heater wiring question

scott17 · 16th November 2012, 10:25 PM

I have a transformer with two 6.3V 4A windings.

The four power tube heaters are 12.6V 1.8A total.
The rectifer tube is 6.3V 1.6A.
The preamp/phase splitter tube heaters are 6.3V 0.9A total.

Can I wire it like this?

If so, is there a best way to obtain a ground reference for the preamp tubes?
I'm not sure the power tubes need a ground reference but can that be done also?

Thanks,

Scott

DF96 · 16th November 2012, 10:38 PM

Provided your rectifier has an isolated heater, and good heater-cathode insulation, then it should be OK. Heaters should always have a DC reference, which may be ground. I would put a humdinger pot between the preamp/PS heater wires, as that is where hum is most likely to be a problem (or just use a pair of equal value resistors to create a virtual CT).

scott17 · 16th November 2012, 10:50 PM

That's great, thanks. Yes, the rectifier is a 6BY5GA with isolated heater. If I understand correctly, I can just create a standard virtual center tap on only the preamp/PS supply with a 100R from each leg of the supply to ground?

I was concerned about that since that also ties the center tap junction of the 2 6.3V supply windings to ground through one of the 100R.

Thanks,

Scott

DF96 · 16th November 2012, 10:53 PM

That will be fine. The power valves won't mind their heaters having a little AC bias as signal levels are higher there.

scott17 · 16th November 2012, 10:55 PM

Quote:

Originally Posted by DF96

That will be fine. The power valves won't mind their heaters having a little AC bias as signal levels are higher there.

The advice is most appreciated.

scott17 · 16th November 2012, 11:08 PM

Quote:

Originally Posted by DF96

That will be fine. The power valves won't mind their heaters having a little AC bias as signal levels are higher there.

Would it help or hurt to tie another 100R from the remaining side of the two windings (other side of the power tube supply)?

scott17 · 17th November 2012, 12:51 AM

Quote:

Originally Posted by scott17

Would it help or hurt to tie another 100R from the remaining side of the two windings (other side of the power tube supply)?

Like this, or does the value of the center resistor change?

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16th November 2012, 10:38 PM	#2
DF96 diyAudio Member Join Date: May 2007	Provided your rectifier has an isolated heater, and good heater-cathode insulation, then it should be OK. Heaters should always have a DC reference, which may be ground. I would put a humdinger pot between the preamp/PS heater wires, as that is where hum is most likely to be a problem (or just use a pair of equal value resistors to create a virtual CT).

16th November 2012, 10:50 PM	#3
scott17 diyAudio Member Join Date: Aug 2009 Location: JFK	That's great, thanks. Yes, the rectifier is a 6BY5GA with isolated heater. If I understand correctly, I can just create a standard virtual center tap on only the preamp/PS supply with a 100R from each leg of the supply to ground? I was concerned about that since that also ties the center tap junction of the 2 6.3V supply windings to ground through one of the 100R. Thanks, Scott

16th November 2012, 10:53 PM	#4
DF96 diyAudio Member Join Date: May 2007	That will be fine. The power valves won't mind their heaters having a little AC bias as signal levels are higher there.