I'm no expert but from the

1

I want to replace the speaker in my Ampeg J-20, it's 8 Ohm, 12". I want as clean and "American" sounding speaker I can get. Tell me what to buy.

2

I'm no expert but from the sounds of it you are looking for a G12C or if you've got the budget the G12A which I would love to get my hands on, just sometihing about that AlNiCo tone, mmm, mmmm.

3

Yep ... I exactly echo the reply made by Amccormick83