[ShinOBIWAN]

I'm about to start fitting out a room dedicated to audio and video. It'll be multi purpose but mostly for music with the odd movie or game occasionally.

I've already drawn up a detailed design from which to work from and here that it is:











There's really not much space to work with and this is literally the only layout that will allow for everything I'd like the system to do.

There's a large cabinet across the front wall that houses all the equipment plus a 40" LCD for daytime viewing. The main doors will be removable so as not to block the speakers.

The side walls are treated with Rockwool. The middle band is 2" RW3 and the upper/lower bands are 3" RW5. The whole front wall is a bass trap that's been moved out 1ft from the structural wall and will be stuffed with a load of RW5. My aim with all this is to reduce bass boom from corner placement with the large bass and also reduce the side wall reflections.

Does anyone have any input into any possible improvements before I start work?

Thanks
Ant

[bpape]

Having the speakers in little 'cubbies' like that is going to cause all kinds of problems in the bottom end.  At a minimum, you'll want some 4" material covering the side walls, side of the cabinet, wall behind the speakers, and ceiling of the cubby or you'll have more resonances and boom than you know what to do with.

If it was me, I'd put the equipment somewhere else, ditch the cabinet, and mount the 40" flat on the wall.  Then at least, all you'd likely have to do is kill the corners behind the speakers.  You'd also get a MUCH better 2 channel image.

Bryan

[stevenkelby]

Tough room.

Instead of the cupboard, how about an open rack for your gear?

Is the screen acoustically transparent? I assume so if you want to use the speakers with it. In that case, can you didtch the 40" and just use the screen?

[ShinOBIWAN]

Having the speakers in little 'cubbies' like that is going to cause all kinds of problems in the bottom end.  At a minimum, you'll want some 4" material covering the side walls, side of the cabinet, wall behind the speakers, and ceiling of the cubby or you'll have more resonances and boom than you know what to do with.

If it was me, I'd put the equipment somewhere else, ditch the cabinet, and mount the 40" flat on the wall.  Then at least, all you'd likely have to do is kill the corners behind the speakers.  You'd also get a MUCH better 2 channel image.

Bryan

Thanks Bryan.

Unfortunately the cabinet has to stay so I'm going to have to work with it. I can get away with the 4" treatments all round providing I can disguise it a little with some matching trim just on the part that faces into the room.

BTW We've got access to whole range of fibreglass densities over here. I'm using 3" 100kg/m3 and 2" 60kg/m3 for the side walls but for the 4" that you've suggested I could use up to 200kg/m3. What would be best suited?

I've ammended the design to reflect your suggested change.

[bpape]

The 100Kg/m3 should be just fine in that application.

Bryan

[ShinOBIWAN]

Is there any benefit to 150 or 200kg types? Or is less more in this case?

[youngho]

What are the dimensions of the room? How far is the listening position? What's going on with the rear wall?

Is that really a window on the right wall? What is your plan for dealing with that? Otherwise, your imaging will be seriously problematic.

Since the left wall is farther from the listening position than the left wall, would you consider making that one less, rather than more, absorbent? Outside of the nearfield, some degree of acoustic symmetry is typically beneficial with stereo. If that's a window on the right wall, you'd better have a damned good plan.

Are you thinking about diffusion at all, particularly towards the sides of the back of the room? The room looks pretty stark in the rendering.

Any thoughts about the ceiling? Cloud? What's on the floor?

Is the cabinet already built? Could you consider pocket doors, rather than removable ones? On another note, for the main two doors between the speakers, could you consider custom fabric-wrapped acoustic panels with a metal frame so that you could put hinges on one side and the handle of the other? This would reduce the deleterious effects of effectively recessing the speakers. I'm thinking of something like Ethan's new Guilford Minitraps, but you're in the UK. The metal frame would allow for mounting of handles and hinges but keep the "door" panel from warping, the absorption would help prevent the effective flush-mounting that you've got going on, and the airspace inside the cabinet itself would only help with the bass trapping.

My understanding is that higher density rockwool/fiberglass becomes increasingly reflective.

I assume this is a two-channel system only. No offense intended, I'm sorry, but I have to seriously question the value of putting what appear to be quite expensive speakers (They look kind of like Dynaudio Temptation or Rockport Hyperion, although I know they're not) into such a seemingly small room. Wouldn't it be worth considering high-end in-wall speakers or others like the AudioNote series designed for usage very close to walls and corners?

[ShinOBIWAN]

What are the dimensions of the room? How far is the listening position? What's going on with the rear wall?

Hi

2.4meter widening to 2.8m and 4.5m length. Listening position is 2.5m and just over 1m from the rear wall.

Is that really a window on the right wall? What is your plan for dealing with that? Otherwise, your imaging will be seriously problematic.

Since the left wall is farther from the listening position than the left wall, would you consider making that one less, rather than more, absorbent? Outside of the nearfield, some degree of acoustic symmetry is typically beneficial with stereo. If that's a window on the right wall, you'd better have a damned good plan.

That's a window

Not considered having less treatment on one wall than the other.

Are you thinking about diffusion at all, particularly towards the sides of the back of the room? The room looks pretty stark in the rendering.

No diffusion at all. I thought they needed to be quite large depth-wise to be effective below 1Khz. Or would this still make an important difference?

Any thoughts about the ceiling? Cloud? What's on the floor?

Ceiling is regular plasterboard over timber frame. The room is on the 2nd floor. There's going to be carpet on the suspended floor, probably thick long pile but laminate with a rug is something that could be OK'd.

Is the cabinet already built? Could you consider pocket doors, rather than removable ones? On another note, for the main two doors between the speakers, could you consider custom fabric-wrapped acoustic panels with a metal frame so that you could put hinges on one side and the handle of the other? This would reduce the deleterious effects of effectively recessing the speakers. I'm thinking of something like Ethan's new Guilford Minitraps, but you're in the UK. The metal frame would allow for mounting of handles and hinges but keep the "door" panel from warping, the absorption would help prevent the effective flush-mounting that you've got going on, and the airspace inside the cabinet itself would only help with the bass trapping.

Cabinet isn't built but its impossible for me to circumvent without feeling some kind of wrath. Acoustic treatments on the doors is likewise a big no-no. Sadly I'm not the only one with a hand in 'designing' the room

BTW I'm not sure if its clear in the render or whether its fully relevant but the baffles protrude out around 1ft from the cabinet.

I assume this is a two-channel system only. No offense intended, I'm sorry, but I have to seriously question the value of putting what appear to be quite expensive speakers (They look kind of like Dynaudio Temptation or Rockport Hyperion, although I know they're not) into such a seemingly small room. Wouldn't it be worth considering high-end in-wall speakers or others like the AudioNote series designed for usage very close to walls and corners?

Yes initially 2 channel but with the promise of a 4 channel setup for HT. I'll build the surrounds after the room is finished but for now it will be just the fronts.

The loudspeakers are DIY so not as expensive as those designs you mentioned but I agree they deserve better but this is what I have right now and will work with that. Drivers are Audiotechnology and Raal.



Overall view individual driver responses and overall response (1/24th octave smoothing). Note this is semi anechoic outdoor conditions and only valid from 200hz up as bass drivers were not connected for the measurements.


This is a step response taken at the listening position in-room with the loudspeaker in the same positions as shown in the render but without any treatments or cabinet.


CSD sonogram showing decay behaviour at the listening position within the 1st second after signal excitation. Again this is with the room as it as now and no treatments.

[youngho]

Nice build! The two speakers I mentioned were the designs that came to my mind based on the shape.

Sorry about my lack of expertise, so please consider my comments with lots of salt.

You're extremely close to the rear wall. I would consider significant broadband absorption directly behind the listening position, if possible, to reduce early reflections, but only there. Don't make the room too dead, especially if the absorption is not truly broadband. Diffusion to the sides of the absorption directly behind the listening position would help reduce the feeling of listening in a small space. You're right, the well depth is related to the wavelength to be scattered, but I was thinking about products like the RPG Diffractal or the RealTraps Diffusor, which are supposed to have diffusion to below 1 KHz, yet are less than 12" deep. Fortunately, reflections become decreasingly specular at lower frequencies.

With the window on the right and the absorption on the left, you're will experience significant right-shifting of the stereo image because the window will reflect much of the frequency spectrum, particularly at mid- and higher frequencies. The window (or an untreated wall) acts as an acoustic mirror. With the significant difference between the left and right walls in terms of proximity and reflection/absorption, you can try to balance the speakers so that the left one plays louder, and you can try to equalize a little, but these are basically bandaids, kind of like putting lipstick on a pig, in the American phrase. You should strongly consider some sort of window treatment that would provide some degree of absorption. Another option would be to put up an absorption panel wide enough to cover the first reflection point of the right and left speakers (and in a small room like this, that shouldn't be a problem in terms of that width) when you're listening to music but to take it down the rest of the time. A third option would be reconsider your approach entirely to the left wall.

For example, if you can accommodate a narrower couch, you might build out a 0.4 meter wide soffit along the ceiling on the left wall corresponding to the wall above the window on the right. This could incorporate a bass-trapping product like the ASC Acoustic Soffit or the similar but now defunct product from Real Traps. You could build out a shallow storage cabinet or else lots more soffit products along the floor on the left wall, going up about 1/3 up the wall, corresponding to the wall below the window on the right. This could also incorporate some bass-trapping. Also, it would give the person sitting on the left a place to set his/her drink. The wall between the sofffit above and cabinet below on the left side would be the equivalent of the window on the right, and you could hang artwork there, but you could use the same approach on these two surfaces in terms of acoustic treatments. Perhaps you could even make the window well a little shallower, although this may not be an option. Anyway, this would give a little more symmetry to the acoustic environment. You'd have to move the loudspeakers forward, though.

In terms of the ceiling, you could consider treating the first reflection points there with some of absorption, hence the "cloud" that I mentioned. The ceiling in the back of the room would be another area to consider diffusion. I also mentioned the soffit trapping products that you could in theory run around the perimeter of the ceiling for additional bass trapping.

Even with the baffles protruding out 1 ft from the cabinets, it's pretty darn close. You're going to have significant issues with the front wall, unless you can store absorption panels in the cabinet that you pull out for serious listening. In terms of the main cabinet doors, what if you picked a product with a vague resemblance to http://www.realtraps.com/p_guilford.htm but in one of the two fabric colors that you've chosen for absorption on the side walls, and the top of the main cabinet "door"/panel corresponded to the top of the absorption on the side walls (would mean bringing down the height of the absorption on the side walls). This might give the room a nice feeling of continuity all the way around?

Alternatively, why not mount the upper line of cabinets on the front wall, then hang heavy velvet curtains just below them? You could simply part the curtains in the middle when watching the LCD TV. This would necessitate moving the speakers forward for clearance, but that would put a lone listener more into the nearfield, which would reduce the effects of the small room, anyway. What's the problem with moving the speakers forward? It's not like there's usable floorspace there in front of them, anyway.

Also, could you explain your thinking in terms of having the middle band of 2" RW3 in line with the upper woofer and midrange? Was this compensating for some vertical anomaly or suckout in the response? I'd rethink the side wall rock wool approach entirely. If you don't deal with the window on the right side, front wall cabinet, and listener's proximity to the rear wall first, it's overkill for the problem it's trying to fix, and with the window on the right, all that absorption on the left will create its own problems. Also, if the rock wall on the side walls was supposed to provide some bass trapping, you should to space it out from the wall, anyway, so that there's some air behind it.

Young-Ho

(edit) on second thought, it's such a tough room, ignore what I said above, just don't put too much time or effort into it, it's not worth

[bpape]

In a situation where you were limited to 4" thick panels straddling a corner, the higher density material would show a marginal improvement. In this application, it's not worth the money and in fact, may not even work as well as the lighter material.

To really get a handle on what's happening, you need to look at a decay plot with zero smoothing, much finer resolution, and only from say 20Hz to 300hz. 

Bryan

[ShinOBIWAN]

Thanks Youngho and Bryan.

I think your right in that the end result is going to be average at best but hey what can you do.

Made a start now so I'll stick to the plan and just hope for the best

Once its finished I'll post a range of measurements to see if the treatments were effective if at all. Eitherway it'll look nice even if its not a room suited to audio playback.

[ShinOBIWAN]

Material to cover treatments.

[ShinOBIWAN]

For those interested here's a raw unsmoothed FR taken at the listening position with NO treatment and the loudspeaker in the same location as the rendered images. Basically this is a 'before' screenshot that I'll be using to compare to the treated room.

Here's the uncorrected FR:


I use probably the most advanced consumer level digital room correction available today and this next graph is to show its effect. Note that the following images still shows plenty of aberrations and is far from perfect. This is DRC done correctly where its not over correcting everything creating a nice pretty graph for an area the size of microphone capsule and utter chaos everywhere else within the room. Here you can see just gentle shaping of the FR and this is an effective correction over a wide listening area. There's a target curve and some psychoacoustic profiling applied to the correction too.


Overlay of uncorrected and corrected.


I hope, with the treatments, to see some of the room resonances smoothed a little and the comb filtering above 1Khz to be reduced.

[bpape]

You're already pretty good realistically - especially in a small room.  +/-5 up to around 400hz is pretty good.  There are a lot of studios out there that don't measure that well.

Bryan

[ShinOBIWAN]

That's good to hear. The treatments should improve things somewhat although I have to admit I'm uncertain as to the exact extent. With a room the size of mine I don't think I can make it any worse using all that absorption. What do you think Bryan? Is it possible to make a room worse with treatments?

I'm planning a 5" bass trap along about 3/4 of the rear wall up to door. Is this wise or would I be better off with some diffusion back there?

[ShinOBIWAN]

[ShinOBIWAN]

Little more done. Not entirely happy with the corner on the bottom one as the glue dried its rippled slightly so I'll have to do something about that. Maybe ironing it on a mild heat setting or failing that I could add some trim to hide it.

[bpape]

Hard to say on the rear wall.  Best to identify what is causing some of the anomolies (preferably without EQ engaged) to address it best.

Also, remember that getting the decay times right and dealing with destructive reflections are as much or more the benefit of treatment as helping with frequency response issues.

It looks like it's coming together very nicely.  Should be a really nice looking space when you're done.

Bryan

[ShinOBIWAN]

2" Rockwool RW3 goes in between the flanking 3" RW5.

[biz97]

Room is looking awesome.  I look forward to seeing how things turn out!  Good luck!