Design Paradymes

[RICK FITZPATRICK]

Hello, this is the first in a series of questions that have plaqued me for a long time. Enlightenment is what I'm after. First, let me tell you this. I am planning on building a studio, a real studio. Maybe with 2 studios/control rooms/ vocal booth etc. At this point in my life, my interests are purely towards having my dream studio fulfilled, as I have other business to cover lifes expenses. I do not expect to make a profit. If I do, that would be nice. However, my motives are aimed purely at self satisfaction. You see, I want to build this myself. This makes it a home studio. Even if it is in a commercial building, it is still going to be my personal project studio. I am a designer/detailer by trade, a musician by avocation, and an audio enthusiast by hobby. I watched my dad spend 20 yrs. building a "homebuilt experimental aircraft in his garage. Its beautiful. He flew it this year. I want to "fly my experimental studio" by next year. But before I begin "designing", I want to say something here. If during my question exercise, please understand, when it comes to experience of designing a real studio, I have absolutely NONE. I have read alot, but I've read alot about other things too. That doesn't make me an expert. I have built incarnations of bedroom/garage/what have you types. But now, I want a room. Or two. Real ones. And since this is THE PLACE for questions regarding this activity, I have only your wisdom to call upon. And from what I have read, there are people here who REALLY DO KNOW WHATS GOING ON. AND YOU KNOW WHO YOU ARE. And I want to pubicly say right now, I respect your experience, knowledge and information, and if I unknowingly piss anyone off with the way I ask questions, I sincerely do not mean to! So verbaly slap me up the side of the head if that happens. Or you can totally ignor me, and I'll get the message. Thats what my wife does. So here we go.
Having not kept up with studio design philosophies, theorys, acoustical and other design methodologies, I am really at a complete loss at what is the current design goal, that studio designers are trying to achieve. I have yet to see a comprehensive set of criteria, that says "This is WHAT we are trying to achieve, and this is HOW we are going to impliment our theorys to REACH THAT GOAL. As Mr. Everest states, nothing is worse than seeing ones first attempt at predicting a rooms RT-60, and seeing a time delay spectrometry plot for the room. Well, like I've said before, how deep are your pockets? Mine are not that deep. But I still want it to sound acousticly good in the studios. I DON"T want it to sound anything at all in the control room. That is MY criteria. I want to hear in the control room, exactly what the mics are picking up in the studio. I plan on one room specifically for acoustical performances, and another for electric. Maybe a control room for each. So heres the question. I have seen Mr. Sayer state in the SAE site, in regards to the control room rear wall, he is NOT partial to RPG's which is the LEDE concept of live end/dead end(correct me if I'm not reading that right), but prefers slated resonators. Your explaination was one of personal experience and that is valid. However, can someone expand on that, so I can see the reasoning in regards to what the goal is you are trying to achieve? I see the use of these devices in various plans throughout the forum, but I do not understand the principal advantage or reason, to use this type of absorber on the back wall. If you absorb, any frequency range unequally, does this not constitute a comb filter? Or am I looking at this from an uneducated numbrain? Please clue me in on this issue, as I am like a sponge right now. A dry one.The only thing I have is enough knowledge to make some BIG MISTAKES, which I have no time or money for. THANKS A MILLION for any enlightenment, and your coutesy to put up with this drawn out question. The rest will be short and sweet. I promise.
fitz

 

[frederic]

There is no such thing as a perfect room, and certainly personal style mixes in with this as well. Some engineers prefer the console room to be absolutely dead - you won't hear a pin drop nor would you hear any acoustical reflections. Others, prefer a more acoustically realistic environment with hardwoods as well as sound control devices to minimize reflections and acoustical colorizations by the room, but not fully eliminate it. Your design goal is also a "soft" goal, whereas its unlikely you're going to design a room that has 6% reflection rate with a 71% dampening rate of frequences higher than 5khz and a 97% dampening rate of frequences lower than 200hz. The math involved would be sickening.

What you really need to achieve:

1: There needs to be good sound distribution in the room, with minimal dead spots and other annoying acoustical effects.

2: Background noise must be masked and controlled. No passing train noise, no lawnmower noise, no hard disk noise, no cats meowing.

3: The reverbation rate should be optimized for the purpose of the room. Live rooms have more, control rooms have less.

There are many ways to figure this out as well. You can use geometic methods, by calculating angles from the source as well as the frequencies and calculating absorbtion and reflections based on surface type and density, as well as the overall shape of the room in question. The problem here is the room is "figured out" empty - i.e. no console tables in the way nor people. Add in objects, and the reflections get very complicated, especially with curved surfaces (poles, pipes, round stands, garbage pails) and curved softer surfaces like humans. Humans actually make excellent bass traps, but thats not a suggestion of duct taping your wife in a ceiling corner

You can also use statistics, and sample the results of the free path(s) the sound takes, as well as wave theory. Both require some really sick mathematical equasions and something that can solve the equasions and you won't be doing that on your free calculator you got when you opened your checking account Wave theory will allow you to calc out where you would expect standing waves, etc, very key in building seriously engineered acoustical space.

There is a lot of talk here about building non-parallel walls, and for good reason. THis helps avoid standing waves, of course. But also, its important NOT to build concave wall/ceiling surfaces
because in essense, you've created a parabolic shell which will have a focus point somewhere in the room, either directly or as a reflection. This spot will have a higher amplitude of sound than the rest of the room (or an outright silence because of phase cancellation). Certainly a bad spot in the room.

Anyway, this brings me to the rear wall. Of all the surfaces in a control room, I for one believe the rear wall is the most critical, because your monitors face you, and your butt faces the back wall. The sound migrates through the room with the majority of sound hitting this surface directly for its first reflection. Some of course hits the ceiling above you (why often an absorber is installed above the console table in larger studios that don't utilize nearfields) and often absorber or diffusers are installed on the side walls. But if you have to treat one wall, do the back wall first.

RPG diffusers are made of multiple blocks of different heights glued together, which in its simplest form, changes the reverbation time for sound hitting each seperate block slightly, some more than others. This creates a diffused reflection coming back behind the engineer, which the brain interprets as less important information. There is a lot of phase cancellation on the reflection thus its weaker and less observed. One of the most interesting things I've noticed is that most RPG devices have each block that makes up the individual tiles have parallel surfaces to the sound source - just many of them of different lengths. Why hasn't someone figured out that angling these tips slightly, in different directions, would diffuse the sound even more.

Anyway, slat resonators are often a better solution because they are adjustable during installation, and often afterwards. If you have too much highs, you can change the materials inside between the slats as well as the size of the slats themselves as well as the slots (gaps between). You can solve some complex problems this way, simply because its adjustable, much like an extremely expensive LeMans car suspension tuned for each race depending which track the car performs on. While "all for one" solutions like slapping foam up is often recommend (I even do it) and solves the majority of problems acoustically, its not mathematically precise.

The smaller the rooms, the less effective any of these devices are, because the sound arrives for its first, second, and third reflection with tremendous power. As sound goes through the air, it dampens due to the "things at rest like to stay at rest" law (I forgot which famous philosoper said that - shoot me) and air molecules are no different than any other molecule. More air, more dampening. The only way to achieve more air is to build larger rooms (or pressurize the room twice what atmospheric pressure is .

Absobers eat up reflections, so if you have too much reflections in a room, mixing absorbers and diffusers often is an excellent solution. The diffusers can dampen overall reflection level for specific trouble frequences and solve oddities within the room (flutter and standing waves) where as absorbers will eat certain frequencies more than others, by not letting the reflections happen in the first place (or minimizing it). Most absorbers suck up specific frequences because the internal structure of foam is a cellulite shape, which means the sound passes through seemingly randomly located and sized pockets of airs for a reasonably random absorbtion rate across the frequency spectrum. Blankets typically absorb lower frequences, because blankets are woven therefore the pattern of the threads (basically some style of weave) is very consistant across the blanket.

There are several rules of thumb I can give you, however.

17M or greater distances between walls make for really nice sounding, easy to tame live rooms. The smaller you make each room, the more sound material you'll need to tame it (generally speaking).

For a live room, typically at least 10% of the original sound should reflect back and around. Turn this down for the control room, and maybe slightly higher for live rooms where you record simple, very soft acoustical instruments such as acoustic guitar, fife, etc.

 

[RICK FITZPATRICK]

Too good!

Ok, this is generally what I have thought. There is no perfect room, so I have to please myself, as I am the only "engineer" here. Well in that case, I DO have my own questions when it comes to these 2 types of acoustical environments. The control room, and the studios. Having been a professional musician for many years, I have had samplings of the sounds I liked in rooms, and looked at why they sounded the way they did. But, recording studio and control rooms are something that it seems like an "experimental aircraft" Like my dad tells me(he has built 3 planes) the planes he built for other people are different than his own. (He was on the PB-Y that was over MIDWAY when...oops, thats another story) To make a long statement shorter, my studio/control room are going to have walls with lots of Louver Panels in the cieling, rear and side walls to hide, change, reflect, absorb, diffuse and measure in many different forms. I want to hear for myself. BTW, if you opened my file I sent to you, and were able to zoom in on the rear wall diffusers, you would see the angled diffuser you described. Thanks! Thats what I like. You put things in the type of format I can understand.
fitz

 

[frederic]

Re: Too good!

There is no perfect room, so I have to please myself, as I am the only "engineer" here. Well in that case, I DO have my own questions when it comes to these 2 types of acoustical

Good. Short of recording on the Nevada salt flats on a non-windy day there is no perfect area to record.

But, recording studio and control rooms are something that it seems like an "experimental aircraft" Like my dad tells me(he has built 3 planes) the planes he built for other people are different than his own. (He was on the PB-Y that was over MIDWAY when...oops, thats another story) To make a long statement shorter, my studio/control room are going to have

Its science: math and physics, nothing more. The complex problem of course is calculating it out ahead of time, but if you have all the formulas and the time, you can fully engineer the room to be "perfect" to your liking and needs.

*I* not being an expert in this area tune rooms the way I have tuned a variety of race cars over the years. Use simple logged information combined with driver "feel" information, and adjust based on educated guesses. As long as the car doesn't crash, I can repeat this over and over until the car is properly tuned for that particular track. Then, I write down all the adjustment settings for theoretical repeatability.

A tone generator, a quality microphone and an o-scope can tell you an awful lot about a room. Instead of an o-scope you can use a level meter.

Test equipment will validate what you think you hear. Often, what you think you hear is not quite reality, because of phase cancellations.

walls with lots of Louver Panels in the cieling, rear and side walls to hide, change, reflect, absorb, diffuse and measure in many different forms. I want to hear for myself. BTW, if you opened my file I sent to you, and were able to zoom in on the rear wall diffusers, you would see the angled diffuser you described. Thanks! Thats what I like. You put things in the type of format I can understand.
fitz [/B]

I saw it on the back, but not when I viewed it on the PC. When I chucked it to the plotter, thats when I saw it. Very cool

 

[Michael Jones]

Here's the lay-out in jpg.

Let me know if there is additional views you want posted.

 

[RICK FITZPATRICK]

Do you mind more?

Thanks so much Michael, do you mind posting the other permutations I just sent you?
I won't bother the forum anymore with things that are only an imaginary layout. However, mine will be similar, depending on space available. These were just ideas for the "contest"!!
fitz

 

[frederic]

Re: Do you mind more?

Thanks so much Michael, do you mind posting the other permutations I just sent you?
I won't bother the forum anymore with things that are only an imaginary layout. However, mine will be similar, depending on space available. These were just ideas for the "contest"!!
fitz

Don't be so sure its imaginary... I liked both layouts very much, and while I've been sliding things around on my own visio diagram, I've been ending up with very close to what you did initially

I think you're going to be the winner Rick

 

[DDev]

Frederic,

You mentioned a couple of replies back that you could learn a lot about the room with a tone generator, a good quality mic, and an o-scope. I have all the above, but what is the process for doing this? I've used spectrum analyzers in a similar fashion in the past (although I was looking at GHz frequencies), but never an o-scope.

I'm in the process of moving my "studio" (really just a production/mixing setup) to my basement, and intend to try to setup some temporary dividers to seal it off from the the rest of the room, and making some measurements of what I've got would help me determine how to construct my dividers.

Thanks,
Darryl.....

 

[longsoughtfor]

From Fredric:
I think you're going to be the winner Rick

Start warming up that soldering iron Rick! LOL.

 

[frederic]

What I have done, and do everytime I build out new space, is to locate the microphone where my ears will be.

Then, through my monitors, I apply a 100hz tone with -1db on the VU meters, through the board.

I then measure the signal level on the scope, received by the microphone. The tone generator produces sinewaves, so in a perfect room, I will have a sinewave (I also pump the original sine wave through channel B on the scope, so I can easily see the original, plus the mic signal in parallel.

I record the results.

200hz, 400hz, continuing up via octaves until I hit somewhere above 18Khz.

Then I plot the signal levels, and have a basic graph of my room, with the equipment inside and the monitoring system. If the variation between volume leves is minimal, meaning reasonably flat, I then insert a 31-band graphic equalizer into the mix and adjust slightly to make it reasonably flat.

If there are significant dips and peaks, then acoustical treatment will be necessary. I then place foam around various parts of the room using thumbtacks and keep testing the bands of freq that are problem. Once its reasonably flat where adjusting an EQ slightly makes sense, I do so, then do the full frequency list again.

Once I'm satisfied (not looking for perfection, just "reasonable", then I pump white noise through (all frequencies 100hz to 20khz equally and simultaniously), then I start adjusting position of foam, diffusers, and the EQ to make it even flatter. obviously stuff I record is not a single-frequency sinewave, it all has to blend.

I've never gotten a room flat - but +/-3db is more than acceptable from my perspective.

Frederic,

You mentioned a couple of replies back that you could learn a lot about the room with a tone generator, a good quality mic, and an o-scope. I have all the above, but what is the process for doing this? I've used spectrum analyzers in a similar fashion in the past (although I was looking at GHz frequencies), but never an o-scope.

I'm in the process of moving my "studio" (really just a production/mixing setup) to my basement, and intend to try to setup some temporary dividers to seal it off from the the rest of the room, and making some measurements of what I've got would help me determine how to construct my dividers.

Thanks,
Darryl.....

 

[Michael Jones]

A couple of new concept plans for Rick. I'll let him explain them.

 

[Michael Jones]

PLan view of the above drawing.

 

[Michael Jones]

And another section.

 

[RICK FITZPATRICK]

Its hot and ready to solder!

Howdy, well I'm glad you liked the layouts, I rotated, scaled up, down, squeezed,streched, manipulated, and tried to get the most out of the space. That doesn't mean that it is correct though. I know that. But it sure was fun! Can't wait to do the same with mine. And Longsoughtfor, my soldering iron has been hot on and off for a month. I was in the middle of changing all my patchbays from rear RCA to 1/4". Boy, what a pain in the..... ! I wish I had never used those@#$^)_#&**@Y#$ RCA's
in the first place. But everyone knows hindsight is 20/20. I wish the forum was around when I started! And to those of you who are ready to buy patchbays with rear RCA's,
DON't!!!! I suppose they are good for some things, but not patchbays. Thats my 2cents
on that. And I have A LOT of cables.(I earned a NASA soldering certificate when I was young!) My tape machine cabinet(2 MSR-16's, a 2 trk r/r, turntable, noise reduction unit etc) is behind my back when I set at the console in my present "bedroom studio", and I built (2) 2" deep x 12" wide sheetmetal lined cable trough mounted about 48" high on each sidewall, that is part of a dimensional graphic design/slatwall panel, that hides the troughs, with a 12" wide 3/4"mdf panel covered with gloss black laminate, that runs from front to back. There are (6) 8 channel 25' snakes and (2)midiizer transport control lines, timecode lines,2 midi cables, and(2) hi z lines in only one of the troughs. All the snakes were RCA's, thats 48+ plugs at one end of the snakes, and 24 at the other that I'm changing to 1/4", not to mention all the gear lines at the console patchbays. Crap, I've seen 1/4" plug solder joints in my nightmares!!!! But I hate cordballs, and do everything in my power to keep cord demons at bay!LOL But thats another story. Anyway, thanks for the info and help everyone. I'll be back with MORE questions, as time goes on.
fitz

 

[DDev]

Thanks Frederic

I realize this is distorting this thread a bit, but thanks for the process you use to analyze your rooms. I'm going to have to try that and see what I get.

By the way, Rick, looks like you've got a fun project lined out. Jealousy is setting in...

Darryl.....

 

[frederic]

Re: Thanks Frederic

I realize this is distorting this thread a bit, but thanks for the process you use to analyze your rooms. I'm going to have to try that and see what I get.

Darryl.....

More than welcome.

Know that my process is in leu of a several thousand dollar machine that will give you that info nearly instantly, in one shot.

Me, I had a used 0-scope I bought at some flea market a while back so since I had it, well, make it cheaper in materials, but more expensive in time.

I can afford time