

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BTW: Note that if your PT didn't result in a bit high B+ you can avoid the use of the 6X4 Tube Rectifier and use Solid State Rectifier

An SE amp will not SAG, so no difference in Vacuum or SS rectification



Like Here


Franco

[goangling]

Thanks Franco - great info - i'm working off the 6x4,6L6,12AX7 schematic - appreciate the help

[goangling]

The HV taps are almost perfect 296-0-296

I went ahead with the diodes and here are the results
7.39 V output
6.62 V after diode
reduction = 0.77 V

I'm much more comfortable with the 6.6 V - and it was a fun little project!

photo attached - (the other opposing diode is under the board)

[Williamblake]

Using diodes to create an AC-voltage drop may have side effects, albeit probably small ones. I guess, if you had heater hum due to lacking cathode insulation it would hum differently than it would without the diodes. If you do not have heater hum, you will not notice that. Maybe i am overthinking this, if it works, it works.