Project : litle 5 watts transistor amp. How to use the good formulas to adapt the valour of the element to the circuitry?

[Gabi Smith]

Hello,

Since my interrest for guitar effect have begun, I've succeeded to solder little circuits with few elements. My last success was a ultra-trebly pre-amp based on the svex'Sho that I use to connect my guitar to the mix table when I practice with my new band. The sound is pretty.

Yesterday, on the flea market, a seller gave me a lil 3.3 ohm Goodmans speaker, from the 50's I think. I love Goodmans speakers. So I thaught to build a litle amp and to adapt the first fender champ circuit (the 5F1) to my need (like everybody seems to do on the internet). I'm Lucky : it's what the litle pignose amp seems to be based on...

In the pramp step, i would like to use 2 bs170 because i like the way they sound, and maybe puting here and there some diodes to add some grain (like in the zvex SHO). For the power amp, I've got little tip41c on the road direct from China.

So, I've got many ideas... and two poblems.

The first one is I don't know what I have to take as input and output transformer. Will things call audio transformers EL-16 and EL-14 do the job ?  

The second is I don't know how to use the different formulas (and the ohm law - U = R * I, like Youri Gargarine), so I need an introduction to all that stuff to design my litle amp :-D.

Thank you guys.