Minimum size a room can be for radio quality vocals?

4' X 4' X 8' - preferably 10' (height). Plenty of vocals have been cut in small vocal booths that size. You'll want it dead though. 6' x 6' x 8 (10) would be better though

I can’t quote actual tracks, but I know the vocal booth at the Sound Kitchen in Nashville is exactly what Bill describes: 4’ x 4’ x 10’, and dead as a doornail. Tons of big time vocals recorded in that booth.

EDIT: OK, probably more like 6' x 6' x 10'

yeah, you’re looking at the room they call the “Big Boy.” That’s the room that makes people book the studio. But that’s not where a lot of vocals are cut. Well, I’m sure some vocals are cut in the big room, but a lot of vocals are cut in the vocal booth. It’s unlikely they would put pics of this online, b/c people would say, “oh, I can build one of those!” The Big Boy is what books the space, because it’s become rare to have rooms of that size. But I can assure you of what the vocal booth looks like, because I have sung in it.

I see the Big Boy room-that is enormous! Pretty sweet looking no doubt.

But most of the studio also features other large vocal tracking rooms.

I imagine these rooms and Big Boy are where serious big time vocals are being cut.

yeah, absolutely, which is why 10’ is definitely better than 8’ for the ceiling. The reason this small of a space can work fine for vocals (if you like a dead vocal sound...) is b/c you can make the walls 12” thick of fiberglass, and then you’re not going to have much build up of problematic frequencies for vocals.

I’ll say that personally, I prefer a larger room than this, but lots of big records have had the lead vox cut in a space like I’ve described.

Certainly podcasting/NPR-style vocals work fine in a small, extremely dead space.

Yeah I have never been a fan of the vocal closet sound, over time it can feel like the room is getting even smaller, plus most lack good ventilation.

All the lead vocals I've ever done in commercial studio live rooms had the mic set up in front of tall gobos that damped down the room sound and reduced the sonic size of the space. Typically there was a rug on the floor where the mic was also. Unlike tracking a band, you didn't want the room sound to register on the recording, even though it still had some impact on the sound, and all ambiences were added later in the mix. 

Since most final vocals were overdubs, they were generally recorded in the main studio space, but they were always damped by gobo walls that usually closed off at least 120º of what the cardiod mic heard behind the vocalist. And the vocal space created was typically fairly close to the control room window and wall, making for a much smaller acoustical room.

You wouldn't record a lead vocal in a live drum room, for example. The less flattering the room sound, the more you'd want to record it as dry and dead as practical. I've also recorded final vocals in vocal booths. Unless a small space is glaringly unflattering, and ruins your vocal, you can still make it sound epic in the mix. Especially with the room IR's available today. 

But think about it, most pop vocals you hear are really up front and intimate with all the compression and limiting, and big room ambience baked in generally would not be what you'd want to hear at that point.

Mark,

The podcast guy also works at my local UPS. I went into his store to ship out a mic and he saw it and we got to gear talking. When I told him I was selling the mic to free up funds for room treatment, he asked me how big my room was. Told him I had a couple of rooms to choose from and he basically said it was much better to go to a local studio instead with a big room. Told me I'd be hard pressed to hear about any real quality vocals being tracked in bedroom size rooms.

Kind of got me thinking as vocals are my #1 priority. If a room is close to 10x10, give or take a little bigger or a little smaller-is 4 inch panels enough or do they need to be thicker for this size?

Gotcha, now I'm onboard. :-)

If you're doing primarily vocals in that space, 4" panels (with an air gap) is probably sufficient--as long as you use enough of them. But if you're also using that space as your control room, you might want to think about deeper panels or other options.

As you're setting aside funds for room treatment, IMO it's worth giving GIK a call. They'll give a free consult and recommend products based upon your specific room and recording goals. You can obviously then decide to buy stuff from them or not, but the consult will be helpful regardless.

^^^ Exactly

Mark never thought of that and the 251, I always thought it was the pretty pictures in Mix magazine and rarity.
As for top engineers and rooms, the best are going to make the best of what they are given. Do remember often what we as AE’s would feel are sub par sonics are often the result of a performance that they just can’t equal with everything dialed in !

I don’t know the answer to the specific question, but I agree that eliminating the room from the vocal sound is typically preferred. Too much room will get weird as soon as you start compressing and tuning.

You must also be aware of comb filtering in booths that are too small without broadband absorption.