zener diode

[firemedic]

My plate voltage is just too high. I'm running a SE 6V6GT at 370V plate to cathode, I like the 6V6 sound so a 6L6 is out. What do you cats think about the Zener diode voltage drop trick? Any issues?

[labb]

The zeners work..If I might ask, what voltage are you looking for on the 6V6. Mostly they sound pretty good from 350 up to 380. (According to which amp they are running in.)

[firemedic]

I see a lot of schems here have them at lower voltage & the talk seems to be that the sweet spot is closer to 300.
I need a 720R cathode resistor just to stop the redplating. That doesn't seem right. I was thinking of a reverse polarity zener on the power CT to drop the entire B+ @50-75V; currently I have a 220R 10W after the recto, dropping @10V, but that feels like poor design, plus I don't want a hot power resistor right next to my filters. There's no room in there. 

[Fresh_Start]

A zener on the center tap will work, but there's a much less expensive alternative.  There was a detailed discussion either here or on AMPAGE within the past month or two of the various methods.  I can't figure out what the right SEARCH terms would be right now but I did save the attached schematic.

Search the net for "MOSFET Follies" and you'll find a discussion of this circuit (I think).

BTW I found that I liked the OT (plate) voltage on a 6V6 at around 300-320 much better in a Tweed Princeton.  Blackface Princeton Reverb voltages much higher.  It all depends on the sound you want.

HTH

Chip

[firemedic]

I already ordered a 50V Zener. I'm hesitant to do much messing w/ the B+ itself. Tho I did a VVR on the TOS which I like.
Oh well.

[labb]

That 50 volt zener is probably going to get pretty hot.

[bakerlite]

[sluckey]

A big ole power resistor right after the rectifier will work just fine in a SE 6V6 amp too, if you want simplicity.

[tubeswell]

That 50 volt zener is probably going to get pretty hot.

Assuming 2 x 6V6s running about 140mA max and another 10mA for preamp tubes, .15A x 50V = 7.5W, so a 20W zener will be fine.

[firemedic]

Just one 6V6. I also want less voltage on the 5879. And the CF grid has 230v, probably exceeding the 12AU7 grid-to-heater max.

[tubeswell]

Just one 6V6.

SE 6V6 Class A uses about 36-40mA, so your 20W zener is ample

 

I also want less voltage on the 5879. And the CF grid has 230v, probably exceeding the 12AU7 grid-to-heater max.

increase the pre-amp supply resistor size in the power rail