Check out Vintage Broadcast Microphones website...for starters

One thing to think about, the vintage RCA mic's are no where near as robust as a Royer or even many of the better Chinese ribbons. I don't know if that would change with a re-ribbon since the design isn't changed during the process.

I think his 77 DX sounds too crummy to be working properly? I have 2 and they sound virtually as warm as a 44. A 1950-60 TV gray & 1968 chrome with the large red RCA block lettering indicating this was one of the last ever made. And did you hear that awful sound come out of his 87 as well? What up with that? That's not how those are supposed to sound either. It almost sounded like he was talking into the side of the figure 8 position. You suppose he also did not properly set his gain staging correctly? It sounds obvious to me that he didn't. I always love these type of microphone examples, especially since you know, they should sound incredible, in virtually any space. Obviously au contraire.

So Bob, why are you hot on finding an old RCA? I have a Junior Velocity, while it sounds like a ribbon, nowhere near as good as the 77's. You could also get a 77 body from Wes Dooley and stick in any kind of condenser microphone that will fit. When Wes actually made his 77's, they didn't have the shorter 77 style ribbon. Instead, he told me, his 77 basically have the same ribbon as his 44's. Those were a long geometry ribbon as compared to the 77 short geometry ribbon. I asked him why he did that? He told me, he really couldn't make the 77 style ribbon properly. So why does he offer to re-ribbon older 77's for you? Obviously he seems to be stymied by some little trick he's never quite figured out?

Eventually, one of my 77's may have a ribbon failure. And when it does, I'm just going to sit down, cut my own and figure out where Wes went wrong. I think the trickiest thing about the 77's, DX series, is that awkward " acoustical labyrinth ", within the back & the body of the microphone? But prior to the DX, the earlier 77's didn't have that acoustical labyrinth but instead, dual ribbons. So early 77's are way different animals to the last DX release. I also believe that shorter geometry ribbon to have been more rugged & is probably the reason why you found more of them on large microphone booms instead of the 44's? To the best of my knowledge, there cinematographic ribbons were more similar to those 77 series than the 44 series? And the DX differed as it was a true poly directional microphone as opposed to the earlier or 77's which were strictly figure of 8.

This is me talking on a $.19 condenser microphone from China expertly manufactured by slave children. And it sounds like it.
Mx. Remy Ann David

East Coast or West Coast, you really have only two good choices for repairs or mods: CA or NJ.

REMY mentioned Wes Dooley, and his company is a good place to start: AEA Microphones, in CA. They'll re-ribbon your mics, help (to some extent) with questions about RCA mics, etc. Wes is one of the best in the business for this sort of thing.

Another place (in Pitman, NJ) is ENAK microphones. Not sure if the original fellow is still doing the work, or if he's trained a helper/tech, but it's a direct connection to RCA. (He used to work there as a design or repair tech...don't know his exact story, but you can find out, I"m sure).

Visit both websites, poke around, and see what you come up with. Happy hunting!
(Ebay always has these for sale, but be careful of what's out there....lots of beat up, tired old ribbons, some are just good for parts, some are ready to go, as-is.)