6V6 line preamp

[merlin el mago]

Do you need 240VAC for 6V6 right?
You don't have 240VAC tx but have two 120VAC?
Look attached schematic isn't unsafe

 

[Doug in Indy]

OK Merlin. I have a 120 to 120 and a 120 to 240, which I thought i could combine to get the volts needed.
Doug

 

[merlin el mago]

Yes, what's your target for B+?

 

[Doug in Indy]

I hope to get 300 to 340 after much smoothing (no reg for now)

 

[merlin el mago]

Try only with one tx 120 to 240VAC.

 

[Doug in Indy]

OK Merlin. I will check later today, but with a load (7k resistor), I seem to recall it was too low. Thanks for your help!
Doug

 

[merlin el mago]

OK let us know

 

[buzzforb]

Salas, I am thinking of trying the 6v6 gain stage coupled to the cathode follower. This will feed a transformer to be used for SE to BAL. DO you have anu guidance or suggestions about how to couple the two. I have read Sy's Impasse article and he does some things I have not heard of.

 

[6L6]

Impasse uses cathodyne phase splitter to make SE into BAL. Smart and simple way to do it.

More info and ideas here - http://www.bonavolta.ch/hobby/en/audio/split.htm

 

[stajo]

I guess Buzz means the neon bulb trick to limit the startup grid to cathode voltage. If you use coupling cap you dont have to bother. Its a DC coupling dilemma.

 

[buzzforb]

Ok, wanted to make sure. i dont mind coupling caps, so no worries. Couple more questions. If coupling, which drain resistor to use after cap and before the cathode follower? 1M or 470k to voltage divider. Also, I had planned to use same rail as gain stage, so I will need to throw away some voltage on the plate of the cathode follower. Can i do this with a simple resistor, or does it get more complicated than that?

 

[Salas]

R in series, C to ground towards the lower Vplate stage

 

[stajo]

Can i do this with a simple resistor, or does it get more complicated than that?

your B+ gets unneccessary slow with a big chunky resistor if youre gonna drop alot. Split rails after rectification and do a small LC or drop it with a regulator.

 

[buzzforb]

Thanks guys.

 

[stajo]

I think you asked for grid leak on the cf also. Anyhing normal, 470 k will do.

 

[stajo]

And, another visually beautiful way to drop some voltage between gainstage and cf without raising the B+ impedance would ofc be VR tubes. Like a 150 plus 85 or 105 in series to ground. Dont affect impedance and make a pleasent look.

 

[gtoro]

Hi boys! finally I've built a decent cabinet for pre

for me it's fine, now I would try to improve supply using a very little space avalaible.
So I'm thinking to apply a gyrator , what do you think about? could be a good idea?
As I say before the voltage on anode is not very high (under 300 V) and probably i will lose something applying it.... can I try simply putting it or I have to use a duplicator in rectifying?

thanks for every answer

 

[gtoro]

 

[stevenrotterdam]

Would it have any positive effect to DC heat the 6V6 for 1 V-level signals?

 

[gtoro]

I'm thinking to use it on anodic rail that actually is CRCRC filtered I want to use it instead of th first R on filter having a virtual CLCRC