DIY QSF - quick sound field?

I've read in EQ mag (June 07) about Bruce Swedien's Quick Sound Field techniques (see http://www.asc-studio-acoustics.com/qsf.htm), and I think it would make the best sound most easily out of my fairly live, but not good-sounding basement. Problem is, I can't spend 3k on sound treatment. The QSF concept is placing around 8 hemispherical diffusors pointed towards the talent in a semi circle around the mic, reflecting high freq's while absorbing low freq's with the rigid fiberglass inside (the other side is non-diffusive and can be pointed toward the talent for a gobo effect). I am wondering if painted cardboard concrete footing molds (tubes - exactly the same shape and size of the QSF units) filled with spray foam insulation might have the same effect, without the option of an absorbent gobo side? I have the tubes already - so I will try them without insulation to see if they improve the room sound on drums... but if the experts here think the insulation would not absorb low frequencies because of the regidity of the tube, or whatever, I will not bother trying to find a spray foam installer and begging for scraps/leftover spray.... Thanks, and I've been lurking here for a few years now, getting ideas for when I finally have my own studio space, and the time has finally come! :) It's been a big help. Actually had a bit of trouble finding it this time... but finally did. My space: roughly 20' by 30' by 7' open plan basement, laminate floor on concrete slab (yay), ceiling tile (ugh) and paneling (double ugh!!). There's couches in the corner, and a mattress against the wall, not for sound treatment... just cause I don't have anywhere else to store it!

pianojam wrote:

... and a mattress against the wall, not for sound treatment... just cause I don't have anywhere else to store it!

...also handy when your clients go bananas... :wink: HOOK

pianojam wrote:

I am wondering if painted cardboard concrete footing molds (tubes - exactly the same shape and size of the QSF units) filled with spray foam insulation might have the same effect

Sorry, no. If you want to DIY some panels, use rigid fiberglass at least two inches thick. Four inches is even better. --Ethan

What about using both? The tubes in front for quick sound field diffusion, with rockwool behind for room absorption? (I say Rockwool bc I already have some 8pcf Roxul that was given to me as construction leftover. I assume there isn't much acoustic difference between that and 703 for this purpose). Also, I presume I would have to fill the tube with something to lower its resonating frequency, or strap the rockwool to the backside of it to dampen it. ...Speaking of resonating frequency, couldn't a tube function as a panel trap at its res. freq.? I envision something like a pipe organ at the back of the room, tubular bass traps of different lengths and sizes tuned to various frequencies. If it worked, the coolness factor and fact that it was modeled after a musical instrument would be amazing! So, for clarity and summation: 1. Would using rockwool mini-gobo / tube combinations produce a quick sound field effect? 2. Could tubes be used as panel traps (or perhaps more accurately bass hemholtz resonators)?

It depends entirely on the thickness and rigidity of the cardboard tubes. If you want to DIY a tube trap, you should imitate the way ASC makes theirs. In that case you'd cut it in half to get two half-tubes, and stuff each half with absorption. --Ethan

It takes 8 DIY StudioTraps to make one QSF acoustic space QSF is an acoustic space that saturates the Haas reflection time period. It can be generated by a particular arrangement of StudioTraps that create numerous early reflections the treble range and all the while maintaining an RT60 of about 1/10 second. I have tried other ways to get this sound effect and always end up pretty much with the same setup. Correction: It is not derived from a hemispherical reflection pattern; it is generated by an array of hemi-cylindrical specular reflectors. StudioTraps normally list at about $360 each, including stand. The goal being discussed here is how to make a DIY StudioTrap. The next issue should be how to set them up so that they create the QSF effect. If I were to try to make a DIY StudioTrap out of sonotube and rock wool, following Eathan's not unreasonable suggestion and others, I'd start with an 8" sonotube (not 12"), cut short into 4' lengths. Then I’d cut sonotube in half to make two half cylinders. When cut, sonotube expands, tending to flatten out. We don't want a flattened out half cylinder reflector. We want a real half cylinder. Side note: The size of the reflecting half cylinder is important. Too big and too much lower treble is reflected, too small and only the high treble is reflected. The diameter of the cylinder is in effect an acoustic cross over, bass pass / treble reflective. The diameter is also related to how loud the reflection is, the larger the diameter, the flatter the reflection and the louder it is. QSF kicks in at about 500 Hz. Get a piece of fiberglass string reinforced plastic window screen 16" by 60". Hot glue the middle 48" of one long edge onto the outside edge of the 4' cut edge of the sonotube, about 1 1/2" back from the cut edge. Now you have two end flaps and the middle 4' along one edge is glued down at one edge. Wait at least 10 minutes for the hot glue to harden. Now compress the half tube back into its cylinder shape and pull the screen tight over the other edge. You may need an assistant or some sort of jig to hold things in place. It’s like alligator wrestling. Hold the screen in position, hot glue it about 1 1/2" in from the edge on the other side and hold it for at least 10 minutes, till the glue really hardens. A jig, made of plywood 12"x48" and a couple 4' 2x2s nailed with an 8" space between makes a nice clamp for this job. Glue lines would be set about 2" back instead of 1/2" but that's OK. Fill the half cylinder, screen faced cavity with some "703" or rockwool or equivalent very absorptive material. Personally, I would go to an upolstery material distributor, or a matress factory and get expensive foam, very soft and dense. Use this material insted of fiberglass or rock wool and make an itch free product but it costs the same as good fiberglass. Pull the end flaps over and hot glue them down to seal the half cylinder. In studio work, it is very, very important that the talent never gets fiberglass or rock wool fibers stuck in their throat. The slightest fiber can choke the talent and stop a session. We also do not want to see glassfibers floating in the air, landing on CDs, getting sucked into hard drives, tapes, switches or mic capsules. At ASC, we go to great pains to literally seal our products. They just can’t ever leak fibers into the air, no matter how loud the sound gets. By the way, make sure that whatever acoustic material you stuff into your cylinder has a neutral smell. All TubeTraps products are devoiced; they have no resonance characteristics at all. Their length has nothing to do with their frequency of operation, only the diameter. If you do not use serious absorptive material in the back side of the hollowed out half cylinder, the unit will resonate and blow sonic colors into the mic. That’s not good. You can make your tube look better by wrapping the screen around the front of the tube, so it gets ride of the spiral groove. Still, the screen does not fiber seal the unit. The window screen only holds the absorptive material in place. We also don’t want the absorptive material to settle, as this would leave a hollow sounding, hollowed out cylinder shape at the top. When glue is under tension, do not reheat it. It will release and things will fly apart. Get some felt at the craft store and lightly spray glue it down over the entire half-cylinder, both the front and back, top and bottom. It is acoustically transparent enough. You can use different colors, have fun with the covering. The felt will fiber-seal the product you have built. Now it is safe to use in an enclosed room, a studio We have gone over what it takes to imitate the acoustic properties of a StudioTrap. The cut off frequency and roll off slope are not exactly the same, but close enough for DIY. What we haven't talked about is how to hold the StudioTrap up. I'd start with 3 long and 1 short stick and make a 6' tall tripod with a cross bar at 30" off the floor. The QSF is created by a horse shoe pattern of StudioTraps, on 18” centers. The center of the reflecting surface is set about at voice or instrument height. High enough off the floor to backscatter the treble back into the mic and separated apart enough to let the bass vent out of the space. There are lots of ways to hold these half cylinders up off the floor. But we do not want to create a giant domino effect, where with one bump, the whole setup tumbles down. With reflectors rotated away from the talent, flat side in, you will recreate that old familiar Studio-Dead sound. With reflectors rotated toward the talent, flat side out, you get that oh so desirable Studio-Live sound. The better the room the farther apart the StudioTraps can be set. As you raise the mic you can acoustically mix the QSF direct with a little room ambience for sweetning. Bruce works in the Hit Factory and sets his 14 Traps about 3 feet apart and randomized the reflection pattern. He has been recording in QSF for over 12 years. A regular engineer in a regular studio likes 10 Studios and will use a tighter pattern. At home, 8 Studios are used and the Trap pattern tightens down to 4 feet in diameter, with the individual Traps about 18” apart and all reflective. Pete Townshend endorsed the QSF sampling booth something like the one shown in F Alton Everest book back in 87. The QSF booth specifically pictured in his book was used to develop deep space voice recognition algorithms. The QSF is acoustically sorta like taking a direct signal and splitting it into two tracks. One track stays direct. The other track gets processed; the bass is rolled off and the treble gets turned into a random set of low level, time delayed signals stretching out about 30 ms. These two tracks are mixed back together, acoustically, to get the sound of the QSF effect. What is missing with the DIY Studio is good looks, cleanlyness, convenience and most important, durability. Working engineers are always handling their Studios and what this DIY is missing is toughness. By the way, whenever you want to know about TubeTraps, or bass traps in general, just call me or email me. I haven’t forgotten that one of my earliest acoustic projects was a DIY TubeTrap. Come to think of it, I’m the one who invented the TubeTrap. Arthur Noxon Acoustic Engineer www.TubeTrap.com

...an array of hemi-cylindrical specular reflectors

That's what I've been saying! How ya gonna get anywhere if ya ain't got no large batch a half round things whats gonna put it back in yer face!

Thank you Mr. Noxon for the detailed post. Very interesting. I do have Everst book you are referring to and the measurement shows a very flat result. Has your company ever had any concerns about formaldehyde binders in the fiberglass? If so, what was your solution or recommendations for DIY folks. Regards

Hai Arthur, welcome to the forum. Great first post ;)

Great to see you here Art! --Ethan

RE: Formaldehyde Binders 1) We were talking about DIY QSF using sonotube. I recommended to skip the rock wool or fiberglass version of sound absorption to avoid the itchy consequences of working with that material in a non factory environment. I recommended using expensive, soft, heavy foam that you can get at your local mattress factory or upholstery supply house. I did not recommend anything with formaldehyde binders in it, that I know of. But now that you mention it, maybe the sonotube is glued together with formaldehyde adhesive. Maybe the foam rubber is formaldehyde based. Maybe the hot glue has got formaldehyde in it. I think I am going to go crazy worrying about all the formaldehyde based construction materials that surround me, oozing poisonous gasses…. Screw it, I’m just going to take a deep breath, hold it and charge forward into the life and world I was born into. 2) New topic. As to formaldehyde binder in 703 or other fiberglass products. About half of all ductwork of all commercial air conditioning systems is made out of a 703 type material. And the rest of the ductwork is metal, and it has a form of building insulation in it, which is a light density version of 703. The point here is that the snorkel tubes used in most occupied buildings to supply and return air for the occupants is made out of this very same material that your are referring to, a formaldehyde based plastic glue. Since this type of product is certified for use in air breathing ducts it probably is good to go for use in a non air breathing objects, things that just hang or stand around in a room. All church sound panels, most all studio absorption and office noise control panels are made out of this material. We’re already surrounded by it, we can’t escape it. My understanding is that the only time formaldehyde becomes an issue is when the material gets soggy wet and stays soggy wet and the glue decomposes. If you are worried about formaldehyde and other gas vapors poisoning your body, you can get a box of low cost monitoring badges. You wear them and they measure your exposure to formaldehyde and other VOL vapors. See http://www.acsbadge.com/residential.shtml#formaldehyde It explains that formaldehyde is used in many residential applications, such as building materials, chemicals and fabrics. In the home you find formaldehyde based products such as glue used in building materials such as pressed wood products (hardwood plywood wall paneling, particleboard, fiberboard) and furniture made with these pressed wood products. Urea-formaldehyde foam insulation (UFFI). Combustion sources and environmental tobacco smoke. Durable press drapes, other textiles, and glues. As to TubeTraps, which you didn’t actually ask about, we do use real fiberglass fiber. Fiberglass building insulation is compressed to density of about 0.4 pounds per cubic foot. Our material is compressed over 10 times, to about 5 to 6 pound density and it takes some serious glue to hold that springy mass of glass fibers together. 3) We have made non plastic glue acoustics. Years ago the top vocal talent in Japan lived part time in Malibu and wanted a west coast vocal studio. We got the job. We ended up with a studio that sounded great and yet had zero glue, zero plastic, zero formaldehyde and even zero paint. She gave all the protytpe products a sniff test before we made anything. Still, I was scared to death that she would start sneezing or her eyes and nose would begin to run. When the studio was done, she loved it. We called it our “hypoallergenic studio”. You guessed it, it was structurally made out of 100% stainless steel screen and a very rare type of sound absorbing material that is made out of 100% pure condensed glass vapor, not fiber. It is sub micron in size 10 times finer than fiberglass) and 100% fiber free because of how it is made. It is normally used in the manufacturing of molecular filters. This wonderful sound absorbing material is twice as good as normal fiberglass sound absorbing and we supply it. It is called “WallWool” and it is not itchy at all. I believe it is the sound absorbing material of the future, only time will tell. The downside so far is that it is a blanket type felted material, a glass version of the blue jean fiber sound blankets that you can find out there these days. Felted blanket materials, like heavy vinyl, are limp sheet goods, which by their very nature are very difficult to hold in place. The only way a bass trap works is if the sound pressure pushes air in and out of the sound absorbing material. It doesn’t work if the sound pressure actually pushes the sound absorbing material around. The core material for TubeTraps is very strong and doesn’t deflect under sonic pressure. Limp materials have no strength and are easily pushed around by the powerful sonic pressures. It takes lots of extra $upport to hold limp materials still while they are being battered by bass sound pressure. Amazing how a question just a couple words long can generate such a long winded answer. I hope I answered your question about formaldehyde, well enough for round one, and then some. When do we get to talk about the QSF around here? I thought this was the QSF discussion group. Has anybody here even heard a QSF recording space? Ever stuck their head inside a QSF recording space? Anybody ever flipped the reflectors inward to get that Haas saturated sound effect or outward for that traditional studio dead sound? What tricks do you have to pass on about QSF successes? What limits have you run into using the QSF? Thanks for having me. Arthur Noxon www.tubetrap.com

Ouch. 1) Ethan says: “It depends entirely on the thickness and rigidity of the cardboard tubes. If you want to DIY a tube trap, you should imitate the way ASC makes theirs. In that case you'd cut it in half to get two half-tubes, and stuff each half with absorption.” I want to be gentle but truthful. This comment is very, awfully misleading. ASC does not and has not ever cut a sonotube in half and filled the inside with sound absorption material. This is not, definitely not, and nothing like how a StudioTrap is made. It does seem doable and I did address doing it in another post. However, I was just contributing my experience towards building this widget. I never built one, I don’t know how it sounds. I don’t know if it sounds good or bad. And after all is said and done, it’s how it sounds that matters, first and foremost. I want to assure anyone who is interested. For the record: The TubeTrap and the StudioTrap are built exactly the same and are not built anything like how Ethan says. 2) The idea of a sonotube hanging in front of a sound panel does not work. I’ve tried something like that. It does works in the treble but it fails to work in the bass. The real QSF system backscatters the treble and vents the bass. You can’t absorb (vent) bass with 2” sound panel. If you don’t vent the bass you end up with that tubby vocal booth sound. Also there ends up being a chatter stored between the sides of two cylinders that is a smearing effect. It’s just not clean and sparkling. 3) I have an idea. Get 8” sonotube cut 7’ long. Glue foam on the back half, good thick dense and soft upholstery or mattress foam. Pug the ends of the tube up with more foam so the tube doesn’t honk. Figure out how to stand the tube up so it doesn’t fall over. That should work. Use QSF out in the open, not against walls. That’s it. Now I really need to get back to work. Arthur Noxon www.tubetrap.com

arthur noxon wrote:

Side note: The size of the reflecting half cylinder is important. Too big and too much lower treble is reflected, too small and only the high treble is reflected. The diameter of the cylinder is in effect an acoustic cross over, bass pass / treble reflective. The diameter is also related to how loud the reflection is, the larger the diameter, the flatter the reflection and the louder it is. QSF kicks in at about 500 Hz. . Arthur Noxon Acoustic Engineer www.TubeTrap.com

Is the above apply to Poly's/cylindrical diffusers too? Or only to half cylinder tube? The size of a poly is chosen in relation of the size of the room? Reflecting below 500hz with a poly is not good? Why the axes of symmetry of the poly's on different room surfaces should be perpendicular? A room full of poly's of the same size it is a bad things? What size or sizes of poly work best for a medium size room with drums?

arthur noxon wrote:

ASC does not and has not ever cut a sonotube in half and filled the inside with sound absorption material. This is not, definitely not, and nothing like how a StudioTrap is made.

Of course, and my point was only that a totally enclosed cardboard tube is even farther away from how your fine products are built. Thanks for being here to clarify. --Ethan

timogiodeson wrote:

arthur noxon wrote:

Side note: The size of the reflecting half cylinder is important. Too big and too much lower treble is reflected, too small and only the high treble is reflected. The diameter of the cylinder is in effect an acoustic cross over, bass pass / treble reflective. The diameter is also related to how loud the reflection is, the larger the diameter, the flatter the reflection and the louder it is. QSF kicks in at about 500 Hz. . Arthur Noxon Acoustic Engineer www.TubeTrap.com

Is the above apply to Poly's/cylindrical diffusers too? Or only to half cylinder tube? The size of a poly is chosen in relation of the size of the room? Reflecting below 500hz with a poly is not good? Why the axes of symmetry of the poly's on different room surfaces should be perpendicular? A room full of poly's of the same size it is a bad things? What size or sizes of poly work best for a medium size room with drums?

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Question: “Is the above apply to Poly's/cylindrical diffusers too? Or only to half cylinder tube? The size of a poly is chosen in relation of the size of the room? Reflecting below 500hz with a poly is not good? Why the axes of symmetry of the poly's on different room surfaces should be perpendicular? A room full of poly's of the same size it is a bad things? What size or sizes of poly work best for a medium size room with drums?” Lots of questions at one time and each deserves a thoughtful answer. We seem to be drifting, and are no longer continuing to discuss the interesting and useful sonic properties of the QSF. We have moved on to talk about an old timer in the world of diffusion, the original diffuser, the wonderful and trusty studio poly. It is very important for the engineer to understand and to hear the sonic difference between the reflective diffusion from wall and ceiling mounted polys and the reflective diffusion generated inside the QSF. 1) Overall, QSF is used to improve the quality of the direct signal while the classic studio polys are used to improve the quality of the room acoustic. QSF cylinders interact with and develop the attack transient of the sound. Studio polys interact with and develop the ambient tail of the sound. We know that each sonic event can be considered to be comprised of an attack transient, release, sustain and decay. These are stages of sonic life over time. And because these occur in air, as sound, they also occur at the speed of sound, over space. QSF operates in the nearfield acoustic space and time, during the attack transient. Studio polys operate in the farfield acoustic space and time, during the sustain and decay. These two acoustic systems operate in very different time and distance scales. The QSF operates at a distance of a few feet, completely within the HAAS effect, to backfill the direct signal with natural sounding very early reflections, in the 3 to 30 ms time range. The Studio poly operates at a distance of a few 10’s of feet to smooth out echo effects in the room, interacting with the wave front in the 50 to 500 ms or more time range. 2) As to the cut off frequency of 500 Hz, it’s not a rule somebody just made up. It’s a matter of geometry, the geometry of the human head and our listening system. Think of our hearing as if it was a set of crossed pair mics. The mics can hear different sounds coming from different directions as long as the ¼ wavelength is larger than the separation of the mics. The ears on the human head act the same. They are 6” apart and a 500 Hz frequency has a ¼ wavelength of 6”. Which is why the magic crossover number is 500 Hz. Free standing cylinders have a “ring frequency” equal to the speed of sound divided by the circumference. For one the size of a StudioTrap this is about 500 Hz. The back side of the cylinder must be absorptive at 500 Hz in order to kill the cylinder ring frequency so the reflective frequency response is smooth. This is why hanging a simple sonotube cylinder won’t work. Sound is reflectively diffused above this frequency. Below this frequency, sound just goes around the cylinder. With Studio polys, the depth of the poly determines the diffusion cut off frequency. Generally they start to diffuse, or scatter sound, for the frequency whose ¼ wavelength is about the same as the poly depth. Higher frequency, shorter wavelength sounds are also scattered. For a poly to reflectively diffuse 500 Hz and above, its depth needs to be about 6”. 3) A small space over amplifies the sonic strength of bass. Vocals in a closet sound awful, bass heavy no matter how much absorption you put in the room. You can’t absorb bass fast enough. It’s much easier and faster to just vent bass buildup away from the mic. QSF has bass vents between each StudioTrap. 4) Polys are vertical, generally. Crossed pair mics are set horizontal. Why? Same reason. The human head has two ears, spaced apart on either side of the head. The human calls it “ambience” when each ear hears similar but different sounding sounds in different ears. Because of the size of the head, this occurs for 500 hz and above. Because our ears are on either side of our head, ambience only occurs when the sound is traveling side to side, and not when the sound is front to back or up and down. Ambience is the condition of lateral diffusion above 500 Hz. Vertical polys 6” deep scatter sound sideways 500 Hz and above. They create an officially “ambient” reverb tail. And if you want to see the ASC version of this product, find our Bastoni Panel on our web site. It kills vertical diffusion and only scatters horizontal diffusion 500 Hz and above, because it is also a bass trap 250 Hz and below. 5) Polys are usually the same size but making them different sizes is not bad. 6) Drum sets need treble backscattering and bass venting and possibly a delayed reverb tail. Try a 20’ by 10’ room with concrete floor. Put drum kit on a persian carpet near one end of the room with about 12 StudioTraps around it. Mic is overhead. The long empty end of the room kicks up a nice low level reverb backfill. The QSF decouples the drums from the room sonically to deliver that fairly lso feeling. The QSF also backfills the direct signal with a great overlay of early lite reflections to give that fresh, lively and natural sounding QSF effect. If you don’t have a long room, set up sorta in one corner. ***New concept to ponder and listen for: Notice we are always talking about poly and cylindrical reflective diffusion, what I call “specular diffusion”? Specular means a mirrored surface. Specular diffusion is a curved mirror surface, like a 1950’s chrome bumper. Specular reflections sound just like the original sound, except a little less loud. This means the reflected sound has the same time and phase alignments between the fundamental and the upper partials as the original sound. What? Yes, I am talking about time and phase aligned reflections. In the world of sound generating instruments, such as quality loudspeakers, time and phase alignment of upper partials with the fundamental is a critical mark of performance. So it is in our world, the world of sound reflecting instruments. In high performance audio, including recording studios, time and phase aligned loudspeakers are required to make an accurate original sound. In high performance audio, including recording studios, time and phase aligned reflections are required to make an accurate reflected sound. Yes, TubeTraps produce resonant free, time and phase aligned diffusive reflections. Notice that we are not talking about vibrating surfaces that can create diffusion, as off the vibrating surface of acoustic guitar tops or membrane absorbers. Notice that we are not talking about acoustic resonators which also can create sonic diffusion, such as Helmholtz resonators or ¼ wavelength wells such as QRD slot “diffusors”. These moving surface diffusers create time and phase distortion in the upper partials. They remind us of when manufacturers used to glue a wizzer cone onto the surface of the moving woofer diaphragm and call it good sound. It is a very important to distinguish between the fundamentally two types of diffusion out there in today’s sonic world. Rigid surface diffusion maintains time alignment of upper partials. Vibrating or resonant well reflecting surfaces scramble the time and phase alignment of upper partials. The human listener avoids distortion, including the devices that produce distortion in the reflected phase and time alignment of upper partials. We are all very familiar with this principle in loudspeaker design but I wanted to remind you that it applies equally well to the design and playing of sound reflecting instruments. Thank You Arthur Noxon www.tubetrap.com

Thank you very much Mr Noxon, Wow! Thank you, ! Thank you . So ...the drum room : 10'x20', concrete floor, drywall on walls and ceiling, Persian carpet under the drums, and 12 studio traps around the kit just like the sketchup I made below? No other room treatment will be needed? No Poly's or absorption for the walls or ceiling?

Mr. Noxon, How would you personally deal with the back wall of a control room if you were looking for some diffusion/absorption? I have personally become partial to rooms that employ an ESS (early sound scattering) system. Would it be wrong to think of the attack wall as employing ESS? The new room I need to treat is going to need to be 5.1 compatible, while still being a good place to mix stereo. I'm interested in difffusion on both the front and back (right now I have skyline diffusors in back) walls. Would a half round tube trap be a good product for such an application? Thanks in advance

Responding to Timogiodeson's questions and that great sketch of the drum room I was talking about, one that is sonically managed by a QSF system. Very nice sketch. We need to add that 9 feet high rooms start to sound OK This set up was originally seen in Michael Wagener’s WireWorld Studio near Nashville. I checked in with him and he decided to join in and share some of his techniques for getting a hard hitting and yet well controlled drum sound. You can google him and you'll like what you find. He’s a great guy and he's been using the QSF for drums and vocals for at least 10 years by now. He has a 6’ glass window on the long wall along side the drum kit that is to the right and sees into the console and engineer. Drummer faces down the room, back is to the end wall, on which is a wide shallow mic closet faced with wood doors. As for the mic setup, Michael says: “Mics change for each session, depending on the drum kit and the player. Also my drums get setup a bit further from the back wall, which is painted wood in my case, and the closets contain the mics. So out of necessity I have to move the drums a bit away from the closet doors.” The sketch of the drum room is very good. The QSF StudioTraps are only 9” in diameter and they are pictured a little large. QSF is left open around the front side of the setup as shown (how’d you know?) so as Michael says: “there is a straight line to the room mics, one of which is “Fritz” the Neumann head, looking at the drums from about 12 feet away.” Michael also relayed some placing advice: “My method for placing the traps is to have the drummer play and then grab the traps with wide open hands, walk around with them and feel where they vibrate the most. That’s where I put them down.” And I have done this many, many times as well. Be sure to lower the Studios down so they intercept and hold drum sound inside the QSF circle. Studios are raised and lowered to their preferred position. The original Studios had a friction pad that held them in place. Later we added a twist grip lock, like a mic stand has, to ensure the Studios didn’t change position overnight, or even worse, during a session. For stand up vocal work, the traps are raised pretty high. For sit down talent, they are lowered. With drums, we don’t want to see too much sound scooting under the StudioTraps when it should have been captured into a nearfield back scatter mode. Remember to start the StudioTrap setup with the reflector towards the drum kit. You can mix up the reflection pattern and even turn one or two Studios around backwards to absorb the sound instead of reflecting it. The bigger and better the room, the more you mix up the nearfield or QSF reflectivity. In bad rooms or areas you keep the reflectivity tight. Here’s what Michael said about QSF reflector setup: I vary which side faces the drums, depending if I want a more open or a dryer sound for that track. It could be a combination, but if I want it dry, the absorbing side on all 8 traps will face the drums. If the absorbing side is facing the drums, it feels like less of the direct sound is getting into the room. If the absorbing side is facing the room, it feels like the room reflections won’t get back to the direct mics and are more obvious at the room mics. The slot between each pair of StudioTraps acts like a line source as it is venting sound out of the QSF setup into the room. What gets out is a chunk of the direct sound that escapes through the rectangular opening along with a bleed down of the blended nearfield ambience buildup. This gives up maybe 6 rectangular slots of sound in different locations, facing in different directions down towards the long end of the room. Each slot being about 6 to 16" wide by 4' tall. Each is separated by a StudioTrap and each is pointed in a different direction. Each slot releases a tall and narrow wavefront that ends up diffusing laterally, to the side. The sound emitted into the room from inside a QSF setup exits the QSF setup in a prediffused form. As scary as it seems, we don't need to soften the far wall bounce because we don’t have a plane wave hitting it. The wavefront hitting it is already a diffused blend of wavefronts, different directions and different delays. It’s like when a photographer directs the spot towards a light diffuser instead of hitting the subject directly with a flash. Sharp shadows are eliminated. In our case, it’s sound, not light and sharp reflections are eliminated. You should always have a few TubeTraps laying around to dial in the voice of the room, room. Typically they would be placed in some or all of the 4 corners, with their reflector set towards the room to keep room diffusion up. Dial the tone and speed of the room to taste. It would not be unusual to set a couple studios or TubeTrap columns about half way down the room, with reflectors set facing the drum kit. This will help soften the delay time of the onset of splashback off the long end of the room. Rotate the reflectors towards the long end of the room and you turn the volume of the long end down and back fill it with more energy. This quiets down, smooths and stretches out the delayed backfill. You’ll find you are actually sculpting sonic space. And special thanks to Michael Wagener for joining in. We are proud to still be a working part of his musical world. Please take some time and visit his web site @ www.michaelwagener.com and take a peek at what MIX had to say about him last year @ http://mixonline.com/recording/mixing/3 ... l-wagener/ Arthur Noxon www.tubetrap.com.

arthur noxon wrote:

Responding to Timogiodeson's questions and that great sketch of the drum room I was talking about, one that is sonically managed by a QSF system. Very nice sketch. Arthur Noxon www.tubetrap.com.

thanks again Mr Noxon, I'm building... this is just my garage and I can only afford the easy version right now, better than nothing ... I hope one day to have the vastly superior studio traps around my drums. just two questions please, see image: Also here my garage, just in case you have specific suggestion for my space in particular. I have 0 replays in my post so I decided to ask for help around.. http://www.johnlsayers.com/phpBB2/viewt ... 4522#74522 thank you in advances

Great sketch and remember, the foam is all down the length of the tube. Tall narrow tubes like to tip over, so come up with some sort of anti-tipping setup. Otherwise, you will become grumpy cause the tubes keep falling over. We do not want the ring frequency of the exterior of the tube to add coloration to our sonic space. We want to add foam to the back side of the cylinder that is good enough to at least kill external the ring frequency of the sonotube. The tube is 8" in diameter, 2/3rds of a foot. The ring frequency is the speed of sound divided by circumference (Pi x Dia). This is 1128/(pi x 2/3) = 538 Hz. I'd use 1" foam, something heavy, maybe like memory foam from a matress factory or upolstery shop. How can you tell if it is good and absorptive? Practice whistling. make a high whistle tone. That's about 500 Hz, and you can see that using your computer mic and some audio spectrum analyzer program. Then take a book or 3 ring binder, and hold it up about 6" away from your mouth right in front of you, facing you so the sound bounces right back at you. Whistle, alternate between whistling square into a book cover and whistling out into the open. Hear the difference? Now you have just become a DIY portable foam analyzer and it would cost you about $2k to buy such a device. Get your foam sample and hold it up against your book or binder cover. Whistle at it and alternate putting the foam against the flat reflecting surface and taking it away. You can always just whistle into the air to recalibrate your ears. If it sounds like you are whistling into the open air when the foam is in place, you are good to go, if not, keep shopping. Yes, they will look at you like you are crazy. You aren't crazy, you are a DIY sound analyzer. Arthur Noxon www.tubetrap.com

I do not have authority to make this a "sticky" or I would do just that :) It should be, great reading, lots of valuable information in relation to the QSF, all in one place! More I read on it the more I want to try a quick sound field myself. Thanks for the education Mr. Noxon!

Thanks, I enjoy sharing the accumulation of my life's dedication and the many years of work in the field, with willing listeners. Included in my repertory are the many reports that come in from the field, from our wonderful customers. Which leads me to tell a true story........ It was in the early days of our world, when TubeTraps were exclusively distributed by guess who?...MonsterCable. Back in the winter of 1985 the big studios heard about TubeTraps and these guys would buy a whole pallet of TubeTraps so their engineers could figure out what the heck these new sound widgets were good for. And they did, they fooled around and chased down sound with those early Tubes. But then something startling began to happen. Each engineer ended up inside a mini stonehenge of TubeTraps that started out dead and ended up live. Each engineer discovered independantly, without knowing anything about the others, the QSF effect. Think of it, within a few days of dumping a pile of TubeTraps on the floor of a recording studio, the recording engineer discovers the QSF by himself, using nothing but a good pair of ears, a healthy curiosity and their mind. I just was the guy they all called. I took detailed notes, replicated their setups, heard what they heard, made the tests, studied the acoustics and psychoacoustics of it, figured it out and published the papers and kept on pushing to this day to keep their discovery alive. I knew it was real because I didn't do it. It wasn't about me, it was about them. I knew I could trust them because I knew they knew what they were doing. I actually saw it happen one time before my very own eyes. We were hanging a truck load of Tubes all around the upper corners in a big live room and the engineer, a micro manager as they all, was busy pointing and listening and thinking and we were so busy, we didn't notice that he had disappeared. After a while I started looking around and then I saw it. He was inside his QSF setup, in front of the big window. I had never even mentioned this to him. He literally bolted them down to the floor and he said he did over 1000 Bimart commercials in that setup before the place got sold and demolished. I didn't invent the QSF, I just kept the faith alive and that's enough for me............. end And anyone can try risk free a set of QSF, just call ASC. All TubeTraps come with 100% personal satisfaction guarantee, always have, always will. And we almost never get a return, which is why we have the nerve to make such a guarantee. But there is another reason we do this. At ASC, we're a crew mostly made up of audiophiles, recording engineers, musicians and acoustic engineers and we feel very lucky to be working in the daytime in the field of our-after hours passion. We'd be embarassed to even imagine someone out there being unhappy with TubeTraps, because TubeTraps are our handiwork. Arthur Noxon www.tubetrap.com

Thanks, good question. But it’s outside the world of DIY QSF. Still the same products that make the QSF make the Awall. The StudioTrap, for the most part. The attack wall is not a ESS system. It is a hard core LEDE system. But the wrinkle is that is isn’t literally a front back setup. I jokingly call it the LSDS, live surround dead surround. The Awall sits in the middle of a room. All reflectors are pointed out, away from the engineer. If you walk around the circular hallway between the outside of the Awall and the walls of the room, you realize how diffusively hot that portion of the room actually is. Then you sit at the desk inside the Awall and you are in a silent zone. No early reflections and the monitors are set midfield, so there is no console bounce at all. Remember, the pattern continues around to the back. There is an optical alignment that is used to place the side traps and all the back traps. The back wall and back corners to not backslap you. The diffusive fill is actually a glow that filters back in underneath and over the tops of the surrounding StudioTraps on all sides. You get an ambient flush from everywhere. And I can tell you, when you light your monitors off, you almost start reaching for your seat belt, because it must feel like you are blasting off in an X-wing fighter. You can see perfectly everything and hear everything. You don’t need extra diffusers with the Awall because it does everything by itself. You have to study how it works, but once you get it, it’s obvious. Visit the Awall section and read all the papers and flyers. ESS as a place in the audio world. I haven't heard it in a studio setting and there certainly are other ways to avoid early reflections besides flooding the space with early reflections. ESS reminds me of a slow QSF. We do make ESS style home theater and it works very well. But this is not the place for that topic. Let me tell another true story, this time about the Awall..... I was working with Bruce Swedien about 12 or so years ago in LA at Rene’s place, MJ’s song writer. Beautiful family and people near Hollywood. Great cars in the garage too… We delivered a whole truck load of StudioTraps and TubeTraps to do Bruce’s video on microphone technique. He was already hooked on the QSF and had been using it since BAD. I had been bugging Bruce to take a seat in front of an Awall and he kept putting me off. We had just finished doing the acoustics of his home studio, TubeTraps in the corners, panels on the walls, pretty regular setup. He was happy with his custom Westlakes with the foam ring. Hauled them everywhere. We were done with the week long shoot, I even got into the movie, at the end, and we all were eating ribs and white bread in the kitchen. I had my assistant sneak into the live room and set up an Awall. It was right next to the control room where the Westlakes were. We plugged in some early Genelecs and played music. Everyone thought the Westlakes were fired up. I begged Bruce to come on over and take a look. He gave in. As we passed through the control room, (the x-dining room) it was shocking to keep looking at the silent speakers and yet the room was so filled with sound. We walked into the x-family room, the live room and the chair was there. He sat down. He carried then and probably still does, a little bag of DATs with clips from all the work he’s ever done, he uses these to acclimate himself to what ever new room he has to work in. he starts clicking in one DAT after another, going faster, rapid fire changes and then he gets to a clean drum and bass track, from the BAD album. God, it was kicking. And he just left it running. We all know the beat, but I forget the song it went to. All of a sudden, BAMM, it exploded and Bruce jumped out of his chair about 6”. I war right behind him, on a stool, bobsled style, so we both could hear exactly the same thing. I leaned into him and quietly whispered…Need a seatbelt Brucie? Now you know he put that damn explosion right there, timing and all and it still got him. He got up and didn’t acknowledge the jump joke. But he did say he heard mic placements he had long forgot about. He said he’s not doing any more work till he has the Awall and how soon can we get him one. I thought I had better remind him that we just finished remodeling his home studio and he didn’t care one whit about it anymore. And remember, he was paying for his Tubes. And so we did it, and we’ve built two more studios for him and he super loves his Awall. Now when he travels, he Red Rockets his Westlakes, his beloved mic case and lhis 14 StudioTraps which he uses for QSF mic tracks and later, around his Westlakes to get the Awall happening. And he hauls all this to whatever studio he is working in. He hauls his own sound with him. Thanks for the visit Arthur Noxon www.tubetrap.com

great story! i don't suppose you offer a trial package? :wink: timogiodeson - maybe Art means something like this (my guess from the literature and postings)