Hey everyone. I was looking into building a cab for myself and I was wondering if it would be possible to salvage the two 12" Blue Marvel speakers from my Peavey Vypyr 100w amp? Or are they so specially crafted that they can only work in the Vypyr? Also, would they sound fine just as a speaker in a cab? Thanks!
What do you mean by "salvage" exactly? Are the speakers damaged? Speakers can be fixed if damaged or broken, but some speakers will cost more to repair than they are worth - prime example being the Blue Marvel speakers.

If you mean just slapping the speakers into another cab - then yeah, you can do that with any speaker. People swap speakers all the time. Just make sure the Ohms are matching. Don't mix 8 ohm and 16 ohm speakers, stuff like that.

As for whether or not they will sound fine - that is subjective. They will sound like whatever amp is being played through a Peavey Blue Marvel Speaker. Different speakers emphasize different frequencies and have different materials making them sound different one model to the other. They also react differently with different amps. That's why there are so many different kinds of speakers out there. Speakers are much like pickups in guitars - different flavors for different tastes.
Gear: Gibson Les Paul Studio, Gibson SG Special, Fender Stratocaster, Fender Telecaster, Fender Jazzmaster, Gretsch Pro Jet, Carvin C350, Epiphone ES-339 P90, Epiphone ES-335 Pro. Peavey 6505, Sovtek MIG-100, Vox AC30, Peavey XXX.
Thanks! That's very helpful I was looking into getting a Vox Night Train 50 watt head, as long as I get the same ohms from amp to speaker, I should be okay?
Yep. The impedance (in ohms) of the amp should match the impedance of the speakers.

The general rule is with tube amps do not use speakers with a lower impedance than the minimum listed for the amp. That can fry a transformer. Usually a higher impedance will just make the amp work a little harder but shouldn't cause trouble.

I think the Night Train has a switch for different impedance speakers, so you should be able to use 4 or 8 ohm speakers, maybe 16 ohm too, I can't remember. It was the 15 watt one I looked at, don't know much about the 50. Except that it should be freakin loud...I wouldn't hesitate to use the 15 watt model onstage. I thought it was a very nice head. Probably more versatile than I need...

If you want to transfer the speakers to a cabinet, how they are wired will determine the impedance. Being a 2x12 they are probably 8 ohms each, wired parallel for 4 ohms total load. Wired in series they would add up to 16 ohms. Same for any speakers. Two 4 ohm speakers wired parallel would be 2 ohms, series would be 8. Parallel divides the impedance of each by the number of speakers, series adds it together.
Hmmm...I wonder what this button does...
Okay, thank you! I'm trying to get into building my own stuff, so this is really helpful!