repurpose regulated PS

[joesatch]

can i use this regulated PS for DC heaters? It delivers a clean 14vdc @ 2.5A.  Or must i get it down to 12dc?

[shooter]

if it's not loaded down at 14vdc, it'll probably get close to 12vdc loaded.  The BIG problem, that is a switch-mode PS, so it makes DC from a many K-hertz sine wave, ...noise.
whether that gets coupled to the surrounding wires and causes headaches....

[joesatch]

tube preamp build. it would be far from the tubes and preamp circuit. i guess i could try it. if it doesn't work i have some dc heater boards i can build, they use the 7812 regulator. This would save alotta work, this chassis came with it all wired up

[joesatch]

previous build with the DC heater board using 7812

[glass54]

Hi joesatch
If you post regulate (with LM7812) you need a minimum of 2.5V and preferably 3V DC higher input voltage for reliable regulation.
There are also Thermal dissipation considerations.
I would consider floating your 14V DC supply, fit a suitable resistor in series (Maths required I assume 4x12A-7 Tubes??)
Target Heater Voltage 12.6V with maximum of 13.2V. I'd stay below 13V. Wire pins 4 and 5 only.
Then fit 150R or 220R to Ground on one Tube.
(There are variations of this idea)
Are you sure there is no trim pot on the Switchmode PS? Often they are fitted with a +/- volt or so variation available.
I would also fit a 100uf 35V Electro and 100nF 100V poly at the first tube (Keeping Shooters comments in mind  )
Pity to waste a good (free) power supply
Regards
Mirek

[joesatch]

no trim pot. looks like someone has been down this road with some success.  https://deathtube667tubeamps.com/smps-dc-heater-supply