REW Results : What Should I Do ?

[Pierre]

Hello guys,

I followed a nice tutorial (in french) to calibrate and measure my future studio.

What I used for the measures :

- Yamaha HS 50 M
- MOTU Audio Express (calibrated)
- Sonarworks measurement microphone

All signal levels were calibrated and ajusted (SPL meter with sonometer).

The room is about 12m2 (39feet). Two parallel walls are made of plasterboard, one in the back in stone (with window built in), and the front one will be the accoustic door.
Ceiling is plasterboard and floor is parquet.

Attached are my REW measures.

So, the things I see :

All SPL

- Problems in the lows (speakers are cut under 50Hz) from 50Hz to 122Hz ; then pit at 211Hz
- Some pits in the mediums : 650Hz ; 740Hz ; 1300Hz ; 2148Hz ; 2563Hz ;
- Some pits in the highs : 3460Hz ; 4210Hz ; 4940Hz ; 7740Hz ; 14790Hz

Impulse

- 500ms to fall

RT60

- 1.3s at 60Hz
- Then it gradually lower to 250Hz (537ms) until highs (400ms at 8KHz)

Waterfall

- Says pretty much the same thing

Spectrogram

- Huge pic at 137 Hz (607ms), and same as above


So here are my questions :

Im I right reading those graphics ?
What should I do to correct those problems ?

Things I consider :

- Bass traps to catch those bass pics/reverbs
- Accoustic pannels on the walls for general reverb and adjusting the frequencies
- As well as diffusion pannels to smooth the frequencies
- A carpet under my desk/chair/etc
- One accoustic pannel on the ceiling ?

If I'm right, how should I place them ?

Thank you for your time


Pierre

 

[John Mulcahy]

- Some pits in the mediums : 650Hz ; 740Hz ; 1300Hz ; 2148Hz ; 2563Hz ;
- Some pits in the highs : 3460Hz ; 4210Hz ; 4940Hz ; 7740Hz ; 14790Hz

Ignore those

Things I consider :

- Bass traps to catch those bass pics/reverbs
- Accoustic pannels on the walls for general reverb and adjusting the frequencies
- As well as diffusion pannels to smooth the frequencies
- A carpet under my desk/chair/etc
- One accoustic pannel on the ceiling ?

All worth doing.

Treatment vendors will often provide advice about where you might place treatment, e.g. http://gikacoustics.co.uk/acoustic-advice/

 

[Pierre]

Okay, thank you very much for the answer

 

[Matthew J Poes]

Can you take a picture of the speaker placement and give the distance between each speaker and each boundary (walls, ceiling, floor). The trough in the bass appears to be the combined effects of some room modes and SBIR. I suspect some speaker placement issues might be the biggest issue and most fixable.

If I am right, then it also can impact where you place the acoustic treatments and what kind you would use.

Otherwise, I agree with John's comments. Everything else looks as expected given the room's current state.

 

[Pierre]

I'm at home right now but I'll do that tomorrow. You can check my profile pic to have the idea but I'll do better photos.
One thing to know and that I'm aware of : I'm in the wrong side of the room (my speakers are against the widest wall). But we'll see that tomorrow and you'll tell me the right way to install my desk if you are ok.

Anyway, thank you for your pieces of advice.

EDIT : about speaker placement and SBIR, I placed them at around 1m (3,28ft) from the wall but I saw a video on GIK where they place some accoustic pannels on the side of each speaker (with a "mirror" technique) and it should help someway.

 

[Matthew J Poes]

I'm at home right now but I'll do that tomorrow. You can check my profile pic to have the idea but I'll do better photos.
One thing to know and that I'm aware of : I'm in the wrong side of the room (my speakers are against the widest wall). But we'll see that tomorrow and you'll tell me the right way to install my desk if you are ok.

Anyway, thank you for your pieces of advice.

I look forward to the additional images and thoughts.

The widest wall is ok. There is not only one way to setup a room. Each approach has its benefits and problems. With music and studio, I actually prefer the wide wall.

 

[Pierre]

The widest wall is ok. There is not only one way to setup a room. Each approach has its benefits and problems. With music and studio, I actually prefer the wide wall.

Oh ok, I thought that you always should be in front of the smallest wall with the widest on your side. That's good then.
And I don't know if you saw it but I made an edit to the previous reply :

EDIT : about speaker placement and SBIR, I placed them at around 1m (3,28ft) from the wall but I saw a video on GIK where they place some accoustic pannels on the side of each speaker (with a "mirror" technique) and it should help someway.

See you tomorrow then

 

[Pierre]

Hello again,

So about the measurements :

- Speakers from the wall (behind them) : 1m
- Speakers from the wall (in front of them) : 2m
- Speakers from my listening point : 1m30
- Speakers between each other : 1m80
- Speakers from the ceiling : 1m30 (center of the speakers)
- Speakers from the floor : 1m15
- Right speaker from right side (window) : 1m
- Left speaker from left side (nothing for now but I'll have the door in a few weeks) : about 1m60

Studio 04

• Pierre
• Jan 11, 2018

Studio 05

• Pierre
• Jan 11, 2018

Studio 03

• Pierre
• Jan 11, 2018

Studio 02

• Pierre
• Jan 11, 2018

 

[Pierre]

Up ?

 

[Matthew J Poes]

Hi Sorry, I just saw this. I didn't get a message that you posted back dimensions. Let me study this information a little and get back to you. Sorry about that.

 

[Matthew J Poes]

Here is a rough model of your room's acoustics showing the LF cancelation effects from modes and SBIR. I didn't really make sure your speakers were perfect matched in the model or that every dimension was perfectly right. These simulations aren't so perfect, but they give us a good sense of what is going on.


As you can see your modes and SBIR effects are all near each other and so you have a broad area of cancelation. This is one reason why small rooms are a problem for mixing, acoustically they are difficult, especially in the bass range.

Thankfully being small also means the problems are higher in the bass range and thus more easily treated. My suggestion is to install bass traps in your corners. Don't get the cheap foam traps as you have a small room and need the most efficient means possible. My suggestion is to use a corner trap from floor to ceiling in every free corner if possible. If not, cover as much as you can. I also suggest a cloud over your mix location. I wouldn't over treat the room for now, stick with bass traps as that is your biggest issue.

Another thing to consider are diffraction sources. I know that your setup is common, but your problem (and that of everyone using the same mix setup) is that you have monitors between and in front of your speakers. Your speakers are diffracting off the monitors. I believe I see evidence of this in your measurements as well. Look at the spikes in the first 2 ms or so. That is caused by some kind of reflection or diffraction off a surface within .3 to .6 meters. One possible solution might be to adhere or temporarily mount acoustic absorbing foam to the back and sides of the monitor, but really, I would much prefer to see the monitors moved so they aren't in the way of the monitors.

Your bass measurements are so off that I don't want to overstate the problem. The THD levels for the bass are very high, but the bass level is very depressed due to the modes and SBIR effects. Instead, I think you just need to fix that problem first, but my guess is that one of the fixes to both the high distortion and acoustic problem is to add some small subwoofers. In a small room like this, I would seriously consider adding at least 2 subwoofers. I would place them along the wall in front of you at 1/3 intersections in from the left and right. This will cancel width modes. A third or fourth could be added in other locations, but for now, the two up front would be a good start. I would also try other locations as simulations actually seem to suggest that corner placement is better. I have my suspicions that this isn't so in practice, but I would experiment none the less. You don't need big subs, two small 8" models should do fine.

I would consider treating the wall behind you as well given how close you sit. Do not use diffusers there, your room is too small. I would consider adding 4" thick panels. Again, you really need LF absorption more than anything, so you might consider a panel that has been designed for more LF absorption such as a Gik bass trap. They have a thinner bass trap that I believe is something like 5" or so thick and would probably be perfect. 4 of them behind you would be a good start. On the front wall I'm more ambivelant. I could see treating that as well, but again, I'm a little worried about turning your little room into an anechoic chamber. I would suggest looking at the bass traps only. Gik has a line called Flex range and the 244 (the model I referenced above) would work perfect. They sell in Europe.

ASC has good products as well and I like their Attack wall design. If you have room and budget, its a great product.

If Gik or ASC isn't your preference then please share what you are looking at, and I can try to see if they would work well. If you want to DIY, then what you want is 4" to 6" thick panels with a membrane over the front. You want the membrane to be thin. I suggest using sticky carpet protective tape which comes in 24" or wider rolls. You can layer it for a membrane. I also use adhesive Cork and cork rubber sometimes and find you can get different results by mixing these materials appropriately. The problem with the DIY route (even if I am a big advocate of it) is you don't know what you are getting until you build it, unless you have loads of experience. Because I can't source consistent materials even I don't know what I'm getting. Difference in membrane density and thickness make a pretty big difference.

 

[Pierre]

Hey Matthew !

You don't have to be sorry !! You help me a lot with your answers so I really don't want to put a pressure on you.
I'll read your answer later and give you an answer ASAP

Thank you very much for your time and advice !

 

[Pierre]

I just read your answer and I have to say that you help me a lot with this ! Thank you very much.

I think I will buy those bass traps / cloud / pannels on GIK since many people gave me that advice. Your answer is so precise and concise that it seems too easy now
About DIY, I like that generally but now I want something truely and easily working.
And nice notice about speakers, I will buy 2 24" monitors and try to place them where there won't be no difraction.

I'll keep you updated

Thank you again !