New Music Room in UK south

Then a whole lot of wood chopping and framing ...

Painted the outside, put some paths around, got some air units fitted...

Now I am into some heavy duty plaster boarding for the inside leaves ....

Looks good! What did you end up going with for the air - are those 200mm diameter ducts? The silencer in the ceiling looks big too, so I'm guessing so? Cheers Gareth

garethmetcalf wrote:

Looks good! What did you end up going with for the air - are those 200mm diameter ducts? The silencer in the ceiling looks big too, so I'm guessing so?

Actually I ended up having 2 x 200mm ducts for each silencer, that was what my contractor recommended. I figured extra ducts leads to slower air so that is all good. Glad I oversized the silencers though.

I figured extra ducts leads to slower air so that is all good.

:thu:

Glad I oversized the silencers though.

:thu: - Stuart -

quick update --- plaster boarding finally finished, something like 270 sheets in total!!! Never again! That is the last of the really big jobs, just 7 doors, 5 windows, piles of electrical stuff, acoustic stuff, audio stuff to do. Here is a couple of photos...

Control room geometry … After all my plasterboarding I am thinking about doing the control room soffitts next and I am wondering about the exact placement of the speakers. At the moment the control room is just a shell with all the walls finished (but without final door and windows). There is no acoustic treatment yet although as a rough plan I am imagining 8” rockwool all over the ceiling, a heavy duty cloud (maybe 2), and I haven’t decided on treatment for rear wall yet. But first I need to build the soffits… I haven’t finally decided what monitors to get but I am quite tempted by Neumann KH310’s - it seams nobody has a bad word to say about them and they are only slightly above my max budget so I am proceeding with that assumption at the moment. I notice in their instructions that it is suggested to mount them horizontally but am thinking that a vertical orientation may be better for a soffit mounted arrangement? The main thing I would like to check is the geomety between the listening point and the speakers and the corners of the room. I drew a sketch of my best guess which should be attached below… I am not sure about what to do on the side walls. My initial feeling was to just put up some thick rockwool on both sides but then I was thinking that heavy angled refective panels with a gap at the top and bottom and filled behind with fluffy rockwool may be better - maybe they would reflect sound past the listening position and also help to stop the room sounding too dead - but it is a little hard to work out the angles! I have tried but not sure if I have suceeded in optimal positioning? Inside dimensions of control room - width - 319 cm length - 410 cm height - 280 cm Starting point listening position at 38% which is 156cm from the front wall. Apex of speaker traingle 20cm beyond this at 176cm. In the Neumann manual is says that speakers should be 175-200cm apart. I guess optimum speaker triangle is 60/60/60 but with my small room this means the speakers are less than 175cm apart (given a 38% listening point) so I thought increasing angle to 70 degrees was probably a better option which has resulted in the speakers being 186cm apart. I am expecting to put them 10cm off the front wall, enough to get a bit of rockwool in between. Speaker height with the acoustic centre around 120cm (or a few cm more maybe). Probably I have some of this a bit wrong so it would be great if anyone can point out my rookie errors before I attempt to start sawing wood. All the best, David

Just noticed that a couple of measurements are off in my diagram, may have to redo it again. rats

Just noticed that a couple of measurements are off in my diagram, may have to redo it again. rats

If you do it in SketchUp, instead of on paper, then it's a lot easier to fix things when you make mistakes like that... Jus' sayin' .... :) - Stuart -

I really really tried with sketchup but I am just too oldskool. I can see that sketchup is an amazing tool but I just don't have time to learn how to use it well enough. I can knock up a sketch in a few minutes (and if I concentrate maybe I can even get the dimensions right) :) Updated drawing coming soon...

Hi, here eventually is another diagram, just trying to optimise the speaker position before I get to work on the soffits. Is this looking kind of approximately right? (dimensions in cm)

Control room geometry … After all my plasterboarding I am thinking about doing the control room soffitts next and I am wondering about the exact placement of the speakers. At the moment the control room is just a shell with all the walls finished (but without final door and windows). There is no acoustic treatment yet although as a rough plan I am imagining 8” rockwool all over the ceiling, a heavy duty cloud (maybe 2), and I haven’t decided on treatment for rear wall yet. But first I need to build the soffits… I haven’t finally decided what monitors to get but I am quite tempted by Neumann KH310’s - it seams nobody has a bad word to say about them and they are only slightly above my max budget so I am proceeding with that assumption at the moment. I notice in their instructions that it is suggested to mount them horizontally but am thinking that a vertical orientation may be better for a soffit mounted arrangement? The main thing I would like to check is the geomety between the listening point and the speakers and the corners of the room. I drew a sketch of my best guess which should be attached below… I am not sure about what to do on the side walls. My initial feeling was to just put up some thick rockwool on both sides but then I was thinking that heavy angled refective panels with a gap at the top and bottom and filled behind with fluffy rockwool may be better - maybe they would reflect sound past the listening position and also help to stop the room sounding too dead - but it is a little hard to work out the angles! I have tried but not sure if I have suceeded in optimal positioning? Inside dimensions of control room - width - 319 cm length - 410 cm height - 280 cm Starting point listening position at 38% which is 156cm from the front wall. Apex of speaker traingle 20cm beyond this at 176cm. In the Neumann manual is says that speakers should be 175-200cm apart. I guess optimum speaker triangle is 60/60/60 but with my small room this means the speakers are less than 175cm apart (given a 38% listening point) so I thought increasing angle to 70 degrees was probably a better option which has resulted in the speakers being 186cm apart. I am expecting to put them 10cm off the front wall, enough to get a bit of rockwool in between. Speaker height with the acoustic centre around 120cm (or a few cm more maybe). Probably I have some of this a bit wrong so it would be great if anyone can point out my rookie errors before I attempt to start sawing wood. All the best, David

I tried out a first attempt at REW today in my empty and unfinished control room, just to get an idea of how REW works and to get a baseline measurement which will hopefully improve as I add some treatment. I had a few problems with the calibration but managed to get something down even if the speaker placement is only approximate and the speakers are only my hifi speakers. I am not sure how to evaluate the results - the frequecy response doesn’t seem too bad but the waterfall shows far too much reverb which I guess is unsurprising in an empty room. The graph with the left right and together readings looks a bit strange, it could be the speakers were out of phase or something the calibration is obviously a bit off. It is not worth posting the entire file so here a few screenshots to get an idea…

Did you follow the instructions shown here? viewtopic.php?f=3&t=21122 :)

I had a few problems with the calibration but managed to get something down even if the speaker placement is only approximate and the speakers are only my hifi speakers.

That's fine for just playing around and learning how to use REW; but for the actual initial baseline test (and all future tests) you'll need to get everything in the right location: speakers, mic, desk, other stuff in the room... and you NOT in the room!

I am not sure how to evaluate the results -

I'm working on writing a follow-up to the above link, to do just that: show how to do very basic analysis of REW data. But it's not ready yet, as there's a lot to cover! It will be a few weeks yet.... sorry!

the frequecy response doesn’t seem too bad but the waterfall shows far too much reverb which I guess is unsurprising in an empty room.

Correct on both observations! But you do seem to have some type of noise problem at around 120 Hz... maybe computer fan? Notebook power supply? Mains hum? You'll need to find and fix that before you can take serious measurements.

The graph with the left right and together readings looks a bit strange,

Not sure which curve that is on your graph: You cut off the legend, so I don't know if it's the red curve, the blue curve, or the green curve. The only thing unusual I see about those curves, is that they are all at roughly the same level! That's impossible, if you set up and used REW correctly. The level for the test with both speakers on at once should be 6 dB higher than the curves for the individual speakers by themselves. (6 dB increase = twice the power, with a coherent source.) So something went wrong there, but the curves themselves don't look to be too much out of the ordinary.

it could be the speakers were out of phase or something the calibration is obviously a bit off.

I'm not seeing that in your data. If that were the case, the combined left-plus-right test would show a large DECREASE in intensity, modulated by the room acoustics. That doesn't seem to be evident in your graphs. And you would be able to see it on the phase graph. Why do you suspect a problem with your speakers? Do they sound strange? Better check the polarity and wiring, to make sure, but I don't see anything that looks like what you describe. - Stuart -

Soundman2020 wrote:

That's fine for just playing around and learning how to use REW; but for the actual initial baseline test (and all future tests) you'll need to get everything in the right location: speakers, mic, desk, other stuff in the room... and you NOT in the room!

Tricky when it hasn’t even been decided where the speakers are going, I have no desk or furniture yet and the back wall is basically a wood storage area. Neither are the doors or windows finished, so all in all not really a proper baseline test.

Soundman2020 wrote:

But you do seem to have some type of noise problem at around 120 Hz... maybe computer fan? Notebook power supply? Mains hum?

Hmm laptop fan probably wasn’t running and I couldn’t really hear anything untoward but maybe a rattle or something vibrating in the room. I couldn’t hear any mains hum but i am running power through several extension leads at the moment (and one is a bit dodgy). I will watch closely for that next time. I was a bit surpried at how low in volume the test was, and there seemed to be quite a high noise floor. In your calibration advice you say that 30db ear protection is a good idea but 80db is a pretty low level, I can’t see why one would need protection at that level (and I am the type who always wears earplugs often even when practicing the piano).

Soundman2020 wrote:

Why do you suspect a problem with your speakers? Do they sound strange? Better check the polarity and wiring, to make sure, but I don't see anything that looks like what you describe.

Ok great, I didn’t even check the polarity (which I really should have done after my friend connected the speakers up) but there were a few places where the left and right speakers readings had peaks and the combined L+R had a dip, which is not what I was expecting. Not that I knew what to expect! I will double check it next time and look at the phase graph.

Soundman2020 wrote:

Did you follow the instructions shown here? viewtopic.php?f=3&t=21122 :)

Great thanks, I hadn’t seen that before and it is very very helpful. I hadn’t even tried to calibrate the interface (I had just assumed it would be flat enough across the spectrum not to bother), but the bigger problem was that the input level in REW was greyed out and there was obviously something wrong going on as one test came back as 176db! Next time I will follow your helpful advice to the letter. But first I need to consider the soffit design and get the wiring ready for the electrician to connect up and build 7 doors and 5 windows. cheers, David

it hasn’t even been decided where the speakers are going, I have no desk or furniture yet

Well, in a room that small you really don't have many choices about where to put the speakers! They absolutely have to go up against the front wall if they will not be soffit mounted, of if they will be soffit mounted then they have to go in the correct locations for doing that. The location of the speakers and the listening position is pretty much fixed fixed by the dimensions of the room, not by what type of desk you buy. It's the other way around: you choose the desk to fit in with the speaker and mix position location, after they have already been set correctly. If you firt buy the desk then try to fit the speakers and mix position around it, that is doomed to failure. That would be sort of like buying the wheels that you like most, then looking for a car that you can put them on... :)

I couldn’t really hear anything untoward but maybe a rattle or something vibrating in the room.

It looks like a constant level, as far as I can see from the limited resolution of the graph. It does not seem to be decreasing at all. I'd suspect a fan, motor, or electrical hum. Upload the MDAT file (with all three tests in it) somewhere like Dropbox, post the link here and I'll take a closer look when I have a bit of time.

I was a bit surpried at how low in volume the test was, and there seemed to be quite a high noise floor.

Probably because you didn't calibrate REW correctly, using a good quality hand-held sound level meter?

In your calibration advice you say that 30db ear protection is a good idea but 80db is a pretty low level,

Careful! Not all decibels are equal (some are more equal than others... :) ). For the REW tests, I am talking about dBC, but noise regulations are specified in dBA. There's a large difference. 80 dBA is a lot quieter than 80 dBC for full-spectrum audio. So make sure you are using the right weighting scale when you set up and tests, both on your meter and also in REW. If you have your meter set on the wrong scale, you'll be very much off. dBC is the appropriate scale for measuring music, so make sure you always have everything set to "C", never "A". You only need to use "A" on your meter when measuring outside for compliance with noise regulations, but "C" for everything else. Also, the calibration level is 80 dBC for each individual speaker, which implies that both speakers together will produce 86 dBC. But that's with constant power pink noise. When you run the actual sine sweep, the room response can easily boost that to 10 or 20 dB louder at certain frequencies where there is strong resonance going on. That's the reason for the recommendation of using hearing protection.

I can’t see why one would need protection at that level

Because the calibration level, which is done with pink noise, is not the same as what the actual levels in the room could potentially reach during the real test, which is done with sine sweeps.

Ok great, I didn’t even check the polarity (which I really should have done after my friend connected the speakers up)

It's possible there is an issue, so it's worth checking before you run the next tests.

I hadn’t even tried to calibrate the interface (I had just assumed it would be flat enough across the spectrum not to bother),

It would be nice if all interfaces really were dead flat, but they aren't, for many reasons. The differences are not huge, of course, but if you really want your room to be as good as it can be then you do need to calibrate both the interface and also the mic, for maximum precision. At this stage in your rough testing it isn't really necessary, as the room issues will be very much larger than the variations in calibration curves, but you might as well get used to doing it all the time now, so yo don't forget later when it is important.

there was obviously something wrong going on as one test came back as 176db!

:shock: Yup, I'd say that's just slightly off! :)

But first I need to consider the soffit design

So you are going to soffit-mount your speakers? I saw your rough diagrams, but then I saw the photo with the speakers on stands, so I wasn't sure. What make and model of speakers will you be using for that?

up and build 7 doors and 5 windows

Piece of cake! :) (NOT!) Have you already done the design for your doors and windows? If so, post them here for double-checking, if you want. - Stuart -

Soundman2020 wrote:

So you are going to soffit-mount your speakers? I saw your rough diagrams, but then I saw the photo with the speakers on stands, so I wasn't sure. What make and model of speakers will you be using for that?

Yes I am planning to soffit mount the speakers (not those hifi speakers). I am thinking of getting Neumann KH310’s - mainly becasue nobody has a bad word to say about them and they are only a bit above my absolute max budget. I was thinking about mounting them vertically rather than horizontally (which is recommended in manual). Would that be right?

Soundman2020 wrote:

Well, in a room that small you really don't have many choices about where to put the speakers! They absolutely have to go up against the front wall if they will not be soffit mounted, of if they will be soffit mounted then they have to go in the correct locations for doing that.

So I have been trying hard to work out the correct locations but it doesn’t seem to work ideally whichever way I look at it. Basically the room is too small so it is a matter of bodging the figures as best I can. I will have another go in sketchup but if there is some theoretical ideal positioning I would love to know what that is. I don’t recall seeing any info anywhere (ie Gevais, Newell etc) that says how far from the room corners the speakers should go or in what proportions for a given width of room, but having tried out a few on paper I am still unsure as which exact geometry is best. cheers David

I have been trying hard to work out the correct locations but it doesn’t seem to work ideally whichever way I look at it. Basically the room is too small so it is a matter of bodging the figures as best I can.

Then you are doing it right! :) OK, on a more serious note, I see what you are up against. In a larger room it would be easier, but with a small room like that it's not so simple. What are the exact dimensions of that room? Is it still 410 x 320 as show on the paper sketch? That is measured to the hard, solid, rigid boundaries of the room, right? What about the ceiling height? Also, you do seem to be aware of this already, but there's actually no need to stick to fabled 30° angle exactly. It isn't carved in stone, and it's perfectly fine to change that a bit. Changing that angle does have an effect on the sweet spot and the sound stage, to a certain extent, so as long as you are aware of what yo are doing there, that's fine. Another issue: The famous "equilateral triangle" is also a myth, and you seem to be aware of that too: so I'm just confirming what you are already doing, not criticizing. Yes, you do have to be the same distance from each speaker, but no, that distance does not have to be equal to the distance between them. One more: the aim point for your speakers (the point where the two axes intersect) is NOT the middle of your head. Another myth. The aim point (intersect point) should be a spot about 25 to 50cm behind that. So you do have a bit of area to play with. Designing soffits is a real challenge. Getting all the angles and distances and reflections and sizes correct is not so easy, and it takes a while. There's a lot of factors to juggle, and try to optimize. Trial and error will get you there.

there is some theoretical ideal positioning I would love to know what that is.

There is, but not in the form of a simple cut-and-dried equation, as there are many factors that all interact. When I'm designing a room, I start with the speakers. If the angle of dispersion is particularly high, then I'll probably angle the soffits in a little more and spread them a bit further apart, for example, in order to keep reflections off the side walls. But that also means that I have more reflections off the opposite side wall, which I'll have to deal with using a combination of a "wing" on the edge of the opposite soffit, plus porous absorption. For a speaker with a lower dispersion angle (tighter Q), I wouldn't be so worried about that, but I would take more care to make the sweet spot as wide as possible, perhaps by moving the desk back in the room a little. I'll also do things differently for a long thin room, than I would for a wider or shorter room. There's just so much to take into account: it's partly science but partly experience. I wish I could give you a set of equations you could use to calculate the location, but it's just not that simple. I can give you some very general guidelines, but that would just be a starting point.

I don’t recall seeing any info anywhere (ie Gevais, Newell etc) that says how far from the room corners the speakers should go or in what proportions for a given width of room,

Probably for the same reasons as above! There's not really a simple way of doing this. Floyd Toole has written a lot about it, and so have others, but all of the "rules" have to be bent a bit to fit the room. So, a few "rules" and guidelines, in no specific order: 1) The speakers should not go in the corner, nor on the line that divides the corner. In other words, if your walls intersect at 90°, then draw a line out from each corner at 45°, and stay away from that: don't put your speaker exactly on that line, since it implies that you'll be getting the same artifacts from the side walls as from the front wall. Put your speakers either outside or inside of those lines. More commonly you'll want your speakers "inside" those lines (more towards the center line of the room). 2) The "38% of room depth rule" is not a rule, but it is a useful guideline for a starting point. You'll generally want to have your listening position a bit closer to the front wall than that location, but do be aware that you might be getting into problematic SBIR territory there. (You can treat that, to a certain extent). 3) Keep the mix position away from 25% and 50% of room depth, and try to stay between about 32% and 44% 4) You can angle your speakers differently than the "textbook" 30° angle: Anything in the range 25° to about 35° will work well under most circumstances. 5) Keep the speakers as far apart as possible, wile not violating rules 1 and 4. 6) Keep the mix position at a good distance from the speakers, within the range of about 1m to about 5m. Further away is usually better. 7) Don't put the speakers at 25% of the room width: that's a modal null for some frequencies, and a peak for others. Try something more like 28% to 34%. 8 ) Make the front baffle of your soffit as wide and tall as you can, within reason. The width should be at least three times the diameter of your low frequency driver. In other words, if you have a speaker with an 8" woofer, then you want the soffit baffle to be at least 24" (60cm) wide. Wider is better. 9) Do not put your speaker in the middle of the soffit baffle: Offset in both directions. In other words, the distances from the acoustic center of the speaker to each edge of the baffle should be very different, by at least 20%. So for example if your speaker axis is 30cm from one side of the baffle, it should be more than 36cm from the other side, less than 24cm from the bottom edge, and more than 44cm from the top edge. (Rough distances, for illustration only...). Larger differences are generally better. 10) Make the baffle as massively heavy as you can, and as rigid as you can. 11) Make the structure inside the soffit (the framing that holds the baffle and speaker in place) as rigid and massive as you can. 12) Mount the speaker inside an enclosure box that is either a very tight fit, in order to keep the speaker rigidly fixed in place, or mount it on suitable rubber pads, to completely decouple it from the the box. Carefully choose the properties and dimensions of that rubber, to make sure the speaker is still decoupled down to at least one octave below the speaker's low cut-off frequency. 13) Take into account that speakers need a lot of space behind them for cooling, and a path through the soffit for cooling air to flow. 14) Rear-ported speakers need special attention: Do not overload the rear port, acoustically, with an enclosure box that is too small, or un-ventilated, or un-damped. 15) Damp the hell out of the soffit interior! Fill it entirely with suitable damping if you want, except for the cooling path. There's more to it than that, but it's a start!

I am thinking of getting Neumann KH310’s

Nice!

I was thinking about mounting them vertically rather than horizontally (which is recommended in manual). Would that be right?

As far as I know, those are not designed to be mounted vertically. Check with Neumann to be certain, but I have a feeling those are only meant to be used horizontal. Some speakers can be used in either orientation by rotating the a section, but not the 310s. Have you considered the Eve Audio line of speakers? I've had good success with some of those, especially the SC series. Also take a look at Adam: they have some good stuff too. So does Genelec, but some of their speakers are hard to soffit mount, due to the highly curved shape. It can be done, but it's not easy. I have just finished designing a soffit mount for a customer in Germany, for the Genelec 8050. Anyway, hopefully the above is helpful, even if not concise and definitive! - Stuart -

re neumann kh310 …

Soundman2020 wrote:

As far as I know, those are not designed to be mounted vertically. Check with Neumann to be certain, but I have a feeling those are only meant to be used horizontal. Some speakers can be used in either orientation by rotating the a section, but not the 310s.

Ah ok, I was originally thinking of mounting them horizontally but then I read a long post by you (can’t find it now typically) where you were saying that it was always best to mount vertically - the reasons sounded right so I went back to take a close read of the Neumann manual which recommends horizontal mounting “except for fixed listening positions” (KH310 getting started). So by then I was a bit confused, but now I am thinking that I should revert to horizontal mounting . I think I remember you saying that you designed a studio recently that had these Neumanns - were those soffit mounted horizontally? (maybe i just imagined that though, apologies if so).

Soundman2020 wrote:

What are the exact dimensions of that room? Is it still 410 x 320 as show on the paper sketch? That is measured to the hard, solid, rigid boundaries of the room, right? What about the ceiling height?

yes… width 320cm length 410cm height 280cm That is to the rigid boundaries - the right side wall is inside out so in effect the studs protrude into the room but I am expecting them to be hidden either behind ‘wings’ or many inches of rockwool.

Soundman2020 wrote:

Anyway, hopefully the above is helpful, even if not concise and definitive!

Thanks so much for the speaker “rules”, I was completely unaware of a few of those so yes very very helpful. I will jiggle all the ingredients around for a little while and see what I can come up with (whilst continuing with building windows etc). cheers David

I think I remember you saying that you designed a studio recently that had these Neumanns - were those soffit mounted horizontally?

Yup! : Partial view of the KH310's in their soffits, for that project. Here's the potential issue with using speakers horizontally: The same thing happens in the vertical axis if you have the speakers vertically, of course, but the difference is that your ears are not arranged vertically on your head, so you don't hear the effect. Your ears are organized horizontally, on each side of your head, so it's only a potential issue for horizontal orientation. The closer you are to the speakers, the more intense the problem becomes. If you can be a two or three meters away, then it is less noticeable, but if you are up close, say only 80cm or so away, then potentially it could be very noticeable. That's why Neumann recommends a listening distance of 1 to 2.5m for those. Now, since these are specifically designed to be used horizontally, I would imagine that they have taken great care to minimize the issue, with suitable positioning and angling of the drivers, precise wave-guide design, as well as electronic control such as timing and phase correction. Everything is optimized for horizontal. If you take a look at the directivity plots in the back of the manual, you'll see that they perform much better in the horizontal plane than they do in the vertical plane. So I suspect that this speaker does not exhibit the problem as badly as a speaker that is designed for vertical mounting, but placed on its side.

width 320cm length 410cm height 280cm That is to the rigid boundaries

I would try something like this as the first approach: Try that first in your room as it is, to see how it works out (REW test...), then put it in your SketchUp model (!) and design the soffits around it, making sure that you have enough space and meet all the "rules" in my other post, and see how it works out. Adjust as necessary.

the right side wall is inside out so in effect the studs protrude into the room but I am expecting them to be hidden either behind ‘wings’ or many inches of rockwool.

Ooops! So your room is not acoustically symmetrical? That's a problem. You'll need to figure out what to do there, to get it back to symmetrical. If that were my room, I'd probably just put some studs on the left wall to match the right, and put OC-703 in both of them, then make then into slat walls for most of the length, except at the first reflection points.

Thanks so much for the speaker “rules”, I was completely unaware of a few of those

I think that's probably the first time I have put them all down together in one place, and I'm not aware of anybody else who has done that (although someone probably has!). I'll probably end up posting that as a "sticky", then adding to it as time goes by...

I will jiggle all the ingredients around for a little while and see what I can come up with

Blend all ingredients thoroughly at low speed, then simmer even more slowly over low heat for many weeks. Check condition frequently, stirring occasionally, adding and removing ingredients at random. When the smell gets too bad to take any longer, you'll know that it is nearly ready to throw out and start again with a fresh batch!! :) :lol: :roll: :shot: (I'll get my coat as I leave :arrow: ....) - Stuart -

Thank you so much Stuart for doing those models for me, very kind of you and so very useful. It will take a while to mull over the details but one thing that strikes me immediately is that the speakers are in a reversed direction with the left speaker being mounted on the right and vise versa. I didn’t know this was possible but now I look again in the manual is says this is ok. I am not sure about any acoustic benefits or differences that this may cause (maybe none) but the physical advantages are pretty clear because otherwise the speakers would be very close together but this orientation spaces them out more for any given listening angle. I would never have thought of that as a possibility. re. right side ‘inside out’ wall with protruding studs …

Soundman2020 wrote:

Ooops! So your room is not acoustically symmetrical? That's a problem. You'll need to figure out what to do there, to get it back to symmetrical. If that were my room, I'd probably just put some studs on the left wall to match the right, and put OC-703 in both of them, then make then into slat walls for most of the length, except at the first reflection points.

I was imagining wings kind of like wall mounted clouds at an angle - do you think false studs and slats is a better bet? I must admit I was having trouble with the geometry trying to get the wings to reflect at the right angles but haven’t tried yet with your new geometry. Slats would certainly be a whole lot easier to build though and save a little of the very limited floor space as well. cheers, David

but one thing that strikes me immediately is that the speakers are in a reversed direction with the left speaker being mounted on the right and vise versa. I didn’t know this was possible but now I look again in the manual is says this is ok.

Yup! There's a lot of tricks up a studio designer's sleeve, when things get tight... :) Take a look at the Studio 3 thread ( link again: viewtopic.php?f=2&t=20471 ), Those are Eve SC-407's which are designed to be mounted horizontally. As I was working through the design of the soffits and the room, I saw that they'd be better off vertically. so I contacted the manufacturer, and they put me in touch with their chief engineer (really nice bunch of people. Very helpful). He agreed with my assessment, and gave his blessing to do that, plus a few other useful tricks. They are also not supposed to be soffit mounted, but he gave his OK for that too. So there they are, not they way they were supposed to be used, but running just fine, as you can see from the acoustic analysis we did on that room. As long as you do things intelligently, following the laws of physics and the manufacturer's recommendations, you can often do things that aren't in the manual, or that most people wouldn't think of.

I am not sure about any acoustic benefits or differences that this may cause (maybe none)

There's a slight benefit, from my point of view with this setup, but those speakers are very well designed, and will work OK either way around.

but the physical advantages are pretty clear because otherwise the speakers would be very close together but this orientation spaces them out more for any given listening angle.

Exactly! That's one of the major issues. The other is that there would not have been enough depth inside the soffit to mount them comfortably in the normal setup: they would have extended too far back for my liking, meaning that the entire soffit would have to move further out into the room to make space, which means that either the angle would have to be tightened (they are at 28° currently) or the mix position would have to go further back, and I didn't like either of those options. Compromise... compromise... shuffle... juggle... simmer.... That's what studio design is all about.

I would never have thought of that as a possibility.

With studio design you often have to "think outside the box", imagine something different, then try it out, run the numbers, ask the questions, analyze, and see if it is feasible or not. Especially in small rooms. People sometimes wonder why it takes so long to design a studio, and that's a big part of the reason. Lots of things to try. Many ideas won't work and have to be thrown out, but sometimes you hit the jackpot.

I was imagining wings kind of like wall mounted clouds at an angle

You will need "wings" at the outer edges of your soffits, yes. Take a look at the image above, of the place I just did with your speakers in it. You can see the main soffit baffles, then to the outside of those are "wing" segments at a larger angle. If you are attempting to do an RFZ-based design, or a CID design, then you'll definitely need those. It's the only way to deal with the reflections off the side wall in that area, and send them away from the mix position. Those need to be fairly solid in the region where the reflections occur, But from that point back (the rear edge of the "wings") you could do slot walls on both sides, as I outlined above.

do you think false studs and slats is a better bet?

Both! :) Solid baffles on the wings, then slats beyond that, behind the first reflection points (basically from in line with your head, and extending towards the back of the room).

I must admit I was having trouble with the geometry trying to get the wings to reflect at the right angles

It's not easy... it takes a lot of trial and error, but you are on the right track for sure. This process is called "ray tracing".

but haven’t tried yet with your new geometry.

Give it a go. It should work. - Stuart -

Soundman2020 wrote:

You will need "wings" at the outer edges of your soffits, yes. …. Solid baffles on the wings, then slats beyond that, behind the first reflection points (basically from in line with your head, and extending towards the back of the room).

Ah thanks Stuart, I am understanding much better now, although I am not sure I have any room for proper slats once my ‘wings’ are built as the windows start quite far forward (1.60 m from front wall - see shot of empty room below). I’ll have to see once I have a provisional design … coming soon. A few quick questions - - Soffits - I know there are different approaches. I was thinking about trying to decouple the front baffle from the speakers by mounting them on separate structures, but is this really worth the effort? I notice that some don’t try to do this. I know there should be a small gap between the speaker and baffle anyway (a mm or 2 I guess) but separate mounting studs for the speaker assembly and baffle seem like an awful faff for someone with my limited woodworking skills even if it intuitively seems like a good idea. - Speaker boxes - should the speaker be decoupled from the boxes? I think the KH310’s come with some hemispherical mounts of some description but I was wondering what is the point of using those if the sides and top of the speaker box are as tight as possible against the speaker. I could use some thin glazing rubber strips all around the box interior just to stop the wood of the box being in direct contact with the speaker? Or should I go for hemispheres underneath and glazing strips? Or neither? - Mic location for REW testing - should it be at the point of the speaker intersection or should it be where my head is going to go? (I want to get my baseline test right next time if I can). cheers David

I am struggling with sketchup, it took me several hours just to do this (below), and I had already worked it all out on paper before .... I know the soffits need to be heavy, I am thinking 18mm osb then 18mm mdf with some 9mm ply to finish. Does that sound about reasonable? I guess the 'wings' can be a little bit lighter (but not much)? Would plywood or mdf better for the speaker boxes? Or does it not make a significant difference? Is it worth beefing them up with a 2nd layer? The KH310's arrived so I am keen to get them up and running as soon as I can. They sound good even in my living room. cheers David