Power transformer question

[Firestorm]

If you want more grit, try raising the value of the 220K grid leak resistors on the PI. Try 470K. This will move it towards Marshall territory. Note: you are fooling with the R/C constant and at some point it will be appropriate to reduce the .022 coupling caps, but they should be OK at 470K.

This is fine with EL34s, but be careful raising grid resistances with 6V6s. Published Design Maximum value for the G1 resistance on a 6V6 is 100K. Yeah, I know we've been using 220K for 50 years without a hitch, but I'd be cautious about 470K. FWIW.

[Phil_S]

Firestorm is right. But I figure EL84's are cheap. Isn't the Liverpool EL84? Try the preamp mod on V2 first.

[Bernardduur]

Firestorm is right. But I figure EL84's are cheap. Isn't the Liverpool EL84? Try the preamp mod on V2 first.

I added the express powerstage to the liverpool preamp. EL34 it is

[Phil_S]

I added the express powerstage to the liverpool preamp. EL34 it is

I missed this, too. By all means, raise the grid leaks to 470K as your first step. I think you will be surprised at how that makes your power tubes work.

[drz400]

Thanks! I'll check into power scaling.....

I want more OD from this circuit; with the current voltage the unit is quite clean...... I can get only slight OD from it..... any more thoughts on getting more OD from this unit?

Personally I dont think it is a great design for more overdrive, you would be better off with a high gain marshall type circuit (gain first then EQ) since if you add more gain to a circuit that has the EQ up front the EQ becomes useless as you get the gain pumping

[Bernardduur]

Thanks! I'll check into power scaling.....

I want more OD from this circuit; with the current voltage the unit is quite clean...... I can get only slight OD from it..... any more thoughts on getting more OD from this unit?

Personally I dont think it is a great design for more overdrive, you would be better off with a high gain marshall type circuit (gain first then EQ) since if you add more gain to a circuit that has the EQ up front the EQ becomes useless as you get the gain pumping

Well, I don't want high gain............ I want some OD. Rigth now it is like playing through a Twin with a very slight edge.......

Maybe it is because I use a telecaster

[Bernardduur]

Ok, I think I screwed up here

Installed the resistors on the heaters, smelled something burning and the tubes don't light. Removed em and now when I power on the right voltage is gotten, but when I turn on the standby the voltage drops to 279V and the bias across the 1 ohm resistor is 0.217V

Tubes light up

[jelle]

Rogier,

I do not know what happened with that last mod....

Guys, can he just use the zener diode trick for lowering the B+ in the amp? I have never looked into this as I love high voltages....

Jelle

[Bernardduur]

I think the powertubes are done; I'll order some new ones and check again!