Rational Acoustics



Dr. J
January 10th, 2011, 06:47 PM
Hi guys -- I know most of you do live sound systems but how many of you tune studio systems?

I am being asked to help tune up a studio system and for the most part -- I am assuming you would do it similar to a live sound system. Am I correct?

When I first walked in -- the guy wanted me to place the microphone directly in the center where they sit and "Tune" the system with both speaker sides going.

Right off the bat -- I knew I was in for a long night. I explained that if his monitors weren't already flat that we would need to establish a known response BEFORE we even started measuring inside the control room.

The other issue is the control room and I am not a acoustician, BUT I can say this room isn't acoustically treated correctly. It is photogetically treated. Everything is real symetrical with little to no acoustic treatment.... No bass traps and a few foam wedges here and there on the walls.

He is using a Driverack to control some "Tapco" monitors and there is one sub on the floor.

I will probably not get him to acoustically treat this room much but as a start what can I begin to do?

1. Make sure all the parts are in working order....ie everything examined and verified....polarity...etc.
2. Take a speaker outside and see how flat it is. If not very flat -- make some corrections to it??
3. Take it back in and continue to use one side while measuring inside the room??
4. Maybe tame down excessive Bass build up peaks?

It sucks because I see this a lot and most of the time -- you get stopped half way thru the job.

Any help would be greatly appreciated.

Arthur Skudra
January 10th, 2011, 10:43 PM
Some good reading here:
http://www.bobhodas.com/publications.html

Ferrit37
January 11th, 2011, 07:36 PM
Hey Dr J,
Aurthurs link is some good reading, you might want to check both sides and see how "equal" the two speakers are.
Also don't neglect to check the Producers area? it's no good if the sweet spot is too small.
horizontal symmetry is important to get stable stereo mixes.
There can never be enough Bass traps, google "super-chunks" and the rear wall behind the engineer is always a culprit, checkout DIY diffusors.
The area around the speakers and especially the always present monitor screen can also be challenges.
checkout http://www.gearslutz.com/board/studio-construction-acoustics/
for some good leads.
hope this helps

Dr. J
January 12th, 2011, 04:37 PM
Awesome guys! I have been doing some searches BUT I like what you guys have come up with even more. Thanks.

Calvert Dayton
January 13th, 2011, 07:13 PM
One difference between tuning a studio and a live sound reinforcement system is that in a studio, the low drivers on the full-range boxes are typically close enough together to couple. So you're likely to get some addition in the low end with both sides running that you don't get working on one side only, meaning that bang-in-the-center measurement with all systems go isn't actually all that crazy, in fact it's probably necessary.

Another is that the room modes in small room move well into the low mid-range and are likely to be a problem. If it's a rectangular room there's a spreadsheet (http://www.rationalacoustics.com/files/Room_Modes.xls) on our site you can use to calculate modal frequencies. I've also heard that just dividing 3x the Speed of Sound by smallest dimension of the room works, but I've never tried it. Anyway those are likely to give you trouble in a small room with no treatment so it's good to know where they are.

Some additional random thoughts: Reflections off the mixing console will tend not to make very audible differences but can play hell with your measurement, so feel free to toss a blanket over it. Watch out for ceiling bounce as well. A bookshelf piled full of stuff can sometimes work as a poor man's diffuser. A couch can sometimes help with LF build-up if you push it out from the wall a little. So can popping out a ceiling tile (or replacing one or two with a grate) in rooms with drop ceilings.

Dr. J
January 14th, 2011, 11:21 AM
Thank you Calvert! Much appreciated.

James Woods
January 19th, 2011, 06:43 PM
Obviously you will find things that youcannot adjust electronically, like room modes (peaks or dips) and reflections. Most of the studios that I have had the opportunity to analize have been less than open to the idea of using an external processor to help tune their system. They will pay a large amount for expensive studio monitors and think that all is well. Much of your work is not going to be technical but diplomatical.

Does your client want a "Flat" system? Does he want a tilt? Does he want to homogenize the sound of varios studios so that he can transfer projects from one to the other without surprises?

Having that said, before doing any EQ, play with the monitor placement. The distance to the wall behind the monitor, the height and angle pointing to the engineer, the distance to the engineer, and distance to boundaries all will have an effect on the response of the system. Studio engineers tend to distrust any tweeking to their system, seeing it as an intromission. Kind of like what live sound system alignment was 20 years ago.

G-Force
January 20th, 2011, 12:29 AM
ProTools, Logic, and I'm sure others have parametric plugins that can be applied to their outputs without affecting the 2 track recorded mix. I use those. Unless instructed otherwise, I eq for the engineer position, and I don't move the mic much. The producer's position should improve, though admittedly not be optimal. That's a compromise I'm comfortable with.

I haven't done a lot of this, but I have done a pair of DynAudio BM5a's. There was some slight low-mid mud that I scooped out. The difference was subtle, but discernible.

I also applied EQ to some ADAM A7's. I used 3 filters that made a dramatic improvement, including some much needed lift in the 12k region.

Here are some benefits to EQ'd studio monitors that I use to sell the service:

If you're a purist, you can always treat the eq as if it's another set of monitors. It's just another reference point to check your mixes with.

So far it's been my experience that people prefer the eq'd sound.

Studio monitors are supposedly going for "flat," but they all sound so different, so obviously they're missing the mark. Smaart reveals this to be true, and aids in illustrating what needs to change.

If you prefer to have your finished mixes to kick hard and have "sizzle," but your monitors don't sound that way, you will overcompensate with channel eq.

Arthur Skudra
January 20th, 2011, 01:39 AM
Just did a project studio tuning today, no treatment on the walls (yet), but I did a quick eq (mostly in the midrange) using a pair of old analogue 6 band fully parametric eq's. Was really helpful looking at the inverted output of the parametric overlaid on top of the measured response curve, then overlaying the 2nd parametric on top of the first one to get both responses the same.

We get so spoiled with the precision of modern DSP's to do our grunt work, I really liked the feel of the analogue eq for a change. Kinda wishing to find a CP10 on Ebay cheap! Does that make me an old timer? :D

Edit: Don't worry, I won't be wishing for a tube based 8 channel USB mic pre...it won't fit in my briefcase! ;)

martindale
January 20th, 2011, 07:36 AM
Arthur, yes you're an old timer but then so am I.....the CP10 was my tool of choice for some time, a clean and powerful eq, and I wish I had a few of them now as well. My company designs and tunes studios, post and film rooms and I tune a lot of rooms every year. I would agree with most everything said in this thread, although I could write a small book with the specifics on smaller room acoustics and tuning.
Now-a-days, the DSP processors available are very good, and I use different boxes for different applications. The power they offer, in eq's, delays, filters, and most especially routing just make them indispensable---and they most of them "sound" very good, or, actually, impart extremely little coloration into the signal path. Although it's nice to consider a "purist" approach, in fact the vast majority of major studios use some processing in their main monitor signal path--the benefits far outweigh any negatives, and in conjunction with good room design and acoustic treatments, can yield amazing results.
Oh yeah, good speakers help too! This is a big topic and there are also other forums that discuss this stuff exclusively---REP and Gear Slutz are two places people might want to check out. Anyone who really wants to talk details about this stuff feel free to PM me.

Kip Conner
January 20th, 2011, 09:01 AM
I was recently put on task to build a temporary studio in a location to record an album for an Americana artist. He wanted to track as much of the band live as possible in the house that had the characteristics of a cabin. It had wood beams, concrete floors and plaster walls. We also had a very small budget so I had to cut as many corners as I could. I also learned a few things along the way...

I choose a room in the house that physically gave me the most room to work in knowing that I would have to move some things around. I had a loft that partially stuck out over the vaulted ceiling where I was somewhat forced to put the Studio monitors. Before I even brought them into the house I measured them in the near-field to make sure they were identical. They were new and they were different enough in the transfer and phase response that I had to exchange them with DynAudio.

Once I knew what they were supposed to do I was able to bring that trace up and move the desk off the wall until I had what I considered acceptable. I then went to Home Depot and bought a large piece of canvas and made a tent so I no longer had a huge vaulted ceiling. That piece was large enough to come down the back wall and lessen the rear wall bounce. I would have preferred to order treatment for the room, but I was given enough budget that barely covered my time.

I'm a firm believer in NOT applying equalization to studio speakers that are already flat. Instead, I used to SMAART to measure before hand and after the temp install so I knew where the build-ups were occuring. We have all mixed in adverse conditions where we picked a point to measure in the optiumum location and then crawled back into the corner mix poostion... the whole time knowing that if I get rid of thise stuff that is bothering me here it's going to adversely effect the mass listening audience. I also kept Smaart running so I could "see" the frequency response was of any given imput.

The single off the album has been in the top 5 adult rock formats for almost 10 weeks so I must have done something right.