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Just moved in! New Studio Build
Old 12th September 2019
  #91
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Quote:
Originally Posted by Starlight View Post
You are right and I apologise; the London 12 kit is made using fibreglass, not foam.

However, have you looked at what you get? Not a single item is deeper than 2". Do not rush into making a wrong decision.
Primacoustic products are pretty high grade. Very good quality boards from my understanding as it is a high-density fiberglass panel which is better than anything available to me from the hardware store here. I'm also in the city core so not really anything close by.

I thought about going DIY but don't want to risk any sort of microfibres circulating in my space since it acts as my living space as well. Seeing as my studio apartment is quite small, have limited tools, and no proper space/time to house open bags of insulation...makes more sense to invest in Primacoustics. Will save me time and give me peace of mind.

Having said that, the two-inch panels can be spaced away from the wall to be more effective with their wall impalers which I plan on doing. Was told they are 30% more effective by doing this. Also, I could always build 6" frames for each of the panels at a later date if I need to get more absorption which I think would look pretty nice.

The London 12 with the addition of the max traps... I think it will be a solid sounding room with peace of mind.
Old 12th September 2019
  #92
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I do not doubt the quality of the products Primacoustics manufactures, rather just the dimensions. See Treating a Small Room - Primacoustic London 8 for a discussion about the depth of Primacoustics' London products and the problem of bass trapping. It comes back to what Johann said after you measured your room:
Quote:
Originally Posted by johannburkard View Post
... you'll need a lot of treatment that works in the 70-80 Hz region.

Last edited by Starlight; 12th September 2019 at 04:38 PM.. Reason: Link
Old 12th September 2019
  #93
Gear Head
 

Quote:
Originally Posted by Starlight View Post
I do not doubt the quality of the products Primacoustics manufactures, rather just the dimensions. See Treating a Small Room - Primacoustic London 8 for a discussion about the depth of Primacoustics' London products and the problem of bass trapping. It comes back to what Johann said after you measured your room:
Link doesn't work....

Quote:
Originally Posted by johannburkard View Post
/\ That's horrible but most naked rooms look like this. The "good" news is that your 55 Hz mode is "relatively" high up. The bad news is you'll need a lot of treatment that works in the 70-80 Hz region.
Which is where the maxtraps come in
Old 12th September 2019
  #94
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Quote:
Originally Posted by recaro19 View Post
Link doesn't work....
Whoops! Treating a Small Room - Primacoustic London 8
Old 4 weeks ago
  #95
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Quote:
Originally Posted by Soundman2020 View Post
... which is about 1 foot too far! (If you are referring to the distance between the rear of the speaker and the front wall) In a small room, speakers should be right against the front wall, or perhaps separated by a gap of no more than 4", if you want to put insulation in there. If not, then your lowest SBIR dip will be way down low. Not quite sure what speakers you have there (KRK?), since you didn't mention it, but the cabinet itself is likely about a foot deep, thus the front face of your speakers is likely two feet from the front wall, placing the SBIR dip at around 140 Hz. Pushing them closer to the front wall would force that frequency up higher, where it is less noticeable and possibly more treatable.
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- Stuart -
Apologies for the hijack - but what room size would you consider "small" in terms of placing your monitors closer than the generally shared "at least 12 inches from the wall".
Old 4 weeks ago
  #96
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Quote:
Originally Posted by TheCarlough View Post
Apologies for the hijack - but what room size would you consider "small" in terms of placing your monitors closer than the generally shared "at least 12 inches from the wall".
The underlying issue here is "SBIR", which stands for "Speaker-Boundary Interference Response". What that basically means is that at low frequencies the sound from your speaker "wraps around" behind the speaker, hits the front wall of the room, then bounces back and "interferes" with itself, causing phase cancellation for a certain set of frequencies that exactly match the distance to the wall and back. Thus, for any given distance from the speaker to the wall, you will get a deep null in your frequency response, because the wave cancels itself out at that frequency.

With a gap of 12" between the speaker and the wall, and assuming a typical speaker depth of another 12" or so, that places the front face of your speaker 2 feet from the wall. For a distance of 2 feet, the SBIR nul will occur at 141 Hz (because the wavelength at 141 Hz is 8 feet, and it is the half-wave that we need to look at, so 4 feet, and the distance is 2 feet to the wall plus 2 feet back again, = 4 feet). So at that frequency you will see a deep dip in the frequency response. If your speaker is further away, for example at 3 feet from the wall, then the dip will be even lower, at about 94 Hz. At 5 feet, it would be worse still, at around 56 Hz. To get the dip low enough that it isn't really a problem any more, you would need to get the speaker at least 10 feet away from the front wall, and the SBIR dip would then be at about 27 Hz, which is OK because there aren't many instruments that get down that low (only the grand piano and the pipe organ really). So, in order to have your speaker ten feet from the front wall and still have the mix position in a good spot (acoustically), the room would need to be about 30 feet long. That's well out of range for most home studios (not many people have rooms 30 feet long in their houses!). So any room shorter than 30 feet is a "small" room in this context.

Thus, for practically all home studio rooms, the only real option is to put the speakers as close as you can get them to the front wall of the room, hopefully with a gap of just 4" between the speaker and the wall, which implies a distance of maybe 16" between speaker face and wall for a typical speaker), and an SBIR dip at about 212 Hz. At that frequency, the dip is less of an issue for several reasons. Firstly, it is less noticeable in the mid range than it is down in the low bass range, secondly it is less intense, and thirdly it can be treated. Treating a wave with a wavelength of 64" is a hell of a lot easier than treating one with a wavelength of twenty feet!

So that's the reason for the recommendation to have your speakers as close to the front wall as possible unless you have a room that is large enough that you can get them more than 10 feet away from the wall.

Of course, the best of all is to flush-mount the speakers IN the wall itself (or rather, an angled extension of the wall): in that case you do not get any SBIR problems at all from the front wall, since the speaker is technically no longer in the room!

Here's a graphic put out by Neumann, that explains the issue briefly, then shows a table of frequencies with distances to avoid (red), distances that are sort-of maybe OK (blue), and distances that are good (green). In other words, avoid any distance between 8" and ten feet! Thus, the advice you saw of having your speakers 'at least 12" from the wall' is not correct. In fact, it should be 'No more than 12" maximum, unless it is also greater than ten feet".

Or you could just add a couple of subs to your room, and kill the SBIR issue like that...



- Stuart -
Attached Thumbnails
Just moved in!  New Studio Build-neumann_loudspeaker_boundary_location_v02-sbir-table-wall-bounce-distance.jpg  
Old 4 weeks ago
  #97
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Interesting, and such a great reply. Thank you!

So, would wall mounting your monitors be a better options than using stands or similar? Since wall mounting would allow to get as close to the wall w/o actually mounting within the wall.
Old 4 weeks ago
  #98
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Quote:
Originally Posted by TheCarlough View Post
Interesting, and such a great reply. Thank you!


Quote:
So, would wall mounting your monitors be a better options than using stands or similar? Since wall mounting would allow to get as close to the wall w/o actually mounting within the wall.
Wall-mouting might be an option, but it adds its own set of potential problems. For example, what is the wall made of? If it is typical thin drywall on studs, then the bracket you use to mount the speakers could well transfer vibrations directly from the speaker into the wall, which then acts as a gigantic speaker itself, re-radiating the vibrations into the room... not a nice situation! With a fixed bracket, you also have no options to move the speakers around.... part of the process of optimizing a room is to find the best possible locations for the speakers and mix position by moving both of them in small increments and checking with REW, to see which spot is the best. For example, you would start with you speakers and mix position in the theoretical "best" location, do a REW test like that, then move them two inches further apart, do another REW test, then another step of 2"... and carry on like that for a couple of feet... then go the other way: 2" closer together from the original locations, then another 2, then another 2... Of course, at each position you would also change the angle to keep the speaker aimed at the right point in space (a spot about 12" to 18" behind your head). Then you compare all of those results in REW to see which one got you the best time-domain response firstly, and also a good frequency response. Then you put the speakers in that "best" location and do the same with the measurement mic: move it forwards and backwards in small increments (once again, adjusting the speaker angle each time), to find the best spot for that... rinse.... repeat.... But if your speakers are on brackets screwed to the wall, then you can't move them... Thus, I prefer flush-mounted speakers (top preference), followed by speakers on heavy, massive stands (second choice), followed by speakers on wall-mounted brackets (distant third choice).

You can't beat flush-mounting, though! After bass trapping, its the best single thing you can do for a room (acoustically), especially for a small room.

- Stuart -
Old 4 weeks ago
  #99
Gear Head
 

Quote:
Originally Posted by TheCarlough View Post
Apologies for the hijack - but what room size would you consider "small" in terms of placing your monitors closer than the generally shared "at least 12 inches from the wall".
You didn't high jack the thread. Happy to have people ask questions and continue the conversation.

I'm still at the beginning of this whole process as I'm trying to learn and figure out how to not only properly measure my room, but see what the best route is to go for treatement and speaker placement.

I'm playing with the idea of either making my own panels using Roxul safe and sound 24" batts with Comfortboard 80 in a 6" frame, or buying the London 12 kit and adding roxul behind them in a frame.

Also still playing with the idea of using the IKEA IVAR corner shelf to build some super chunk bass traps but haven't bitten the bullet on anything. I'm so lost.
Old 4 weeks ago
  #100
Gear Head
 

Ok, so i think i'm finally going to make a move this weekend and start with two bass traps for the corners of my room. Thinking of pulling the trigger with my hybrid Superchunk idea I initially had using the Ikea Ivar corner shelf system since i don't have access to tools or a space to construct panels.

Thinking of purchasing two of the Ikea Ivar corner shelfs at the highest height available. Basically you have to but these in pieces so will be going with:

4 of the side units at 20x89 " or 12x89 " (2 for each side)
https://www.ikea.com/ca/en/p/ivar-side-unit-87489409/

2 of the corner posts at 89"
https://www.ikea.com/ca/en/p/ivar-co...pine-37489609/

2 of the corner shelf's at 30x30x20 " or maybe the 22x22x12 "
https://www.ikea.com/ca/en/p/ivar-co...pine-73763709/

My only concern is how to fill these up and which size to go with as it seems the corner shelves can come in 30x30x20" with 20x89" sides or 22x22x12 " with 12x89" sides. Should I wrap these in a thick material then just stuff them with safe n sound insulation or use two layers of comfortboard 80 on the front faces leaving an open-air gap behind?

The shape a bit odd since it's not a true triangle so worried about waste and inconsistent gaps with the insulation. Also worried if the shape will effect the trap. Am I better off putting in some more effort and just making triangular frames to fill or some rectangular panels with a 1.5" piece of comfortboard with foam in front like the guys at Sound on Sound did in this link: https://www.soundonsound.com/techniq...stic-treatment

I'm not sure if Lowe's will make angled cuts but I could have them make cuts for rectangular frames no problem. I like the idea of the shelf because I do have to raise the traps off the floor to make room for the outlets. The Ivar system comes with pre-drilled holes for placing the shelf so it just seems much easier to work with.

Also, am I right in thinking that layering two Comfortboard 80's together to make 3" panels will be better than using 24x48" pieces of Safe n Sound? Perhaps a hybrid panel of a single comfortboard 80 and a piece of safe and sound together would be ideal? The comfortboard 80 seems to have a greater density at 8 lb/ft³ (128 kg/m³) where the safe n sound has a density of 2.5 lb/ft³ (40 kg/m³).

Let me know what you think!
Old 3 weeks ago
  #101
Gear Head
 

Anyone there???

I'm really stuck here and although there is a wealth of information it's all very debilitating as there are a lot of contradicting statements and a ton of products and ideas. I really want to make sure it's doing what's best for the room.

I was also thinking of buying the Primacoustic London 12 and then beefing up the panels with Comfortboard 80 to increase their low end absorption. Is this a good idea? Basically make a frame with 2 x 1.5" comfortboard 80 panels with the primacoustic panel over top.

I'd appreciate the help ladies and gentleman. Hoping to make a decision today if my thinking is correct, I'll get started on frames this weekend and pick up the comfort board as well.
Old 3 weeks ago
  #102
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Comfortboard 80, at 128kg/m^3 which, according to the second graph in this post, may be around 80k rayls is going to be too dense for low end absorption.
Old 3 weeks ago
  #103
Gear Head
 

Quote:
Originally Posted by Starlight View Post
Comfortboard 80, at 128kg/m^3 which, according to the second graph in this post, may be around 80k rayls is going to be too dense for low end absorption.
Everything I have read about comfortboard 80 or rockboard 80 says that it is BEST for low-end absorption.

See, this is what i'm tlaking about in regards to contradicting information. A wealth of posts but no clear answers on proper direction.

ATS even says it's recommended for LOW END:

https://www.atsacoustics.com/page--S...erial--ac.html

So what is comfortboard 80 good for?
Old 3 weeks ago
  #104
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Should i build 6" frames with 3" of safe and sound at 2.5 lb/ft³ (40 kg/m³) with the primacoustic panel over top?
Old 3 weeks ago
  #105
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If the Primacoustic panel has a lower GFR then place it in front of the safe and sound but if it has a higher GFR then place it behind.

3" is not enough to be a broadband trap so that is far too little for a bass trap. The shelving you showed us in post #7 would be best filled completely with 16" by 19" pieces of safe and sound. 6" deep traps, set 6" off the wall will be fine for broadband traps.
Old 3 weeks ago
  #106
Gear Head
 

Quote:
Originally Posted by Starlight View Post
If the Primacoustic panel has a lower GFR then place it in front of the safe and sound but if it has a higher GFR then place it behind.

3" is not enough to be a broadband trap so that is far too little for a bass trap. The shelving you showed us in post #7 would be best filled completely with 16" by 19" pieces of safe and sound. 6" deep traps, set 6" off the wall will be fine for broadband traps.
What is GFR? How do I find this information?

Also, 6" frame, filled with 6" safe and sound should be space 6" away from the wall??? That's going to stick out a foot. I don't know if my space will look good that way. Would it be okay to just hang them flush?

as for filling the shelving unit, what do you mean by 16" by 19" pieces? do you mean safe and sound that comes in 16" width instead of the 24" or to use the rectangular fram instead of the corner frame pictured in post #7 ?
Old 3 weeks ago
  #107
Gear Head
 

Not that posting on here will yield any responses since most of you have given up on me....(LOL) but I'm going to continue to post here so that I have everything in one spot and for the next person who needs the help.

I've finally decided on a path I'm going to. Going to ditch the IKEA Ivar system idea and instead get two pieces of 2x2 MDF board cut into equal triangles to build superchunks. It will be 72" high (need to leave some space for the wall outlets on either side) and I will be using safe and sound to stuff them with with a small layer of 6 mm poly to wrap them.

I found out what was going on with my SPL measurements as well. Apparently, the readings were off because every time i went to do a measurement and REW would tell me that the input was to low or high i would adjust the input gain. Doing this will mess up the SPL graph and if you do adjust you have to recalibrate everything SO I will be taking new measurements to post and hopefully, will get things right.

Once things look ok, i'll start trapping then take a second measurement to see what is happening. After Superchunks are done, i'll be starting on some 6" panels.

Look forward to next steps and thanks to everyone for putting up with my posts so far. This acoustic stuff isn't as easy as I thought.....
Old 3 weeks ago
  #108
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Quote:
Originally Posted by recaro19 View Post
... SO I will be taking new measurements to post and hopefully, will get things right....
Hello,

Pls show us where the microphone is positioned relative the acoustical axis of your monitor. On the acoustical axis? What kind of mic clamp?
Preferable a photo.

Any reflecting object close to the speaker or microphone?

Just want to understand what's causing the reflection ≈0.7ms after the direct sound. (see my post 40)

(...which in turn might cause the high frequency ripple Jtalden mentioned at AVN Forum).

Best regards
Old 3 weeks ago
  #109
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Quote:
Originally Posted by akebrake View Post
Hello,

Pls show us where the microphone is positioned relative the acoustical axis of your monitor. On the acoustical axis? What kind of mic clamp?
Preferable a photo.

Any reflecting object close to the speaker or microphone?

Just want to understand what's causing the reflection ≈0.7ms after the direct sound. (see my post 40)

(...which in turn might cause the high frequency ripple Jtalden mentioned at AVN Forum).

Best regards
I've built a new shelf for my monitors to bring them a bit closer together and lessen the distance for my sweet spot. They were pretty spaced apart before so once I set everything up, I will be sure to take a photo for you.

My room is pretty weird since it has a number of nooks, an L cove, and two large bay windows. So who knows what's going on...

I'll update you as soon as I can.

Thanks akebrake
Old 3 weeks ago
  #110
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Quote:
Originally Posted by recaro19 View Post
What is GFR? How do I find this information?
GFR is gas flow resistivity. It is not always the easiest of details to find and that is why DanDan started the topic Common Gas Flow Resistivity numbers.
Old 2 weeks ago
  #111
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Quote:
Originally Posted by Starlight View Post
GFR is gas flow resistivity. It is not always the easiest of details to find and that is why DanDan started the topic Common Gas Flow Resistivity numbers.
Got it! Thanks for the clarification.

I'm in over my head as it is with all this acoustics stuff and room measuring so I'll just avoid the GFR topic for now.

Pretty sure the Roxul Safe N Sound is what I will need from all the advice i've been given and the details I've researched.

Anyway, I will be measuring tonight so I'll have new measurements up soon.
Old 2 weeks ago
  #112
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Quote:
Originally Posted by recaro19 View Post
I'm in over my head as it is with all this acoustics stuff and room measuring so I'll just avoid the GFR topic for now.
Put really simply, the light fluffy stuff which will come as rolls will be lower density and useful when used thicker (8"-24" depth) for bass traps. The heavier, denser stuff, which can be rolls but more likely to be batts, will be useful for broadband traps, often 4"-8" deep, and placed 4-8" away from the wall or ceiling they run parallel to.
Old 2 weeks ago
  #113
Gear Head
 

Quote:
Originally Posted by akebrake View Post
Hello,

Pls show us where the microphone is positioned relative the acoustical axis of your monitor. On the acoustical axis? What kind of mic clamp?
Preferable a photo.

Any reflecting object close to the speaker or microphone?

Just want to understand what's causing the reflection ≈0.7ms after the direct sound. (see my post 40)

(...which in turn might cause the high frequency ripple Jtalden mentioned at AVN Forum).

Best regards
As promised, here are some photos of where I have the mic positioned. It is approximately at the height of where the centre of the woofer and tweeter on are the Neumans. Distance between the two speakers i 30.5" and the tip of the mic is at about 30" away from both L & R speakers.

Some things have changed int he room. I built a studio/monitor shelf so I am now able to have my speakers closer together to allow for the sweat spot to be much closer.

I moved the TV to be behind me on my dresser since the TV set up behind the desk was pushing me away from the front wall and really wasn't ergonomical for me. Look stupid on a keyboard stand too. You can see the new set up in the photos below.

I'm about to take some measurements now so will have some files uploaded shortly. I'm just running it through the Audi0 6 soundcard for now as i'm not sure how to run the test through the RME and D-Box set up. I'm sure it wouldn't matter either way.
Attached Thumbnails
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Old 2 weeks ago
  #114
Gear Head
 

Quote:
Originally Posted by Starlight View Post
Put really simply, the light fluffy stuff which will come as rolls will be lower density and useful when used thicker (8"-24" depth) for bass traps. The heavier, denser stuff, which can be rolls but more likely to be batts, will be useful for broadband traps, often 4"-8" deep, and placed 4-8" away from the wall or ceiling they run parallel to.
I see. Well, i'm making two superchunk bass traps at 24"x24 with a face of approx. 34" face. I'll then be making 6" deep panels which will most likely be 4x2 with two sheets of safe n sound.

I was told the safe and sound would work fine for what i plan on doing. At this point, I just want to get my measurements right and start building traps.
Old 2 weeks ago
  #115
Gear Head
 

Ok... here goes nothing... AGAIN

Please let me know if this looks right?

I think i did it correctly this time. On the last pass when measuring the L&R, I got a notice that there was some clipping but it still gave me a reading. I'll do it again if necessary.
Attached Files
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