2 6L6, 5 12AX7 Current

[ChrisM]

Thanks Mark.

I feel all warm and fuzzy inside now .

[M Fowler]

Glad to help I was going to suggest it earlier but forgot.

I want to use this in a Princeton build if BillyZ approves

Billyz you out there?

[20to20]

Edit

[Tone Lover]

You can use the first two 12ax7 to cathode bias the 6l6.

You'll get a regulated DC heater for the most critical stages.

you'll also regulate the plate current of the 6l6 to around 150ma.

you'll take the load off the heater winding.

you wont waste space or components on bias

and you can save more space by dropping the stand by.

the heaters are dressed series to ground, very simple.

Do you have schematic for doing that andy better yet a layout I suck at sch. but could figure it out sounds good. Bill

[Andy Le Blanc]

It works with 4 6v6 or 2 6l6, its a stable current... the static dissipation of the
power tube... you dress two 12ax7 12v series, its an old trick.
I gig with a 50 w 6l6 amp biased that way , the only drawback is that the
controlled warm up of the 12ax7 makes an instant on standby impractical
but its cathode bias, the most stable and conducive to tube longevity.

[Tonegeek]

It works with 4 6v6 or 2 6l6, its a stable current... the static dissipation of the
power tube... you dress two 12ax7 12v series, its an old trick.
I gig with a 50 w 6l6 amp biased that way , the only drawback is that the
controlled warm up of the 12ax7 makes an instant on standby impractical
but its cathode bias, the most stable and conducive to tube longevity.

Thanks! Putting that on my bucket list. Now back to the regularly scheduled program...

[Structo]

As an example the Heyboer that Brown Note included in my kit was a 325-0-45-325 @ 300ma
6.3vac @ 6 amps
5vac @ 3 amps

2 x 6L6, 3 x 12ax7

I'm sure it could handle another two or three tubes.

[M Fowler]

Yeah Tom I had noticed that before he was running 300mA in the newer version PT offered. Was that for four 6V6?

Mark