Soft Flush mount specs

Hi All! I am building my production/recording/mixing studio, and now it's time for build the control room. I'm trying to build an RFZ control room, with a soft flush mounted speaker inside the front wall. The room dimensions are: W=4mt L=5,2mt H=3,2mt I'm thinking to put my speaker (Amphion One18, passive speaker, green in the pics) on studio monitor stand, but inside the wall, and make it flush to the front wall. I also thinking to put inside the wall, around the speaker, in all the cavity, some hanger bass trap panels (like the John design) (yellow in the pics). In these front wall i have 2 maintenance hatch (blue in the pics), because i have a lot of cable and electrical plants behind the wall. i have attach some pics to understand what i mean. Question time... 1) can i put the speaker only on the stand, without cabinet in "open air" behind the wall, or i have to build a "cabinet" around the speaker and fix it really strong at the wall structure? 2) do 2,6cm of drywall work good for front wall surface? 3) i have to uncouple the speaker from the stand using rubber or other material? 4) i have also to put fiberglass in the metal stud?

Soffits need very sturdy, strong, rigid framing. What you are showing is too light weight. This is what typical soffits look like, when down correctly: FRAMING: PARTLY COMPLETE, With hangers below a d to the sides (behind the soffit "wing"), and packed with insulation above: Here's another room:

on studio monitor stand, but inside the wall,

If you do that, the stand would have to be very massive, rigid, and stiff, and you'd have to brace it in some manner, to ensure that it does not move. You would also be using up the space that is needed for hangers down below the speaker. I have found that it is easier to just put a rigid shelf across, just below the speaker, as you can see in the images above.

I also thinking to put inside the wall, around the speaker, in all the cavity, some hanger bass trap panels (like the John design) (yellow in the pics).

Correct! See above. That is, indeed, the best way to do it. Note the very large size of the hangers behind the soffit "wings" in one of the studios above.

In these front wall i have 2 maintenance hatch (blue in the pics), because i have a lot of cable and electrical plants behind the wall.

Move all of that to the center of the front wall, between the speaker soffits. You will not be able to have access to it where it is right now. The soffits, hangers, and absorber box will be in the way.

1) can i put the speaker only on the stand, without cabinet in "open air" behind the wall,

If you did that, how would prevent the speaker from moving? :)

or i have to build a "cabinet" around the speaker and fix it really strong at the wall structure?

Right! I always build strong, rigid, massive enclosure boxes around the speakers in my soffit mount designs, but I do use Sorbothane rubber pads between the speaker and the enclosure box, to isolate the speaker.

2) do 2,6cm of drywall work good for front wall surface?

In theory, yes, but drywall is not really a good material for this, because it is brittle and flaky. You have to cut a hole through it for the speaker, and that leaves a messy edge. I prefer to use wood: either solid wood (expensive!), or you can build it up from several layers of MDF.

3) i have to uncouple the speaker from the stand using rubber or other material?

That's what I do, yes, but it is not easy. You have to calculate the compression ("deflection") of the rubber correctly, in order to get the system resonant frequency low enough that hte speaker actually is decoupled across all of its spectrum.

4) i have also to put fiberglass in the metal stud?

See above... Your last image above, with the layout for the studio, shows two "kinks" coming out of the side walls, with the speaker soffits ending just behind those. That will create a large discontinuity in the surface, and will like create artifacts. I would eliminate those, and blend the soffit wings smoothly into the side walls. - Stuart -

Thanks for answer me Stuart! So...

Soffits need very sturdy, strong, rigid framing. What you are showing is too light weight.

Ok, you think that i can fix the structure adding wood stud, and every what is necessary for make it sturdy, strong and rigid?

With hangers below a d to the sides (behind the soffit "wing"), and packed with insulation above

Ok, so i have to put hangers below and to the sides of the speaker, and insulation pack above, right?

If you do that, the stand would have to be very massive, rigid, and stiff, and you'd have to brace it in some manner, to ensure that it does not move. You would also be using up the space that is needed for hangers down below the speaker. I have found that it is easier to just put a rigid shelf across, just below the speaker, as you can see in the images above.

Ok, i think that i'll do with the rigid shelf across, and build a speaker enclosure... But, just a explanation... You have say that you use Sorbothane rubber for decoupling the speaker, but the speaker enclosure is attached in very solid way to the front wall buffer... So, the speaker decoupled from the enclosure, but the enclosure attached very well to the front wall buffer? I understand well?

Move all of that to the center of the front wall, between the speaker soffits. You will not be able to have access to it where it is right now. The soffits, hangers, and absorber box will be in the way.

I have a problem! The center front wall is large 1 meter, but the distance from the concrete wall of the structure is only 18cm! If i'll put the maintenance hatch here, i'll can't pass trought it! And I'm not really skinny... :lol: Maybe i can leave them and if it's necessary, just move temporarily the hanger? What you think about?

Your last image above, with the layout for the studio, shows two "kinks" coming out of the side walls, with the speaker soffits ending just behind those. That will create a large discontinuity in the surface, and will like create artifacts. I would eliminate those, and blend the soffit wings smoothly into the side walls.

Unfortunately i can't eliminate those (i think, maybe), because they are there for angle the sides wall of the room... if i remove there, the sides wall become flat and not angled... This will cause some reflection problem i think (correct me if I'm wrong)... Maybe i can fill those spaces with fiberglass, or i can cover it with drywall, or fill with fiberglass and cover?

Ok, you think that i can fix the structure adding wood stud, and every what is necessary for make it sturdy, strong and rigid?

Pull out the metal framing and build it all out of wood.

Ok, so i have to put hangers below and to the sides of the speaker, and insulation pack above, right?

Hangers are preferred where ventilation is required. Super chunks work in the other areas. Or just use hangers everywhere for bass trapping.

You have say that you use Sorbothane rubber for decoupling the speaker, but the speaker enclosure is attached in very solid way to the front wall buffer... So, the speaker decoupled from the enclosure, but the enclosure attached very well to the front wall buffer? I understand well?

If you don't de-couple the speaker enclosure from the frame, it can be attached to the baffle, but the speaker must not touch the baffle anywhere. It has to "float" on the Sorbothane. If you go an extra step and de-couple the speaker enclosure from the framing, then it too must not touch the baffle.

I have a problem! The center front wall is large 1 meter, but the distance from the concrete wall of the structure is only 18cm! If i'll put the maintenance hatch here, i'll can't pass trought it! And I'm not really skinny... :lol: Maybe i can leave them and if it's necessary, just move temporarily the hanger? What you think about?

I'm not sure why you have to crawl into these hatches. Like Stuart said, why aren't you able to put any important stuff in the center and just leave it accessible? Why don't you just cover this stuff with a fabric covered piece of wood that is lightly tacked on with brad nails or something like that? Then you can remove that panel and get at your stuff.

Unfortunately i can't eliminate those (i think, maybe), because they are there for angle the sides wall of the room... if i remove there, the sides wall become flat and not angled... This will cause some reflection problem i think (correct me if I'm wrong)... Maybe i can fill those spaces with fiberglass, or i can cover it with drywall, or fill with fiberglass and cover?

Extend the soffit wings further towards to the front of your room so that they "connect" with your soffit baffles. Did you do ray tracing to ensure a RFZ? Greg

Hey Greg!

Pull out the metal framing and build it all out of wood.

Done! 8) Thanks! Now the frame are really strong and rigid! It does not move for nothing! All the wood is really massive, and 3 or 4 cm of thikness, holds me without problems, and i'm not light. Tomorrow i'll do other "wing".

Hangers are preferred where ventilation is required. Super chunks work in the other areas. Or just use hangers everywhere for bass trapping.

Ok, i need to absorb low frequencies... Hangers are really cool, but can i build some fiberglass pack, maybe square, maybe round, to remove easy for access behind wing? (maybe a fiberglass column?) Do they work good like hangers?

I'm not sure why you have to crawl into these hatches. Like Stuart said, why aren't you able to put any important stuff in the center and just leave it accessible? Why don't you just cover this stuff with a fabric covered piece of wood that is lightly tacked on with brad nails or something like that? Then you can remove that panel and get at your stuff.

Here in italy there's a lot of regulations on electrical safety, and i must, put all the plant in that corner, because there are really a lot of corrugated... I prefer to put the electrical plant distant much possible from the audio cables... so i have decided to put all the audio connections in the center of front wall, but there's not other space for electrical plants here!

Extend the soffit wings further towards to the front of your room so that they "connect" with your soffit baffles.

Do you think i simply fill those triangle spaces with some fiberglass, or cover those with drywall?

Did you do ray tracing to ensure a RFZ?

Of course! Below some pics from amcoustics amray... the shape that you see is the correct shape of my room, with correct dimensions... I have considered 100 degrees as Speaker irradiation. Do you think that maybe i'll use sorbothane feet, or large pad?

Done! 8) Thanks! Now the frame are really strong and rigid! It does not move for nothing! All the wood is really massive, and 3 or 4 cm of thikness, holds me without problems, and i'm not light. Tomorrow i'll do other "wing".

I know that holds you up when you sit on it, but besides strength, another main characteristic of the soffit framing is to be massive so that it does not allow vibration. Personally I'd build that about 3 times as "heavy" and strong.

Ok, i need to absorb low frequencies... Hangers are really cool, but can i build some fiberglass pack, maybe square, maybe round, to remove easy for access behind wing? (maybe a fiberglass column?) Do they work good like hangers?

Superchunks work great but they don't allow for ventilation. Maybe you could install some hangers and design them such that they can be removed from the front.

Do you think i simply fill those triangle spaces with some fiberglass, or cover those with drywall?

They act as an extension to the front soffit baffles, so they too must be massive and rigid. Behind the massive rigid baffle it is smart to use that area for yet more bass trapping. So, large hangers is a good idea. The bottom portion of the baffle can be removed and fabric can cover that area.

Of course! Below some pics from amcoustics amray... the shape that you see is the correct shape of my room, with correct dimensions... I have considered 100 degrees as Speaker irradiation.

Can you post some more design photos? On the forum it is drilled into our heads to have the design 100% complete before any major construction (like building your soffits) starts. We typically work through peoples designs for quite a while. After everyone on the forum agrees that it is a good design, then the construction starts. Luckily myself and a few other members regularly chime in to help with designs (for free). So please post all of your design photos and calculations so that we can check over things. The last thing we want is to have you build a bunch of stuff then find out it was designed poorly and you have to rip it all down. I see some flex duct HVAC work in your pictures. For most applications flex duct is pretty horrible but it does come in handy for a few things. I'd love to make sure your HVAC is done properly before any more construction happens because HVAC is difficult to change once things like your soffits are built!

Do you think that maybe i'll use sorbothane feet, or large pad?

Again, this goes back to my post above regarding having your design 100% done. You have to decide how you want to mount your speaker and then design it accordingly. We use SketchUp Make exclusively on the forum as it easily allows you to work out every detail of your design before you do it in real life. I know you're excited to see progress, but it's evident that you haven't completed your design stage. I'd stop the construction stage and finish your design. Again, post pictures and your calculations for us to review. It costs nothing. It will give you confidence in your build. I look forward to seeing the pictures and watching your build take shape! Greg

I'm trying to build an RFZ control room, with a soft flush mounted speaker inside the front wall.

Are we all on the same page here? I understand 'soft flush' to simply mean the speakers are sunk into a thick absorbent FW treatment. DD

I know that holds you up when you sit on it, but besides strength, another main characteristic of the soffit framing is to be massive so that it does not allow vibration. Personally I'd build that about 3 times as "heavy" and strong.

All wood frames are about 4x8cm, and everthing is glued and screwed up. But i can adding some other wood for make more rigid and massive...

Superchunks work great but they don't allow for ventilation. Maybe you could install some hangers and design them such that they can be removed from the front.

Ok i think i'll do that. Just an explanation... I'll have passive speaker, so i need ventilation just to avoid mold, or there is other reason?

They act as an extension to the front soffit baffles, so they too must be massive and rigid. Behind the massive rigid baffle it is smart to use that area for yet more bass trapping. So, large hangers is a good idea. The bottom portion of the baffle can be removed and fabric can cover that area.

I am talking about two "kinks" coming out of the side walls. Are you talking about these?

Can you post some more design photos? On the forum it is drilled into our heads to have the design 100% complete before any major construction (like building your soffits) starts. We typically work through peoples designs for quite a while. After everyone on the forum agrees that it is a good design, then the construction starts. Luckily myself and a few other members regularly chime in to help with designs (for free). So please post all of your design photos and calculations so that we can check over things. The last thing we want is to have you build a bunch of stuff then find out it was designed poorly and you have to rip it all down. I see some flex duct HVAC work in your pictures. For most applications flex duct is pretty horrible but it does come in handy for a few things. I'd love to make sure your HVAC is done properly before any more construction happens because HVAC is difficult to change once things like your soffits are built!

Ok... i have 2 wall air conditioning machine for controlling the rooms temperature and humidity (with sleep low noise mode). The flex duct, is only for air recycling, and it's a sound-absorbing duct, positioned not straight but with many curves from live room to control room (Like in Alton Everest - Master Handbook of Acoustics). Now i'm thinking to put 2 ventilation grids in the front wall, or in the hugh part of the buffle to connect the duct, and buy 2 silenced air fan, and instal behind the right baffle.

Again, this goes back to my post above regarding having your design 100% done. You have to decide how you want to mount your speaker and then design it accordingly. We use SketchUp Make exclusively on the forum as it easily allows you to work out every detail of your design before you do it in real life. I know you're excited to see progress, but it's evident that you haven't completed your design stage. I'd stop the construction stage and finish your design. Again, post pictures and your calculations for us to review. It costs nothing. It will give you confidence in your build. I look forward to seeing the pictures and watching your build take shape!

Unfortunately, the Italian bureaucracy has many errors, and the problem is, that i need to go fast, because i have a deadline for build the room... That's because i am going fast, without everything planned good :( But, i'll do everything i can, to follow your advice! I think that i will decouple the speaker from the enclosure, and attack the speaker enclosure to the baffle and the frame. ok Greg, now i see what i can do tomorrow in the studio, and with SketchUp Make. Thanks for your time and your help! - Mattia ;)

Are we all on the same page here? I understand 'soft flush' to simply mean the speakers are sunk into a thick absorbent FW treatment. DD

I believe he meant soffit/flush mounted. This does not mean that speakers are sunk into a thick absorbent front wall treatment. It actually means that they are mounted in a wall such that it creates an "infinite" baffle.

But i can adding some other wood for make more rigid and massive...

:thu:

Ok i think i'll do that. Just an explanation... I'll have passive speaker, so i need ventilation just to avoid mold, or there is other reason?

I've read that it's good to have ventilation for passive speakers, but in my mind, it just makes sense to future-proof your build allowing you to use active speakers if you ever decide to go that route. Granted, you can typically remove the amp from the back of active speakers, this would prevent you from having to do so. Maybe someone else can chime in with some thoughts on this.

I am talking about two "kinks" coming out of the side walls. Are you talking about these?

There shouldn't be "kinks" anywhere. The wings I'm referring to are just the connecting wall between your angled baffles which you speakers are sticking through and your straight side walls. So, the wings are just more angled walls. Again, they can't be "kinks". They have to be smoothly connected so that they act as a single baffle.

Ok... i have 2 wall air conditioning machine for controlling the rooms temperature and humidity (with sleep low noise mode). The flex duct, is only for air recycling, and it's a sound-absorbing duct, positioned not straight but with many curves from live room to control room (Like in Alton Everest - Master Handbook of Acoustics).

That book is amazing! However, it did lack great studio isolation techniques, specifically in HVAC. If you use the search feature on the forum and look up "silencer boxes" you will be able to find many threads talking about them. I'd suggest reading the newer threads as the information is more relevant and detailed than older (5+ years) threads! Also, from what you've written, it sounds like you're sharing stale air between your live room and your control room. That's usually illegal. Where is your FRESH air coming from and where is it going? Pictures would be great.

Now i'm thinking to put 2 ventilation grids in the front wall, or in the hugh part of the buffle to connect the duct, and buy 2 silenced air fan, and instal behind the right baffle.

Your fresh air outlet should be above your "air conditioning machine" as you called it so that it can blow fresh air around your room. The stale air intake should be at the opposite side of your room. Whatever fan you use, make sure that it can move the correct CFM for your room. Furthermore, the "ventilation grids" as you called them, need to be able to pass that same CFM at slower than 300 feet per minute and the "grids" as you call them should be rated with NC as low as possible. Preferrably =< 15. The manufacturer specs should provide you with the NC rating at x amount of CFM. Achieving the slow air velocity and NC is typically as easy as increasing the outlet size as necessary.

Unfortunately, the Italian bureaucracy has many errors, and the problem is, that i need to go fast, because i have a deadline for build the room... That's because i am going fast, without everything planned good :( But, i'll do everything i can, to follow your advice!

That's a bummer. I'm surprised they gave you a building permit without detailed drawings and plans though. Here, you need quite a bit of detail in order to obtain the permit. And the permit typically lasts 1 year. If you are not done building in that time frame, they will extend it providing you are making some progress. Hopefully we can prevent some major mistakes. The only problem I foresee will be you asking a question and there might not be anyone on the forum that day or whenever to answer your question. You may have to split up tasks so that you are able to wait for confirmation on certain aspects of your build. If you work REALLY hard on the SketchUp drawing and finish it before you continue construction, that might be the best and will save you time in the end as you'll have all of your questions sorted out and you'll be able to build fast with confidence!

I think that i will decouple the speaker from the enclosure, and attack the speaker enclosure to the baffle and the frame.

It may be smart to ask Stuart (soundman2020) if he can whip up some Sorbothane calculations for you so that you don't have to spend a week sorting through the dumb Sorbothane information. You can't just throw a random amount under your speaker. It's quite convoluted and you have to make sure that your frequency calculations are correct. This is a very delicate part of the design.

ok Greg, now i see what i can do tomorrow in the studio, and with SketchUp Make. Thanks for your time and your help!

I look forward to it! Greg

I've read that it's good to have ventilation for passive speakers, but in my mind, it just makes sense to future-proof your build allowing you to use active speakers if you ever decide to go that route. Granted, you can typically remove the amp from the back of active speakers, this would prevent you from having to do so. Maybe someone else can chime in with some thoughts on this.

Speakers are very, very inefficient at converting electrical power into acoustic power. The actual acoustic power coming out of a speaker playing really loud (100 dBC SPL) is maybe around one watt per square meter. So if you could set up a frame at the mix position that measures one meter on each side, and measure the acoustic power going through that frame, you'd get about one watt, typically (give or take a hundred milliwatts or so.) Now take into account that, in order to create that acoustic power level, your amps are probably pumping out a few HUNDRED watts... do the math.... speakers are highly inefficient, in this sense. So, if most of the power reaching the speaker drivers is NOT going out as sound, where is it going? Yup: heat. That's where. Speakers are actually very, very efficient at converting amplifier power into heat power! One way or another, the amplifier power that did not go into producing acoustic power, went into heat power. And a fair amount of that "heat power" gets dissipated by the driver itself, inside the speaker cabinet. There are also heat losses in other parts (the flexing of the cone mountings, for example), as well as just lost as heat to the air due to the impedance mismatch, but in a typical speaker, the driver itself is sucking up a large amount of that electrical power, and converting it into heat. That heat then has no place to go, except out through the cabinet walls, and into the air around the speaker. If your speaker is tightly held inside an enclosure box, then the heat works it's way out through that, eventually. But it DOES get out. Then it needs to go some place... You can't just trap it inside the soffit, and allow it to build up.... So, even for passive speakers, I always ventilate the rear face of the speaker cabinet, just like I do for active speakers. I leave a clear, open ventilation path up the back of the speaker, with at least an inch of clearance all around, and a much more if I can spare the space, or if the speaker is large, or dissipates a lot of heat. OK, for a passive speaker, the surface area of the cabinet is large compared to the amount of heat, so it hardly gets warm at all to the touch if you have it sitting in the meter bridge, or on a speaker stand... but that's only because it is exposed to air all around! Mounted inside a soffit, it's a different story. You don't need as much for a passive speaker as you do for an active, but it is still wise to allow some ventilation.

Again, they can't be "kinks". They have to be smoothly connected so that they act as a single baffle.

:thu:

If you use the search feature on the forum and look up "silencer boxes" you will be able to find many threads talking about them. I'd suggest reading the newer threads as the information is more relevant and detailed than older (5+ years) threads!

Yup! Here's some examples... some good, some not so good: viewtopic.php?f=2&t=15430&start=45 viewtopic.php?f=2&t=1929&start=74 viewtopic.php?f=1&t=11542&start=5 viewtopic.php?f=2&t=9761&start=0 viewtopic.php?f=2&t=11485&start=98 viewtopic.php?f=2&t=11508&start=157 viewtopic.php?f=2&t=13821 viewtopic.php?f=1&t=15378&start=44 viewtopic.php?f=2&t=18202&start=16

it sounds like you're sharing stale air between your live room and your control room. That's usually illegal.

:thu: True. And even if it is not illegal where you live, it is still bad practice. You should never have the stale air from one room going into another room. Not good.

If you work REALLY hard on the SketchUp drawing and finish it before you continue construction, that might be the best and will save you time in the end as you'll have all of your questions sorted out and you'll be able to build fast with confidence!

Excellent advice!

You can't just throw a random amount under your speaker. It's quite convoluted and you have to make sure that your frequency calculations are correct. This is a very delicate part of the design.

Absolutely! It's complicated to get right... - Stuart -

Hey Guys! Thanks for reply! Happy new 2019 for all of you!

it sounds like you're sharing stale air between your live room and your control room. That's usually illegal. :thu: True. And even if it is not illegal where you live, it is still bad practice. You should never have the stale air from one room going into another room. Not good.

Maybe you can't see good from the bad pics... I have 2 air duct, one for incoming fresh air, and one for pull out stale air from the studio... Every duct is soundproofed duct, but maybe i can build a silencer if i need. I'm working on sketchup for building my room, and soon i'll send some pics!

You can't just throw a random amount under your speaker. It's quite convoluted and you have to make sure that your frequency calculations are correct. This is a very delicate part of the design. Absolutely! It's complicated to get right...

Ok... I read that i have to calculate the weight of my speaker and the critical frequency of the system. It's right? Any suggestions or explanation?

I read that i have to calculate the weight of my speaker and the critical frequency of the system. It's right?

You need to know the total weight that you will be "floating", which is the weight of the speaker plus any enclosure box around it (if that's the method you intend to use). You also need to know the lowest frequency where your speaker will b putting out significant energy, which as around 30 dB below the specified lowest frequency. You need to tune the system to a frequency that is not more than half of that. If you use a sub along with your mains, then the lowest frequency will be a lot higher than if you just use the mains by themselves. In that case, use the crossover frequency and calculate the -30 dB point based on the slope of the crossover. Some people make the mistake of thinking that speakers only move up and down, so they only put pads under them, but in reality speaker cabinets vibrate in all three dimensions... So you need to take that into account with your design. - Stuart -

Hi all! Finally i have make some drawing in sketchup! Sorry for some error, i'm using this software only for 1 week... I have apply some advice that you have tell me... What do you think about the round absorber to remove for enter behind front baffle in case of maintenance? If you have some advice or something wrong in this project please tell me! I have include the project file for let you modify something, if you want.

Hi Matt, Great work with SketchUp!!!! Have you done ray tracing in SketchUp yet? I'd like to see that to confirm that you indeed have a reflection free listening position.

What do you think about the round absorber to remove for enter behind front baffle in case of maintenance?

Well, it won't work the magic of hangers and won't be as effective as a stuffed full superchunk style bass trap, but it certainly would do some amount of good for your acoustics. I've never seen insulation sold in a roll like that though, so how do you plan to find that product or build it? It is a solid chunk of insulation right?

I have include the project file for let you modify something, if you want.

I don't see any link for your .skp file.

If you have some advice or something wrong in this project please tell me!

- You need a layer of insulation (like 2 to 4 inches worth) entirely covering the walls, ceiling and floor INSIDE your soffits. - You should have a back on your speaker enclosure. Leave a hole in it to pass heat and cabling. - It might be wise to put a divider shelf above your speaker. This will allow you to stuff a ton of loose insulation all around the speaker enclosure to dampen the heck out of it. - The shelf the speaker sits on needs a hole cut in it just behind your speaker enclosure for air to pass up behind the speaker. The shelf I mentioned in the previous point would also need the same type of hole in it. That way convection can happen. The other thing you need to include is some chicken wire or something like that to maintain the air path while preventing any insulation from falling into it's path. - Again, you need to do ray tracing to make sure all of your angles work out properly. - What are you using for your soffit baffle? - I can't tell from your pictures where your soffit face changes from the very hard material to just fabric/absorption. The same question applies to your soffit wings. - It looks likes like there are some 2x4's or some type of dimensional lumber standing upright at the end of your soffit wings (on the door side of the wings). Those will screw up your RFZ as they will reflect sound back towards the front of your room. Remove those. If you're thinking you're going to need some depth on your side walls for acoustic treatment, you won't be able to have as much angle on your wings, or you have to re-think the entire front half of your room as being thinner. Again, this is where your ray tracing will point out issues. - For ray tracing, you have to do it for your ceiling/cloud as well. This is very very important. - I know it's only been a week on SketchUp, but before you continue any actual construction, you should design your rear wall. Are you doing hangers back there too? How thick are you able to make it? - You didn't include your mix position in your pictures. Again, that all comes with ray tracing as well. How far back (percentage) are you going to have your mix position in the room? - Have you decided where exactly your supply and return diffusers/registers/grilles are going to go in your room?

Every duct is soundproofed duct, but maybe i can build a silencer if i need.

Those look like flex duct. First off, unless they have the same surface density as your walls and provide an equivalent amount of insertion loss as your walls provide transmission loss, they will allow sound to pass and compromise any isolation you've attempted to obtain with your walls. Therefore, if isolation is a requirement of yours, you WILL need silencer boxes. I don't know what is on the other side of the wall where the ducts penetrate the walls. You would need silencer boxes there for sure. Is your room a room in a room design? If so, you will need a silencer box on each leaf. So one for the outer room wall and one for the inner room wall. But, that means for both supply and return. So, a total of 4 boxes. They are going to be very large. You may have to have them inside your room and since the ducts are penetrating your wall right behind your soffit, that will be very difficult to fit your silencers in that location. What you may have to do is build thick sleeves out of MDF and run them to other locations in your room. You could use Stuart's Y style silencer box design and have your supply silencer/outlets at the rear ceiling of your room and your return silencer/inlets up hidden above your cloud. Now, again that all will affect your ceiling height and ultimately your vertical ray tracing. As you can see, there is still a lot of SketchUp work to do before you start building stuff! Keep at it. Now that you've got a good grasp on using SketchUp, this design stage should go pretty smoothly! Greg

Hey Greg! I'm preparing the answer and the modified design for your last post... i've only a question... How can i do ray tracing in sketchup??? I have installed the raytracer plugin, but i don't understand how can i use it for speaker reflection simulation...

Don't confuse raytracing with raytracing! :) There's two very different things that both use the same word. One of those is a video rendering technique that can produce very high quality photo-realistic images, with real lighting, shadows, reflections, textures, etc. That's not what you want. That's the plugin you got, but that's not what you need. The other type of raytracing, you do by hand, one painstaking step at a time. Long, slow, boring process, but the only way to check that your room is acoustically sound. You do this type of tracing by drawing out many "rays" that leave the acoustic center of your speaker, at many angles, and seeing where each ray goes: what surfaces in the room does it hit. When a ray hits a surface, you make it "bounce" by drawing the reflected version of that ray, as though the surface was a mirror and the original ray was a laser beam hitting it. So the angle of reflection is equal to the angle of incidence, but flipped over in the opposite direction. You do that with a whole bunch of rays leaving your speaker at small intervals, such as every 5°, or every 10°, in both directions. After you have done a few dozen of those, you'll be able to get a picture of where the sound is going in your room, what surfaces it is hitting, and where the reflections from those surfaces are going. After you have done that in the horizontal plane, you then also do it in the vertical plane, because sound is 3D not 2D. Like I said: very slow, boring, painful, maddening process. It would be nice if there was a plugin to do this type of raytracing for you, but there isn't... The "picture" can end up looking something like this: Another way that I've developed to help with this, is a geometric component with colored segments at 5° increments, that I just attach to the acoustic axis of the speaker. It helps to get a quick idea of hos things are working out, and I then use it as the basis for ray-tracing: - Stuart -

Ok, i got it. How much i have to consider for speaker sound irradiation in degrees? 60, 90, 100? The speakers are Amphione One 18.

Guys some help?

How much i have to consider for speaker sound irradiation in degrees? 60, 90, 100?

- You should have a back on your speaker enclosure. Leave a hole in it to pass heat and cabling.

Maybe i can not do that... my monitor have a back passive radiator, and i don't know if i can cover it with cabinet...

- What are you using for your soffit baffle?

I think 26mm of drywall, because large and big wood panels here in italy cost really much... Here you can see some progress of sketchup project... Maybe this can be a solution? One reflection don't bounce because hit a fiberglass triangle absorber... what do you think?

How much i have to consider for speaker sound irradiation in degrees? 60, 90, 100?

What speakers are you using? What is their dispersion like? What frequencies fall off at what angles? What treatment would you need at each angle to deal with the remaining frequencies? It's all about directivity. Check the directivity plot for YOUR speakers, and compare that to YOUR room...

Maybe i can not do that... my monitor have a back passive radiator, and i don't know if i can cover it with cabinet...

Of course you can! If you build the enclosure correctly. The speaker won't blow up or burn out if you soffit-mount it. Take a look at this thread (click here) and note the speakers. Those are Eve Audio SC-407s. They have a massively huge bass reflex port on the back, yet there they are, mounted in soffit, with an massive enclosure box around them on all sides except the front, and the seem to be performing rather well like that... :) Why would yours be different? A passive radiator is basically the same as a bass reflex port, just implemented in the form of a damped speaker cone, instead of a tuned tube. It still moves air in roughly the same way as a port, except that it avoids some of the pitfalls of reflex ports. But as far as the soffit is concerned, it's pretty much the same...

I think 26mm of drywall, because large and big wood panels here in italy cost really much...

Not drywall, no. You have to cur a large hole in the baffle for the speaker to go through, and you can't do that with drywall: the edges would be brittle, flaky, and pumping out powdered gypsum all the time, from the pressure changes inside the soffit. Use something like MDF, OSB, or plywood. It needs to be heavy, thick, and rigid.

One reflection don't bounce because hit a fiberglass triangle absorber... what do you think?

That won't work. That discontinuity in the baffle where the fiberglass is, will create all types of artifacts. You should angle the soffit "wings" more, as well, such that the reflections go a long way behind your head. Also, you are only drawing rays on ONE side of the speaker: it emits sound in BOTH directions... :) - Stuart -

What speakers are you using? What is their dispersion like? What frequencies fall off at what angles? What treatment would you need at each angle to deal with the remaining frequencies? It's all about directivity. Check the directivity plot for YOUR speakers, and compare that to YOUR room...

Ok i have send a message to the tech support that will tell me something about speaker irradiation...

Of course you can! If you build the enclosure correctly. The speaker won't blow up or burn out if you soffit-mount it. Take a look at this thread (click here) and note the speakers. Those are Eve Audio SC-407s. They have a massively huge bass reflex port on the back, yet there they are, mounted in soffit, with an massive enclosure box around them on all sides except the front, and the seem to be performing rather well like that... :) Why would yours be different? A passive radiator is basically the same as a bass reflex port, just implemented in the form of a damped speaker cone, instead of a tuned tube. It still moves air in roughly the same way as a port, except that it avoids some of the pitfalls of reflex ports. But as far as the soffit is concerned, it's pretty much the same...

Ok i'll try to do that!

That won't work. That discontinuity in the baffle where the fiberglass is, will create all types of artifacts. You should angle the soffit "wings" more, as well, such that the reflections go a long way behind your head.

Ok, i have modified something... - Speaker moved just 15cm to the front center wall - "Sides baffle wings" more angled (in the picture there is not window, but i'll put soon in the project (same angle of the wall) - This appear a nice RFZ (in the horizontal plane), what do you think? - Is there some problem if i build with MDF only the speaker wall baffle and build with drywall front center baffle and sides baffles? - What do you think about the rear wall broadband absorber, with the corner? (it's covered with some tipe of fabric)

Also, you are only drawing rays on ONE side of the speaker: it emits sound in BOTH directions... :)

:D yes i know, just trying...

You still are not tracing rays out far enough, in either direction. You are doing maybe 40° or 45°. Take a closer look at the examples I gave you. I'm pretty sure you have first reflection issues on your side walls. Also, you have a skyline diffuser on the rear wall: I doubt that your studio is large enough to do that successfully. What frequency range will you tune the skyline for, and what is the distance from the front of the skyline to your ears? - Stuart -

I'm doing 50 degree for each side, 100 in total... I'll tune the skyline (or maybe other tipe of diffuser, you can suggest me) maybe around 1khz... I have read your post (and something about Alton Everest) about the time for return the reflection at hears, after at least 20ms for avoid problems... For a directly and clear reflection, from the speaker to the rear wall (or diffuser), and from the rear wall to listening point (speaker/rear/listening point) i have about 797cm... So something like 23ms at 20 celsius... maybe good? The skyline (or other diffuser) / listening point distance is 320 cm.

I have modify at 120 degrees the irradiation of the speaker... Here the result, what do you think?

That's not 120° !!! 0° is straight ahead. 90° is straight out to the side, along the face of the speaker. 120° would be going BACKWARDS, behind the speaker, into the wall... Take another look at what I posted earlier: Look at the numbers.... - Stuart -

I think you could get a much bigger RFZ by decreasing the length of your soffit wings and increasing the angle at which they splay out. In my experience the length of the soffit wings only needs to extend as far as the listening position (imagine there’s a horizontal line going through your ears to your side walls) that’s about as far as is needed to make it decent... of course I can only speak from experience designing my own RFZ and the dimensions are different to yours... but try it. In my opinion it’s better for the sweet spot to be wider rather than longer as you’ll be mainly moving from side to side as you mix to get to your hardware. Paul