I'm not into mixing (or V30s), but I am a blackbird owner checking in. The Blackbird sounds great and has a relatively high resonant frequency. It gives the low notes an extra fatness. Great sound and has a unique voicing which makes it quite different from the typical Celestion sound. It's Alnico and is nice and smooth -- whereas the V30 is a bit firm and harsh. I did own V30s for a few years, btw. On the Celestion side, I go with the blues these days. Hope you get some better responses, but I kinda expect you won't get many because AFAICT not many people use the Blackbird. I've not tried the Nighthawk.
I prefer the V30's "rudeness", as it's termed. I've always enjoyed that slightly vocal quality about it, and many lead sounds specifically (although rhythm sounds as well) that are my favorites come from a Vintage 30.
I have actually found more demos for the Blackbird than the Nighthawk, so I think more people use the Blackbird. Which is actually encouraging for me, because I'm aiming to create more of my own sound than copying a similar tone to others. (Otherwise, I would pair the Vintage 30 with a G12H30 or a Celestion Gold.)
Thanks for your response, though, eigentone!
What type of amp will you be using it with? Love my Blackbird with my Amplified Nation Wonderland, which is a Two-Rock style amp. Didn't care for it with my Vox style amps. I personally wouldn't detract from it's tone and feel by adding a V30. Being that the V30 is supposed to be the ceramic version of the Blue, I don't think adding an Alnico is the way to go. Many people, including DR. Z, feel that the G12H-Anniversary is the best mate for the V30.
I'd be using a Fender Mustang III with it; tones range from clean Fender to Vox to Marshall (with a little help from one of my pedals...) to Mesa to Peavey.
I am considering these two Jensen speakers to pair with the V30 because I am looking to create a tone of my own, as well as pair the V30 with a speaker that gives a little more bass without rolling off much more of the treble. I do have a separate thread for a couple of Celestion speaker pairings with the Vintage 30 I'm considering, but I figured I'd get more specific responses by splitting the possibilities.
I have never been fond of mixing an Alnico with a Ceramic in any situation.
Nighthawk is a great speaker, I think the Lightning might be another good choice.
The lightning is a pretty fat sounding speaker.