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[bigaudioblowhard]

I'm trying to build a new Mastering Room from what was a rehearsal room. It is quite big, 15' W X 25' L X 15' H. Clientele were dying to get in so we went with a coupla carpets, couches and some absorptive panels on all four walls and some angled reflective panels that hang from the ceiling. The floor is sand filled between the joists on slab concrete and not connected to the walls. Monitors are Tannoy 10" duoconcentrics, Soundanchors stands  and a Dynaudio sub. There are no bass traps to speak of, corners are open. The results we are getting are a little dissapointing. Some things sound good in the room with nice controlled bass, and sound boomy elsewhere. Some stuff sounds nice and clear, then either bright or dull elsewhere. Some things sound fairly open in the room and overcompressed elsewhere.

I'm a pro mastering engineer and so kinda know what I'm doing. In fact, I'm just doing what I usually do, a little compression, a little high end, clean up the bass, bring up the level with the aid of metering. No rocket science.

Everything is all over the place. I have no idea where to start. The speakers have been recently reconed, and the amps, converters etc. are all fine and checked out by techs before setup. I figure its partly me not used to the room and partly the room itself.

Does a room affect our perception of compression? Will something sound looser than it is?

We'd like to have an acoustician in to look around and give an assessment and basically help get this thing up to snuff. We are in LA, not far from Hollywood. We'd also like to consider doing some of it ourselves to save money, but have no idea where to start looking, or for what?

I'll be starting with the Realtraps site, and FM Design, then who knows.

Any suggestions would be appreciated. Acousticians reading this thread may also solicit their services by PM.

very sincerly, bab

[Tom C]

Ethan's Realtraps site is a good starting point, read what's there
and you'll have enough information to ask the right questions.

BTW, I'm just in the middle rebuilding my mixing room (about 70%
of the absorbing part is done, diffusion will follow after that.
That's why I post rarely these days) and it's by far the most
improving (acoustically) investment I've every done.

Your work will translate much better.

Tom

[jfrigo]

bigaudioblowhard wrote on Fri, 02 February 2007 02:50

I'm trying to build a new Mastering Room from what was a rehearsal room. It is quite big, 15' W X 25' L X 15' H. Clientele were dying to get in so we went with a coupla carpets, couches and some absorptive panels on all four walls and some angled reflective panels that hang from the ceiling. The floor is sand filled between the joists on slab concrete and not connected to the walls. Monitors are Tannoy 10" duoconcentrics, Soundanchors stands  and a Dynaudio sub. There are no bass traps to speak of, corners are open. The results we are getting are a little dissapointing.

Clearly you'll need some bass trapping. You'll also want to do something about that ceiling height if possible. Having two dimesnsions exactly the same is not good. If you could lose a few feet of ceiling, it would help. You could even build bass trapping into the cavity created by reducing the ceiling height. The 25' depth is good, and 15 wide is enough, though with 25 long, a couple feet wider would be even better. Still, no biggie, 15 X 25 is workable.

You want a combination of absorption, reflection, and diffusion. The bass trapping should include broadband traps, though a few tuned traps based on dimensions will also be good. If you were to get some broadband stuff up, and then "shoot the room" you could know exactly where the remaining problem modes are, and tune traps to knock those out. However, an acoustician should be able to predict where to place tuned traps ahead of time too. The other thing to keep in mind is speaker placement and listening position. These factor can have a huge impact, and getting those right to begin with will make the room treatment more forgiving.

[bigaudioblowhard]

jfrigo wrote on Sat, 03 February 2007 11:28

... Clearly you'll need some bass trapping. You'll also want to do something about that ceiling height if possible. Having two dimesnsions exactly the same is not good. If you could lose a few feet of ceiling, it would help. You could even build bass trapping into the cavity created by reducing the ceiling height. The 25' depth is good, and 15 wide is enough, though with 25 long, a couple feet wider would be even better. Still, no biggie, 15 X 25 is workable. You want a combination of absorption, reflection, and diffusion. The bass trapping should include broadband traps, though a few tuned traps based on dimensions will also be good. If you were to get some broadband stuff up, and then "shoot the room" you could know exactly where the remaining problem modes are, and tune traps to knock those out. However, an acoustician should be able to predict where to place tuned traps ahead of time too. The other thing to keep in mind is speaker placement and listening position. These factor can have a huge impact, and getting those right to begin with will make the room treatment more forgiving.

Thanks Jay, I remeasured the room more accurately. Ceiling is 13'0", Width is 14'6", Length is 24'0".

I assume the difference between the Width and Height isn't enough to make a difference, so I'll still have to do something about that as you suggested. I'll be getting into the reading next.

Exactly what does "shoot the room" mean? I assume its pink noise. I have about 10 bands of differnt pink noise on a test disc. Would this be useable?

bab

[jfrigo]

bigaudioblowhard wrote on Sat, 03 February 2007 15:23

Thanks Jay, I remeasured the room more accurately. Ceiling is 13'0", Width is 14'6", Length is 24'0". I assume the difference between the Width and Height isn't enough to make a difference, so I'll still have to do something about that as you suggested. I'll be getting into the reading next.

That's definitely better than having 2 dimensions exactly the same, but I'd have to run the numbers to see exactly what that ratio will give you. You could get modecalc or something and plug it in to see what the axial mode spacing is. The ratio is roughly 1: 1.1: 1.85, and it looks to be at the outside of the range, and having the two lesser dimensions be a bit farther apart would be better, but it may actually be workable.

Quote:

Exactly what does "shoot the room" mean? I assume its pink noise. I have about 10 bands of differnt pink noise on a test disc. Would this be useable?

Yes, use pink noise and measure the room response. Ideally you would use a calibrated mic from B&K or ACO Pacific, but some common studio mics like Earthworks omnis will get you by too. You want to play full bandwidth noise, and the analyzer needs to have a greater resolution than the usual 1/3 octave RTA to be of use. 1/12 octave starts to get useful, but the more the merrier. You want to be able to compare input to output, and it's best to have something that will show you a waterfall plot over time so you can see ringing and not simply frequency response.

It sounds like you've actually got some potential in the raw space. It just depends how extensive you want your build-out to be, and how exacting your tolerances must be.

[franman]

Jay is all over this... I'm just gonna watch!