6V6 line preamp

[Zen Mod]

A voltage doubler on the 6,3 taps gives me 11,9 VDC over a 12R, so I guess I will go for a CSS right on that, no headroom for a voltage reg inbetween.

no need for voltage reg

 

[buzzforb]

THnks BAs.

 

[Bas Horneman]

THnks BAs.

You are welcome. This psu could be improved on I'm sure, but it works for me.

 

[RCruz]

The PSU I use for my Salas 6V6. The first cap after the rectifier is an electrolytic on purpose.

Hi Bas

Why do you use the 6AX4 after the rectifier bridge ?

 

[Bas Horneman]

Why do you use the 6AX4 after the rectifier bridge ?

Slow startup. (Even though I'm told cathode stripping does not occur because of HT when the heaters aren't warm yet) And to "hide" the noise from the solid state rectifier. I suppose it is just a habit as well...since I'm told the capacitors filter it all out...(the ss rectifier noise)

 

[RCruz]

Why not use only a tube rectifier ?

 

[Bas Horneman]

Why not use only a tube rectifier ?

Good question! I used a transformer without center tap. And the transformer had only a 6,3v heater supply. Which lead me to the 6AX4 a tube I already had in my parts bin. The 6AX4 not being a full wave rectifier...I decided to use it the way I did.

 

[buzzforb]

You can use 6AX4 in Graetz configuration, from what I have read.

 

[stajo]

You can use 6AX4 in Graetz configuration, from what I have read.

Its a diode so yes. 4 of them per graetz. 4,8 apmz current for the filaments

 

[flatheadmurre]

If your transformer is missing a centertap you can add a couple of SS diodes to ground from your reftifier tube forming a hybrid rectifier.

 

[Bas Horneman]

Its a diode so yes. 4 of them per graetz. 4,8 apmz current

Even as a hybrid graetz with 2 of them. 2,4A but I did not have that much juice....hence one.

 

[buzzforb]

who''s gonna go out on a limb and say what is best.

 

[flatheadmurre]

who''s gonna go out on a limb and say what is best.

Simple whats at hand and works .

 

[buzzforb]

Simple enough.

 

[stajo]

I have 2 6AX4 in hybrid in one of my EL84 PPs. The ups is nice and slow wake up time, stability and ability for current and voltage. Downs are their own filament current draw. They're a bit of an overkill as a pair for a 6V6SE (330 mA, for a need that might be 40 to 100mA depending on your thought config, ie single/dual CSS etc.

An AZ1 mesh plate would be a good option that I like up to some 80 mA if you got one.

 

[buzzforb]

I uahve 5u4g winged C and some fancy Sic diodes. Anything else is a purchase.

 

[flatheadmurre]

I uahve 5u4g winged C and some fancy Sic diodes. Anything else is a purchase.

If your transformer has a 3A heater winding use it !

 

[stajo]

........

alter R3 to 18R , if needed

If I calculate right this circuit gives me between 2,79-2,84 in CSS resistor value (edit, calculated with 18R on R3, which I had handy). When I tested some different tubes CSS regulated they were close to a voltage, atleast it was over half a volt as I remember, in difference between each other with he same resistor values.

Ie different 6V6es give about the same voltage (linear or regulated) voltage driven but differs alot when current regulated.

The thing is that I would not only want to tweak some with starvation, I would very much like to compare different tubes with the same voltages over the filaments.

Almost done soldering, I'm beginning to wonder if this is going to work.

The 10 R Flathead pots is good for a watt or 3 I guess. Maybe i should rethink?

 

[stajo]

Skipping R2 and make R3 a 12R?

Cant find any data on the Colvern but I think its 1 W. This looks almost identic on the outside.

http://uk.farnell.com/te-connectivity/tw1100ka/potentiometer-wirewound-10r-1w/dp/1502910

 

[Zen Mod]

time for beer

ook electronic