GUIDE FOR SETTING UP YOUR ROOM

A quick update! putting the monitors on stands and getting them a little bit closer to the wall has definitely improved the low mid buildup, and it has significantly shifted the SBIR upwards in the frequency spectrum. However, the mode at 123 and the cancellation at 104 Hz have remained the same. I should probably take more acoustic measures, but I'm not sure where to use the bass traps most effectively. As I move around the room, the mode is loudest in the four corners at mid-height and right in the centre of the front and rear walls. I am now considering placing two GIK 244 bass traps directly between the monitors on the wall to reduce the axial mode. The GIK modules have the highest effect at exactly 125 Hz.
Have you tried your room dimensions in Amroc? you can see which frequencies are affected by which boundaries.

If it’s the mode associated with room length, and you have space, leave the front wall reflective and treat the rear wall. 125hz should be possible with absorbers, when you get to below 100hz you need resonance based traps. GIK soffits and monster traps are good, and their scopus panels are good too so long as they’re used right. The 100hz dip could well be another boundary interference dip from the floor, I wouldn’t worry too much about it.

Build up is always highest in corners (and at surfaces generally, corners have several combining), but absorbers aren’t particularly effective. Porous absorbers work best when the wave is moving, and at boundaries the velocity is 0 and pressure is highest. So something with a pressure based element will be most effective in these areas, especially when tackling frequencies below 100hz.

You’ll probably find the positioning to be quite forgiving when placing bass traps. I’d recommend putting your room dimensions in amroc, and then try the panel in a few positions and measure if possible. and always check the time domain, the frequency response doesn’t really show much of what’s going on in the room.
 
My room has a huge 130Hz peak, I use REW or ARC to calibrate, I can't listen to my monitors (room) without calibrating anymore, I'm spoiled.
It’s quite normal to have a big peak in that area, especially in most rooms with “normal” ceiling heights. It’s definitely worse in rooms with bigger desks and no cloud, and more so if there are dimensions that are similar or multiples of that (quite common too).

What does the time domain look like?
 
@MirrorProfiles Thanks for your tips and advice! One question: I have noticed that the room mode at 123 Hz is particularly pronounced in the corners and in the middle of the front and rear walls, in each case halfway to the ceiling. I already have bass traps hanging in the front corners and the rear wall is covered by a bookshelf. I have now considered hanging bass traps (GIK 244) on the front wall between the monitors to reduce the build-up of the wave there. However, I noticed that you advised leaving the front wall reflective. Can you explain the reason for this?
 
Can you explain the reason for this?
For frequencies that low (below the Schroeder frequency), they don’t fire out the speaker like a ray but it’s more like pressure changing at that frequency. This means it can be a bit more forgiving on where you reduce the energy of that frequency - it’s related to the modes of the room.

Keeping the front wall hard means:

- you aren’t overly dampening the room. Our ears hear what’s in front of us and it’ll feel more natural if that surface is reflective. No point making the room dead and uncomfortable to be in unless it’s working effectively.

- the panel is most effective from around 125hz upwards, but generally speaking, it’s more effective higher up and less so in the bass. Low bass comes out of the speaker omnidirectionally, and gradually gets more directional as you go higher in frequency. The panel won’t be too effective for those low frequencies anyway. You can absorb more effectively in other positions in the room.

- The speakers work more efficiently if they can use the energy from that front wall. If you absorb behind it, the speaker works harder so more distortion/less headroom.

You can absolutely try the panel between the speakers, especially if there aren’t other spots you can put a panel easily. Ultimately you have to pick the most sensible compromises. Generally speaking, it won’t be the most effective area to treat and you can find somewhere else in the room that’ll do more good and less bad.

Are you able to try moving the panels off the wall a bit? so there’s a bit of an air gap behind them? Porous absorbers are velocity based and so work most effectively when velocity is high and pressure is low. Right against the wall, velocity is low and pressure is high, so absorbers aren’t going to be their most effective. A lot of rooms have a dip in the low end and then a peak around 120hz-130hz. Ceiling heights and desks etc can all emphasize those more.

Do you have a spectrogram or waterfall plot?

This Axial Mode Calculator can be helpful too: https://carltatzdesign.com/acoustic-tools/
 
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Worth bearing in mind too, these panels are more effective with an air gap behind them. Don't put them flush against the wall. Try and leave 5cm or so behind them if you can.
 
[...] Do you have a spectrogram or waterfall plot? [...]
Here are some graphs from a REW measurement I just took. Looks like shit. While the most energy is around 125 Hz, the decay time is worst at around 95 Hz. I guess I need more bass traps.

SPL 1/12 Smoothing
SPL.jpg


Spectrogram
Spectrogram.jpg


Waterfall
Waterfall.jpg
 
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I guess I need more bass traps.
Yeah, way more broadband absorption (which hopefully do as much as possible for the low end too) will do wonders for you. It’s not looking too bad at all, it just needs more treatment. Have you got photos of the rest of the room from different angles?

A cloud would help a lot, probably an ideal place to start for biggest gains. The good news is that basically every step you take from here should make a nice improvement to things. DIYing panels is a pretty cheap and effective way of doing it, you can make 6” panels for way less than what GIK would charge.

Maybe longer term I’d really consider the Neumann subwoofer but probably best to get the room more controlled first.

Also it’s worth doing the measurements for L and R seperately if you can be bothered. On the measurement screen there should be an option for sequential channels.
 
Yeah, way more broadband absorption (which hopefully do as much as possible for the low end too) will do wonders for you. It’s not looking too bad at all, it just needs more treatment. Have you got photos of the rest of the room from different angles? [...]
Here are some photos. I have already contacted the fine folks at GIK to get a little more advice on what panels to buy and where to place them in the room. BTW, the picture above the computer is a DIY panel with 5 cm (yeah, I know, that doesn't do much) of rockwool.

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Raum_Decke.jpeg
 
GIK’s soffit panels are the best thing they make (40cm deep), if you can get a few of those on either side of you they’d be really effective (they may need custom sizes to be able to stack them up but GIK can do that). Putting up a thicker cloud will help a lot too
 
Fascinating. I have just entered the room data into ChatGPT and asked where in the room absorbers should be placed to be particularly effective against the room mode at 123 Hz and the reverberation time at 95 Hz. Within seconds I had a very detailed and, above all, easy-to-understand explanation as well as a graphical representation of the pressure points. As I had already suspected, the area right in the centre of the front wall is indeed problematic at 123 Hz. In addition, of course, all corners and edges.
 
Sooo… I just ordered 6 additional absorbers from GIK for my room - two Tri-Traps for the front corners on the floor, two half sized Tri-Traps for the back corners at the ceiling and two 244 Bass Trap panels for the front and back walls (at places where the 123 Hz mode is building up). I'm really curious to see whether I will achieve an audible and measurable improvement as a result. Wish me luck!
 
Sooo… I just ordered 6 additional absorbers from GIK for my room - two Tri-Traps for the front corners on the floor, two half sized Tri-Traps for the back corners at the ceiling and two 244 Bass Trap panels for the front and back walls (at places where the 123 Hz mode is building up). I'm really curious to see whether I will achieve an audible and measurable improvement as a result. Wish me luck!
More absorption will definitely help so there’s no way you won’t get a good benefit from that.

Generally speaking, even though I have quite a few tri traps, they aren’t by favourite. They actually work more effectively spinning them around and having a cavity in the corner, as velocity of sound is 0 at surfaces, so they work better away from the wall. For the same reason, the soffit panels work way better as there’s more absorption and it’s further away from boundaries. The only thing I really buy from GIK is monster panels for ceiling or walls with limited space, soffits wherever they can fit, and scopus traps for modes.

You’ll still get good mileage out of that stuff, more is always going to help. When doing comparison measurements be sure to check the time domain. Sometimes you can actually improve things even though the frequency response looks worse. The time domain is where you’ll be able to easily see improvements being made.

Would be cool if you’re able to measure after adding each panel to see what effect they all have. Hope it helps!
 
[…] Generally speaking, even though I have quite a few tri traps, they aren’t by favourite. They actually work more effectively spinning them around and having a cavity in the corner, as velocity of sound is 0 at surfaces, so they work better away from the wall. For the same reason, the soffit panels work way better as there’s more absorption and it’s further away from boundaries. The only thing I really buy from GIK is monster panels for ceiling or walls with limited space, soffits wherever they can fit, and scopus traps for modes. […]
Of course there‘s always stuff that works better. However, the two bass traps I already have, which have a gap behind them (EQ Acoustics L10C), have actually had little effect. And I compared the manufacturers' measurement data and the GIK Tri-Traps seemed to me to have the best effect for the price. As a hobby musician, I simply can't justify spending tens of thousands on absorbers. It has to stay within reasonable limits somehow. I have now invested 1000 euros in the new, additional panels. What really annoys me about buying acoustic measures is the negativity that surrounds the subject. No matter what you do, you never really have the feeling that you can enjoy it, because it never seems to be good enough. And there are always people who tell you that everything is wrong and that the measures you've taken are crap anyway (not directed at you, Ed. You've been really helpful!).
 
Of course there‘s always stuff that works better. However, the two bass traps I already have, which have a gap behind them (EQ Acoustics L10C), have actually had little effect. And I compared the manufacturers' measurement data and the GIK Tri-Traps seemed to me to have the best effect for the price. As a hobby musician, I simply can't justify spending tens of thousands on absorbers. It has to stay within reasonable limits somehow. I have now invested 1000 euros in the new, additional panels. What really annoys me about buying acoustic measures is the negativity that surrounds the subject. No matter what you do, you never really have the feeling that you can enjoy it, because it never seems to be good enough. And there are always people who tell you that everything is wrong and that the measures you've taken are crap anyway (not directed at you, Ed. You've been really helpful!).
You bought good, well made stuff that will absolutely help your room, and it’s within your budget, matches the aesthetics you want etc. GIK are also fast, reliable, flexible, courteous. Their stuff isn’t cheap but for the money you get good products and good service, so it’s worth it. There’s lots of considerations to make and factor in. From the measurements and photos you posted, broadband absorption is absolutely the thing you need so you should get pretty noticeable improvements instantly.

Generally speaking (unfortunately) it’s a topic with so much conflicting and bad information about online, coupled with there being a HUGE amount of snake oil products being sold that do either nothing at all, or even make things worse. If you go on a generic music store website and look at their acoustic products, it’s things like foam triangles, and 5cm panels and things like that. Most commercial products called “bass trap” will not do anything at all to the bass. It’s a topic that companies can take advantage of the fact that the customer doesn’t really know what they’re doing, and are promised “if you buy this, all your problems will go away and your dreams will come true”. I had a friend who worked for one of the bigger online studio stores here (which now doesn’t exist), and that was the sort of thing that was always drummed into them. All of their treatment was essentially junk as far as a studio goes. Musicians are targeted constantly with sales and advertising, it can be very difficult to judge or know when something is genuinely what they promise. GIK products are good, well made, use proper materials, and their employees are helpful. I wouldn’t personally put too much stock in their data and diagrams - many use some weird and uncommon data along their axes that is hard to gauge much from, and it’s even harder to predict how they’ll actually perform in your own space. And as much as I like their service of helping you work out what treatment you need (I’ve used it before), it’s worth remembering that ultimately they want to sell you their products. It’s obviously best for them to sell you products that help you and keep a good relationship, but their business is making and selling acoustic products. I see other companies who make good panels, and in their product videos they’re demonstrating the effectiveness of 4-6” panels by clapping, as if echo reduction is the goal.

The same is true for a lot of the advice and things that get written. There’s good stuff out there, but so much conflicting information and very little that’s backed up with any proof.

So I think there’s going to be people who want to try and help others avoiding making the same mistakes they’ve made over the years. I’ve certainly made ALL of the mistakes (with good intentions) over the years with my room and it’s taken a long time to address and get a (slightly) better understanding of. I’ve been so close to dumping a load of money on super chunk corners, tube traps, as well as building my own panels and putting too many of them in the wrong places.

The treatment is expensive, takes up a lot of valuable space and the results can be unpredictable. So a lot of the time help is to try and avoid costly purchases that could have been done with something cheaper, or used the space better. I’ve bought panels before, put them up and my room measures almost identical before. Sometimes things even look worse, which can be REALLY frustrating when you get your hopes up. spend money, take loads of time getting them in, and then getting different results to what you expect.

There’s always going to be compromise, all we can really do is pick the best compromises we can, and get the room to a point where we can comfortably get on without doubting things.
 
While waiting for my new absorbers, I experimented a little with the speaker position yesterday and was quite surprised at the difference the height actually makes. I measured again and realised that the tweeters were not at my ear level, even though it always looked like that to me, but 5 to 10 cm below, depending on my sitting position. I then set my stands one level higher and was completely surprised at the difference in sound. Fascinating.
 
While waiting for my new absorbers, I experimented a little with the speaker position yesterday and was quite surprised at the difference the height actually makes. I measured again and realised that the tweeters were not at my ear level, even though it always looked like that to me, but 5 to 10 cm below, depending on my sitting position. I then set my stands one level higher and was completely surprised at the difference in sound. Fascinating.
it’s crazy how much difference it can make. Frequencies get really directional as they get higher up, so it’s really important to set the acoustic centre of the monitors where the manufacturer recommends.

There’s a corresponding dip in the lows that you get from floor bounce. Even the best designed $1,000,000 Northward rooms have it, and that’ll change depending on the height of the speakers (much in the way the rear SBIR changes with distance from the front wall).


There’s some dips in the room that can’t be solved with panels or even EQ, and in practice aren’t really something our ears can hear - our brains are amazing at filling in the gaps and knowing what should be there.

A good blog post about some of this stuff:


There’s frequency plots seem easy for us to understand but the focus when working to improve the room should be on the decay times (spectrogram+waterfall). The way we hear is more complex than what a measurement mic and frequency graph shows us, so they can be helpful to understand what might be happening in a room but they’re far from the full story.
 
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