Salem Oregon conference center studio

Here is a birseye view of the floor plan "painted" on the floor and the framing, so far, of the control room. (Couldn't get the sketchup file to load. Got an error message.) Never mind the console surface. I'm just playin' around with the shape! :wink: -Ron

I moved the speakers out another 6.5”, still focused on the same point. Now they’re 33.3 degrees.

Looks fine to me, except that the axes of the speakers do not seem to be perpendicular to the front faces? Probably your axis lines are attached to each other at the old intersection point, so when you move the speakers, the point didn't move: it stayed where it was, and the lines just angled a bit more, away from 90°. That's one of the quirks of SketchUp... You need to make the axis lines into "components" so that doesn't happen.

I’m sure liking the side walls better now that they’ve been flared outward. It gets the doors out of the way of the RFZ and allows more elbow room in the ctl room.

:thu:

I am installing two ductless heat pumps units: One in the control room (South wall) and the other in the large sound room (West wall). That addresses the “H” and the “AC” part of HVAC. A separate ventilation system is going in above the control room and will house the silencers and feed out and back from the two rooms (separately, of course).

:thu:

The vocal booths will have to open the door when it gets stuffy -

Why would air move in or out when you open the door? That's like saying "The jam will rise out of the jar when I take the lid off". No it wont. Not unless you tilt the jar to give it a reason to move. Ditto with your booth: the air won't come out unless you give it a reason to come out: There has to be a second path that air can follow as well as a pressure differential between the two paths, in order for that to happen. In a typical house, that isn't an issue at all, since there are multiple tiny "leaks" into and out of all rooms. But in a studio, all rooms are sealed absolutely air-tight: they are hermetic, twice over. No reason at all for air to move if the only path is an open door. You seriously need to re-think your ventilation plan here!

admittedly just drew out a section (teal blue color) that I expect to build the frame for the soffets on what I learn from the forum.

Soffit framing is rather complicated: multiple strange angles, and serious bracing, plus shelves, support points, ventilation paths, ....

The room treatments are, admittedly, pretty much arbitrary. The Bass traps are lime green

The entire bottom section of each soffit, below the speaker shelf, is bass trapping. And I often leave an open section above the top of the soffit, where I add even more bass trapping. To me, it looks like you don't have enough bass trapping in that room.

I just ignorantly picked 6” for depth and added 18” either side of the RFZ point. I figured I would learn the details a bit later (I know what you’re going to say about that!).

:ahh:

“There comes a time in every project when you have to shoot the engineer and ship it”. Good point.

Possibly, ... but only if there's enough engineering in place already that the product will actually power up, and do what it is supposed to do! Or at least make a vague attempt to pretend that it works... :)

I “bravely” tried enclosing the latest sketchup file but it is too big and I get an error.

It's probably too big to upload: there's a limit on file size. Try purging the file (SketchUP allows a lot of unused geometry to accumulate in the file: you need to purge that manually, every now and then). OR upload the file to a file-sharing service, and post the link here. - Stuart -

Thanks Stuart, as always, for all your comments. I've been away a bit and just noticed your reply.

Looks fine to me, except that the axes of the speakers do not seem to be perpendicular to the front faces?

That's because I took off the axes lines. Those lines show the RFZ reflections on the walls, not the axes of the speaker. I took that off because it was making the drawing so busy. Sorry for the confusion. The blue dot is the spot that marks the apex. Cheers, Ron

You seriously need to re-think your ventilation plan here!

OK, you convinced me. We added another branch to the ventilation to the Vocal1 booth plan (the one to the left of the control room). The one to the right is actually an entryway but CAN be used as a vocal booth in a pinch. Since it will not likely be used much at all, and the fact that it opens to the outside as well as the control room, we are not adding more ventilation to that room. Thanks for looking out for me! -Ron

I finally was able to make the time to give an update on the studio progress. Sorry that I disappeared for about 22 months, but you wouldn’t believe the schedule I’ve had to keep in order to keep the studio work going as well as the rest of life. The help I’ve received on this forum has been instrumental and several times I was guided away from certain disaster in the design. Thank you so much for that! …. especially to Soundman2020 Here is a summary of the last two years (pictures and more details follow): When I last posted, the outer walls were nearly complete with two sealed layers of drywall mounted to the inner side of the plywood exterior sheeting between the studs. Since then we’ve pulled in bigger power to handle the power budget for HVAC, lighting, and electronics and moved the breaker panel. We insulated the outer walls with Rockwool and framed the inner walls for four separate independent rooms. We installed two ductless heat pumps and a fresh air system with baffled vents. We finished the AC wiring and put in signal conduits, then insulated the inner walls. Next came interior drywall – (ceiling, walls, acoustic seal, ceiling, walls , acoustic seal again). Texturing and painting came next. Next came the installation of four sets of opposing solid core doors and two windows. We are currently finishing up with rubber door seals & adjustments and have begun installing flooring. Flooring has to wait in the control room until the front soffit area and back bass traps are built (I will be having some detail questions on that soon - sometime after this update and after I search the forum first!). Photo 1: Insulating outer wall in progress: Photo 2: Framing drawing of the four inner rooms. The control room ceiling is limited to 8’ to allow fresh air system to be installed overhead: Photo 3: Moving the breaker panel to inner wall. We put up a patch of two layers of drywall (offset) so we could seal around the in/out conduits – both on the inner side and outer side: Photo 4: Part of the fresh air system with interior baffles (hard to photograph): Photo 5: Recent photo of exterior heat pumps and new paint: Photo 6: Fresh air input and outgoing fan. (Door and trim awaiting paint): Photo 7: Interior units are also mounted on 2-layer offset drywall to allow to seal seal on both sides of drywall with OSI SC175 acoustic seal: Photo 8: Showing detail of inner power wiring method and signal conduit on a back wall. We came up with this method for the AC wiring using Romex and a short piece of conduit to extend through the two layers of drywall. Each layer gets sealed as well as the inside of the conduit. I haven’t seen this anywhere else. I show more detail below: Photo 9: Second layer of drywall nearly done. Each layer is sealed with acoustic seal in corners and anywhere a common joint is on both layers: (continued to next post)

Continued from last post. (I was worried about size limits with so many photos). Photo 10: After mudding, taping, texturing and paint: Photo 11: One example of electrical wiring as it enters the room through short conduit. Sealed on each layer of drywall and inside conduit: Photo 12: Detail of surface-mount plate mounted to the conduit and into stud: Photo 13: Finished surface-mount receptacle: Photo 14: Preparing split window frame for glass: Photo 15: Put a layer of Rockwool in the crevice then covered it with a layer of compressed fiberglass wrapped in black felt. Doors are in process of being mounted too: Photo 16: Glass installed on both windows. One side is 3/8” and the other side is 5/8”. Same thing on each door pair: Photo 17: Flooring is now in progress for three of four rooms. The control room must wait until the soffit speaker area is built first. The quality of this flooring is very good according to the experts I’ve got contact with. One thing of concern is that the short ends on this particular brand CANNOT be taken apart without breaking! This can be bad if there is a problem and you have to undo the floor up to the error point. That whole section will be trashed. I learned there are better brands that don’t do that. This is “lifeproofRigid Core Luxury Vinyl flooring” from Home Depot. That being said, we haven’t had that issue yet: I seem to have lost my pictures of the door seals. I’m using GM type “K” automotive trunk rubber seal. We are in the tedious process of adjusting the door stops in the fine line between “leaky” and “so tight you can’t shut the door”. That’s about everything I can think of. I hope this is helpful and/or inspires! I welcome comments!

It's looking pretty good! How is it sounding? - Stuart -

It's looking pretty good! How is it sounding?

Sounds like an echo chamber! Ha ha! I was really jazzed when the glass went in and we shut the doors (as they are at this point) and shouted as loud as possible. Pretty amazing! When I was in the vocal room and my friend was 4' away in the large recording room (facing 90 degrees away), I was trying to get his attention. The door was shut and I was yelling at him and couldn't get his attention. Had to pound on the glass. :yahoo: Another great relief is that it is really hard to hear the ventilation fan when it is full on. It is actually a bit louder when in slow speed. I was really concerned whether the fan noise would be a problem, but I could not think of a way to really test the quietness until the walls and doors and windows were in. I am very satisfied and relieved, to say the least! Next is the front soffit area. I will be digging into details on the forum and will start some drawings. Prepare for a few questions soon! Thanks again, Stuart, for all your help and patience with me!

I was planning on using my Roland DS-90 speakers since they are front ported. The bass roll-off only goes down -3dB. Do you think this is a lost cause right from the start?

I was planning on using my Roland DS-90 speakers since they are front ported.

Porting is not an issue. It is entirely possible to soffit-mount rear-ported speakers. So don't limit your speaker choices to front-ported only.

The bass roll-off only goes down -3dB.

That's probably fine. And if it isn't enough, then there are ways of dealing with that. An external cross-over, for example. Or my famous-but-secret "digital tuning" method.... :)

Do you think this is a lost cause right from the start?

Not at all! Pretty much ANY speaker (with few exceptions) will benefit greatly from being soffit-mounted, as long as it is done right. IF the Rolands are all that you have, then they can work fine in there. But if you have some extra cash to spend, you could move up to something more befitting of that beautiful room... Top class speakers to match the top class workmanship... - Stuart -

Okay, that's a relief! I'm really liking the Barefoot approach, which will allow for easier speaker upgrade down the road. I've been struggling to get some good "homework" time, researching the forum on soffit details. I've got to get some drawings started to get the ball rolling. I'm supposed to be sleeping now, but my eyes are "glowing in the dark"! :shock: :D Thanks! -Ron

I've been struggling to get some good "homework" time, researching the forum on soffit details. I've got to get some drawings started to get the ball rolling.

:thu: Take your time with the design: soffit design is not something you should rush. Actually, STUDIO design is not something you should rush! :) But soffits especially. If you need to have your speaker easily replaceable, think about putting it in some type of "tray" that can be bolted in firmly, but also easily removed if needed, to switch speakers. Make the "tray" much larger than the speaker, so you can upgrade to any other size in the future. That's what I did for Studio Three originally with their Genelec's, and it paid off when they wanted to upgrade to the Eve SC-407's a couple of years later. viewtopic.php?f=10&t=5842&p=40923#p40923 - Stuart -

I'm really liking the Barefoot approach, which will allow for easier speaker upgrade down the road. I've been struggling to get some good "homework" time, researching the forum on soffit details. I've got to get some drawings started to get the ball rolling.

I'm in the middle of designing my soffits as well. I'm trying to isolate the speaker from an enclosure with Sorbothane, then isolate that box from the wall as well. In order to get the isolation frequency low, like floating a floor, you need extreme weight. I'm trying to emulate weight by strapping down the enclosure.

If you need to have your speaker easily replaceable, think about putting it in some type of "tray" that can be bolted in firmly, but also easily removed if needed, to switch speakers.

I was having a hard time picturing in my head how to make a module that I could replace for speaker changes. I suppose some T-Nuts under a divider would allow for easy replacement of modules.

If you need to have your speaker easily replaceable, think about putting it in some type of "tray" that can be bolted in firmly, but also easily removed if needed, to switch speakers. Make the "tray" much larger than the speaker, so you can upgrade to any other size in the future. That's what I did for Studio Three originally with their Genelec's, and it paid off when they wanted to upgrade to the Eve SC-407's a couple of years later.

Thanks for your encouragements, Stuart. I hope to spin up Sketchup today. I had a drawing already started a while ago.

Gregwor, Thanks for chiming in. I'll be watching your progress too! :-) -Ron

I'm in the middle of designing my soffits as well. I'm trying to isolate the speaker from an enclosure with Sorbothane, then isolate that box from the wall as well. In order to get the isolation frequency low, like floating a floor, you need extreme weight. I'm trying to emulate weight by strapping down the enclosure

Yes, you sure can use mechanical "things" to strap down your speakers, and apply more pressure to the Sorbothane, thus improving the deflection, and the isolation. Barefoot did that with canvas straps, but there are other ways... - Stuart -

Here is the first-step drawings of my soffit area – borrowing (stealing) from Barefoot’s method. After reading some of the other posts…

Yes, you sure can use mechanical "things" to strap down your speakers, and apply more pressure to the Sorbothane, thus improving the deflection, and the isolation. Barefoot did that with canvas straps, but there are other ways...

… I came up with this idea of clamping down the speaker with sorbothane sandwiched between a plywood top and the plywood shelf underneath using threaded rod and nuts. My thinking is that canvas or nylon straps could loosen in time. I could be way off with this idea, but what do you think? I was looking at the sorbothane “hemispheres” and temporarily drew them in (can’t draw hemispheres, so I drew them as disks). I’m not understanding their instructions for selecting the correct product and amounts just yet. My Roland DS-90 speakers weigh 15 kg. (33 lbs. 2 oz.). At this point I would like to know if I’m heading in totally the wrong direction. Here is the rear frame assembly with the speaker: Here is the front frame assembly added (not touching the back assembly): Here is a closer detail of the speaker / sorbothane “sandwich”: … and once more without the speaker: I’m already getting the drift that there is not enough sorbothane here. What think ye? Also, another question: Looking ahead at making bass trap hangars, what is the difference between Homosote and the cheaper 4’ x 8’ “Acoustic Soundboard” that Home Depot sells? Is the cheap stuff worthless for bass traps? I used the cheap stuff years ago and it had a heavy "cardboardy" odor to it - not good if it’s not buried under another layer of something! -Ron

… I came up with this idea of clamping down the speaker with sorbothane sandwiched between a plywood top and the plywood shelf underneath using threaded rod and nuts. My thinking is that canvas or nylon straps could loosen in time. I could be way off with this idea, but what do you think?

That should work quite well, actually. And definitely better than canvas straps. Finer control on the pressure, too.

I’m already getting the drift that there is not enough sorbothane here. What think ye?

You'd have to do the calculations, but yeah, I agree. Not enough, and not thick enough. Don't forget to take into account that the pads on the bottom have the weight of the speaker PLUS the pressure applied by the rods, while the ones on the top ONLY have the pressure applied by the rods... :)

what is the difference between Homosote and the cheaper 4’ x 8’ “Acoustic Soundboard” that Home Depot sells?

Not sure about that stuff: what¿s the density? Is it similar to Homasote?

and it had a heavy "cardboardy" odor to it

Better check the data sheet for that, and see what chemicals go into it. It sounds like it was off-gassing something unpleasant... - Stuart -

You'd have to do the calculations, but yeah, I agree. Not enough, and not thick enough. Don't forget to take into account that the pads on the bottom have the weight of the speaker PLUS the pressure applied by the rods, while the ones on the top ONLY have the pressure applied by the rods...

Yeah, that’s the part that I’m not sure how to figure into the equation. Here’s my current thinking: I’m looking at a hemisphere that has a weight range of 5 – 10 lbs each. It is 1.25” in diameter and 0.625” tall. They say to expect 20 to 30% deflection when statically loaded. The speaker is 33.125 lbs. If the speaker only had absorbers underneath, five or six hemispheres should suffice bearing 6.625 lbs or 5.52 lbs respectively. When you add more on the top, I’m not sure if that will throw everything out the window, as far as correct calculations. As we all know, under-loading as well as overloading will cause poor isolation. They say “Remember: A bad design can actually make things worse for vibration damping. Consult the factory if you are having problems.” I think I will do just that. I will send them the proposed design and see what they recommend. I’ll post the results. -Ron

It is 1.25” in diameter and 0.625” tall.

The thicker the Sorbothane, the lower the frequency.

They say to expect 20 to 30% deflection when statically loaded.

Using some rectangular chunks and some trial and error, you can torque down your lid with the ready rod to achieve the deflection required on both top and bottom. You might want to consider adding an oversized baffle on the front of your soffit so you can remove your speaker or change it out with ease. Some turnbuckles might be easier to adjust than nuts on the top and bottom. You could also further lower your frequency by mounting your entire assembly onto more Sorbothane pads and torque it down super hard onto your wall supports. What I'm suggesting is the speaker on pads, then your speaker mount on more pads. So two layers of pads. Greg

Thanks for the input Greg! :D

You might want to consider adding an oversized baffle on the front of your soffit so you can remove your speaker or change it out with ease.

Yes, that's my plan too. I'm concerned about the warnings from the factory about too much sorbothane can actually have a reverse effect. Frankly, I'm wondering if just putting the recommended material ONLY under the speaker with no clamps will suffice. I'm thinking that the speaker is not likely to move - just sitting level on pads on the shelf (no clamp). I hear how "sticky" the sorbothane can be. I hope to get in contact with the factory tonight or tomorrow night and get their recommendation. -Ron

I'm concerned about the warnings from the factory about too much sorbothane can actually have a reverse effect.

That's why you need to calculate! Not guess. It isn't hard to do... :)

Frankly, I'm wondering if just putting the recommended material ONLY under the speaker with no clamps will suffice.

Then the top of the speaker will still be able to move, from vibration, so you'll have to leave a large gap around the speaker front, between the baffle and the speaker, thus creating a different set of problems... :)

I'm thinking that the speaker is not likely to move - just sitting level on pads on the shelf (no clamp).

Well, that would be fine as long as you never plan to turn it on and play loud music through it... :)

I hear how "sticky" the sorbothane can be.

Not sure I understand why that would be good? - Stuart -

Not sure I understand why that would be good?

Well I figured this sticky stuff would keep the speaker from migrating around on the shelf, considering comments from others as to how hard it is to move the speaker once it's on the sorbothane. .... just thinking out loud. Stuart, I'm beginning to realize that I must be missing the boat on the theory here. Now I'm wondering just what the goal is. Up to now, I thought the idea of the sorbothane is to isolate speaker vibration from the mounting frame, which would flank into the ceiling, etc. I have been seeing the whole surrounding cavity (Front and sides - insulation, bass trap hangers, ventilation) as the method of enclosing and damping the sound from the back hemisphere coming out from the speaker. Can you clarify better what the goal is and how it works? I don't think it has quite sunk into my brain completely just yet. :( :oops: :(

I thought the idea of the sorbothane is to isolate speaker vibration from the mounting frame, which would flank into the ceiling, etc.

That's the basic concept, yes. Actually, it is one of two basic concepts. The other one (which also works well) is to clamp the speaker in place so rigidly, and with so much mass, that it also has a hard time transferring sound into the structure. To do that method, you don't use rubber at all: you make your enclosure box very tight fitting, and you build a massive, rigid, heavy frame to hold that all in place, very tightly, as though it were held in a large vice. That can work too, and John prefers to do his rooms that way, so it CERTAINLY is a good option if you want to try that. Personally, I prefer to "float" the speaker the way you describe: fully isolated and decoupled from the soffit. It just sits there surrounded by its rubber pads, and it is free to vibrate any way it wants, but it cannot transmit any of that vibration to the structure, because it is decoupled, floated. The floating system is tuned so that it's highest resonant frequency is still an octave lower than the lowest frequency of concern. You need that much to ensure that there won't be any significant transmission, even at low frequencies. Thus, if your lowest frequency of concern is a four-string bass, which goes down to about 40 Hz, then you could get away with tuning the system to 20 Hz. But if you plan on using a six string bass, which goes down to about 31 Hz, then you should tune it below 16 Hz. Of course, that assumes your speaker can actually get down to 31 Hz! If your speaker only gets down to 50 Hz at -6dBm then it won0t be putting out a lot of energy at 31 Hz. If you needed to mix like that, you'd probably add a sub with a cross-over then you wouldn't need to worry about tuning the floating system so low. So a lot depends on YOUR needs in YOUR room: the spectrum you expect to mixing, your speaker make and model, whether or not you use a sub, etc. However, since the speaker can move, very slightly, with the floating system as it vibrates, you do need to leave a small gap around the front of the speaker, between the edges of the baffle and the speaker cabinet itself. That allows the speaker to vibrate if it wants to, without touching the soffit baffle, which would transfer the vibration into the baffle. Some people seal that gap with very flexible caulk, but I have a different method. In truth, unless you are going for extreme precision, you don't really need to seal it at all, as long as it isn't very big. A couple of mm is fine, but if you make it larger than that, then you can get air movement through that gap, due to the pressure changes around the speaker itself inside the soffit, as compared to the pressure changes outside the baffle, due to the woofer cone moving. If the gap is big, you can get a lot of air flow "luffing" through that gap, which can create an audible sound, and also mess with the acoustics in other ways. If the gap is small, it's not much of an issue. And if it IS an issue, then you can seal the gap and kill the problem.

I have been seeing the whole surrounding cavity (Front and sides - insulation, bass trap hangers, ventilation) as the method of enclosing and damping the sound from the back hemisphere coming out from the speaker.

That's about right, yes. There will ALWAYS be potential resonances inside ANY cavity, so you need damping in there to deal with that, definitely. It's a large box, so the resonances could potentially go down to lowish frequencies, thus the need for shiploads of insulation inside. But you also need to cool the speaker, so you do need to allow a suitable airflow path up the back and around the speaker body. That's another reason I prefer floating: if the speaker is clamped rigidly, there's no airflow around the sides, top and bottom, but with the floating system, there is. There's space between the pads for air to move, in addition to a much deeper space at the rear.

Can you clarify better what the goal is and how it works? I don't think it has quite sunk into my brain completely just yet.

To me, it sounds like you have it about right. Did I say something that confused you, and led you to think that there's something else going on here? Maybe what you are missing here is that the speaker WANTS to move, and WILL move, due to the vibrations. The woofer is a rather large mass that is chugging in and out over a large distance: it has inertia, and "for every action there is an equal and opposite reaction", so the speakers cabinet wants to move as well, in the opposite way (180° out of phase). The cabinet itself is also vibrating in many different ways, and the rubber ALLOWS that movement to happen... it just prevents it from getting into the soffit structure or the baffle. The movement is not large, of course, if you do the mounting correctly, but it is still there, and you do need to consider it. If you do not restrain the TOP of the speaker, only the bottom, then the top will move MORE than the bottom, and that's a problem. So you need to restrain the speaker with Sorbothane pads all around, not just underneath. For a speaker sitting out in the room on a speaker stand, or the meter bridge, it doesn't matter, since there's no baffle around the speaker for it to "bump into", so it's fine to just have rubber feet for decoupling in that case. But soffit mounting is different, because there IS a baffle, and you have to prevent the speaker from ever coming into contact with it. - Stuart -

OK, Stuart, that helps a lot! Thanks! :) So.... Do you think my mounting system as drawn above will work as it is drawn - with sorbothane on top and bottom, providing I get the right amounts of sorbothane worked out? -Ron