Not fully transparent background on urxvt

I looked up several answers on StackExchange network, neither of them worked as I wanted. I started using urxvt on Ubuntu instead of gnome-terminal, and wanted to configure it's look to be similar. I succeed with fonts, but can't beat transparent background. What I want is mix __60% background and 40% Ubuntu Mid aubergine (#5E2750)__ -- that's how my gnome-terminal was configured. I tried several combinations of values for Urxvt*background (tried with alpha channel too), Urxvt*transparent, Urxvt*backgroundPixmap, Urxvt*fadeColor, Urxvt*fading (doesn't look actually useful here, but most examples I met set that too) and Urxvt*shading in .Xresources. Every one was not even close, most of them gave completely black background. Looks like I am wrong at understanding backgroundPixmap and background settings, but documentation is not so rich about them.