quick dc heater question

[fossilshark]

If I understood valvewizard correctly, this circuit is correct and it shouldn't be causing me bad hum? It is running x3 12ax7s. I am getting ready to stick the O'scope to the heater lines and see if I have a bad resistor or something.

[fossilshark]

Got a ripple at about 1v p2p. Could this cause hum?

[sluckey]

Pin 3 is not a filament pin on a 12AX7. To operate from a 6.3v transformer you need to use pins 4 and 5 tied together and pin 9.

[PRR]

"Balanced DC" doesn't make sense here. Ground one side.

Break-up the filtering with small resistors.

Even so, 11,000uFd (10mF) is not enough for low-ripple 6.3V 0.9A.

[fossilshark]

Pin 3 is not a filament pin on a 12AX7. To operate from a 6.3v transformer you need to use pins 4 and 5 tied together and pin 9.

My bad i just quickly spun up this schematic using premade models, rest assured my 12ax7s are definitely not wired with heaters to those pins 

"Balanced DC" doesn't make sense here. Ground one side.

Break-up the filtering with small resistors.

Even so, 11,000uFd (10mF) is not enough for low-ripple 6.3V 0.9A.

So is it ok to ground the (-) side of the heaters with that artificial ground coming off the transformer or should i get rid of the artificial ground?

[sluckey]

Totally remove R1 and R2. Ground the negative side of the FWB and all filter caps to chassis. Recheck the ripple on the positive side of the FWB. Any better? Same? Worse?

[fossilshark]

Totally remove R1 and R2. Ground the negative side of the FWB and all filter caps to chassis. Recheck the ripple on the positive side of the FWB. Any better? Same? Worse?

No change, same exact ripple. Although grounding after the rectifier is much nicer as far as the layout goes.

[PRR]

Do you see why Peavey, among others, implement DC heat with a series-string of heaters, 37.8V@0.150A?

In this 21st century you can buy great 12VDC regulated supplies our forefathers couldn't dream of.

[kagliostro]

Add a common mode choke

Franco