Power Transformer Question

[TurboGuitarMelton]

Can you guys check my calculation and see if I have this right? Thanks!


I am using a 6g15 Reverb unit PT to power a cool biased 6v6G, a 12ax7, and a 6av6. Its got tremolo! The PT does NOT get hot and Im trying to see how hot I can bias the 6v6 before the PT starts having troubles. I think its maxed out though. I have a 1k resistor on the cathode like the 6g15 6k6 and have an 820 ohm on hand i was going to try.


Heres the specs on my transformer:
250-0-250 @25ma
6.3V @ 1a


B+ is 326V


6v6G is biased @20ma 303V on plate (~6w)
12ax7 is drawing ~2ma
6av6 is drawing ~1ma


So that's ~23ma? And .9A on the filaments


If this is okay (which to me sounds really good and is pretty loud for a practice amp) it puzzles me why people dont build with the 6g15 PT more often for those tiny 2-3w amp projects.. I saw on a website where someone was spending $60 on a hammond PT for a teeny tiny 2w amp build. Amplified parts sells a fender reverb unit PT for a measly $25 and the OT was also only $15.

[shooter]

#'s look close enough, If you can "keep" your hand on the PT after a 20min jam, it's dissipating the heat just fine, bump the 6V6 up a watt 

[PRR]

I bet a 12VA transformer won't burn-up until loaded and sagged to 50% of nominal voltage. (Similar-size transformers for doorbell service can be shorted forever.)

However with OT impedance already picked, you may already have as much current as it really needs.

[Greenwichpaul]

Ooh, sorry to be OT, but that sounds interesting, with the trem, could you post the schematic?

Good information re that PT, thanks. If only they were anything like that price in Europe.