Power Transformer Rating Help.

[wozt]

Hi, I am looking to build a guitar amp with 4X6v6's and 412ax7's. On the Dreamtone calculator (solid state rectification) a figure of 182mA is given for a 300-0-300 transformer. What Ma rating would you go for to give the transformer an easy life.

Thanks.

[potatofarmer]

Are you designing in some sag or do you want the power supply to be stiff? What B+ are you shooting for?

[Chuck H]

What Ma rating would you go for to give the transformer an easy life.

It depends on a couple of things but you should be pretty safe with 200mA+. Any PT made for a typical 50W amp with enough filament winding capacity (4A) should do.

[wozt]

Are you designing in some sag or do you want the power supply to be stiff? What B+ are you shooting for?

I don't want sag and want a stiff power supply. I have just finished a cathode biased 6v6 amp and ended up with around 410v B+ about 385v on the plates. That was with a 290-0-290 tranny with solid state rectification.

[wozt]

It depends on a couple of things but you should be pretty safe with 200mA+. Any PT made for a typical 50W amp with enough filament winding capacity (4A) should do.

I have a Carlsbro 50 top which has partridge transformers. The PT was for 2 EL34's at 50 watts. The amp circuit board has had some poor cap replacement and mod's. It is an amp that needs a turret board making to make it reliable again, but that isn't something I really want to do.The schematic doesn't show the mA rating but it does have a bias widing which is good. You think this would be a viable doner amp?
The schematic shows 440v on the plates, too high for 6v6's?

[pdf64]

A stiff high VB+ may result in the power tube plate/screen grids over dissipating, as B+ sag acts to mitigate this.
If there's little sag, it may be better to start out with a lower VB+.