Heater Schem Question

[C Moore]

http://www.el34world.com/charts/Schemat ... _84-40.pdf

So...In the above schem... Are these are DC heaters connected in series (either -12 or +12)...so you get a voltage drop of 6 Volts across each dual triode...for 6 Volts.?
And then the power tubes are connected in pairs...for the same effect...6 Volt drop across each pair of Power Tube heaters.?
Thank You

[ToneMerc]

The powern tube filaments are AC fed. The taps are before the rectifier and appears to have a +/- 12V supply hanging off the filament winding of the PT.

TM

[martin manning]

So...In the above schem... Are these are DC heaters connected in series (either -12 or +12)...so you get a voltage drop of 6 Volts across each dual triode...for 6 Volts.?
And then the power tubes are connected in pairs...for the same effect...6 Volt drop across each pair of Power Tube heaters.?

In both the preamp (DC-supplied) and power tube (AC-supplied) heater circuits a 12V supply is connected to pairs of 6V heaters wired in series for a 12V drop. The preamp heaters are not drawn correctly, but applying 12V across pins 4 and 5 as marked accomplishes this.

[C Moore]

So...In the above schem... Are these are DC heaters connected in series (either -12 or +12)...so you get a voltage drop of 6 Volts across each dual triode...for 6 Volts.?
And then the power tubes are connected in pairs...for the same effect...6 Volt drop across each pair of Power Tube heaters.?

In both the preamp (DC-supplied) and power tube (AC-supplied) heater circuits a 12V supply is connected to pairs of 6V heaters wired in series for a 12V drop. The preamp heaters are not drawn correctly, but applying 12V across pins 4 and 5 as marked accomplishes this.

So the schem is wrong...as far as the pre tubes.?
They must be taking the DC feed from somewhere after the rectifier...right.?
Maybe it is more common than I realize, but.....it seems kind of funny that R56 and R57 are different values.
7.5 Ohms vs. 18 Ohms.?

[Tubetronix]

The schematic shows pins 4 and 5 as connections to the heater in one of the two triodes, which is not the case. The actual arrangement is as shown below. The resistor values are different to get a better balance on the +12 and -12V supplies.

[C Moore]

I thought they were just assuming there was no external connection to Pin 9.
There is always that internal connection.
So they just show the series connection...for both triodes...in one triode...for ease of drawing. Otherwise they would have to have a long dotted line from the "A" to "B" dual-triode.
I was really asking about the feed for the DC. In the schem...it shows it from the same place...for both AC and DC. Wouldn't the DC need to be taken from After the rectifier.?
Thank You

[martin manning]

I thought they were just assuming there was no external connection to Pin 9.
There is always that internal connection.
So they just show the series connection...for both triodes...in one triode...for ease of drawing. Otherwise they would have to have a long dotted line from the "A" to "B" dual-triode.

If I were drawing it, I'd have shown pin 4 grounded on one triode (as it is now), and the +12V or -12V connection to pin 5 on the other triode.

I was really asking about the feed for the DC. In the schem...it shows it from the same place...for both AC and DC. Wouldn't the DC need to be taken from After the rectifier.?
Thank You

I don't see that. "FIL1" and "FIL2" are AC, going to the power tubes, and the +12 and -12 are filtered DC going to the preamp tubes. Two 12AX7's are supplied from the +12 side and only one from the -12 side, which is likely the reason for R57 being a larger value than R56.

[C Moore]

OK...that makes sense.
I did not notice the uneven numbers of AX7.
I also was seeing things in the pre heater supply.
It CLEARLY says it is coming from either the -12 or the +12 supply line.
Do Not know why I was seeing Fil 1 and Fil 2 for the pre heaters as well...??
Funny how you see what you have in your head.
Thanks