ECC802S 12AU7 ECC82 heater question

[korabetsni]

hello,
i wanna ask how to connect the ecc82s heater.The pins 4, 5 and 9 are the heaters. The pin 9 is the common pin. If i want to use 6.3vdc i must connect in parallel the two heaters?(4,5 together and 9 the second pin).
and if i want to use 12,6vdc i must use only the pin 4 and 5?(connected in series)
What is the difference of those two modes? (exept the different supply)

 

[MrCurwen]

There is no audible difference.

 

[DF96]

There might be a small difference in hum with an AC supply, depending on how the heaters are wired and how the triodes are used. Some data sheets may suggest which triode to use first for low hum. This will not be an issue for a line stage, and ECC82 is probably not a suitable valve for a phono input so probably of no practical significance.

 

[korabetsni]

the heater must be connected in one of those two ways (parallel or serial)? can i use only the one heater?

 

[DF96]

You can use one heater if you only want to use one triode. In that case, an alternative is EC90/6C4 which is half an ECC82 on a B7G base.

 

[century tek]

Just a side note, the 12AU7/12AX7 tube types were designed with the option of using 6.3 or 12 volt taps depending on the circuit topology. The 6.3 volt tap was usually used in all power transformer applications where as the 12 volt tap was usually used in the power transformerless or hot chassis designs.

 

[korabetsni]

The polarity of the heaters supply matters? I mean if i connect the two heaters (12AU7) in parallel, the + of the 6,3 Vdc power supply must be connected to pin 9 or 4,5? or it does not matter?

 

[DF96]

Does not matter.

 

[carageae]

ECC82 heater in DC

In this case I should connect the 9 pin to GND and 4,5 to +6,3V.
In the eventuality of change for example to ECC88 we can keep the 9 pin to GND and use the 4,5 pins for heater supply - useful especially for PCB designs, it's easier to modify the heater supply.