Johns Standard Control Room

i would take a set of measurements as is, the the soffit (assuming you need it), then another measurement, finally the furniture.

OK, Floors done. Bought some padded underlayment, did a test, made a plywood sandwich... useless. Looked round the barn and found several new rolls or carpet padding. Remade the sandwich, fantastic damping. Put the padding down on the floor. Bought more underpayment, put tongue and grooves joints on ALL edges and glued it all together. No screws. One giant plywood board, resting on top of the soft rubber padding. Sanded the joints flat with the belt sander. Mixed up some polyurethane resin and poured it into all the seams. Sanded again. Mixed up some floor leveler and filled in a couple of knot holes etc. Sanded again. Bought some vinyl "floating" flooring, that looks like maple wood, and was real easy to install. Maybe 1/8" inch thick and very dense/heavy. The result is a super quiet, comfortable, maintenance free floor that cuts down on what little flanking noise was left. Last night, ordered the Dayton EMM-6 measurement mic. Meanwhile I tried test fitting my old desk which was in storage, but its not right for the new room. The old desk was designed for a corner of the room setup (bad) and to use it in the middle, takes up too much depth. Also I'm tired of turning left or right to reach my midi keyboard master controller, so time for a new desk. So...being a Vermonter, I looked round the barn and found a couple of display cases that came from a J. C. Penney store which look an awful lot like slope front rack mount cabinets. Got on the internet, looked at some pro furniture and came up with my own design. Meanwhile shopping around for some 703 waiting for quotes. (internet deals are no deal after the $50 or more UPS shipping charges!) But first jump over to Glenns soffit design, figured out the details while (not) watching TV with the wife. Drive to the lumber yard next day, get some nice straight 14 foot long pine boards and start building. When the mic comes in I'll pull stuff out and start testing. Based on the way the room sound (like a small cathedral) I'm pretty sure the soffit won't hurt. Pictures below

Glenns ceiling corner absorber design question. Why is there both 703 and fiberglass batts? How would performance change without the 703 skin? I'm working on finding some or equivalent locally.

the 703 works on the velocity and the pink stuff better on the lower velocity and pressure side and LF. compacting the pink stuff can result in roughly the same performance so tying it in tight bundle with mesh will work.

Thanks Glenn, That makes sense. I may go "pink" on the soffit and save my money for 703 (or equivalent) on the rest of the treatment.

"it only takes the first 80% to get to 80%, but another 80% to complete the last 20%"

80/20 rule applies to much of life. Worked on desk again today, should be finished tommorow. Have a great weekend. Here's another 80% rule about golf. "Eighty percent of putts that fall short don't go in." Yogi Berra :|

Lot has happened in the past week. DISASTER NEWS We had disaster level storms and flooding in the area. Unbelievable amount of rain came down in one night, almost 6 inches. Even paved roads were washed out. 50% of our local roads were washed out including Route 5 and the railroad tracks along the Connecticut River. Our home was spared but the waters came over the bank in the wee hours of the morning before receding back into the raging river. We were lucky compared to the hundreds of others that had to be evacuated. SEARCH FOR 703 After searching for a month, and finally giving up on finding any OC 703, insulshield, ductboard or equivalent, I received a phone call from my local lumber yard that supplies me with most everything. He tracked down some 703. $13.50 per sheet, delivered. Ordered 3 packs (24 sheets of 2 inch). Be here in 2 weeks. NEW DESK Finished (mostly) my new desk, made out of 100% recycled materials. 2 former J.C. Penney display cabinets, to become cool slope front rack cabinet and computer isolation cabinet. Also some recycled laminate shelving, white pine, some glue, a few screws, bolts and a little black paint. Why pay $4000 when you can use junk. TESTING Spents hours with Room EQ Wizard and the laptop. Discovered it won't work with my laptop, no line in jack (had to download manual for laptop to identify the tiny jacks on the side. (Note to self: get electron beam microscope bifocals next time, It sucks getting old) So that meant, dragging my big studio system in the new control room... darn. :yahoo: Its been a long time since I've used spectrum analyzers. I started B.C. before computers. It was all hardware. Bill Gates was probably still in college. Calibration was easy, glue an accelerometer to a shaker and you've got a 1 G signal to verify the manufacturers sensitivity. (I used to find errors in equipment). (Peak vs. RMS) But, alas, acoustic analysis is not my specialty. I'm still not sure I even have everything calibrated properly. However here's what we got so far. It's relative so I wouldn't stake my life on the amplitude values being abolute and traceable to NBS. I put a speaker on the floor, right front.I gaff taped the RS sound level meter to the mic stand and stuck it up in the diagonally opposite corner.Did a few tests and here's what I came up with. (BTW - waterfall plots were a real big deal back in 1985.)Definitely not a smooth response as the waterfall display shows. I did a manual subjective sweep as well. 67.5-72.5 Hz loud 73-83 Hz quiet 83.5 - 104 Hz medium 105 - 115 LOUD 116- 121 medium 121.5 - 126.5 quiet 127 - 137 medium quiet 138 - 142.5 LOUD 143 -159 quiet 159.5 169.5 LOUD 170 - 175 medium If this were grinding machine, I'd say it had major structural design problems causing critical frequencies, but the bearings and the motor look fine. Can this room be tamed? The big broad band bass basket (rear ceiling soffit) is ready to install. Unless you recommend otherwise, I was planning on the wire mesh method of packing in the insulation in. Thought I'd save the 703 for clouds, sidewall absorbers and corner traps if needed. Also the Dayton EMM-6 measurement mic came in, but I'm still trying to figure out how to incorporate it into the signal chain. I used the computers built in sound card with the RS meter. But I'd prefer to use the MOTU 828 MkII with the microphone. Or maybe the mackie mixer preamp. The EMM-6 needs phantom power and a decent preamp. What's the best set up with the equipment I have on hand and how would you calibrate it? There seems to be too many gain controls and volume controls in the loop. But maybe calibration is not that important. Relative values might be good enought? We're basically trying to make a flatter response in the room, right? HELP?

good thing you built this on the second floor :-) i'd say that since you have no absorption in the room, you are very clearly seeing the floor-ceiling mode, a side-mode slightly weaker, and the second and third order modes. on REW you want to follow the instruction particularly the loopback carefully to ensure you system is recording things correctly but what we're seeing is not too bad - +/-10db without any room treatment. once you get in your absorption, clouds, etc you will see this change radically. if they had 703 4" that would be a better choice for your cloth covered absorbers but you can also double up sheets as needed.

I bought enough 2" 704 to make 4" thick side wall absorbers. Any particular cloud design that you'd recommend? Your help is appreciated so much more that you know. Thank you Glenn.

I have the rear ceiling soffit absorber partially installed and wow, what a difference in the bass. I post photos and FFT data soon. PS: Noahs 2nd flood has receded for now. What's next, locust?

Glenn, I finished the ceiling soffit today except for the final trim. I might as well get ready to build the cloud(s) while waiting for the 703. Many posts back you showed an angled cloud over the mix position, and parallel cloud in the back. What are the design details for the clouds I should make?

maybe something like this? you could use solid backing and make the absorption to the edges.

Very nice looking! If I have studied well, the plastic is to keep fiberglass particles from dropping down, also adds a little high frequency reflection. Two questions: 1. Does the plastic go only on the bottom face, or around the exposed edges too? 2. What holds the 703 in? Press fit into the 1x1 frame or glued to the plywood? Any other construction hints particularly about the fabric / 703 attachment and frame would be appreciated. Thanks again Glenn! John

plastic on the face, press fit into frame, cloth on outside of frame.

Back from vacation and ready to continue the project. The OC 703 is supposed to be in and I'm trying to pick out fabrics. Glenn, I have some questions about the clouds. Cloud positioning: (edit) I have a track lighting unit right over my mix desk 5'-8" from the front wall) running parallel with the desk. Will the clouds work optimally with the track light located in the 6" gap between the front and rear sets of clouds? Any adjustment is needed? Regarding cloud size: On the larger cloud units, the size (2'-7.75" x 5' ) makes for a lot of waste with a 4'x8' sheet of plywood. Also 703 comes in 2x4 sheets. What's the thinking here? Thanks

unless you buy sheets in 3'x5' (and just go with that)... the 3x5 then leaves around 6" all around the edges. you could leave a slight gap for the track lights or even suspend them down between the clouds.

3'x5' sheets of plywood are new to me. What type should I be asking the lumber yard for?

3/4" interior finished grade A-B or A-D plywood. if they don't carry it in 3x5 (or 30"x60") let me know and we can resize the clouds a bit to use what is available efficiently.

I tried. Can't get 3'x'5' plywood. Only 4'x8' Unless special order. So resizing would be my choice.

maybe go with 2'8 width (3 cuts per 8' sheet). front row is angled 22.5 degrees (or so) and back row 12 degrees (or so). this should cover most of the width of your room and back to almost the middle.

Thanks Glenn, The 703 just came last week and I purchased some decorative fabrics to cover all the treatments. We're scheduled to start building the clouds and sidewall absorbers next week. One question: Why slotted plywood vs. an open back?

mass. the angles and mass are disruptive. an open back is simply absorptive and might not be as effective.

gullfo wrote:

mass. the angles and mass are disruptive. an open back is simply absorptive and might not be as effective.

Ok. How about for side wall absorbers? I was planning on 4" thick, open back spaced an 1" or so away from the wall. The typical broadband absorber that everyone builds with coeficients around 0.9 in all freq bands (according to the charts)

the proximity of the wall to the open back on the side absorbers will provide the reflection function (and the walls are already disruptive :wink: )