For as long as I can remember I've always biased my amps around 60% of maximum dissipation. But I just ran across a site that claims 70% is optimal for a Class-AB amp. So I tried it on my go-to Plexi patch and I do believe it sounds better.
Set Power Tube Grid Bias to 0.7 to do this.
Set Power Tube Grid Bias to 0.7 to do this.