Old Studio Rehab.

20 years ago I built a small home studio in my attic. About 10 years ago, with kids in college, I sold off a bunch the gear worth money and took a job with an insane amount of travel. Last year I started dusting everything off, bought a new Mac and some gear and have been figuring it out all over again. I live out in the country, no issues with noise abatement. The studio control room is 12.5 x 18 ft with the angled ceilings at both ends. I built the desk up tight the wall but pretty deep. Used a lot of mass, ton of insulation and cases of silicone. Its a quiet and in the right places, a good sounding room. Room currently has about 200 sq ft of fiberglass panels. Still with desk placement, I miscalculated the sweet spot and found myself alway rolling my chair back a bit. I spent the morning searching to see if there was much to be found but came up with little. Though John's old post with the small studio design has a detail that corresponds to one of the ideas I have and subsequently part of the questions I have. The small studio design has soffit mounted speakers which seems kind of unusual for a small space. My main curiosity starts with how well does this work in a small space? What are the monitor choice considerations? How far back works for this sort of near midfield set up? I'm posting a picture of the current desk and a quick sketchup capture image I made this afternoon. I resized both as suggested in one of the posts I read. I'm looking to move the console to the side window for tracking with rack space underneath and use a smaller desk further back but still keeping listening position in that 38% range. Aiming the monitors just slightly behind my head would give me a distance of 90 inches to the front wall strait ahead. Hope this give you enough info. Crossing my fingers I enclosed the images correctly.

it should work nicely since it will reshape the room ratios and provide a space for the LF trapping you need. the back slope ceiling will need some additional treatment, and you could also "soffit" the back wall as well to provide for more LF trapping.

gullfo wrote:

it should work nicely since it will reshape the room ratios and provide a space for the LF trapping you need. the back slope ceiling will need some additional treatment, and you could also "soffit" the back wall as well to provide for more LF trapping.

Thanks for the input. With the angled ceiling, it just seems like I am building a horn lens out of the front of the room. The goal is to redo the rooms sound treatment overall. Back wall is fairly well treated already though this room is a sort of reverse live end, dead end due to the desk being up against the wall. I'm just regretting not putting up 2inch panels instead of 1inch fiberglass sandwiched with 1/2 inch soundstop fiberboard. I had a lot of leftover fiberglass so I bundled 6 together and wrapped them up in burlap and placed them each of the back corners. It is time to do something a bit more elegant. When the futon was in the back of the room and the sub was in the right place, the bass curve wasn't too far off. With ever wider computer monitors, it has really wrecked havoc with the placement of everything. Sub is currently in the wrong place but I got tired of hitting my knee against it. Moving the desk will solve some some issues and likely create new ones but hoping it ends up better overall. Plan is to continue to use my ancient little KRK's up close and begin to shop for larger monitors. This is why I asked about what considerations need to be made when choosing monitors for soffit mount ie front ports vs rear?. 9ft triangle is about what I am looking at. Option B would be to place the bigger monitors on stands and just build big wedge absorption traps for both front and back.

As to bass in the room, here is a graph from 40-1khz of the average of 6 measurements within box area of old and new mix position. My little 4" KRK don't do low end so I grabbed an old pair of KRK ST6's from my video editing setup. These were placed about where I'd mount them with or without soffit. Keep in mind these are hyped at the bottom end. As I indicated, I've not moved the sub back to a better position so I'll work on that once I have the new desk moved up so this is without sub. Then I can see how monitor placement affects the response to see if I can't tweak placement a bit in this new configuration.

Took a little time to work on this. After a lot of searching, reading and thinking (took a good bit of drubbing to), soffits are not making sense. It seemed like an interesting idea but probably one I'd rather not risk the time. money and possibility of getting it wrong. I've torn out the old desk and built a new desk with a new rack to hold the console. The new furniture gives me more flexibility as to movement and monitor position either forward or back depending on where I end up with treatment. If you look at the sketchup above you'll see the soffit detail. Remove that angle and replace it with a 4ft W x 4ft H x 2ft deep absorber filled with low density fiberglass. I can't go completely across because I have two quad outlets but can treat the area above the outlet, probably go a bit less deep and put my amp rack there. Rear of room with get the same except completely across the entire back. I'm losing guitar case storage. Think I'll survive. As you can see in the picture, I'll need to build a window plug and I also have another window to my left. I previously built a wood extension for the outside window case and have a plug made with 2 inch 6lb rigid with a compress fiberboard backer that snugly fits. I'll probably extend this once I figure out how far out to come with the side treatment. Probably 6 inch Safe n Sound framed around the entire front to just behind the window which would leave a box cut out for the two plugs. Still working out the physical design of the cloud but the flat part of the ceiling only covers 12.5ft x 8ft and then I have those two angled ceilings. From the listening position the front is 4ft away and back 8ft. Don't want the room entirely dead. Got a ways to go to figure out calculating slats and how they would affect the absorbers. (working on it). The angled ceiling and the floor are all that remain to be decided on. Carpet, stay or goes? What to do with the two angled surface areas?

you can think of the ceiling peak as a corner - span that with as deep as you can spare with a "corner trap" as the first part of adding a cloud system to the ceiling.

gullfo wrote:

you can think of the ceiling peak as a corner - span that with as deep as you can spare with a "corner trap" as the first part of adding a cloud system to the ceiling.

Thanks, I was already thinking of extending up from the 4x4ft floor traps in front and back with a wedge of sorts which would also raise absorption up to 66 inches. That would take care of the lower transition. wall "corner" and the wall would look a bit taller that way. I hadn't thought of the tops of the ceiling. I'll have to figure out some sort of framing detail and attachment or could just angle the front and rear cloud so it extends out. Based on early measurements and the room calculators (they track to an extent) I am starting to see trends in peaks at various speaker and mic placement. The consistent 90hz spike related to 12.5ft width is below Schroeder and still working on educating myself on how best to treat a pressure region below Schroeder. Thinking at this point of building the front and rear traps first even if temporarily framed and measuring bass response before moving on to the side treatment. The way it measures now, I am not certain 6 inches along the sides will be enough but don't have enough knowledge and experience to predict.

the advantage of the ceiling is that sound is 3D and you preserve floor space. for treating pressure you need to build pressure based traps, not porous (flow) absorbers.

There are Absorption Data for 6" of various fibres at bobgolds.com Given figures like 1.3 in the 125 or 100Hz octave it seems your 90Hz should be amenable to simple fibre treatment. Area is a a factor though.

DanDan wrote:

There are Absorption Data for 6" of various fibres at bobgolds.com Given figures like 1.3 in the 125 or 100Hz octave it seems your 90Hz should be amenable to simple fibre treatment. Area is a a factor though.

I had initially looked through the Bob Gold site but there are but few 6 inch references and there is also the issue of trying to match what can be obtained relatively easily. I instead started looking at GFR data and plugging that into the porous absorber calculator which I've have been advised isn't always accurate of real world results. The two products I compared that I can just pickup locally is OC EchoTouch R19 with a GFR #2900 and Rockwool Safe n Sound #10000. At least in the calculator, it seems to come up short. Should I instead simply rely on the NRC specs when I can get those? I do get that the calculators are normal incidence (slowly starting to understand some of this). At least at a basic level. I also have another question if I could be permitted two. My current plan is instead of deep wedge corner traps, build instead 4ft x 4ft x2ft box traps for each of the 4 corners as I can only extend up 4 ft before the ceiling transitions. Side wall treatment will go all the way forward into those angled corners. My goal is to get enough treatment to offset moving my desk and monitors out from the front walls. Larger bass traps means I cannot move the monitors back against the wall. Just want to know if I am on the right track with my thinking. Will enough absorption against both back and front offset the rear monitor reflections? I'm talking 2ft of pink fluffy at both ends.

gullfo wrote:

the advantage of the ceiling is that sound is 3D and you preserve floor space. for treating pressure you need to build pressure based traps, not porous (flow) absorbers.

And somehow I completely missed this post. I've been reading a lot on both limp membrane and panel calculations including isothermal variants. I've entered the formula into a spreadsheet with each (coefficient?) so I can enter mass per sqft and depth for each type. Slowly identifying the material available and plugging those numbers in. Question becomes don't side wall modes need treatment mounted on those side walls? Then how to balance the need for broadband absorption and more targeted absorption in the limited side areas especially between mix position? Then how much do I need to be effective? Minimum size I can build them in blocks? (for lack of a better term). Like if I wanted broadband at ear level, can these go below and above in 2ft x 4ft units mounted laterally. For clarity, isothermal membrane nearer the floor sideways with a broadband flow absorber above at ear level and another membrane trap above.

Should I instead simply rely on the NRC specs when I can get those? I do get that the calculators are normal incidence (slowly starting to understand some of this). At least at a basic level.

Try Random incidence or even better, 65 degrees, it's more encouraging and gets somewhere closer to the Lab tests. I am not sure if I follow your second question, but I will take a chance. Big deep corner absorbers are always welcome. Absorption between Speaker and Front Wall quite often causes a bigger problem than it attempts to solve.

DanDan wrote:

Should I instead simply rely on the NRC specs when I can get those? I do get that the calculators are normal incidence (slowly starting to understand some of this). At least at a basic level.

Try Random incidence or even better, 65 degrees, it's more encouraging and gets somewhere closer to the Lab tests. I am not sure if I follow your second question, but I will take a chance. Big deep corner absorbers are always welcome. Absorption between Speaker and Front Wall quite often causes a bigger problem than it attempts to solve.

Perhaps more simply. Triangle shaped wedge in the corner vs big large square box absorber. Wedge, I could at least get a mid-nearfield speaker close to the wall. Big box absorber, I am out at the desk with both monitor pairs. It's one approach vs the other. I guess alternately, wedges up front and big boxes in back. At the new desk position, bass response is not great. I lack the experience and intuition to know if the bigger bass absorbers will do enough to improve response. I have an old pair of 4 inch KRK that I've used forever up close. Low end is not a thing with these but with the desk away from the wall, well just not the same. Further back and I'm at mid point, further front, I might as well have stayed against the wall.

it's a reasonable approach - front corners using wedges, large boxes in the back, big boxes on the main axial points, and smaller rectangular units on side walls for reflection control, and some big units overhead for clouds.

gullfo wrote:

it's a reasonable approach - front corners using wedges, large boxes in the back, big boxes on the main axial points, and smaller rectangular units on side walls for reflection control, and some big units overhead for clouds.

I've been spending time learning some of the "how to's" with treatment design so that I'd have at least a couple tools under my belt in re-orienting this room. I've also been a bit stuck in analysis paralysis. I read one of your posts that convinced me to just get it moving and try to do this a bit more progressively. You had said that you have never seen a room not improved by adding bass traps. So I'll be heading out in the next couple days to pick up some R38 fiberglass and am going to just mock up the 4 corners and then measure while I adjust placement of the desk and monitors. Something is telling me I'll need to move the desk orientation forward but I feel I'll benefit from getting something in the corners first, then adjust.

It is very hard to shake the inclination to move the speakers further into the room. But at typical distances this will create big SBIR nulls right in the musically vital region of 40-100Hz. Try the speakers kissing the Front Wall. Try them nestled into your corner traps. Keep and open mind and be guided by Test Trumps Theory.

DanDan wrote:

It is very hard to shake the inclination to move the speakers further into the room. But at typical distances this will create big SBIR nulls right in the musically vital region of 40-100Hz. Try the speakers kissing the Front Wall. Try them nestled into your corner traps. Keep and open mind and be guided by Test Trumps Theory.

This thread started out with the idea of soffit mounting after reviewing one of the small room designs. It would probably be the route I would take except for one issue. Right now I am using old passive monitors with some Hafler amps. I am hoping to treat myself to new monitors at some point. So my thinking was to sort out the room first. Soffits would require knowing what I am going to end up with. So big traps in the back, wedges up front and use what I have to work out tuning the room. I had also read a suggestion that you could mount monitors into bass traps if they are sufficiently deep. Modify the layout I did above by building out the flat surface further into the room so that there is enough depth. I figure it wouldn't be too much work to incorporate into what would be a big front trap. I've got a lot of 6lb rigid I could use face the opening instead of plywood as one would for a soffit (only above and around the monitors) and also to create an enclosure inside the trap for the monitor (Hope that is clear enough description). If I improve things enough, perhaps this won't be necessary. So treatment first and then cross those bridges when we get to them.

one consideration - is building your soffit to handle future speakers and build an (smaller...) frame inset to hold the current ones. so maybe you're using 8" and know that in the future you'll want 12" in the baffle, you could "speculate" on the options of 12" speakers and size the main framing to support that, and then build a smaller frame/box to house the current speakers. who knows? you might just keep the existing ones... i've had to do this on any number of projects, and sometimes to incorporate a second pair mounted in the same baffle system. a pair of 8's and a pair of 12' with their acoustic centers as close as possible so switching between them is fairly even, or sometimes it's because they're used to hype the mix to clients...

gullfo wrote:

one consideration - is building your soffit to handle future speakers and build an (smaller...) frame inset to hold the current ones. so maybe you're using 8" and know that in the future you'll want 12" in the baffle, you could "speculate" on the options of 12" speakers and size the main framing to support that, and then build a smaller frame/box to house the current speakers. who knows? you might just keep the existing ones... i've had to do this on any number of projects, and sometimes to incorporate a second pair mounted in the same baffle system. a pair of 8's and a pair of 12' with their acoustic centers as close as possible so switching between them is fairly even, or sometimes it's because they're used to hype the mix to clients...

Thanks Glenn, You'll get a good laugh at what I've been using as a sort of midfield and it might help you understand why what is next is so up in the air. I've a couple smaller old KRK models. The smallest one, I actually like quite a bit. The other is a cheaper pair that have always been tubby in the bottom end. One day I hooked up a old pair of Bang & Olufsen (in the picture above) as I had just finished working out a cabinet buzz and wanted to test them. They are voiced very similarly to the KRK's I like, except tighter, better defined bass and being a 3 way, slightly better at mid. I paired these up with a Tannoy 15 inch sub I got for nothing and it has been what I use to check my mixes since I got rid of pretty much anything worth money years ago. So the newest thing I listen to is at least 20 years old. Shopping and comparing right now is a bit of a challenge and everyone is telling me a lot has changed. I have no idea what I want so will fix the room best I can with what I have, then move forward. A bit longish story, sorry. I don't mind if I have to reconstruct the front of the room later. Given the shape of it and all the testing I've been doing, I really just ended back where I started with monitor placement. I'm only moving mix position back a bit and reducing all that desk surface. Oh, and adding 32 cubic ft of bass trapping. I did an experiment last night where I unwrapped the 6lb density bundles I had in back of 1 inch and straddled 3 in each front corner. Even those tubby KRK sounded much better. I went out today and picked up insulation and some framing materials and will mock it all up and test again. At least for now, I feel like I am moving in the right direction.

A lot of reading later and I finally got around to the applied physics part (construction) of this project. Back wall is simply picture framed in at a 2ft depth and loaded with batts of R38. I've covered it with light poly batting and will cover with fabric once I make some color choices. Front wall are 2ftx2ft freestanding in the corners. These can be moved into the other room later if I decide to build the soffit. Will engage someone then to do the design. Ceiling cloud I kept super simple. 8ftx8ft drop tile grid with light fiberglass acoustic tiles and R30 above. Grid is in place but will install last as it is still a bit of a work area and don't want to damage the delicate tiles. I didn't go full width of the room with the grid as it would be in the way of the window plug. Still figuring out some of the challenges for the wall treatment. I have a baseboard heater to contend with along with an outside window, studio window and a door. May need pressure traps so also want to leave some space if so. I'll probably have some questions when I get there but still reading and studying this topic.

nice workmanship. just wondering if you testing it yet. i think i would have simple spanned the entire wall - like the opposing wall.

gullfo wrote:

nice workmanship. just wondering if you testing it yet. i think i would have simple spanned the entire wall - like the opposing wall.

First, thank you. Pretty simple carpentry. Next a question. I kept reading you don't want to put monitors up against treatment and want them up against the boundary wall. Was why I started my first post here about soffits. I'm clearly missing something in your suggestion. Does a full span bass trap become the new boundary?

it doesn't become a new boundary unless you add a hard surface to it, and not all speakers work well against the wall without some baffle step compensation (reduce the bass level to compensate for boundary effects). and you should have absorption there to counter reflections off your desk/console etc. so one option - build your front wall same as opposing wall, except - place 3ft wide 3/4" thick panels behind your speakers placement. this drives a boundary effect but leaves the bulks of the wall for absorption. you could leave the corner units and simply add the additional (say 8-12") absorption between them. you could make these as standalone absorbers as well and if you find the SBIR really cannot be solved without pressing them against the wall, you can move them out to use as other absorption including gobos (nice in front of an amp or drum kit).

gullfo wrote:

it doesn't become a new boundary unless you add a hard surface to it, and not all speakers work well against the wall without some baffle step compensation (reduce the bass level to compensate for boundary effects). and you should have absorption there to counter reflections off your desk/console etc. so one option - build your front wall same as opposing wall, except - place 3ft wide 3/4" thick panels behind your speakers placement. this drives a boundary effect but leaves the bulks of the wall for absorption. you could leave the corner units and simply add the additional (say 8-12") absorption between them. you could make these as standalone absorbers as well and if you find the SBIR really cannot be solved without pressing them against the wall, you can move them out to use as other absorption including gobos (nice in front of an amp or drum kit).

Thanks, This all came about as a question about treating the adjacent room for recording. When the studio was built, I was mixing live recordings from when I operated my sound company. Somehow I ended up tearing apart the control room first. I need to purchase a new pair of monitors but it will be a while before I can really audition them anywhere. When I get the chance, I am hoping to hear the Neumann 3 ways. It's a bit out of my budget right now but I'm hoping my main business which is commercial AV picks up in a couple months. It is also why soffits don't make sense till I pick something. So I can certainly build more boxes to fill the front but there will still be questions unanswered but I don't need the answers today. That is the advantage of building the front modular. What make the idea so intriguing is that it would push me further into the room which is what I wanted in the first place. So build something now and then later after I have a pair of monitors I like, perhaps build soffits if I feel the need. Note: I did run a test of both channels today with the room empty. I needed to quickly dig out a 20 year old ProTools projects for someone which will halt progress for a day or so. I also have some tests I did before I tore it all out. I just need to gather them all together. Some were done on my Mac Mini the rest on my laptop. Interesting enough, the other room has ceilings just like the control room. So I need to build a lot of treatment as the other room is double the size. So nothing I build would go to waste. It just made sense to me to treat the control room first before doing much else. Also, it has been 20+ years and it needed paint.

gullfo wrote:

it doesn't become a new boundary unless you add a hard surface to it, and not all speakers work well against the wall without some baffle step compensation (reduce the bass level to compensate for boundary effects). and you should have absorption there to counter reflections off your desk/console etc. so one option - build your front wall same as opposing wall, except - place 3ft wide 3/4" thick panels behind your speakers placement. this drives a boundary effect but leaves the bulks of the wall for absorption. you could leave the corner units and simply add the additional (say 8-12") absorption between them. you could make these as standalone absorbers as well and if you find the SBIR really cannot be solved without pressing them against the wall, you can move them out to use as other absorption including gobos (nice in front of an amp or drum kit).

Ok, I re-read this a couple times. I had to set up a quick edit for someone so I decided to just mock this up after I was done. I also got a chance to download your drawing and have a better look. From the screen shot, it looked somewhat flat. So 2ft out isn't quite the right spot. Thinking of building some 16inch deep absorbers. I currently have some R38 and a ton of 703 panels so will mock this up tonight when I have a chance. The middle between the quad outlets I may leave open below with enough space behind the absorbers to vent. I have the powered sub and a small rack that I could place there which would solve another problem of where to put a couple things. The sub only gets used for casual listening and occasionally when mixing so not a critical part of the system. Above the sub and rack would match along the surface of the 16 inch traps. I do have a question. I see you have the slats in a various width pattern. If the absorbers are built as just an open frame, does this serve any particular purpose?