6V6 line preamp

[rongon]

On the 6V6-triode, has anyone tried a low voltage, low bias operating point? Something like Va = 160V, Vg = -7.5V, Ia = 30mA, Ra = 10k, Vbb = 450V.

I was also looking at Va = 160V, Vg = -10V, Ia = 20mA, Ra = 15k, Vbb = 450V.

Just curious...

 

[Salas]

Nobody did so as far as I remember.

 

[rongon]

6V6-triode loadlines w/ Vbb = 450V, Ra = 10k or 15k

Looks pretty linear, no?

 

[Salas]

Best symmetry around the -10 and -15V centres again. More load and B+ as you suggest is always more linearity if you got the capacity.

 

[stajo]

components

Which pot values seemed to work out best for the CC version, 50 or 100 k?

I used a 1 k Dale CW-2B-13 non magnetic wirewound as gridstopper, seemed to work. Other preferences?

Did you find other cruical components like anode/kathode resistors, bypass caps etc, except the output cap of course.


Staffan

 

[SGregory]

I am using 100k Blue Alps initially and then 100k ladder type on final with metal film. Actually prefer the Blue Alps. 50k Will work, but input impedance is very high with CF arangment like mine so 100k to me was best as it provides a lighter load to source.

Grid stopper I use 1/4W 1K carbon Comp like kiwanee, Also use Vishay Dale 1k for prototype. Input cap I use the FT-3 as it has been a consistant performer. The output is a Mundorf Supreme. In both versions either the Cthode bypass or the input caps need to be of high quality. The caps become more personal choice.

 

[stajo]

In both versions either the Cthode bypass or the input caps need to be of high quality. The caps become more personal choice.

Cathode bypass 1000 uF high quality, what might that be, Black Gate?

Staffan

 

[Salas]

I recommend Dale 1K gridstopper after I used Kiwame there too.
Cathode bypass is audible. BG if you still got its fine. High quality capacitor to preference there anyway.

 

[InSides]

Any thoughts on having the tubes mounted horizontally for this very design? I've read that DHT's might show some issues when mounted horizontally, but does this apply for 6V6 and 5AR4, for example?

 

[Salas]

Tube datasheets usually notice if horizontal mount is not allowed.

 

[InSides]

Thanks for that - the original GE datasheet for 6V6 notes that any mounting position is fine. Couldn't confirm for 5AR4 though.

Also, on the note of the cathode bypass capacitor, I've seen several values used on the thread, ranging from 220uF to 1000uF in various schematics. Has the consensus been reached at 1000uF? Elna Silmic II is readily available in 1000uF @ 35V.

 

[Salas]

Its a nice one, had used it also for long.

 

[InSides]

How about the 1M Kiwame at the output? I was only able to find a 5W 1M Kiwame, but I see some of the schematics also used smaller values. Is that value critical?

 

[Salas]

Down to 470K not critical.

 

[merlin el mago]

Which pot values seemed to work out best for the CC version, 50 or 100 k?

I used a 1 k Dale CW-2B-13 non magnetic wirewound as gridstopper, seemed to work. Other preferences?

Did you find other cruical components like anode/kathode resistors, bypass caps etc, except the output cap of course.


Staffan

My choice:

Resistor: Mills
Capacitor: Black Gate

 

[merlin el mago]

Thanks for that - the original GE datasheet for 6V6 notes that any mounting position is fine. Couldn't confirm for 5AR4 though.

Also, on the note of the cathode bypass capacitor, I've seen several values used on the thread, ranging from 220uF to 1000uF in various schematics. Has the consensus been reached at 1000uF? Elna Silmic II is readily available in 1000uF @ 35V.

If you don't get BG look for Panasonic FM.

 

[InSides]

If you don't get BG look for Panasonic FM.

I had thought Elna Silmic II is preferred over Panasonic FM. I can readily acquire Elna Silmic II.

 

[Bonsai]

Any recommendations for a good line out transformer? I will need to drive quite a low load impedance (few k) so capacitive coupling is not the preferable output coupling option.

http://www.veiset.net/BO/BO26MAI07A.gif

 

[scott17]

I had thought Elna Silmic II is preferred over Panasonic FM. I can readily acquire Elna Silmic II.

I have had excellent results using the Elna Silmic IIs as cathode bypass caps if that helps.

 

[tinitus]

if you open a new thread with your power amps, I will move these post over

seems like 'wasted' here, once this thread returns to topic